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Learning to lathe [things]

bombelman

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Anglepoise said:
....Now the tool to cut that would have a curve ground into the tool to closely match the final groove. If the sides of the tool were straight......instant breakage....
Can someone illustrate this ? (for a wannabe lathe owner) :grin2: :rock:
 

Anglepoise

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bombelman said:
Can someone illustrate this ? (for a wannabe lathe owner) :grin2: :rock:

dg_od_fgrov.jpg


This is the best I can do but clearly shows the curve .....

This insert is specially made for diameters 25> 30 mm.

In Fred's case, the insert or tool would have to be smaller and ground in a tighter curve to fit his groove of 3/8ths inch ( guess ).

Anyway it gives an idea as to what is happening when one attempts a 'face groove'.
 
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PhotonFanatic

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OK, since we seem to have a little interest in face grooving tools, here is one of the IFanger face grooving tools that I haven't yet broken. :D

Photo taken from above, trying to showing the width of the tool to be 1.5mm:
FromAbove.jpg


And here are a couple of shots, looking head on to the tool, to show the outer, righthand edge of the tool to be beveled to match, or actually to be even tighter than, the radius of the groove that the tool can cut:

FromFront.jpg

FromFront2.jpg


I believe you can also surmise that these are fairly fragile tools in the size shown. This particular tool can be used for cutting a groove with a minimum diameter of 8mm; larger diameters are, of course, no problem as the outer edge of the tool has a smaller radius than the groove you would be cutting.

David: Pretty good guess--it was 10.5-11.5mm diameter.
 
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will

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just a quick picture to show what can be done on a mini-lathe


this is a maglite 2D

d.jpg
 

PhotonFanatic

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will,

Don't you mean with a mini lathe and a good plater? :lolsign:


So let's hear how you did it all, please. Especially keen to hear how you held the body while putting in the grooves.
 

will

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is it with a mini-lathe? or is it on a mini-lathe? as the work is on a mini-lathe.

at any rate -

A piece of tape on the chuck divided in 3/4 inch segments - that translates to 3/8 horizontal lines on the mag body.
Unplug the lathe. Mount a grooving tool sideways in the tool holder, Basically broaching the lines in. I just held the chuck by hand for the first 2 passes. I only take .003 on each pass. Once the first pass is done the tool will follow the groove. This works for shallow cuts.

This would have been easier with a milling machine and an indexing head, but this works too..

This is just polished aluminum, not plated.
 

will

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modamag said:
Will, how long did that hand broach job takes you?
Most of the time was spent getting it laid out correctly, centered around the switch, centered on the knurling. Each horizontal line took about 8 passes. The broaching took under 25 minutes.
 

will

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I went looking for something the other day and ran across this. It is a user manual for a mini-lathe. There is enough information on working with a lathe to make it worthy of a quick read.

www.littlemachineshop.com

click on learning center

Getting Started with Mini Lathe Tooling
OR
Mini Lathe Users Guide
 

PhotonFanatic

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OK, don't know if we can really call it "learning", at least not as much as some of the earlier lessons. :D

Tonight I sought to put drawing to metal. I had modeled this in SolidWorks, but wasn't at all confident that it could be done on my machine.

The hardest part is getting the lengths of the taper to match, some 15 times! To be honest, they do not perfectly match in length, but they are fairly close. I need to solve how to make them identical, and then I will be 100% satisfied with the design.

So here is the overall view:
Slanted2.jpg


And a close-up, while on the lathe of the two ends:

OnTheLathe.jpg

OnTheLathe2.jpg


These are basically just milled slots, with the piece held at an angle to the end mill.

A few more shots:

TaperUpClose.jpg

RoundedEnds.jpg

Vertical.jpg



Ultimately, it is destined to be an 18650 Twisty, ala:

18650BattComp.jpg


Still to be made is the head, which will sport a similar milling profile to match the body. Hopefully, it will come out looking like a Light in Motion. :D

The grip on this is fantastic, perfect for a twisty, in my opinion. BTW, this is 6061Al, not Ti. Total time spent doing the slots: four hours. Each line took six passes to complete. Perhaps I could have been a bit more aggressive with the infeed, but at least I didn't break any parts, nor ruin any part of me in the process. :lolsign:
 
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will

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photon
can you take a picture of the setup you used to make the cuts?

For every .001 the work is out of concentric the length of the slot will be off .015 - These are made up numbers - the work has to be dead on to make the ends come out the same.
 

PhotonFanatic

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Will,

Here you go:
FullViewSetUpTaperCuts.jpg


From the operator's viewpoint--a little crowded. :)
OperatorViewTaperCuts.jpg


Workpiece showing cuts:
UpCloseTaperCutView.jpg



I will admit that I was more interested in trying to do the cuts than I was in preparing the piece.

So, what would you do, given my options, to prepare the stock to be as concentric as possible. Here's the scenario: 6"/150mm long, 25.4mm diameter stock. I have a four-jaw chuck, which can obviously hold that size no problem.

For the indexing, I like to use the Schaublin W20 collets to hold the piece, so that means that the stock needs to be reduced on one end at least to 20mm diameter, by about 30mm long.

In this case, the length of the tapered slot is 50mm. I try to do that as close to the collet in the indexing head as possible, for stability's sake.

Looking forward to your advice, or anyone else's, too. Thanks.
 

will

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Make sure everything is snug, no loose anything,

Put a dial indicator on the work piece, spin it 360 degrees, make sure there is no runout and that nothing moves.

try a few cuts see if the ends match, you should be able to do that in 2 cuts, one gets most of the material, the second is for a smooth finish.

If the ends don't match and the work had no runout, then something has moved. put the dial indicator back on, make sure there is still no runout.

I am not sure if you can clamp down the various parts on the carriage to prevent them from moving.

there may be other things that can be done, but start there.

Once you start to cut the work, don't turn the lathe off, sometimes bearings 'settle' and don't go back to exactly the same place.
 

lukus

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will said:
sometimes bearings 'settle' and don't go back to exactly the same place.

If the bearings are loose enough to settle, wouldn't that cause so much chatter that you wouldn't get a good cut anyway?
 

will

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lukus said:
If the bearings are loose enough to settle, wouldn't that cause so much chatter that you wouldn't get a good cut anyway?

It's possible - I should have said that I am really dealing in the .0001 range. not enough to really make an easily measurable difference, but possibly enough to make a difference in the horizontal lines being milled. There are a lot of moving parts in a lathe, bearings, gears, etc. In a perfect world everything will be exactly the same time and time again. That is probably true if you are working within a .001 tolerance. When I worked in the field some of the parts we made had very tight tolerances, We had fewer problems leaving everything running.

I will even open myself for an additional area - heat and heat expansion of the moving parts in the lathe. Keep in mind - I am really talking about a very, very small difference.
 

Griz

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Fred,
I'm looking at the last picture and have a suggestion or two.
1) Will is right when he says to indicate the part in......do it. Always do it.
2) Reverse the direction of your cut. The deepest cut should be as close to the collet as possible.
3) Spray mist coolant will take care of any heat build up, as well as blow excess chips away from the end mill, which leaves a nicer finish.
4) What ever collet size your using, your part must be the same size. WHAT?

Let me explain #4. If you have Spring collets, like the one in my picture, you've got nothing to worry about. If your collets are similar to a 5C collet then the size of your part should not vary by more than .001-.002 thousands. 5c collets do not tollerate large variations in finished diameters. If your part is too big or too small by .005-.007 thousands, it will still fit in the collet, but the collet will not clamp evenly on each end of your diameter. Too big, and the part will want to push out. Too small, the part has a tendency to wobble.

Back to my picture
.jpg

This is an ER16 collet. You see how they are split from each end, and they have a double taper. This collet will expand or contract over a .040 range, which allows a .375 collet to clamp a .355 dia. just as good as a .395 dia.
These are well known for their accuracy and tight grip. If you have the budget, consider buying a set of these. Well worth the money.

I hope this helps.....and keep at it !
 

PhotonFanatic

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Griz said:
Fred,
I'm looking at the last picture and have a suggestion or two.
1) Will is right when he says to indicate the part in......do it. Always do it.
2) Reverse the direction of your cut. The deepest cut should be as close to the collet as possible.
3) Spray mist coolant will take care of any heat build up, as well as blow excess chips away from the end mill, which leaves a nicer finish.
4) What ever collet size your using, your part must be the same size. WHAT?

Let me explain #4. If you have Spring collets, like the one in my picture, you've got nothing to worry about. If your collets are similar to a 5C collet then the size of your part should not vary by more than .001-.002 thousands. 5c collets do not tollerate large variations in finished diameters. If your part is too big or too small by .005-.007 thousands, it will still fit in the collet, but the collet will not clamp evenly on each end of your diameter. Too big, and the part will want to push out. Too small, the part has a tendency to wobble.

Back to my picture
.jpg

This is an ER16 collet. You see how they are split from each end, and they have a double taper. This collet will expand or contract over a .040 range, which allows a .375 collet to clamp a .355 dia. just as good as a .395 dia.
These are well known for their accuracy and tight grip. If you have the budget, consider buying a set of these. Well worth the money.

I hope this helps.....and keep at it !

Griz,

1. Indicating the part--no problem, I can do that.

2. Deepest cut closest to coller--no problem, I can do that, too. [Edit: Turns out that I can not do that--physical ly impossible given my set-up.]

3. There wasn't much heat buildup as I was taking very small depths of cut. I did use a spray bottle to wash the chips away. I do not have compressed air at hand either.

4. The only collets that will work with my spindle, or at least I believe that to be the case, are the Schaublin W20 collets, which are split collets (120 degrees apart) and can handle a range within .5mm, or .02" roughly. In practice, I cut the end of the part that is to be held by the collet to within .02mm of the nominal collet size, i.e., for the 20mm collet, the piece is turned to 19.98mm.

I really think the source for the uneven lengths was in not making 100% sure that there was zero runout in the piece before I transferred it to the dividing head. Should have heeded the old adage to measure twice, cut once. :D

I am looking forward to implementing all the suggestions on the next piece, which will be the head of the light. I've decided that while the battery tube wasn't perfect, it is good enough to warrant completing the project and building the light.
 
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plasmaman

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Nooblather here!

Can anyone tell me what the best thread cutting tool, and drivegear settings, I need to attempt internal threading of AA cell,D cell and C cell size Mags, working on my 7x14 mini?

I want to be able to make some cutdown hosts.

Thanks guys.
 

cmacclel

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Great Job Fred. I think you need to get a compressor :)

So you have an indexing head mounted to your compound slide.....cool.


Mac
 

will

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plasmaman said:
Nooblather here!

Can anyone tell me what the best thread cutting tool, and drivegear settings, I need to attempt internal threading of AA cell,D cell and C cell size Mags, working on my 7x14 mini?

I want to be able to make some cutdown hosts.

Thanks guys.

I have a 7x10 mini-lathe. I bored out the 3 inch chuck so the body of a mini-mag will fit inside the chuck. I did not bore it all the way through, there are 3 screws in the back of the chuck that I wanted to leave alone. Maglite C and D will not fit inside the chuck. You will need a steady rest to do any cutting of the larger Mags. The mini is really not big enough for these.

I picked up an internal threading tool from MSC industrial - solid carbide.

check out my post number 129 in this thread, the brochure from little machine shop is very helpful.
 
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