True up 5c collet chuck nose with a boring bar?

[jmecruz]

I got LMS 5c collet chuck it has about 2 thou run out on it. I was advised by Roger at LMS that concentricity only needs to be achieved in the nose front area where the collet sits. (provided everything is sitting correctly behind it and chuck is mounted snug tight indicated with witness marks.) no runout on my spindle or adapter plate anywhere. I have seen the successful dremel tool post method to true out the front be very successful. I was going to make a dremel tool post holder from some steel and harden it. but before I do, my question is can I use a boring bar to true out the front going glow of course and get the same results??

 

[Swifty]

I would not touch the nose with a boring bar, it will lead to bigger problems. You mention slow speed, most hard turning is done at a higher speed, light cuts and using ceramic tips. If the collet chuck is a permanent attachment, can you not give a slight clearance to the location spigot and then tap the chuck into true position. Have you tried tightening the bolts up and checking how the nose reacts using a dial indicator, you may be able to apply more pressure to one bolt to adjust runout.

Paul.

 

[rklopp]

I trued up a Hardinge Sjogren collet chuck by machining the back, which in my case was a D1-3 camlock mount. I turned a short stub with the collet thread and profile, and then, without removing the stub from the lathe, grabbed the stub the Sjogren. Then, I lightly machined the back of the Sjogren.

You should do some sleuthing with a dial indicator to figure out the nature of the error, likewhether the error is due to radial runout (like a crank) or angular runout. You might consider correcting an angular runout problem by scraping.

 

[jmecruz]

the nose indicates the least runout now where I have the bolts. The adapter plate will never be removed from this collet chuck but I put marks on it anyway for fun. I have another plate for my 4 jaw. I actually started out with eight thousands and got it down to here. I am sooo close

Please help me

 

[rodw]

Hmm, I just fitted a LMS collet chuck yesterday and I have the runout to 0.00039" (.39 thou) when measured on some 12mm drill rod chucked up.

Is the boss too high? I initially measured the recesson the chuck as being 5mm deep but it was shown in the specs as being 4mm so after I shortened it, it was all good. I did find however that how you tightened it did affect the runout. I started to think like it was a 4 jaw chuck with a single bolt on one side paired with the other two bolts controlling the imaginary opposite chuck jaw. I then tightened the single bolt first, trying different combinations of bolts.

There is some details in my "Rod's Aussie Shed" thread.http://www.homemodelenginemachinist.com/f15/rods-aussie-shed-19885/index23.html#post249850

 

[MachineTom]

A Dremel is not a precision tool, don't treat it as such. Sleeve bearing, plastic housing, Really!

The tool to use is a tool post grinder, with a small fine stone, set it on the compound, get the spindle dead centered and set the compound to the single angle for a 5C, 20° if I recall. A cut with a TPG is about .0005" or less, There is some spring with the extended nose of the grinder, so deal with that on your return.

I assume you don't have a TPG, so ask around for someone that does, and can provide info on all the details of its use.

 

[Swifty]

I'm always loathe to alter anything purchased until all other avenues have been addressed. Check the mounting again, work on the bolt tightening etc. Re grinding on a new item should be a last resort.

Paul.

 

[jmecruz]

ok I am down to just under a thousandth. The trick is super tight fit with adapter plate. Super tightening the bolts and the tightening sequence like a 4 jaw chuck indication only you have 3 bolts. A mallet and some time patience. I am gonna call it a success at about .0008. on a 3/4 inch rod stock about 1/2 inch out from the collet. I did not grind the nose but that probably would defeat the remaining runout

Thanks for the help

Hari Shiva

 

[Swifty]

Just make sure that the stock that you are using to check the runout is truly round. A ground dowel would be ideal to use, or even a milling cutter shank. If it looks OK, I would remove the test part from the collet, then replace it in a different position and see if the reading is consistent.

Paul.

 

[jmecruz]

pretty sure it is round I trued it on my 4 jaw indicated dead spot on. I also checked the collet all slightly less than a thou

 

[rodw]

It's good you had a win with this. I spoke with an experienced machinist when I had a similar result and he thought there was nothing to worry about. Then I got it a bit better (after making it worse initially)...... I would not touch it again.