Jacob's Rubber Flex Collet Chuck-Lessons learned

Janderso

Janderso

Jeff Anderson
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Mar 26, 2018
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I traded for two Jacob's Rubber Flex Collet chucks a few months ago. Having no experience with them I had no expectation as to accuracy or total indicated reading of run-out.
The first time I mounted the better of the two, I placed a 1/2" to 9/16" (I think) put a piece of stock in and checked TIR. I was very disappointed to find it was in excess of .005".
I took them apart and cleaned-oiled them. I also used my precision stones (thanks Bob) to de-burr the outside of the collets. The set came with three boxes of collets including the square and hex I believe.
I checked TIR again, no better. Then I watched a Youtube video on a method of mounting the D1-6 chuck loosely and tapping like you would a 4 jaw chuck. That helped a little bit but still not very good.
Last weekend I decided to get to the bottom of this issue. I decided I would try clocking the way I mounted it and try to identify and mark the best clocked position true to accuracy. In the process, I found that when I really tightened the lugs, the TIR got much better.
Eureka! That's the trick? Tighten the lugs of the cam lock? Really tight? = YES.
I have less than .001" on every collet I tried. Each collet was cleaned and deburred.
If you have struggled with your Flex collet chuck, try it.
I hope it works for you.
 
Janderso said:
I traded for two Jacob's Rubber Flex Collet chucks a few months ago. Having no experience with them I had no expectation as to accuracy or total indicated reading of run-out.
The first time I mounted the better of the two, I placed a 1/2" to 9/16" (I think) put a piece of stock in and checked TIR. I was very disappointed to find it was in excess of .005".
I took them apart and cleaned-oiled them. I also used my precision stones (thanks Bob) to de-burr the outside of the collets. The set came with three boxes of collets including the square and hex I believe.
I checked TIR again, no better. Then I watched a Youtube video on a method of mounting the D1-6 chuck loosely and tapping like you would a 4 jaw chuck. That helped a little bit but still not very good.
Last weekend I decided to get to the bottom of this issue. I decided I would try clocking the way I mounted it and try to identify and mark the best clocked position true to accuracy. In the process, I found that when I really tightened the lugs, the TIR got much better.
Eureka! That's the trick? Tighten the lugs of the cam lock? Really tight? = YES.
I have less than .001" on every collet I tried. Each collet was cleaned and deburred.
If you have struggled with your Flex collet chuck, try it.
I hope it works for you.
Click to expand...
I have the set and seem to have extra run out BUT I have L00 mount. I do like the flex ability of the Collets. I got my chuck for $30 sold as not working parts. Helps if you pull the ring out to mount the Collets.
 
Ed ke6bnl said:
I have the set and seem to have extra run out BUT I have L00 mount. I do like the flex ability of the Collets. I got my chuck for $30 sold as not working parts. Helps if you pull the ring out to mount the Collets.
Click to expand...

I have an L1 mount and find that my TIR is measured in the low-end of tenths. I would expect L-series mounts are much more repeatable due to the taper.

I DID find when I got mine that I had to adjust the backing plate connection to match my lathe, but my runout is basically non-existent.
 
I will have to see if there is some adjustment in the back p look plate, thought it was inteagal to the chuck
 
Thinking about having to really pull the chuck into the tapered register makes me think the fit is tight, that's a good thing right?
I always make sure to run my hand through both mating surfaces to watch for chips/debris.
 
I got a Jacobs spindles nose collet chuck with my lathe, but it had no backplate. I bought a semi-finished backplate with an l00 mount and cut it to fit the chuck. I also have basically 0 runout. I think that cutting it on the lathe had a lot to do with that. I really that chuck.
The only bad thing that I have heard about the Jacobs sncc is that if you take very heavy cuts, the metal fingers in the collet can lay over. I don't think that I could ever push things that hard with my 1hp Clausing.
 
Yeah, I can see a potential problem with taking an aggressive cut. Unless the steel fingers were touching metal to metal (bottomed out) there has to be some lateral flex.
It's a quick way of holding cylindrical parts that should be able to repeat. I haven't tried yet.
 
Yes, extremely repeatable. I read somewhere that the reason that it was discontinued was because of the price point, around $6000 in todays dollhairs.
 
The manual mentions that multiple impacts from the tightening ring insures the grip on the part.
I have suspicions that the TIR is reduced as well when the collet is fully seated
 
Ulma Doctor said:
The manual mentions that multiple impacts from the tightening ring insures the grip on the part.
I have suspicions that the TIR is reduced as well when the collet is fully seated
Click to expand...
I haven’t read any manual, good to know.
Thanks Mike.
 
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