# Taps and Dies



## mountaineer (Dec 27, 2004)

Could someone help me out and tell me where I could buy a 13/16 x 20 bottoming Tap and Die . I want Make and/or Mod some battery tubes for Aleph / surefire heads and cant get that size Tap and Die over here in Europe . I would have to order it through the mail . Thanks !

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Kenny


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## gadget_lover (Dec 27, 2004)

I found one on KBC tools for $15 US. 
http://www.kbctools.com/usa/Navigation/NavPDF.cfm?PDFPage=191


Good luck with your project.

Daniel


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## Chop (Dec 27, 2004)

I get my stuff from msc-direct.com

They ship pretty quick. I do just want to note that the term bottoming tap is a bit misleading. Even they have a taper on the end and don't actually bottom out. I have two taps in 13/16-20. Once is a standard taper to start the threads and the other is a bottoming that I ground down to really bottom out. I've found this necessary when threading heads. Unless you're just chasing threads, you'll need a way to make sure that the taps go in straight. I use my lathe or drill press to do this.

As for dies, I suppose that msc has those too, but I usually cut outside threads on my lathe, so I can't help you out there.


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## wasabe64 (Dec 27, 2004)

Just a heads up on the tap, KBC only stocks the plug version of the tap. A bottoming version can be ordered but at extra time (~2 weeks) and cost.

The catalog price is great for such a tap, bottoming or not. I'm guilty of grinding down plug taps myself to create bottoming taps. IIRC, the selection of dies @ KBC is not as extensive and a 13/16-20 die is definitely a custom order tool.


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## Chop (Dec 28, 2004)

The tap is a "regular" item at MSC and I got mine in a few days.


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## mahoney (Jan 3, 2005)

www.travers.com has pretty good prices on the 13/16-20 taps and die. They have plug, taper, and bottoming style taps in 13/16-20. The smallest die size in 13/16-20 is a 2" round. 
Oddly enough, they are made in Poland. The tap has a logo consisting of the letters "VIS" on the shank. Perhaps you can track down the manufacturer and get the tooling without having to ship it back across the Atlantic.


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## mountaineer (Jan 10, 2005)

Thanks you guys . I ordered them from MSC and I got them yesterday . 

----------------------
Kenny


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## gadget_lover (Mar 30, 2005)

I need some advice from the good folks here.

I was making a backplate adapter to mount a 4 inch chuck on my 7x10 lathe. I'm reworking a steel spindle adapter designed for another chuck and another lathe. It's over 3/4 inch thick, so I had plenty to work with. One side is finished, with the proper recess for the spindle nose.

I sucessfully centered the backplate on my huge (4 inch) rotary table and drilled the 4 hole pattern for the 6x1 mm mounting studs. To my suprise, my locating was right on! The holes are right where they belong and are square.

Here's the problem. I was wearing my bi-focals, and they create an optical illusion that makes straight lines look crooked. I realized this after tapping the first two of the holes. They were at a slight angle. The last two of them went straight in. The end result is that the plate fits perfectly, as long as I have only 3 studs installed. I install all 4 and they don't locate properly.

Is there anyway to straighten out the tapping without drilling it out, retapping and using a bigger stud?

I can also widen one of the holes in the spindle flange, but I'd rather not alter that end of it if I can avoid it.

Any help?

Daniel


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## wasabe64 (Mar 30, 2005)

I wouldn't take any shortcuts on the backplate. Centering and rigidity are critical.

The best thing to do is to start a second series of holes and abandon the first set of holes.


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## MoonRise (Mar 30, 2005)

NG.

General rule is not to use a pattern of threaded holes (or a single threaded interface) to locate a precision object. You use dowel pins or a shoulder-recess to LOCATE the objects with respect to one another and then use the threaded fasteners to hold it together. A partial grey area is using shoulder bolts to locate and fasten things.

Straighten out a crooked tapped hole? No way to do that. It might be possible to machine a new over-sized hole in the correct position and orientation and then put a thread insert in there. Look up HeliCoil stuff, if you're not familiar with it.

Like wasabe64 said, abandon the bad holes and redo all four. Just think how good the second set will come out now that you practiced with the first set of holes!


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## Chop (Mar 30, 2005)

You could just get the 5" chuck and back plate kit from the little machine shop and take the head ache out of it. The 5" works really well with the mini lathe. I've been running one for a while now and I don't know how I every worked without it.


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## gadget_lover (Mar 30, 2005)

Thanks for the feedback. No way to fix them? Darn!

I'm always lothe to redo a whole project for a simple mistake. In this case, the shoulder of the lathe's spindle does snuggly fit into the recess cut into the adapter plate. The studs and nuts hold it in place. Will it compromise the rigidity if I enlarge one of the holes in the spindle flange by 1/32 or 1/16? 

I thought about setting up another series of holes, I did not want to end up with a swiss cheese project. Besides, the silly thing already has an extra 3 bolt pattern out near the outer edge for the chuck it was designed for.

My particular lathe spindle flange has a 6 hole pattern, with 3 holes spaced 120 degrees apart and another 3 holes 90 degrees apart (sharing one hole from the 3 bolt pattern). This allows a 3 bolt or 4 bolt chuck. 

Would I have balancing problems or warping problems if I use one of the holes from the three bolt pattern (only about 30 degrees off). That would leave me with a stud at 0, 120, 180, 270 degrees. 

I don't have any more 4 inch diameter steel stock, so I have to find a local source for cut-offs if I start over. It might not be a bad idea anyway to do a nice, clean one from scratch.

Daniel


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## gadget_lover (Mar 30, 2005)

Thanks Chop. That's not a bad idea, but then what do I do with my 4 inch chuck? /ubbthreads/images/graemlins/smile.gif

Such nice problems to have.

Daniel


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## Chop (Mar 30, 2005)

gadget lover, I know that presents a bit of a problem. I thought about making my own backplate as well. The thing that kept me from tackling that was that I consider machining a means to an end, rather an end in itself. The short of it is that the time spent making the plate would have been time NOT modding, so I decided to just buy the stuff.

As for the 4" chuck, just consider the 5" an upgrade that you've been needing to make. With the 5" chuck, I actually parted at 2" diameter piece of stock in my mini, without the use any sort of steady rest. The chuck is that massive.


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## gadget_lover (Mar 30, 2005)

You make a good point, Chop. It's not the most productive. Well, unless you count my lack of experience. I decided the experience working with a large chunk of steel was worthwhile. I felt kind of intimidated going into this, and feel much more at ease about it now, even though I screwed it up a bit.

I'm still only 1/2 done, as next I need to do the face that the chuck will mount to. I'll sleeep on it and decide tomorrow.


Daniel


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## Chop (Mar 30, 2005)

Just a little nudge.

It took me all of ten minutes to get up and running, once it came in. That includes the time it took to get the muck off of it.


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## tvodrd (Mar 30, 2005)

Daniel, use the 3 bolts and (red- I forget the number) LocTite the assembly. I'm guessing it will be sufficient.

Larry


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## gadget_lover (Mar 31, 2005)

Chop, you are evil! It's not like I need encouragement to buy spare toys. I am trying to watch my toy budget a bit closer. I must say, though, that your encouragement is probably just my Karma catching up with me. This month I convinced a friend that he needed a lathe, and I even picked it up form him.

Thanks for the suggestion Larry. Is the red the permanent one? Were you suggesting a set of holes every 120 degrees, or just using 3 of the 90 degree offset holes? I'm worried about vibration as well as holding it tight.

Daniel


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## rwolff (Mar 31, 2005)

[ QUOTE ]

Here's the problem. I was wearing my bi-focals, and they create an optical illusion that makes straight lines look crooked. I realized this after tapping the first two of the holes. They were at a slight angle. The last two of them went straight in. The end result is that the plate fits perfectly, as long as I have only 3 studs installed. I install all 4 and they don't locate properly. 


[/ QUOTE ]

How much off-straight are the threads? Also, does the chuck mount to the backplate with studs (threaded both ends) or capscrews? If the holes aren't too much off-straight, you might want to try using a pulley tap (tap with extra-long shank ground to the clearance diameter of the appropriate screw). Mount the chuck to the backplate using the "good" holes, with the "bad" onces roughly halfway between one lining up and the other lining up, and tighten the 2 screws really well. Then, re-tap the bad holes using the pulley tap (it'll guide into the start of the threads) - the "brute force" of the tap being held in line by the clearance hole for the screw is frequently enough to be able to get screws in. We do this fairly often at work.

If it's still a bit too much, the next step is "Michigan screws" - you've gotta make your own, to fit the application. They're capscrews that are ground to a smaller diameter starting just below the surface of the threaded plate, and ending about 1/2" below the head. The reduced diameter lets them move a bit more to the side than a full-diameter screw.

It's too late now, but you should get yourself a piloted tap wrench (KBC part numbers 1-397-101, 102, and 103). After drilling the holes, you leave the part set up in your indexing table and clamp the "hat" of the tap wrench in the drill chuck (other piloted tap wrenches don't have a "hat" - on those, you grip the pilot *loosely* in the drill chuck) and slide the pilot of the tap wrench into the "hat". Since the hole is directly under the drill spindle, and the pilot keeps the top of the tap wrench concentric with the spindle, you'll tap it straight every time.


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## gadget_lover (Mar 31, 2005)

Thanks for the idea Rwolff. It uses studs, not capscrews. The threads are only off a bit, maybe 10 or 20 degrees or so. The problem appears to be that I held the piece differently, so one leans to the left and the other to the right. When all 4 studs are inserted the two bad ones fight each other, with one pressed against the left side of the mounting hole and the other rubbing against the right hand side of the hole.

I've thought of making a stud that is threaded 6x1 on one end and 5x1 at the other. That would provide the clearance. 

Thanks for the pointer to the piloted tap wrench. I think I need one more than most people. /ubbthreads/images/graemlins/smile.gif



Thanks for all the info and advice.

Daniel


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## MoonRise (Mar 31, 2005)

Little bit off, only 10 or 20 degrees? /ubbthreads/images/graemlins/crackup.gif

A little bit off is maybe 2 degrees.

BTW, the red Loctite is the semipermanent one. Not removable without the use of heat (torch) and hand tools. Blue Loctite is the general use one, removable with hand tools. Green Loctite is the thin wicking one for already assembled threads, needs heat and hand tools to remove. These are the 'consumer' Loctite products, the industrial/OEM stuff covers more levels and variations.

You can try modifying some fasteners, but I think you have a bit too much OOPS for that.

IMHO, redo the holes. Machine out the bad ones so you don't use them by accident, and put four new holes in.

Hint, Drill the hole and then unplug the drill press and don't move anything on your set-up. Chuck the tap into the drill press and use the press to hold the tap square to the workpiece. Apply feed pressure with the quill feed handle and turn the tap BY HAND (open the pulley cover and rotate the tap from up there). Lather, rinse, repeat.

With 10-20 degrees out-of-square and metal parts, you would stand a good chance of popping the heads off of the cap screw (or bolt) when you tighten it up. Nuts and studs might give you a little more leeway, but not all that much.

Redo the holes. Or buy the backplate/adapter. littlemachineshop.com has chuck adapters for $15-$20.


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## Chop (Mar 31, 2005)

Don't sell the red loctite short. Altough it is a consumer grade product. It really does its job. I used to use the stuff for compensators on 1911 barrels. After the red stuff set, removing the compensator involved cooking the barrel and compensator in an oven at 350 for an hour or so and then the liberal use of a large vice and a very large cresent wrench.

Considering what you are doing, I wouldn't expend any effort on trying to make a mistake work. I'd either re do it, or just get the adapter from the LMS.


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## gadget_lover (Mar 31, 2005)

[ QUOTE ]
*MoonRise said:*
Little bit off, only 10 or 20 degrees? /ubbthreads/images/graemlins/crackup.gif

A little bit off is maybe 2 degrees.

[ text deleted ]

With 10-20 degrees out-of-square and metal parts, you would stand a good chance of popping the heads off of the cap screw (or bolt) when you tighten it up. Nuts and studs might give you a little more leeway, but not all that much.



[/ QUOTE ]

I'm going to go ahead and start over. I always try to examine my mistakes so I can avoid them next time. Just to save a little face (not much) I measured the slant with a protractor. Both are only off 3 degrees. The bolt pattern was OK, but I could have made it a smidge smaller. One of the many challenges I face is learning to estimate both lengths and angles. I'm learning... Slowly. 

Daniel


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## Iron_Man (Apr 6, 2005)

Heli coil gets my vote. Make your self a tapping block. Just a scrap of metal with holes drilled thru the are the size of the tap shank. With one of them you can tap straight while blind drunk /ubbthreads/images/graemlins/smile.gif

Les


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## tvodrd (Apr 6, 2005)

Iron_Man,

Welcome to CPF! I've read your posts, and you've been there and done that! /ubbthreads/images/graemlins/thumbsup.gif

Dan, Iron_Man's suggestion for making a (I call it) bench block for tapping holes straight is the ticket. Helicoil kits are kinda pricey- I know, I have several. If you drill a 6mm hole in say, a 1" block of alum to just clear your tap, you could clamp it to your plate and likely "streighten" your crooked hole. You will need a quality, sharp tap, and the resultant threaded hole will be somewhat loose with your screw. (LocTite time /ubbthreads/images/graemlins/grin.gif ) Give it a try.

I mailed the chuck jaws monday.

Larry


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## gadget_lover (Apr 6, 2005)

Thanks for the suggestions. I'll make a tap bench block to see what happens. I've been house bound due to a bad back and have not been able to drive across town to get fresh stock for this project. 

Is there any reason why I should (or should not) use aluminum for a backplate? I have a coupele 1 inch thick by 6 inch round disks that I could use.


Daniel
(thanks again Larry)


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## wasabe64 (Apr 6, 2005)

Stick to cast iron or mild steel for the backplate, it is denser and harder.

Aluminum would be too light and soft to withstand the beating that you would be giving it. It would start tearing around the tapped holes (steel studs vs. aluminum). Typical behaviour when mechanically joining hard metals with soft ones and then stressing the parts.


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## tvodrd (Apr 6, 2005)

More importantly, steel/cast iron has a Young's modulas 3-times than for aluminum. It is "stiffer," and the increased mass will help damp vibration and give better results with interrupted cuts. 

(At the "end of the day." aluminum will be just fine for a chuck mounting plate on a micro lathe. /ubbthreads/images/graemlins/grin.gif )

Larry


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## gadget_lover (Apr 7, 2005)

Thanks Wasabe. I kind of figured that would be the case. I'll wait till I can get some more stock.

Daniel


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## gadget_lover (Apr 7, 2005)

[ QUOTE ]
(At the "end of the day." aluminum will be just fine for a chuck mounting plate on a micro lathe.)

[/ QUOTE ]

Those of us who just happen to be able to pick up our lathes without the use of a forklift prefer to call them "mini", not "micro" thankyverymuch.


/ubbthreads/images/graemlins/smile.gif

I figured with the reduced load of the fractional HP motor that the aluminum would probably hold up for quite a while. I don't like the idea of the possibility that it might give way at high speed, trashing something in the headstock while it's at it. Yuk!

I will keep that in mind if I need to do something similar for a stop-gap.


Again, thanks for the info and advice.

Daniel


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## HarryN (Apr 7, 2005)

Daniel - give me a call on Thurs PM - I might be able to pick up some stock for you while you are nursing that back.

Harry


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## gadget_lover (Apr 7, 2005)

Ya know, you meet the nicest people on this board. /ubbthreads/images/graemlins/thumbsup.gif

Harry; PM sent.

Daniel


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## gadget_lover (Jun 9, 2005)

I finally finished making the adapter to mount the 4 inch chuck on my lathe. 

As the experts advised, there was no way to cleanly retap the holes without drilling to the next size and using a larger tap. I was able to straighten it a little bit by retapping with a bench block to keep it straight.

I plugged the holes and drilled and tapped new ones.

I followed Moonrise's advice, with a twist.
[ QUOTE ]
Hint, Drill the hole and then unplug the drill press and don't move anything on your set-up. Chuck the tap into the drill press and use the press to hold the tap square to the workpiece. Apply feed pressure with the quill feed handle and turn the tap BY HAND (open the pulley cover and rotate the tap from up there). Lather, rinse, repeat.

[/ QUOTE ]

Instead of putting the tap in the chuck. I put a small 3/16 inch brass tube in the chuck and used that as a guide. The end of the tap is tapered and bigger than the tube. The tube centered the tap and provided downward pressure. I turned the tap by hand using a small wrench.

I used the same technique to tap a hole in the end of an arbor mounted in the lathe's chuck. I put the tube in the tailstock's chuck and held it steady with a wrench as I turned the chuck by hand.

Thanks for all the help, folks.

Daniel


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## MoonRise (Jun 10, 2005)

Daniel,

Thanks for the follow-up on your project. It's nice to hear how it all came out, mistakes and fixes and all.


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