Too close to the spindle.

[davidwdyer]

I noticed you used a die to cut the threads on your holder for the cap.
Die cut threads are not accurate axially or radially. Not enough precision
for a spindle chuck. Consider lathe cut threads are really the process
that gives you the accuracy best for an application like this.

-Doozer

Well... the threads were cut with a die holder on a lathe tail stock. I can detect no run out when I use it, mainly for drill bits.

Drill bits have run out anyway so I have not lost anything it it has a little. So far I'm very satisfied for the result and have not needed it for any work

that requires getting between + - .001. As for tapping, the tap follows the hole.

Obviously, I had to cut the threads in the cap with a single point and not hit the end and break things. That was fun.

I think I had to turn the chuck the last little bit by hand.

The truth of it is, when I can use a die in the tail stock, I use it!

[bborr01]

Better to have tools you don't need, than to need tools you don't have.

That was one of my taglines until the software decided we didn't want them anymore.

[Doozer]

The tap does not follow the hole just the same that a die does not follow a shaft.
I either case, threads will not be straight and concentric. Maybe to a tolerance
that works for you, and that is fine. Just be aware that you are making assumptions
or engaging in faith based machining.
If you need to tap something, and you want the threads concentric with another
feature or axis, the procedure is to make a mandrel in the lathe, cutting new threads
in the same chucking. Then screw the tapped piece on your newly made mandrel
and turn the subsequent features that need geometry relative to your tapped threads.

-Doozer

[Jim Stewart]

That was one of my taglines until the software decided we didn't want them anymore.

Brian, it still is in your tagline. Perhaps you're set up to ignore sig lines? Can you see mine?

-js

[BCRider]

The tap does not follow the hole just the same that a die does not follow a shaft.
I either case, threads will not be straight and concentric. Maybe to a tolerance
that works for you, and that is fine. Just be aware that you are making assumptions
or engaging in faith based machining.
If you need to tap something, and you want the threads concentric with another
feature or axis, the procedure is to make a mandrel in the lathe, cutting new threads
in the same chucking. Then screw the tapped piece on your newly made mandrel
and turn the subsequent features that need geometry relative to your tapped threads.

-Doozer

I do agree that when accuracy is paramount it's good to single point the thread. But at the same time due to the shape of the thread form dies and taps will tend to self center themselves if they are started well.

It would be very interesting to run a die over some stock with a die holder and then put the small ball of a DTI into the V and roll the chuck over while engaged in the suitable thread gearing to see how much wobble there is. The next time I run a thread of suitable size to accept the ball nose I think I might try that myself. Or anyone else?

[BCRider]

My new toys ....er.... TOOLS just came in. A fast and quick inspection indicates that this Accusize ER20 chuck is dead nutz on. I only tested it with the .001 dial indicator quickly in my lathe. And the 3 jaw was holding it with a .001 runout. But I marked the "high" spot and the ID of the taper was out by the exact amount in exactly the same place. So things are looking good that this is a very nicely made item. I'll do a mini review next week with more serious testing. But right now I'm pressed for time getting ready for some events on the weekend.

For this post I'll focus on how it fits and how I'm looking to use it for extending my mill's reach when working in close to features that limit access.

The pictures should be pretty self explanatory. In the first two where it's held by the collet from the nose of the collet nut to the face of the lower bearing cover is 2.75 inch. With 1" of the shank still in the collet the reach is 4.25. With the 3/4" end mill holder as a solid extension the reach with the collet chuck fully inserted is 5.37. And extended to where it catches the set screw fully it is 6.5 inch.

[BCRider]

Pictures per post limited.... Part 2

The collet nut is 1.32" diameter so I might look at options for reducing that 3/4 inch holder from 1.7" OD to more like 1.4 or 1.5. And put in a smaller set screw since using it this way would be a light duty sort of deal.

All in all I'm happy that I've got my options now for working out a bit when there's a feature blocking access to normal setups. Light cuts only of course. But at least now they are possible.

And here's two options for attacking the facing job on that angle plate. Using the big end mill holder will be the more sturdy so that's how I'll go. I will also need to make up a small flycutter with a 1/2" shank.... Or perhaps a small but handy size with a 3/4" long shank and "skip the middle man" for this and some other uses. I'll see.

[Doc Nickel]

They make "slim" collet nuts for ER holders. You have to use a funky spanner to tighten them, but at that size, I think it's close to half an inch smaller in diameter.

Doc.

[BCRider]

I like your thinking Doc.

But for the cost I might just bite the bullet and buy a whole other chuck with the small nut. The nut is $13 up my way (or down my way from your perspective ) and THIS CHUCK I found is $38 with the smaller nut.

If I'm scaling the side view correctly it looks like that nut is about 1.08 to 1.10 inch diameter. So enough to make a difference when things get tight. No user reviews though. No reviews of a couple of their other listings either. That seems odd unless they are a brand new Amazon member. Ah well, it's only $38. About the cost out for a night at the pub with a beer or two.