5c collet chuck

[kd0afk]

Happy to see you enjoyed it even though you had a few problems. Part of learning.
Hope the rest of it comes out ok for you.
Once you complete it and use it you will be happy with the results.
The accuracy is a very nice addition.

So .0015" tir is good?
I think what happened is that the washer I used on the jig wasn't completely flat so it was askew. The holes are not aligned. Also the main body is a few thousandths off and it's visually distracting.

 

[mc_n_g]

I did not do any final boring of the 5C hole until I had everything together, including the threaded nut and bearing races, this way all errors would be minimized.
I did not do the final shaping of the outside of the chuck until everything was together.
The area where the two halves were joined was also finished in this final process so I could always get the chuck back together with minimal error.
If you bored the hole and taper when all parts were together try and determine where your error is.
Are you reading the error from the piece of metal sticking out from a piece of rod being pushed into the chuck?
How does that compare to the error using an indicator of the bored 5C hole? If the 5C hole is almost 0 then you have a problem with your 5C collet.
Good is a relative measurement. Is 0.0015" good to you? I don't know.
Can you verify the proper seating on the threads when you take of and put back on the chuck? Are the measurements in the TIR the same?
Too many variables to determine via text.

 

[mc_n_g]

I just read your previous post again. What is the TIR 0.0015" or 0.00015"?
They give completely different interpretations of accuracy.
If it was the later I think that is much better and you do not have any problems with it.

 

[kd0afk]

I just read your previous post again. What is the TIR 0.0015" or 0.00015"?
They give completely different interpretations of accuracy.
If it was the later I think that is much better and you do not have any problems with it.

Sorry, .0015 is the correct measurement.

 

[kd0afk]

The only part of the outside I did before assembly (minus nut) was to turn it so I could chuck it up. After machining the inside and the backplate I mounted the main body to the backplate. Then I bored the collet hole and the taper. Then I finished up the nose. Some of the collets I have are a very snug fit and I still haven't lapped the bore yet so the accuracy may improve. I will machine the nut today, assemble it and see what's up then. I will double check the runnout of the bore hole.

 

[kd0afk]

I checked the spindle and it's running as true as I'm able to measure. 0.0000" runnout. I then checked the collet chuck bore and got a tir of. 0015" again. I will finish up what's left and check it again and see what's up.
If it doesn't improve I don't know how to make it better. I took very light cuts with a very ridged boring bar and made sure everything was either locked down or tightened up.
If it doesn't get any better It will still be way more accurate than my 3 jaw which is at a tir of. 003"

 

[kd0afk]

I've been thinking about it and there should be absolutely no reason why the tir should be as bad as it is assembled or not. Can someone lend some advice on this? If the chuck is mounted on the lathe and fits perfectly (no play at all) and the hole is bored then it should be concentric right?

 

[mu38&Bg#]

Is the runout on the chuck body consistent when the chuck is remounted? If it is, retruing the collet taper after everything is done should fix it.

If it's not consistent, poke around and see what's causing it:
Did you make sure the spindle and chuck threads and shoulder were clean when you mounted it to cut the collet taper?
Any burrs or ridges?
Chamfer to clear the radius on the shoulder?

Greg

 

[kd0afk]

Is the runout on the chuck body consistent when the chuck is remounted? If it is, retruing the collet taper after everything is done should fix it.

If it's not consistent, poke around and see what's causing it:
Did you make sure the spindle and chuck threads and shoulder were clean when you mounted it to cut the collet taper?
Any burrs or ridges?
Chamfer to clear the radius on the shoulder?

Greg

The runnout is the same if I recount. Spindle and Chuck threads are clean, I just got an air compressor and I love having a clean spindle. No burrs or ridges. The chick seats very nicely on the register. It is a Hardinge backplate already machined to fit the spindle. I had to take a skim cut to fit the spindle.

Could I have been taking too light a cut? It was a brand new bit. Should I swap it out with an insert with a positive rake?
Also, I'm unfamiliar with insert terminology.

 

[mu38&Bg#]

The collet taper was cut with no changes to the chuck (reassembly) and there is runout? Try to determine where this is coming from before cutting any more metal. Did you take the chuck apart? As suggested above, the exterior and taper should be the last operation to keep things in line. Cast iron should machine well. I used a carbide tippped boring bar when I trued my ER16 spindle, but that was made of steel. The only other thing I can think of is material variation, but I think this product is known to be good.

Greg

 

[kd0afk]

The collet taper was cut with no changes to the chuck (reassembly) and there is runout? Try to determine where this is coming from before cutting any more metal. Did you take the chuck apart? As suggested above, the exterior and taper should be the last operation to keep things in line. Cast iron should machine well. I used a carbide tippped boring bar when I trued my ER16 spindle, but that was made of steel. The only other thing I can think of is material variation, but I think this product is known to be good.

Greg

I have repeatability when I disassemble. There were no changes to the chuck after the bore and before machining the collet taper
I'm completely stumped. When I was taking the light cuts (with the brand new insert) it was removing material the whole way and the sound was a nice cutting sound and consistent and not a scraping sound.

 

[mu38&Bg#]

By repeatable you mean the runout is in the same place, or you consistently get the same TIR reading?

Now, I'm confused. You had the chuck together and cut the exterior and the taper. We are assuming it was true at this point because we expect it to be. After this we have to assume it was dismounted and/or disassembled. Now, you check it and it's not true. To me this means there was something behind the chuck backplate that threw it off when those cuts were made. If that's all it was, just skimming everything should fix it. This time, check the runout before moving anything. If there is still runout after cutting, something else is wrong. Could be material hardness is inconsistent, could be spindle bearings are loose/worn. It's an unusual situation you have, but somewhere there is an answer. A small nose radius tool with a sharp edge will help reduce tool pressure.

Greg

 

[kd0afk]

By repeatable you mean the runout is in the same place, or you consistently get the same TIR reading?

Now, I'm confused. You had the chuck together and cut the exterior and the taper. We are assuming it was true at this point because we expect it to be. After this we have to assume it was dismounted and/or disassembled. Now, you check it and it's not true. To me this means there was something behind the chuck backplate that threw it off when those cuts were made. If that's all it was, just skimming everything should fix it. This time, check the runout before moving anything. If there is still runout after cutting, something else is wrong. Could be material hardness is inconsistent, could be spindle bearings are loose/worn. It's an unusual situation you have, but somewhere there is an answer. A small nose radius tool with a sharp edge will help reduce tool pressure.

Greg

There was nothing between the spindle and Chuck except for a thin coat of oil, no chips, no burrs, nothing. I didn't think to check if the runnout position changes with removal and replacement of the chuck but the runnout amount is consistent. And it's repeatable after disassembly and reassembly. Spindle bearings are in as good a shape that they could be in, spindle play (deflection) is .003" when I do a lift test.
I will change the insert and take a skim cut and if that doesn't help I'll try the Dremmel and see if I can't grind it.
I'm completely stumped on this. But it's typical with my life. I can do everything right and still get crapped on for my reward.

 

[kd0afk]

Just to clarify, TRI is the from the high reading to the low reading and not how much above and bellow 0 right? Zeroed on the low spot my dti goes from 0-.0015" that is TRI right?

 

[Swifty]

TIR, or true indicator reading, is the total reading in one revolution of the workpiece. With .0015" reading, this would mean that the piece is .00075" off centre, because half the reading is below centre and the other half is above centre. Similar when using a 4 jaw chuck to machine an offset cam, to get .100" offset on a round piece, the indicator will show .200".

Paul.

 

[kd0afk]

I just checked and I'm at .001 tir and all but my oldest collet fits well. I can live with that.
Thanks for the help.

 

[kd0afk]

I just finished the body except for the bearing race. I still have the nut to thread and then I'll do all of the grooves at the same time. Can't wait to use the thing.

 

[kd0afk]

It's finished. The runnout didn't improve but it didn't get worse either. I'm not sure what to lubricate the bearings with oil or lithium white grease. There really isn't a way to lubricate the chuck completely unless it is disassembled.

 

[kd0afk]

Today I'll make a new nut. Somehow my setup got tweeked and it came out horribly wrong. It works but it looks like poop. I have a different strategy this time and I think it'll come out much better.

 

[kd0afk]

I don't know what happened but I chucked up a 1" piece of round bar in the collet chuck and I got .0005" tir. I can live with that. I guess the bore is concentric it's just out of round.
Since it's concentric would lapping the bore and taper help get rid of that pesky .0005"?