5C Collet Chuck from LMS

[Maryak]

Yes, shrink fitting cast iron is a "Fine Line between Pleasure and Pain."

For parts operating at ambient temperature I would use a 1:1 fit. For parts at elevated temperatures, e.g. sleeving a pump steam cylinder. 0.0005" per inch of cylinder diameter, absolute maximum 0.001" per inch of diameter and that's only when you have plenty of meat left on the bored out for sleeve original. Any more interference and your liable to crack the original casting. Then you have to have a new one cast........................and "The Beat Goes On."

Amazing how the old pop songs fit real life. ;D

Best Regards
Bob

 

[vascon2196]

I checked the runout on the adapter plate it it was o.k.

I then stepped down to the collet chuck flange and it was 0.005" out. I tapped a hammer around the face and got it down to 0.002" but on the flange. It still wobbles like crazy on the business end of the chuck. I will attempt more tomorrow....just don't want to make it worse by fussing with it. Any of you pro's live close to Providence, RI.?

I'll flip the chuck around and hold it in my 3-jaw to check the back pilot hole tomorrow.

 

[Blogwitch]

Chris,

It looks like you are getting very frustrated by it, don't go doing anything rash. Take things in logical steps, and write down the readings of each stage you check.

Where you are showing your clock measuring has no bearing on the runout of the chuck, in fact, when the whole setup is running true, that area is usually turned down until it is just a tiny bit larger than the OD of the chuck.

I honestly wish I could be there with you, but the air fare is a little prohibitive, I just hope someone local to you with experience of such things can help you out.

I don't think holding it in your three jaw will give you any meaningful results, as you can almost guarantee your three jaw doesn't run perfectly true to begin with.


John

 

[steamer]

Chris,

As Bogs has stated....now is the time to make haste ...slowly.
A three jaw by itself is a terrible standard....they all run-out

What you need is a reference, and artifact to compare to. Something that is straight, round, and has no run-out.

As mentioned earlier, I would take a piece of stock, steel would be my preference, but anything will do, and turn a nice, clean, 3/4" diameter shaft with the stub end mounted in what ever other chuck you have. Make it long enough to go through the chuck about 1" beyond

Once turned, and to size.....DON'T even think about MOVING IT!

You now have an artifact...a reference standard to compare against that shouldn't have any run-out what so ever. If you take it out of the three jaw now, it will never go back the same way, so like I said....don't touch it!

Back your tailstock away, and mount the collet chuck on this shaft with the back of the chuck facing the tailstock.

Tighten the collet chuck down on your "standard", and bring your tailstock up to support the bar and the added weight, and now measure the face run-out and the register diameter run-out. That will be what your interested in.

As Bogs has stated, right it down....on paper, and keep track.... A notebook is a godsend here. Actually a note book is a good idea anywhere!

do this and get back to us.....it will start to all make sense by then.

I'm in North Central Mass....but I work in New Hampshire....I don't get to RI much.....but I will be glad to help any way I can.

Take your time and think about what your doing......

Dave

 

[BobWarfield]

No idea why the "other chaps" like the shrink fit. As for me, it's easy to do. The difference in size is about 4 tenths, which is what I wound up with while shooting for 5 tenths. That was easy enough for me to machine and the process of putting the pieces together is also obviously very easy. I was simply looking for a fit that would be precise and not require me to drill mounting holes and fool around.

It has worked well for a couple of years now, but let's consider what stress it may be causing. The formulas are called out in Machinery's handbook.

For my two pieces of cast iron that are shrunk with a 4 tenths difference, this exerts about 5800 lbs per square inch. The spigot is probably about 0.2" deep, so we can reckon a little more than 1100 lbs per inch of circumference. No question that it is on there tight. That's good, flying lathe chucks are bad!

The tensile of the cast iron is 25 kpsi, so I have almost a 5x safety factor there. I can live with that. I'd be careful about cranking up something more like the 0.005 potential fit the temp differences would allow though, LOL.

If you're concerned, skip the shrink fit and just focus on an accurate fit with bolts to hold it together. Better yet, make your own "adjust-tru" design. My main interest was in properly machining the recess to fit the spigot, and in always mounting the chuck the same way. It made a cheap 5C chuck into a nice bit of tooling for me.

Cheers,

BW

 

[vascon2196]

Chris,

It looks like you are getting very frustrated by it, don't go doing anything rash. Take things in logical steps, and write down the readings of each stage you check.

Where you are showing your clock measuring has no bearing on the runout of the chuck, in fact, when the whole setup is running true, that area is usually turned down until it is just a tiny bit larger than the OD of the chuck.

I honestly wish I could be there with you, but the air fare is a little prohibitive, I just hope someone local to you with experience of such things can help you out.

I don't think holding it in your three jaw will give you any meaningful results, as you can almost guarantee your three jaw doesn't run perfectly true to begin with.


John

Thank you John. I am getting frustrated but it's simply because I've never done anything like this before. Once I'm finished with this (and it's documented) I'll be much happier.

Chris

 

[vascon2196]

Chris,

As Bogs has stated....now is the time to make haste ...slowly.
A three jaw by itself is a terrible standard....they all run-out

What you need is a reference, and artifact to compare to. Something that is straight, round, and has no run-out.

As mentioned earlier, I would take a piece of stock, steel would be my preference, but anything will do, and turn a nice, clean, 3/4" diameter shaft with the stub end mounted in what ever other chuck you have. Make it long enough to go through the chuck about 1" beyond

Once turned, and to size.....DON'T even think about MOVING IT!

You now have an artifact...a reference standard to compare against that shouldn't have any run-out what so ever. If you take it out of the three jaw now, it will never go back the same way, so like I said....don't touch it!

Back your tailstock away, and mount the collet chuck on this shaft with the back of the chuck facing the tailstock.

Tighten the collet chuck down on your "standard", and bring your tailstock up to support the bar and the added weight, and now measure the face run-out and the register diameter run-out. That will be what your interested in.

As Bogs has stated, right it down....on paper, and keep track.... A notebook is a godsend here. Actually a note book is a good idea anywhere!

do this and get back to us.....it will start to all make sense by then.

I'm in North Central Mass....but I work in New Hampshire....I don't get to RI much.....but I will be glad to help any way I can.

Take your time and think about what your doing......

Dave

Thanks Dave!

Let me get this straight.

1. Mount my 4-jaw chuck
2. Turn a piece of round steel bar stock to 3/4"
3. Put a 3/4" collet into the LMS collet chuck to mount on my newly turned steel bar
4. Use tailstock to hold it all together (with a center I'm guessing?)
5. Check for runout on the register diameter and back face

Is this correct?

Chris

 

[steamer]

Yes.

Possible pitfalls that are there and to be aware of.

If you have a cheap collet.....it may have run-out all its own. This run out may cancel the runout in the chuck...or make it worse. No way or knowing.

If you have or have access to a very good quality 3/4" collet...nows the time to use it! Lyndex makes very good collets.....

Now baring getting a good collet. There is way to remove the collet run-out from the equation

Turn the arbor to the dimensions of the collet. This is a more advanced way, and I hesitate to recommend it to you unless your experienced enough to deal with it......only you can answer that.

I hate to complicate things....but some times it's complicated,,, ;D

Dave

 

[vascon2196]

O.K.

Here goes....

I installed my 4-jaw chuck. Turned a piece of stock to 1". Mounted the 5C collet on the 1" diameter stock. Checked for runout on the chuck pilot hole and face.

Chuck pilot hole (register diameter) has a runout of 0.015".
Chuck pilot hole face has a runout of 0.006".
Outer flange face has a runout of 0.010".

I took a light chip on the O.D. and got it within 0.001" but have not taken it off the lathe yet. Right now now the 4-jaw chuck, 1" diameter stock, 1" collet, and collet chuck are in-line and still on the lathe.

Now what? Can I now mount the collet chuck on the adapter plate and re-mount to the lathe?

I know you guys will know what to do next...

Thank you!

Chris

 

[steamer]

Hi Chris,

Just saw your reply...sorry about the delay.

My question to you is. Do you trust the collet your using?

This is important. Your accuracy is solely based on this collet!

Assumeing you do....you should be able to make the cuts you need.

If you don't, or don't know , STOP.

Send me a PM off line, I can help you with the collet if required.

Let me know...


Dave

 

[vascon2196]

Dave,

The collet is brand new...at least it looks like it's never been used. I'm going to attempt to finish this up tomorrow afternoon so hopefully I'm going about this the right way.

Chris

 

[steamer]

Good , new collet.

Now...a good brand name or "other"?

Just trying my best to get you off to a good start....

Dave

 

[vascon2196]

I can't remember the collet name at the moment.....I think it starts with an "L"

 

[mu38&Bg#]

Lyndex don't put their name on them, but are good quality.

 

[jackfrost]

What ever happened to this Chuck issue ?

 

[vascon2196]

It works good now....thanks to everyone's help.

Chris