Bridgeport J Head Pulley Collet Align Screw Replace..?

[EmilioG]

I'm thinking of changing the collet alignment screw on the BP at work after my new R8 collet started binding. (old collets do not bind?)
The job looks pretty straight forward, but I have a question. Do you have to knock the spindle down and out a bit to access the small screws?
And will this action change the pre load on the bearings? I've never changed this alignment screw or have even removed the spindle nose, which may also
need a face pin spanner. Or can I access the screws w/o knocking the spindle down (with a dead blow of course).?

 

[Bob Korves]

Collets have different widths and depths to the pin slot from the factory. There are no standards, Bridgeport never published dimensions for the R8 collet. See if you can determine if it is rubbing on the side of the pin or the end of the pin. If the end, and you feel brave, you can CAREFULLY use a long shank Dremel type tool or a diamond file and dress a bit off. The sides of the pin are more difficult to do without disassembly. Sometimes the pin is bent. I have not disassembled a BP head so no help there. For working inside the spindle nose, rotate the head 90 degrees to make it easier access for better viewing and making any minor work on it easier.

 

[EmilioG]

Thanks Bob, I think it would be best to replace the dog point and lock screw. It feels mushroomed. I won’t chance putting a grinder in that spindle. I’d like to know if the spindle needs to be “knocked” out to access the screw. I watched a YT video where the tech had a difficult time putting it back in.

 

[chips&more]

All I can remember is if you over tighten something when installing you can cause a bind in quill travel. I guess it doesn’t take much to distort the circumference of the quill and then bind up in the head…Dave

 

[jmarkwolf]

There is a good video (somewhere) on Youtube for doing exactly this. Saw it a couple years ago so I can't be of any more help than this, but I'll bet you can find it pretty easily.

 

[JimDawson]

Lower the spindle an inch or so. Pull off the nut on the bottom of the spindle, right hand thread as I recall. I think there is a set screw locking the nut, I don't remember. Once the nut is removed, then the collet alignment screw is accessible.

 

[jmarkwolf]

IIRC there may be two set screws back to back in there as well.

 

[Richard King 2]

Yes lower the quill down a few inches and on the backside of the quill is either 1 set screw that was green loc-tited in or 2 sets screws. One is a thin jam set screw to lock the 2 nd screw. Take them out and put them in a plastic bag for safe keeping. Then if you have a pin spanner wrench loosen the retaining nut. It is regular right hand threads. Or if you don't have a spanner. Have someone help you. Use 2 punches, one the same size of the hole and slide it into the hole vertically and then have your helper use a 1/2 drift or punch (or Bigger) and hit the first punch to loosen it.

Please don't use 1 punch and bugger up the hole(s). Then you will see another hole with the set of set screws in the spindle. If you buy a new one from H&M or Quality Parts it's a long key and not a dog point. before screwing the nut back on check the collets and how they slide up in there.

Chips and More is correct about the double set screws in the quill. Just snug the lower on into the threaded quill and loc-tite it or use the 2nd thin jam set screw. If you reef on the lower screw it will warp the quil. Another issue when tightening the retainer nut, sometimes on used bearings when you tighten the nut it will travel past the set screw detent hole in the nut. I have had to redrill that hole with a # 8 drill.

Be sure to clean everything and don't use an air hose as you might blow chips into the spindle bearings.

Rich

 

[benmychree]

Why not just massage the collet a bit until it slides in without binding?

 

[Richard King 2]

If the set screw is worn or buggered up it needs to be replaced. I have seen them that are broke off or squashed / burred up. I have used a small file to deburr the collets keyway too. He would be better off to slide in a new colet when adjusting the lower set screw. I'm sure he knows to clean the taper too.