Stripped screw on J-HS head

[custom59]

I have a T-ram B/P with the J-HS stepper head and that collar on top, the one you move to go from hi to low has the two shoulder screw guide pins that run in that angled slot, well one of those screws stripped out. Hi range runs fine but low will do a partial gear grind because the inner piece isn't getting lifted like it should.

The screw thread looks like 10-32, and it's the threaded hole that is hashed, the threads on the screw still look ok. Has anyone else had this problem and how did you resolve it? Seems like a Helicoil is the only thing with a narrow enough wall section to work in this spot.
Thoughts, suggestions? thanks c-59

 

[franketrozzo]

If I remember back when I did that repair the stud is configured like you say. It screws into the aluminum housing that is elevated by the cam ring. I can't recall if I was able to run a 5/16 fine tap through the housing without tearing it down and re-make a stud with matching threads and a slotted end on the other side. It lasted until I sold the mill. That is a common design flaw in the Bridgey.

 

[custom59]

Yes it does seem like a very puney screw considering the amount of thrashing it takes.
Thanks for the reply.

 

[ZAGNUT]

if this set up is the same as the regular j head then the pins are threaded 1/4-32. every bridgeport i've seen has another pair of fresh holes in the bearing housing that i guess were put there because these threaded holes got thrashed on a regular basis. on my machine i saved the fresh holes for the future and reamed out the buggered holes to take an M8 tap. then i made a new set of pins by chopping up partially threaded M8 bolts.



dave

 

[rons]

I have a T-ram B/P with the J-HS stepper head and that collar on top, the one you move to go from hi to low has the two shoulder screw guide pins that run in that angled slot, well one of those screws stripped out. Hi range runs fine but low will do a partial gear grind because the inner piece isn't getting lifted like it should.

Thoughts, suggestions? thanks c-59

There is a very small Allen set screw that secures the guide pins. If you did not
loosen the set screw that may contributed to the stripped thread on the pin.
Like Dave mentioned, you can use the other set of holes.

 

[custom59]

ok, thanks a bunch. i need to take a better look at it, my eyes are getting worse lol

 

[rons]

You can get guide pins from www.hqtinc.com. I have no affiliation.

In my opinion try this:
Back out the allen set screw. Run a tap into the hole to clean it up. Machine a
new guide pin by turning down a larger allen screw.

 

[franketrozzo]

Oh yeah, I remember finding out about those allen screws long after the job was finished.