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Criterion boring head shaft removal

Posted: Mon Jun 04, 2012 3:49 pm
by neanderman
I just picked up a used Criterion boring head set, with a DBL-203 head on an R-8 shank. My mill uses a B&S #9, so I'll need to buy a new shank, but first I need to get the R-8 shank out of the head.

Is there a trick to this? Is it a RH or LH thread? I've tried gripping the head and shank with my bare hands, and twisting both ways, and I can't budge it.

Ed

Sorry... I put this in the wrong forum. It probably should be in the Milling Forum.

Re: Criterion boring head shaft removal

Posted: Mon Jun 04, 2012 7:45 pm
by Bruce_Mowbray
Ed,
It's a right hand fine thread. Some guys put loctite on the threads before assembling so that may be what's holding things together. The arbor has a flange on it which also makes for a really tight joint. Try a little heat on the arbor to see if that helps. you might just have to bring out the big wrench to get things to come apart. Clamp the boring head on the flat section of the bar holder in a vise with some soft jaws. Tighten the set screws and use a pipe wrench on the arbor. This will make a mess of the arbor so be prepared to get a new R8 arbor if you intend to use the head in a Bridgport or similar R8 spindle.\

Re: Criterion boring head shaft removal

Posted: Mon Jun 04, 2012 10:40 pm
by neanderman
Thanks. I'll give the heat a shot tomorrow evening.

Ed

Re: Criterion boring head shaft removal

Posted: Mon Jun 04, 2012 11:39 pm
by spro
Only a thought how once the neat boring heads were affixed to Large B&S taper shanks and many converted them to R-8. :)

Re: Criterion boring head shaft removal

Posted: Tue Jun 05, 2012 11:39 pm
by neanderman
spro wrote:Only a thought how once the neat boring heads were affixed to Large B&S taper shanks and many converted them to R-8. :)
Just my luck! :(

Ed

Re: Criterion boring head shaft removal

Posted: Wed Jun 06, 2012 8:59 pm
by earlgo
Mr Mowbray is most likely correct. The threads on the boring head I have are RH. Might the suggestion be made instead of gripping the R8 with a pipe wrench, drill a hole in the shank flange for a spanner wrench pin. That might work as well but leave less marks.
--earlgo

Re: Criterion boring head shaft removal

Posted: Thu Jun 07, 2012 12:24 am
by neanderman
I have a few ideas to avoid using a pipe wrench, should that be necessary. One of them is to make a wrench that utilizes the keyway.

Ed

Re: Criterion boring head shaft removal

Posted: Fri Jun 08, 2012 4:46 pm
by BobCMW
If the previous owner has not used Loctite (and sometimes even if they have) you can put a long 1/2" bar in the cross-hole and unscrew the head from the shank it is attached to. You need to hold the shank well because you don't want it spinning when you are working the lever.

Bob