Creating a concentric reference surface on ER collet adapter

[Aaron_W]

I have the same Taig ER16 chuck and it fits my Sherline without issue. I've seen others using it as well, and have never heard there was a need to modify it.

Usually the Taig lathe is the one that needs to adjust for Sherline hardware. Taig on Sherline usually works as is, but Taig users will often fit a thin spacer (washer) onto the Taig spindle when using Sherline tooling since the Sherline tooling is made for a shorter spindle.

There may be something weird going on with your chuck.

 

[Shotgun]

Concentricity isn't a big deal here, as you're trying to shear the bottom off in a flat plane. Getting the piece rigidly mounted without taper is the critical concern.

If I couldn't get the adapter mounted in the chuck with the ER nut removed, I'd indicate it in a mill and take a facing cut. If all you have is the lathe, mount a tool in the chuck as a make shift fly cutter then mount the adapter to the cross slide. Again, indicating the base.

 

[ChazzC]

It is not, fortunately


I don't see where else it could, so I'm fairly sure it's supposed to register against the face of the spindle. I appreciate your input!

Yes, the register is the face of the spindle. Here is what Little Machine Shop sells to go the other way (Sherline chucks, etc. on a Taig):

 

[Nubbles]

On a regular thread on chuck mount the threads don’t position the chuck to the spindle.The face and the counter bore does. The threads just hold the chuck on the spindle. This is what you are proposing to cut off. I haven’t worked with ether a Sherline or Taig so I can’t say if they are the same as a standard thread on chuck or not. Just be careful that the chuck will still has a reference to center on the spindle after it is machined.

Pretty sure for these machines the below face is the reference surface, it's the only part other than the threads that the chucks make contact with. I certainly wouldn't be surprised if this is not the same as a "normal" lathe.

I have the same Taig ER16 chuck and it fits my Sherline without issue. I've seen others using it as well, and have never heard there was a need to modify it.

Usually the Taig lathe is the one that needs to adjust for Sherline hardware. Taig on Sherline usually works as is, but Taig users will often fit a thin spacer (washer) onto the Taig spindle when using Sherline tooling since the Sherline tooling is made for a shorter spindle.

There may be something weird going on with your chuck.

I don't know if there is a need, true. By my measurements, because of the throat the Taig adapter has before the threads start, roughly 1/3 of the threads on the Sherline spindle won't be engaged, and it only has about 3 threads. The Taig's threads start about 90 thou after the Sherline's. Was just thinking if I could get it shortened a bit that'd be better.

Do you have a milling machine? Could you lock the chuck in the vise and indicate it dead vertical off the inside machined bore, then gently fly cut the excess material off?

No milling machine unfortunately (yet). And no test indicator limits my indicating options. I've certainly been looking at buying one, just haven't had an explicit use for it yet.

If all you have is the lathe, mount a tool in the chuck as a make shift fly cutter then mount the adapter to the cross slide. Again, indicating the base.

I do have a Taig 3/4-16 fly cutter, hmmm...

 

[Shotgun]

A test indicator can be had for $15 off Amazon, and once you have it you'll use it constantly. Get you one of the cheap Noga arms while you're at it.

Also, from my limited experience, larger lathes that use a threaded spindle have an unthreaded area right behind the threads. The chuck then registers on both it and the landing area you indicate in the picture.

 

[Nubbles]

wwwwwwwwelp, it's about as good as I can measure with the tools I have. Indicator barely wiggles. I know there's some error since it isn't square to the piece, but it's not a huge angle so not a huge error and there's no way to get it square.

At this point I'll either go forward with the plan, buy more things to measure better/do a different plan, or decide it's good enough as it is and leave it be.

Cheers everyone for the discussion

 

[Shotgun]

@Nubbles, what isn't square? That looks like a decent setup as long as you take light cuts and keep the tool sharp.

 

[Nubbles]

@Nubbles, what isn't square? That looks like a decent setup as long as you take light cuts and keep the tool sharp.

The indicator is at an angle to the face I'm measuring. Doesn't that create essentially cosine error with the reading?

But yeah, light cuts for sure.

 

[Shotgun]

Ah!
Yes. It creates cosine error.
But. It doesn't matter.
In this instance, you don't care about the absolute measurement. You care that the needle doesn't move as the adapter turns.