# How do I make threads?



## Greymage (Apr 26, 2004)

I'd like to use the FF two-stage switch in some Arc twisties. I can drill a hole, but how do I make the threads? Can anyone post a link to a thread maker or whatever you call those things that let you make threads in something?


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## wasabe64 (Apr 26, 2004)

[ QUOTE ]
*DSpeck said:*
... you would have to tap afre drilling. It is a standard 2-56 thread. The screw used is a stainless steel button head cap screw, which Wayne sells in a kit with the boards and an Allen key (hex wrench). 

[/ QUOTE ]


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## Greymage (Apr 26, 2004)

A tap, that's what they're called! /ubbthreads/images/graemlins/ohgeez.gif Thanks.


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## jtice (Apr 26, 2004)

Greymage,
Many places sell taps, Enco for one has alot of them.

BTW,
Anyone know where to get a text file, or excel sheet, or other,
that tells what size hole to drill for each tap size?

Thanks


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## McGizmo (Apr 26, 2004)

jtice,

I have a mobileDB file in my palm with drill and tap sizes. I can export it as a .csv file. I tried opening it in Excel and Excel converts someof the fractional drills to dates before I can specify any format on the column. /ubbthreads/images/graemlins/frown.gif

Send me an e-mail and I can sent it to you if you want. It consists of letter, number, fractional and metric drills up to 1" . It gives metric equivilant and shows the tap drill for standard and metric taps. It does not have the clearance drill bit size.


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## Ledean (Apr 26, 2004)

While on the same subject can someone please tell me what 
are the tap and die sizes used for the cr2 light or rather the larry light. 
I have no idea which one to buy , there seem to be a lot of them.


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## Doug S (Apr 26, 2004)

[ QUOTE ]
*jtice said:*
BTW,
Anyone know where to get a text file, or excel sheet, or other,
that tells what size hole to drill for each tap size?

Thanks 

[/ QUOTE ]Here is an online reference. The links are about half way down the page
tap/clearance hole sizing


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## jtice (Apr 26, 2004)

ah, thanks alot Doug.

Now, if I find an Excel or text version to print out, I am SET ! /ubbthreads/images/graemlins/smile.gif

Don, I saw that MobileDB pocket pc one too ! /ubbthreads/images/graemlins/smile.gif
I just didnt want to pay for MobileDB,,, is that program worth it?
Seems to be alot of files out there for it.

I think you should be able to get it to format correctly,,, you can make the excel sheet first, before importing it,,, i think.
Email on the way.


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## wasabe64 (Apr 26, 2004)

Don, have you tried importing the .csv file into Access?

If you don't mind sending the file to me, I would more than happy to have a look at it (and make a copy for myself). /ubbthreads/images/graemlins/naughty.gif


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## PEU (Apr 26, 2004)

Don, can you send me the mdb to my signature email? 

there is a open source db called pilot-db its free, may be it helps not to buy mobile db

Thanks


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## McGizmo (Apr 26, 2004)

wasabe64,
No need or time at the moment.
PEU, .csv file coming at you; the mdb file is in laptop which is currently not on.

If this is something that others want, I can upload it to my web site later and provide a link to it.


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## tvodrd (Apr 26, 2004)

Chart in front of me says to use a #50 (.070" dia) drill for the #2-56 tap which is used in the firefly and my CR2 design.

Larry


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## idleprocess (Apr 27, 2004)

I have an Excel spreadsheet for common tap drill sizes at work. I know I went as small as 2-56 on it, but it's even-numbered sizes only, 2-12, with a few fractional sizes.


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## McGizmo (Apr 27, 2004)

While on the subject of tapping holes, I would like to point out something I learned quite a while ago when I worked for an aerospace fastener manufacturer. Your pilot hole for the tap is selected based on a certain percentage of thread engagement. This would be easier to explain with pictures but I'm too lazy to go to that extent. /ubbthreads/images/graemlins/tongue.gif 

Ultimate failure of a fastener will depend not only on the loads exerted as well as other forces but on the direction of the load as well. The threads are used to keep the fastener in place under loads of tension, for the most part. When the fastener and the parent material are the same, the cylinder of shear where the threads will fail is roughly at 50% of the thread; that is to say half way between the root of the fasteners thread and the root of the tapped thread. In a case where the fastener has a considerably higher tensile strength than the parent material, the shear will occur much closer to the root of the thread in the parent material. My point? In the case of tapped holes in materials like aluminum, The fastener would shear close to the root of the thread in the aluminum which means that a larger pilot hole would not effect the ultimate strength of the mechanical bond. This is important and a good thing to keep in mind because a larger pilot hole is easier to tap and those of us who have broken taps can appreciate this!


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## Doug S (Apr 27, 2004)

Good info, Don. Is it correct to interpret what you say to mean that for the case where the strength of the parent material does not exceed that of the fastener, there is little to be gained strenth-wise to exceeding 50% engagement?


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## McGizmo (Apr 27, 2004)

Doug,

I am in over my head here but since the material will deform prior to shearing, I *believe* that 60% thread engagement is typically considered the minimum for materials of similar shear strengths. I am sure that there are some real engineers among us who can shed light on this. My main point was to consider the case of a relatively soft parent and the fact that the fastener need only sink its "teeth" slightly to be as strong in tension as if it had a full "bite". Another consideration for threads on our lights which join the component parts is that full thread engagement may not be necessary in terms of the strength and loads encountered. Perhaps some have noticed, for instance, on some of the older SF E bezels where the female thread that accepts the battery tube is barely more than a scratch in the surface. There are times when the thread overlap can be fudged to allow fit of parts and components that would not be possible if a "classic" thread were used. If one looks at the tail cap thread on the L1 or A2, you will notice that the profile is more of an Acme thread than a standard thread. With extra effort or special tooling, one can increase the pitch without needing the depth of overlap dictated by a conventional thread geometry.

Oh yeah, I opened the mdb file in access as suggested and then exported it to excel. For those who want it, it is available HERE (excel file for tap drill sizes) .

Some day, I want to append this file with the thread height of the various thread pitches. If I want to put a 28 pitch thread on a 5/8" OD tube, I want to know the required bore in the female part that I plan to screw on this. I know that this information can be gleamed from the machinists handbook but not readily by someone like myself who doesn't understand all of the conventions and defintions. /ubbthreads/images/graemlins/frown.gif


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## RussH (Apr 27, 2004)

There's a whole chapter (100+ pages) in my Machinery's handbook on this subject. I'm paraphrasing some, but the following is from that handbook, 25th edition.

Often a 55 to 60 % thread is satisfactory, although 75% threads are commonly used to provide an extra margin of safety. In general, when the engagement length is more than 1-1/2 times the nominal diameter a 50-55% thread is satisfactory. The handbook then provides a table of tap drills and hole size limits and then several tables for different threads generally based on 75% of full thread depth. this formula is given for calculating the actual % of thread engagement:

Hole size= basic major diameter- (1.08253x%full thread / No. of threads per inch). 

After that it goes into more detail, then into thread cutting and lathe setup, rolling threads, milling threads, and the necessary setup details. There appears to be enough detail for you to figure out how to do this for any size we might need for flashlights. Do like I did & buy the older edition for half price when a new one comes out.......


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## McGizmo (Apr 27, 2004)

RussH,

Thanks for that formula! I want to write a script for my palm pilot using it. /ubbthreads/images/graemlins/thumbsup.gif


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## dat2zip (Apr 27, 2004)

Here is a drill tap chart with some additional numbers.


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## tvodrd (Apr 27, 2004)

For years I have just used the large chart on the shop wall. We know it's on the "tight" side and go the "next size up" when warranted. It calls for a #51 (.067") for a #2-56. The wall chart in my office is on the looser side and calls for a 5/64" (.0781) and claims "approx 65%", and after looking at (and printing) Wayne's bitchin chart, I suspect mine is in error! #2-56's are very easy to bink and for a case contact a #49 (.073) is probably most appropriate.

Larry


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## chalo (Apr 29, 2004)

[ QUOTE ]
*RussH said:*

The handbook then provides a table of tap drills and hole size limits and then several tables for different threads generally based on 75% of full thread depth. this formula is given for calculating the actual % of thread engagement:

Hole size= basic major diameter- (1.08253x%full thread / No. of threads per inch). 


[/ QUOTE ]

Okay everybody! You are making this way too complicated. 

I have been machining professionally for quite a few years now. The tap pilot hole size that I have always used for conventional fasteners and materials, which seems to result in the same sizes recommended on my tool-company wall chart (which says "for appoximately 75% thread"), is simply this: 

Nominal thread size, minus one pitch length. 

That's it. For 1/2"-20, it's 1/2" minus 1/20" or 450 thousandths. For 1"-8 it's 1" minus 1/8" or 7/8". Easy as pie. 

For metric threads, which are specified by pitch length instead of TPI, it even easier. M6x1.0 uses a 5.0mm drill. M24x1.5 uses a 22.5mm drill. 

It's worth noting, for cases like the C cell mag with its neither-one-nor-the-other thread diameter, that male thread measured diameter runs about 1% under its nominal diameter for most mass-produced threads. You can use that figure for matching an unknown but measurable male thread. In the example of the C mag, the measured 1.090" male thread becomes 1.101" for the purposes of calculating the pilot hole diameter. So the pilot hole size I'd use would be 1.051" to match its 20TPI. 

Nominal thread diameter minus one pitch length. Got it? 

Chalo Colina


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## Greymage (Apr 29, 2004)

[ QUOTE ]
Nominal thread diameter minus one pitch length. Got it?


[/ QUOTE ]That makes it simple, thanks!

But... um... what does a 2-56 specify? 2mm, 56 threads per...inch? cm? how does that convert to pitch?


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## McGizmo (Apr 29, 2004)

Cool Chalo!

So for #2-56 it would be the measured diameter of a #2 - 1/56" /ubbthreads/images/graemlins/thumbsup.gif

So what have you guys found with roll forming taps? Larger pilot hole?


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## tvodrd (Apr 29, 2004)

Chalo,

That's a new one for me, and it makes a lot of sense! Thank you!

Don, I've only used roll-forming taps a couple times. They seem best for sheet metal and lube them well. I don't like them!

Larry


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## PEU (Apr 30, 2004)

Speaking of threads, does this thread pitch gage is a good purchase?

and how about this tap set ?

I already purchased this Quick Change Tool Post 

I'm building my shop, for my soon to be received lathe. 

I'm looking for a knurling tool.

Any suggestions on tools are welcome!! /ubbthreads/images/graemlins/blush.gif

Pablo


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## tvodrd (Apr 30, 2004)

PEU,

Thread pitch gages are a must. They are available by Starrett, Mitutoyo and others. A high quality one isn't necessary to do the job. Taps and dies are a must have too, but I would recommend purchasing name brand HSS ones individually as you need them. Carbon steel are fine with aluminum. Cutting fluid is a must when threading. 

Larry


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## gadget_lover (Apr 30, 2004)

When making threads, what's the demarcation point between cutting threads on a lathe rather than using a tap/die? If you have the tap do you always use it? Are there special times when a lathe is just better? Do you ever start with a tap or die and finish with the lathe?

And then there's the whole issue of duplicating existing threads. Is there a trick there other than using a thread guage and micrometer?

Daniel


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## McGizmo (Apr 30, 2004)

GadgetLover,

Others will likely have differing opinions but I feel that if you have a tap or die, it is a quicker and easier way to go. However, in some cases, you need the thread to be either real short or the thred must be full to the "bottom". In this case, a bottom tap might work but sometimes you just need the full thread and can't get it with a tap or die that leaves partial threads.

For duplicating threads, I first uyse a thread guage to determin the pitch if unknown and them I measure the existing parts major OD (male thread) or bore (female thread) I usually shoot a bit smaller on OD or larger on bore and then cut the thread until the parts will mate. I then take a few thous more off to allow for anodize or variation in tolerance for other mates that I can't confirm.


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## tvodrd (Apr 30, 2004)

/ubbthreads/images/graemlins/grin.gif Of course, there's always thread measuring wires and a micrometer. /ubbthreads/images/graemlins/grin.gif I fully concur with Don. Sometimes you need a ******* diameter and it is easiest to thread the mating part to fit.

Larry


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## gadget_lover (Apr 30, 2004)

Thanks Guys. That helps.

The next question that comes to mind is diagnosing problems. There are a lot of ways to screw things up (no pun intended) and not know it. 

How do you tell what's wrong when your threaded parts don't fit together?

Thanks

Daniel


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## tvodrd (Apr 30, 2004)

Hi Daniel,

Asssuming both parts are threaded to the same pitch/tpi and your cutter was 60deg and square to the workpiece??? Small pitch errors in deeply tapped holes can cause things to wedge-up. This is usually the result of an out of spec tap or die. Geometry "V" errors usually don't bite you unless you're trying for 90+% engagement. If you can, cut a 45deg chamfer on both male and fem parts before threading- this reduces the everpresent burr. I also usually sandpaper the crests of a thread after cutting it- single-pointing leaves small burrs everywhere. If it is a lack of pitch diameter clearance, you're in deep doodoo. It is possible to "pick-up" on an existing thread- put it back in the lathe and cut it deeper. It's not too hard for a male part where you can cut in the air next to the part and carefully eyeball it in. If you are fighting a slightly too tight thread, the parts can be lapped together with an abrasive to fit. Hope some of that helps.

Larry


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## chalo (Apr 30, 2004)

[ QUOTE ]
*Greymage said:*
But... um... what does a 2-56 specify? 2mm, 56 threads per...inch? cm? how does that convert to pitch? 

[/ QUOTE ]

The "56" part is threads per inch, and the #2 part is arbitrarily .086 inch. Here are the diametral values for number screws as given by Machinery's Handbook:

#0000 - .0210"
#000 - .0340"
#00 - .0470"
#0 - .0600"
#1 - .0730"
#2 - .0860"
#3 - .0990"
#4 - .1120"
#5 - .1250"
#6 - .1380"
#8 - .1640"
#10 - .1900"
#12 - .2160"

Or, as McGizmo suggests, you can just measure a screw. That should be good to within a percent, and the error will fall on the side of deeper threads. 

Chalo Colina


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## KC2IXE (May 1, 2004)

RE Threads on a lathe vs tap and die

For ME, on INTERNAL threads, under 3/4", I'll almost always use a tap, and I can't remember the last time I cut an internal thread smaller than 1/2 on the lathe

As for EXTERNAL threads - as someone said, it depends. If your going to the bottom of a shaft, the lathe works better - again, over 1/2" I'll always use the lathe if I can - you ever price a big die? Smaller than that? If the part is in the lathe, these days I'll almost always cut the thread. It will guarntee that the thread is straight (yes, taps can start crooked - some rare times I will start single pointing a thread, and finish up with a die to make sure the thread forms are right

The exception for the above for me is metric threads - I don't have a set of metric transpostion gears for my lathe, so I almost always use a die


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## LoneRanger4404 (May 10, 2004)

Hello folks,

On the subject of threads, I am just in the process of sorting my first "homebrewed mod" and have been trying to find out the thread specs needed to fit a kroll "clickie" tail switch. Can anybody help please? 

Thanks in advance & regards.

Lawrence W.


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## McGizmo (May 10, 2004)

5/8" X 28


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## Chop (May 10, 2004)

You can order the tap from MSC-direct.com among other places.


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## LoneRanger4404 (May 10, 2004)

What can I say? Rapid response or what? /ubbthreads/images/graemlins/grin.gif

Many thanks McGizmo, much appreciated.

Regards

Lawrence W


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## LoneRanger4404 (May 10, 2004)

My thanks to you too Chop. Much appreciated.
(I think we were posting at about the same time)

Lawrence W


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## gadget_lover (May 16, 2004)

I sucessfully cut the .75 mm threads needed to mate a new body to a Dorcy AA head. Thanks for your help, guys. Now I need to do internal threads. Don't ask me why. Well since you asked... /ubbthreads/images/graemlins/smile.gif 

I want to make a cr123a body to work with the electronics of the Dorcy 2AA - 4 LED light. I've modified a Dorcy AA head to use a TV1J LuxIII. It puts out over 30 lumens when run from 3 volts. I can use that head with a pair of AA or 1/2 of a CRV3 or a single AA alkaline or lithium. I guess it's a poor man's UBH.

I want to do internal threads because after boring out the body to fit a CR123A there is not enough meat left to use the original tailcap. I could build a custom tailcap, but that would require internal threads too.

I've found many references that told how to set up the lathe to do eaternal threads. Do the same things apply when doing internal?

Do I run the bit from right to left? Do I cut the inside wall furthest from me or closest? Do I set the compound for a 29 degree angle? I'm working with a .650 inch bore, so the tools have to be small. Do you make your own tools? If so, what do you start with?

I still don't have any of my Harbor Freight accesories, like the tailstock drill chuck or the QC tool post with holders. I did get some 1/4 inch indexibe and some 3/8 inch indexible tools to go with my HSS set (hand ground).

As I write this, I remembered that I do have alot of taps and matching dies, so I could go that route, though it's never been my forte.

Thanks for any help.

Danniel


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## Rothrandir (May 16, 2004)

if you've got a tap and die, that's a much easier way to do it, especially internal threading.

internal threading requires a different bit, because you need it to be like this: v------- (you know what i mean /ubbthreads/images/graemlins/tongue.gif ). an internal threading tool is much like a boring bar.

like i said, taps are better for internal threading, because with the internal threading tool, it will flex a bit, like a boring bar does. this means that your threads aren't 100% the same diameter at the entire length. this can be a big problem when you are trying to get *really* tight tolerances, because you can start screwing the piece on, but screw it on too far and it's *permanent* /ubbthreads/images/graemlins/icon15.gif
of course it's still possible, by running several times at the same setting, but internal threading is just a lot more complicated than tapping, and you have to reset the gears each time you change the pitch.

basically, what i do:
if i'm internally threading for something which i have a tap for, i use a tap.
if i'm externally threading, and the gears are already set for that threading, i lathe thread. if the gears *aren't* already set (setting them is _such_ a pita!), and i have a die for it, i'll use the die.

lathe threading can result in a more precise fit, but is sometimes more difficult to do and set up.

something i found that makes tapping a lot easier though, is that if you've got an endchuck (you said you ordered yours from hf right? (it'll be weeks before it gets there! /ubbthreads/images/graemlins/icon15.gif)), is to chuck the tap into the tailstock chuck. this ensures that you're tapping straight.
the same principle applies for a die, but you need to machine something to hold the die in place, and chuck the thingy into the tailstock chuck.


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## gadget_lover (May 16, 2004)

Thanks for the feedback, Roth. I'll think I'll try to find a suitable tap. I picked up a 2 inch, 3 jaw chuck with MT2 spindle that was a couple bucks at the local HF store. It's not deep (no through hole), but I did manage to drill a hole in some scrap using it with a standard drill bit.

Sadly, I ordered all the accessories from HF over two week ago and 2/3rd of them are on back-order. The last thing they shipped took 2 weeks from the time they showed that it was mailed. Sigh. My wife thinks it's a marketing scheme. Every time I check the order status I end up ordering something else. 

On the bright side, the HF 7x10 lathe is on sale again for $329.

I'll be cutting some inside threads for a D cell sized body soon. I think I can make a suitable bit from a AL indexible bit. The back end of the trianglular insert sticks straight out to the side. Do I still need to set the compound to 29 degrees when doing inside threads?

Thanks.

Daniel


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## tvodrd (May 16, 2004)

For a pretty cool internal threading bar check out http://www.criterionmachineworks.com/ (online catalog/"Z" series threading bars.) They are very easily resharpened many times due to their design. They also have a list of their reps. They aint cheap!!!! Holding them may present a challenge for some small lathes.

Larry


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## Rothrandir (May 16, 2004)

dan, that's exactly what i did.

i took one of my hf indexable bits (only one of them vill vork), and ground the shaft down.

i know jtice has made internal threaders from blanks, but my grinder isn't precise enough to do that /ubbthreads/images/graemlins/frown.gif

larry, that link isn't vorking for me /ubbthreads/images/graemlins/frown.gif


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## wasabe64 (May 16, 2004)

Larry, those threading bars look very interesting, just hard to source.

The 3/8" bars are about right for a 7x10/12" lathe.

I've been trying to avoid the indexable tooling $$, and my skills with a grinder suck, so I rely on what I can get from my supplier ready-made.


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## jtice (May 16, 2004)

Daniel,
If you are going to do C or D size Mag threads, you will most likly not do it with a tap.
Yes, you can find them that large, but I bed they are very pricey.
You might be able to adapt them to go in your lathe, so that will make it easier to lineup.

Yes, I have made about 5 internal threading tools from tool blanks now.
Its not all that easy, but if you take your time, and do it slow, ... and have an ok grinder, you can pull it off.
If you have trouble finding one (they are ussually out of stock) or if you dont want to spend the $$$ on a large tap, let me know, I will make one for ya.


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## gadget_lover (May 16, 2004)

Thanks for the offer, Jtice. I'm going to use the lathe to cut the C and D threads. The tap will be used for the single CR123a body that I'm making for practice. I have a fairly good set of taps for USS and metric threads.

It just occured to me that it should be easier to learn internal threading on the D sized tubing. More area to work in, better visability, etc.

Can you post some pictures of the internal threading tools you made from blanks? I think I know what they should look like, but sometimes a picture is worth... wel, you know.

Thanks

Daniel


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## Tom_Ayers (May 18, 2004)

*Disclaimer: I have not tried this yet*

Use a tap that is significantly smaller in diameter than the minor diameter of the hole to be threaded - something with a 3/8" shank would be convenient for a mini-lathe - and grind away all but one (full) tooth on each flute. That should give you a threading tool and you can rotate it 90 deg to bring up a "new" cutting edge.

The "bit" will have to be held parallel to the work, of course.

I have been grinding my own threading bits but it's a fair bit of work.

Anyone done the tap-as-bit routine that can comment?

Tom


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## jtice (May 18, 2004)

DOH! /ubbthreads/images/graemlins/ohgeez.gif
Sorry, ment to upload a pic of them last night, but forgot. /ubbthreads/images/graemlins/frown.gif
I will try to remember when I get home tonight.

You may want to search on www.littlemachineshop.com they sell them, and have a pic, but they are ussually out of stock.


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## KC2IXE (May 18, 2004)

I'm sorry - I can't resist this any longer

Making threads? Simple - at the top of each section of the forum, there is a button that says "post" - you click it, and start and interesting topic - if folks reply, you have a new thread /ubbthreads/images/graemlins/smile.gif


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## gadget_lover (May 18, 2004)

Thanks for the pointer to the little machine shop. I found a picture there. Reminds me of an old man my grandfather used to hang out with. /ubbthreads/images/graemlins/smile.gif 

Here's theirs. It should be within my skill set to grind somethimg similar.








Daniel


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## McGizmo (May 18, 2004)

Tom,

Sounds like a lot of grinding to clear all but a full form tooth on the tap but seems to work in theory to me! Now what might be cool is taking a 1/2" x20 bottom tap and grinding away all but four of the teeth (at the rear where they are closest to full) If your lathe is geared for 5 TPI, this four toothed tap should give you the 4 start thread in the mini-mag head?!?!? /ubbthreads/images/graemlins/icon15.gif


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## jtice (May 18, 2004)

Yep, thats the pic /ubbthreads/images/graemlins/smile.gif

What I dont understand is the tip of that one is real thin.
Each side of the angled tip should be 60 degrees.
Those look alot less then that,,, or, more,, /ubbthreads/images/graemlins/thinking.gif

But you get the idea.
Its basically a triangle at the tip of the bit, the makes your thread groove.


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## gadget_lover (May 18, 2004)

Hey Don, I LIKE that! 

The 1/2 inch part was chosen becasue it's close to the correct diameter???

Daniel


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## gadget_lover (May 18, 2004)

I wonder if they are ground to a sharper angle because they have to be at an angle inside the tube? If the compound is set to 29 degrees and the cutting tooth's leading edge is at 30 degrees would you end up with the proper shaped threads by cranking in the compound as you cut deeper?


Trying to visualize that now.

Daniel


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## unnerv (May 18, 2004)

Where it looks really thin in the insert pic, it is showing the bottom of the tool. It tapers thinner so there is clearance underneath the cutting surface. Also it shows that the bottom is rounded out to make sure it clears the inside diameter of the part you are cutting. The larger part of pic shows the correct 60 degree from the top. If you want I can take some pics at different angles tonight. I have one that my dad ground for me when I first started moding that looks almost just like that one.


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## McGizmo (May 18, 2004)

Daniel,

I chose the 1/2" part because of rigidity and the fact that this example would only be used inthe case of trying to replicate the M-M head thread. The Axial load on the cutting tool would be 4X that of a single point cutting tool so rigidity would be more critical, me thinks. I would think you would still want your compound at 29 degrees but the tool would still need to be on axis to get the same depth in all 4 threads. Will it work? Heck if I know! /ubbthreads/images/graemlins/tongue.gif I would certainly go for a larger pilot hole than the stock M-M.


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## jtice (May 18, 2004)

Heres a pic of some of the internal threading bits I have made.


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## gadget_lover (May 20, 2004)

OK, I'm about to try my first internal threads on the lathe. They will be in an adapter that I've already shaped and threaded (external) for a D cell Maglite head.

What tricks do you guys use to ensure that you don't blow it at this stage? I'm working with delrin this time, so it's pretty forgiving. It does not have to be pretty inside.

Daniel


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## jtice (May 26, 2004)

Well, I dont really know what to tell you, 
I had to make about 15 passes to make threads, taking ALITTLE off each time.

And, I didnt use the little thread dial thing, that lets you know your position,
There is enough play in the lathe, to make that just about useless.
Just make a pass, back the bit out, reverse the lathe, then put the bit back where it was,,, plus a mm or so, then make another pass. 
Over, and over and over again. /ubbthreads/images/graemlins/wink.gif


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## gadget_lover (May 26, 2004)

I haven't quite figured out the usage of the thread index dial. I've done threads like jtice did, Run it forward then back the bit off and run backwards, then dial in a few more....

Anyone know of a good tutorial on threading?

Daniel


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## tvodrd (May 26, 2004)

The thread dial allows you to engage the half nut on the leadscrew such that the carriage will exactly track the previously cut groove. *Usually,* any line will work for even number of tpi and the odd numbers (if yours is numbered) are for odd no. tpi. Set the cross slide dial at zero and use the compound (set at 29deg) to increase the depth of your groove on each pass. This causes the V-tool to only cut on the front edge and lessens the load on the tool. Use the cross slide to pull the tool out from the workpiece at the end of your thread. Back the carriage up, reset the cross slide to zero, dial in some more depth with the compound and repeat. For the final pass to cut to size, use the cross slide a few thou past zero. If you have the luxery of a thread relief (like an O-ring groove,) you only need _one_ fast hand for the half nut instead of two for the half nut and cross slide. Sorry in advance if that was confusing. 

Larry


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## PhotonFanatic (May 26, 2004)

Daniel,

You might like this website, which has a decent explanation of how to cut threads:

http://easyweb.easynet.co.uk/~chrish/tscrewct.htm /ubbthreads/images/graemlins/thumbsup.gif


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## gadget_lover (May 26, 2004)

Thanks for the pointer oeo2oo! I'm reading it now /ubbthreads/images/graemlins/smile.gif

Daniel


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## sflate (May 27, 2004)

While we're on the subject of threads, does anyone know the thread size for some common lights? I'm particularly looking for those of the Mag-D (Outer head thread and inner tail thread). Perhaps we could add common threads to a sticky.


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## unnerv (May 27, 2004)

If I recall correctly, the mag d uses 20 tpi threads on the head and tail


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## gadget_lover (Aug 14, 2004)

I cut internal threads this weekend on my lathe for the first time.

It worked so well and was so easy that I was suprised. I did 32 TPI threads in a 3/4 inch (approx) bore for a new body on my VIP. That was aluminum. I also did 32 TPI in a 1/2 inch bore in delrin to make a holder for a Dorcy AAA body that I was modifying.

I used the single point technique,. I was able to use an indexable tool that I got from harbor freight. The tool is part of a set of 5 (part number 39931) that have a 1/4 inch body but a larger insert. The right hand shoulder tool There are 5 tools in the set. I had to figure out which is which. It took a while. The one that points straight ahead is good for making external threads. The one for cutting square right shoulders is the one that I used to cut internal threads. They use inserts with 60 degree tips, so they are just right for most threads.

Here's the right shoulder tool.








The tip of the carbide insert extends past the edge of the tool's shaft, so it's free to make cuts on the inside of the bore. I ground a little more off the square shaft on the lower left side (you can't see it in the picture) so that I'd have clearance even with real small bores.

Here's the tool in use on a larger (1.5 inch) tube. The tool is parallel to the bore of the tube. I did not try to change the topslide angle, but simply ran the tool in/out using the cross-slide. This means it was cutting equally with both sides of the tip, with more wear on the side of the insert nearest the chuck.






Daniel


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## PEU (Aug 17, 2004)

Nice thread Daniel!

Today I tried to do the same with a kludge I made using a welding electrode but failed miserably /ubbthreads/images/graemlins/frown.gif it wasnt rigid enough...

May be the tool kit you bought @ harbor freight is not a bad idea, I looked arond here and the less expensive (one unit) is about u$d 40...


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## gadget_lover (Aug 17, 2004)

Thanks Pablo.

You can make your own threading tool easily enough using a 1/4 inch square HSS blank and a grinder. The one that I saw at Unnervs was ground from a 3/8 inch blank. The general idea: one tooth sticking out to the side. The tooth should be ground to a 60 degree angle. You should provide some relief under the trailing edge.

The one Patrick had looked like this:








A close up of the working end:






I made this in 5 minutes and just guessed at the angles. I would have measured a 60 degree angle on that tooth if I was going to use it. The underside of the tooth is ground slightly so that only the top edges of the tooth will touch the work piece. I used a bench grinder for the majority of the grinding and a diamond cut-off wheel in a dremmel for the final touches.

Hmmm. It is kind of pretty.


Daniel


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## PEU (Aug 18, 2004)

I'll order a tool set similar to yours at LMS, but in the meantime I purchased a round HSS blank (18% cobalt) I think it will need less grinding.

Will grind, will tell /ubbthreads/images/graemlins/smile.gif

Pablo


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## gadget_lover (Oct 27, 2004)

I ordered a tool from Enco called a 60 degree center guage. The picture below shows the interesting design. I have not found any information on it's useage, but I did find some other information that makes it fairly straight forward.






Each of the angles is 60 degrees. This helps when grinding a tool which should be ground to be 60 degrees. The small side notches are used when aligning the tip of the tool with the work piece. The bit should be perpendicular to the work. The long flat is laid parallel to the work and the lathe bit should align with the sides of the V notch in the side.

The scales running up each side are used to determine thread pitch. There are 4 scales, 14, 20, 24 and 32 per inch. It's easy enough to see when you have one thread every two marks, so you can use it for 7,10,12 and 16 TPI too. You can also tell when you have two threads for every mark, so 28, 40, 48 and 64 are also easy to see.






The numbers printed on the tip puzzled me. I finally realized the meaning of "Double Depth of Amer Nat Thread". That's abreviated DD. It's twice the thread depth if you are cutting American National Threads. The DD for 24 tpi is .054. This is used two ways; 

1) You can use this to determine the proper size rod to use when threading to an existing hole. The rod should be the size of the hole + 2 times the thread depth. If the hole diameter is .5 and the thread is 24 TPI, the depth of the thread would be .027 and you should turn your rod to .5 + .054 (.554) before you start threading it.

2) You can divide by 2 to determine how deep to cut your threads.

Unfortunately, the unified thread has become more prevelant, so you'd use the more general formula of double depth = 1.227 ÷ TPI. So 24 tpi should have a DD of .0511 insted of .054. There's a double depth table at 
http://shopswarf.orcon.net.nz/thread2d.html



There is a great table at http://www.mini-lathe.com/Mini_lathe/Premium/Thread_cutting/threading2.asp#Depth that shows the depth AND the reading you get on your dials when cutting threads. 

I recommend the premium content on that site. I hope this is coorrect, and will gladly change it or delete it if anyone lets me know that I'm off base.

Daniel


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## PEU (Oct 27, 2004)

Daniel, I see you finally subscribed to the premium content /ubbthreads/images/graemlins/smile.gif , it's a great resource!


Pablo


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## gadget_lover (Oct 28, 2004)

Yeah, I did subscribe to the mini-lathe.com premium content. There's some good info there. 

I see a difference between their calculations and mine when it comes to determining the depth of cut with the compound's micrometer. They say 
[ QUOTE ]
The 60º angle of the compound relative to the lathe axis or centerline dictates that the tool is advanced by sin(60) or .866 times the dial reading. Thus, if the dial is advanced by .010", the tool only advances by about .0087


[/ QUOTE ]

I've been told to set the compound to 29.5 degrees on the built in protractor. That should be 60 degrees relative to the lathe axis. Please let me know if I'm wrong here.

At that setting I measure .010 forward movement for every .020 registered at the compound. Thats a 2 to 1 ratio. That makes the double depth even more useful, as that's how far you crank the compound to get the right thread depth. In the example used by mini-lathe.com, if the dial advances .010 the tool advances .005

Just as a point of interest, I've cut a half dozen threads so far using a "cut and try" technique for depth. It's worked, but I've ended up with threads that are not quite right. They fit one light but not the next, or they fit too loose or too tight. I wish I'd understood these concepts the first time I read them.

Daniel


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## gadget_lover (Nov 24, 2004)

I've built up a web page that will calculate the gears that are needed to cut threads on the HF mini-lathe. It has the list of the standard HF gears or you can add your own gear set.

Currently I've locked out adding gears, since my web server is a 90Mhz laptop with restricted storage space. Each set of 14 gears is 300,000 to 500,000 bytes long.

You can come very close to the proper threads for metric items. For instance, The basic pitch of 1.0 mm per thread comes out to 0.9991 mm using the following gears: 45	65	50	55
This is fine for most everything up to several inches long.

Here's the link to calculate gear changes on the HF Mini-Lathe http://www.tanj.com/cgi-bin/tpi.cgi

Daniel


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## PEU (Nov 24, 2004)

I use a program called GearsVB, I downloaded the previous version from the www.varmintal.net site, then contacted the author and he made a little modification that I found very useful.

Here is the zipped file (24k).

I use it every time I do threads!


Pablo


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## gadget_lover (Nov 24, 2004)

What was the modification? I think this may the code that I based my program on.

The thread depth calculations are from a C program called, appropriately, threads. I don't generally use windows, so the visual basic programs are not much use in my case. I have to boot up my game system to run basic programs.

Dan


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## PEU (Nov 24, 2004)

Basically the previous version did not save the gear set properly. 

I forgot to tell, but I did some hex-editing of the program so it looks at the current dir for the database instead of the hard-coded c:\gearsVB /ubbthreads/images/graemlins/smile.gif

No other modifications so far.


Pablo


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## CNC Dan (Nov 24, 2004)

[ QUOTE ]
*gadget_lover said:*

Just as a point of interest, I've cut a half dozen threads so far using a "cut and try" technique for depth. It's worked, but I've ended up with threads that are not quite right. They fit one light but not the next, or they fit too loose or too tight. I wish I'd understood these concepts the first time I read them.

Daniel 

[/ QUOTE ]
See if you can find information on how to measure threads using the
"three wire method" or sometimes called "over wires".

If you have money to burn you could get a set of "pitch micrometers".


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## gadget_lover (Dec 14, 2005)

I've updated the web page that produces the 7x10 gear information.

The thread depths I was useing were for a "formed" thread as opposed to a cut thread.

The new output looks like this....

For a thread of: 20.00 TPI
the pitch is: 0.0500" per thread
the sharp V depth is: 0.0433" (UN and UNR)
UNR external cut depth 0.0379" (V * .875)
UNR internal cut depth 0.0325" (V * .750)

The web page explains that it's assuming a sharp tipped 60 degree tool.

The web page also allows you to add your particular combination of gears.


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## TranquillityBase (Dec 14, 2005)

Now this is my kinda of thread, no pun intended.

I have to add my two cents. 

If you wish to get away from the cut test cut method and don't want to spend big bucks on a thread micrometer. Buy a set of thread measuring wires or thread triangles. The wire sets are usually less than 10 bucks. Triangles are about $30 All you need is a outside diameter micrometer in the range that matches the part you are working on.

The wires are frustrating at first, but once you get the hang of it you'll wonder how you got along without them. The triangles I've personally never tried, but they look much quicker and easier to use.

I have one of the three piece mic sets from Harbor Freight and a Mitutoyo 0 ~ 1" digital. The Harbor Freight set is the first set I purchased and I'm still very pleased them. HF now sells this set for $20 sale price.

Second item that is money well spent, is the Machinery's Handbook, about $85 for the current edition, gulp! Yes it's expensive, but all the information you will ever need is in this book.

If anybody wants photos or a better explanation on any of the above, chime in.

TB


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## gadget_lover (Dec 15, 2005)

I don't think I've heard of the thread triangles What are they?

Did anyone see anything wrong with the new gear/thread calculator on my website? ( http://www.tanj.com/cgi-bin/tpi.cgi )

Daniel


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## TranquillityBase (Dec 15, 2005)

gadget_lover said:


> I don't think I've heard of the thread triangles What are they?
> 
> Did anyone see anything wrong with the new gear/thread calculator on my website? ( http://www.tanj.com/cgi-bin/tpi.cgi )
> 
> Daniel


They are a precision ground triangle about 1 inch long, give or take, with a rubber sling thats holds them to each end of a standard outside micrometer. Take a measurement and then subtract the constant. 

TB


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## TranquillityBase (Dec 15, 2005)

Here are some great products, reasonably priced, with a good explanation and photos of wire sets, triangles, and wire holders that I didn't know about.

http://www.flexbar.com/PDF/282_283.pdf#search='thread%20triangles'

TB


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## gadget_lover (Dec 15, 2005)

Thanks for the pointer. That looks worthwhile.

Daniel


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## HarryN (Dec 16, 2005)

I am still trying to figure out this whole "thread selection" area. Most of the threads I see on bolts have relatively sharp points, not the "flattened" UNF type. It also seems that the home lathe seups are more setup to cut that type. Is there a tool set for cutting UNF threads with the flattish / roundish base ? Sorry for the newbie aspect of this question.

It seems like there should be an insert that has the right shape.


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## TranquillityBase (Dec 16, 2005)

Next time you are at Barns and Noble, look for Home Shop Machinist and Machinist Workshop in the magazine racks. Very good information, a lot of the best stuff comes from old timers. The computer age is turning much of this knowledge into a lost art. I have to admit, even I take the easy way out with many machining tasks, i.e. I skipped over tool grinding one-o-one and bought all indexable tooling.

TB


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## gadget_lover (Dec 16, 2005)

HarryN said:


> I am still trying to figure out this whole "thread selection" area. Most of the threads I see on bolts have relatively sharp points, not the "flattened" UNF type. It also seems that the home lathe seups are more setup to cut that type. Is there a tool set for cutting UNF threads with the flattish / roundish base ? Sorry for the newbie aspect of this question.
> 
> It seems like there should be an insert that has the right shape.




There are. This page at carbide depot ( http://www.carbidedepot.com/detail.aspx?ID=12748 ) lists some inserts for various threads. At $16 per insert, I can get the inserts for the most common threads for only $320. That would give me internal and external inserts for the 10 most common threads. OOPs. That's for left hand only. A different set is needed for left hand threads.

That's why I'm content with the modified sharp V.

On the other hand, If I were cutting threads for a commercial product that needs to meet standards, I'd only be doing a few thread pitches so I would only need a few inserts.


Daniel


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## coldsolderjoint (Dec 22, 2005)

LoneRanger4404 said:


> Hello folks,
> 
> On the subject of threads, I am just in the process of sorting my first "homebrewed mod" and have been trying to find out the thread specs needed to fit a kroll "clickie" tail switch. Can anybody help please?
> 
> ...





McGizmo said:


> 5/8" X 28




This is the same kroll switch that the Mini [email protected] AA uses right?


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## HarryN (Dec 22, 2005)

Hi Daniel - I looked at your link and almost bought some for you (for my projects  ) for the thread sizes that are interesting at the moment (SF C and M size, which are pretty much all 20 TPI in various sizes, and a metric one for the custom body). I clicked buy and noticed that they are sold in packs of 5 each only, making the price more like $ 80 / cutter style. I will look at this a bit more and see what is practical.


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## gadget_lover (Dec 22, 2005)

HarryN said:


> Hi Daniel - I looked at your link and almost bought some for you (for my projects  ) for the thread sizes that are interesting at the moment (SF C and M size, which are pretty much all 20 TPI in various sizes, and a metric one for the custom body). I clicked buy and noticed that they are sold in packs of 5 each only, making the price more like $ 80 / cutter style. I will look at this a bit more and see what is practical.




Yeah, a minimum of 5 AND there are different sizes for different tools. A small 1/2 inch bore would take a small tool holder for inside threads but a large bore would be better suited for a lrger tool holder.

Just part of the fun of machining... figuring out which tool is which.

Daniel


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## Anglepoise (Dec 22, 2005)

I think these special threading inserts ( different part # for each thread size ) are very expensive and entirely un necessary for the work we do.

In my experience any 60 degree tool will work fine and as long as you know the correct in feed and have a way of measuring it ......you are away to the races.


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## HarryN (Dec 22, 2005)

Anglepoise said:


> I think these special threading inserts ( different part # for each thread size ) are very expensive and entirely un necessary for the work we do.
> 
> In my experience any 60 degree tool will work fine and as long as you know the correct in feed and have a way of measuring it ......you are away to the races.



Hi - I think in general you are right, but for applications with very thin walls, the shape of the thread can make a difference, especially on inside threads.


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## gadget_lover (Dec 23, 2005)

TranquillityBase said:


> Next time you are at Barns and Noble, look for Home Shop Machinist and Machinist Workshop in the magazine racks. Very good information, a lot of the best stuff comes from old timers. The computer age is turning much of this knowledge into a lost art. I have to admit, even I take the easy way out with many machining tasks, i.e. I skipped over tool grinding one-o-one and bought all indexable tooling.
> 
> TB




I must second this recommendation. I was wondering how the Bison 5C collet chuck worked, but could not figure it out till I read an article in Home Shop Machinist about building one. They have a lot of good articles. It would make a good stocking stuffer.

Daniel


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## nemul (Dec 23, 2005)

Greymage said:


> .....but how do I make the threads? Can anyone post a link to a thread maker or whatever you call those things that let you make threads in something?







:thinking:


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## gadget_lover (Dec 23, 2005)

That is soooooo bad namul.

The question that comes to mind is "how many TPI is that button?"



Daniel


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## Anglepoise (Dec 23, 2005)

This is a good page to save as a reference on carbide inserts for threading.

Reference page

The box on 'Infeed Methods' alone is worth a look.


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## TranquillityBase (Dec 23, 2005)

Anglepoise said:


> This is a good page to save as a reference on carbide inserts for threading.
> 
> Reference page
> 
> The box on 'Infeed Methods' alone is worth a look.


 Now that is a great link. Thanks Anglepoise!

TB


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## gadget_lover (Dec 23, 2005)

Thanks for the link. It's the first article I've seen that explained the 29.5 degree VS 30 degree. That was very helpful. I think it's also the first time I have understood the "full profile" single point threading insert.

Daniel


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## Anglepoise (Dec 23, 2005)

Here is another great article in infeed. Anything that reduces strain on the threading operation is OK in my book and 29 1/2 degrees really works wonders.

Link


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## wquiles (Feb 8, 2006)

What a great link Anglepoise :bow:

Will


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## LuxLuthor (Jul 6, 2007)

Resurrecting this old thread to ask this question.

If I were to cut a Mag D to a custom length based on battery(ies) size, would it work to try and find a tap to just create the inside threads that would match a standard Mag tailcap....without having a lathe to do it?

I know most all you guys do it on a lathe, but as soft as aluminum is it at least seems like it is worth asking. I will be doing so few of them, it really doesn't make sense to get involved with a lathe.

If it can be done, I think I read above that Mag uses 20 TPI, but what other size specs would I need to find the right tap? Thanks!


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## wykeite (Jul 7, 2007)

LuxLuthor said:


> Resurrecting this old thread to ask this question.
> 
> If I were to cut a Mag D to a custom length based on battery(ies) size, would it work to try and find a tap to just create the inside threads that would match a standard Mag tailcap....without having a lathe to do it?
> 
> ...


 
The Mag tailcap thread is not one that you're going to find as an off the shelf item, readily. Looking in Machinery's Handbook** it is actually 1 7/16-20 UN. (Ref. Page 1555 in Edition 24). It's going to be expensive even if you find one, unless you're going to be doing lots the price will be difficult to justify. May just be better to enlist the aid of a local machine shop if it's only for a few.

Post #8 in this thread has the dimensions https://www.candlepowerforums.com/threads/51647

** Fantastic volume but at 2500+ pages it takes a lot to track down info even with an index.

A handy quick reference is Zeus tables, fits nicely in the top pocket of your coverall and is laminated (more like a plastic coating), I've got 2 dated 1975 when they were 75 pence, now £5ish, the coating was durable then and thing's have only got better right?:devil:. http://www.tool-up.co.uk/shop/diy/MISZC.html Should be VAT free if they post overseas. Anyone want's one and has a problem getting it delivered it will not be more than the +VAT price and £1.50 postage. Going to work on the VAT aspect as I believe, probably wrongly that books are VAT free


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## KC2IXE (Jul 7, 2007)

Yeah, I was going to say a custom tap (which I'm sure the Mag thread is - or a 'near custom') is going to COST you. How much? I could see it costing enough that you could go out, and buy a used lathe, and learn to use it. Not kidding


EDIT:
Heh - I was wrong, believe it or not, MSC ( www.mscdirect.com ) has them IN STOCK - "ONLY" $135.


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## LuxLuthor (Jul 8, 2007)

KC2IXE said:


> Yeah, I was going to say a custom tap (which I'm sure the Mag thread is - or a 'near custom') is going to COST you. How much? I could see it costing enough that you could go out, and buy a used lathe, and learn to use it. Not kidding
> 
> 
> EDIT:
> Heh - I was wrong, believe it or not, MSC ( www.mscdirect.com ) has them IN STOCK - "ONLY" $135.



How expensive did you guys think this was going to cost? They have a "plug" and "bottoming" style. I'm guessing bottoming is the one? Is there any other variation like depth or shape of thread that would have to match up? I don't know what "NS" thread type means, or if that would work with a Maglite cap.

I don't know what kind of tool you need to hold onto a tap this size, as I only have a smaller tap and die set.

Thanks


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## will (Jul 9, 2007)

A bottoming tap cuts threads to the bottom of a blind hole. ( blind hole does not go all the way through ). A bottoming tap is difficult to start in that the end is not tapered in any way. Taps this large are not real easy to work with. Also - the inside diameter has to be the right size for the tap to cut the threads.

finally - anodize on the inside is going to dull the tap, .


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## LuxLuthor (Jul 9, 2007)

Will, you don't think the HSS would hold up to anodized aluminum? The image of the bottoming version on this page gives a reference of it starting tapered for 1-2 threads, vs. Plug style tapered for 3-5 threads. I know what you mean about starting with the right ID of the tube, and I have not used taps this large, so I'm not sure how this would work out.


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## will (Jul 9, 2007)

I grind my own HSS lathe tools, The anodize is much harder than just plain aluminum. I have to sharpen them after an hour or so when I am cutting through anodize. Keep in mind - these are single point tools and just require a touch up. If I am spending $135 for a tap - I want it to last a long time. ( I am not a real big fan of very large taps - They require a lot of force to use. They have to be started perfectly straight, not easy to do by hand. )

The bodies have an undercut at the end of the tube for the 'O' ring. Then there is the problem of cutting the body to length. 

IF you are doing a few C or D bodies - I would be inclined to send them off to get done. If you are considering a lathe - a mini lathe will not work for threading a C or D body - the bed is not long enough ( 7 x 10 mini ). also the body will not fit inside the chuck on most mini lathes.


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## KC2IXE (Jul 9, 2007)

LuxLuthor said:


> How expensive did you guys think this was going to cost? ...snip.... I'm guessing bottoming is the one? Is there any other variation like depth or shape of thread that would have to match up? I don't know what "NS" thread type means, or if that would work with a Maglite cap.
> 
> I don't know what kind of tool you need to hold onto a tap this size, as I only have a smaller tap and die set.
> 
> Thanks



I was figuring you might have to go to a custom tapmaker - you would have been looking at LEAST mid 3 figures then!!

NS = National Special - "N" is the National threadform, "S" is anything that is not "C" (corse)"F" fine, or EF "extra fine" (in some sizes)

You would normally use a plug tap for most uses, unless you need to go to a blind hole, OR you need an abrupt end - they you use a bottoming tap - but usually START with a plug tap anyway

What do you use to drive a tap that big? A BIG tap wrench. Biggest tap I've ever driven was 1 1/4" NC - that was NOT fun - biggest die I ever had to use was 1.75" - that was fun - the machine shop had messed up threading some shafts, and NOT finished the thread - we had a choice - thread in place, 3 sections of scaffolding up, in a real bad place, or spend 2 weeks bring the whole overhead crane system down to the floor, and having it fixed. We did it in the air - safety belted to the girders with a BIG spline drive ratchet - had 4 shafts to do, about 2 to 3 inches of thread each. Took about 4 hours, and the client personel watching us thought we were insane - that scaffold was rocking - you REALLY had to put some weight into moving that die


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## LuxLuthor (Jul 9, 2007)

OK, I get the message to forget this idea. I didn't realize how hard HA makes aluminum. Thanks for your expertise.


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## gmhoover (Aug 3, 2007)

*What about mini mag threads*

Is it possible to purchase a tap and die for mini mag threads. Both internal and external for head and tailcap? And the mini magLED? Money isn't an issue, finding the right size and a stock number is.


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