SpudFiles

I recently bought a nice tap and die set for the weird use of..cutting threads.

I do it all correctly, use an appropriate lubricant, reverse cutting to break off chips et cetera et cetera.

Though I constantly run into the problem of round materials (aluminum especially) slipping in the vice and gouging into the metal. After using the lathe I end up with the tap slipping in the drill chuck or the arbor not holding well enough.

How do I combat these problems? Thanks guys

So you are using the lathe to do the tapping? Or is this a hand tap and die set? I can't picture how you are doing this.

I'm using a hand tap and die set. I want to use the drill chuck in my lathe to hold the tap, but it slips at the arbor or in the chuck.

Tapping with a cutting tool is slow, sloppy, annoying and will often end in tears.

Can't you clamp stuff harder in the chuck?

You could solve the slipping at the arbor by first starting to tap with the tap chucked in the drill chuck, and when it starts slipping go on by hand with a tap handle.


Do you have to put a lot of force on it? Is the tap sharp? Is the hole you are tapping large enough? (a slightly smaller diameter is acceptable, but will require more force to tap)

IMO and if i understand correctly.

wouldn't it be harder to use a lath to do this as the speed of the lathe and feed of the chuck will have to be perfect and you won't be able to stop and start like you would if you did it by hand?

Taps are square ended, MOST chucks are 3 pronged this would be hard to get a good centered grip.

He probably turns the lathe by hand, and lets the tail stock slide freely so that it will get pulled in to feed (possibly pushing the tailstock too.)

The 3 pronged chuck will probably grab the tap past the square end, where it is round.

I would just do it by hand. Using a lathe sounds like a PITA. You don't even need a vice at all. Just hold the part and tap it by hand. Aluminum is easy that way.

This article/link may be of interest for some ideas and methods for taps/dies in a lathe tailstock.

http://nbutterfield.com/d.aspx

You make a V channel out of two plates, then put the pipe in it and clamp it to the table. I think that's one of the first things i was taught about the drill press in my shop class.

He probably turns the lathe by hand, and lets the tail stock slide freely so that it will get pulled in to feed (possibly pushing the tailstock too.)

The 3 pronged chuck will probably grab the tap past the square end, where it is round.

Exactly correct sir.

Just hold the part and tap it by hand.

You either have monstrously strong hands, material with large handles to hold onto or are tapping into foam.. Not easy to do with 1" o.d. high quality aluminum tube stock. (I'm tapping 20mm+ threads into the breech ends of pipe).

Thanks dewey, I think I'll make a simple tap holder which is held by the drill chuck (not to take load, only center and guide the tap) with a handle similar to a vice to turn the tap, with something to lock the chuck. Even stepping on the foot brake.

And as a last resort, I could try Hi's method.

You could solve the slipping at the arbor by first starting to tap with the tap chucked in the drill chuck, and when it starts slipping go on by hand with a tap handle.

Yes, but holding it in something like a vice will end in marring and damage to the pipe. Holding the foot brake on and turning the handle by hand would work I suppose.

I drilled out my piston with a 1" drill bit on a drill press by holding the round bar stock in a huge pair of pliers with cloth wrapped around. Tapping shouldn't be too big of a deal with pliers in one hand and a tap in the other.

inonickname wrote:I do it all correctly, use an appropriate lubricant, reverse cutting to break off chips et cetera et cetera.

I constantly run into the problem of round materials (aluminum especially) slipping in the vice and gouging into the metal.
How do I combat these problems?

Change the type of tap you're you're using. Switch to a "Spiral Flute" tap. They are designed for high speed ridged taping (a CNC feature) so they don't have to be reversed to break the chips while taping. You just crank them down like a bolt and the long, continuous stringy "chips" feed out the top. They cut with almost no resistance and cut extremely clean in aluminum or steels. If you once try a Spiral Flute Tap......you may throw away your new tap set. Spiral Flute taps are expensive compared to conventional taps but, well worth the difference in cost.

Perhaps peruse through this post. Bloody interesting site as well.

http://www.homegunsmith.com/cgi-bin/ib3 ... =8;t=22423

inonickname wrote:I recently bought a nice tap and die set for the weird use of..cutting threads.

I do it all correctly, use an appropriate lubricant, reverse cutting to break off chips et cetera et cetera.

Though I constantly run into the problem of round materials (aluminum especially) slipping in the vice and gouging into the metal. After using the lathe I end up with the tap slipping in the drill chuck or the arbor not holding well enough.

How do I combat these problems? Thanks guys

Use the lead screw to drive the carriage and cut threads the normal way on a lathe. Light multiple passes prevent chuck slippage.

www.metalartspress.com/PDFs/60_degree_threads.pdf

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A short video showing thread cutting is here. The camera is mounted on the moving carriage so it appears the rod is moving out instead of the carriage moving sideways.

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Tighten all 3 positions/holes in you tail stock chuck (drill type chuck?). As for not marring finished work with a vise, do the work you need the vise for first, then the finishing with the lathe. You can also wrap your finished work with cut up aluminum cans or rags then clamp your work tight so it don't spin.