# Bridgeport J Head Pulley Collet Align Screw Replace..?



## EmilioG (Feb 22, 2018)

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).?


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## Bob Korves (Feb 22, 2018)

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.


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## EmilioG (Feb 22, 2018)

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.


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## chips&more (Feb 22, 2018)

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


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## jmarkwolf (Feb 22, 2018)

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.


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## JimDawson (Feb 22, 2018)

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.


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## jmarkwolf (Feb 22, 2018)

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


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## Richard King 2 (Feb 22, 2018)

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


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## benmychree (Feb 22, 2018)

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


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## Richard King 2 (Feb 22, 2018)

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.


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## Bob Korves (Feb 22, 2018)

Per Emilio, the new collet is what is having the issue, the old ones do not (?).  Emilio would not likely be buying a cheap collet, but he said this BP is at his work, so it might be one they bought with poor quality control in production.  I would first vet the collet before I would go to the trouble to replace the pin to accommodate it.


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## EmilioG (Feb 22, 2018)

There are a total of three set screws.
A. The spindle nose set screw
b. jam nut lock set screw
c. dog point collet alignment set screw  3/32" protrusion. 
Q:  do I need to lower the spindle taper an inch more for better access to the alignment screw?  I read that this can change the pre-load on the bearings?

Bob;  I was using a brand new USA Hardinge R8 collet.  The collet was working fine w/o binding, then one day, it got stuck.
The head on the alignment pin is mushroomed., not smooth and the Hardinge  R8 looks fine., not worn, so that may be part of the problem.
The machinist at my job was telling me that he recently replaced the collet screw and that it is only one screw.  I tried to explain that there should be a jam nut set screw behind it, but he got angry and said NO! it's only one! I said, OK, No problem. One screw.  That's the other problem. 

I'll just use the worn R8 collets and when I buy my own BP mill, It will be well maintained.


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## Richard King 2 (Feb 22, 2018)

He may have screwed it in to far.   look at parts 112 to 114       You can call these guys too as they are rebuilders too.  They will gladly help over the phone too.
http://www.machinerypartsdepot.com/store/1478157/page/552237


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## Bob Korves (Feb 22, 2018)

Richard King 2 said:


> He may have screwed it in to far.   look at parts 112 to 114       You can call these guys too as they are rebuilders too.  They will gladly help over the phone too.
> http://www.machinerypartsdepot.com/store/1478157/page/552237


113 appears to be the one that runs in the collet slot.


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## aliva (Feb 22, 2018)

Don't waste your time replacing the screw, just remove it . A lot of people remove it , just becomes a pain dealing with it. Mine was screwed up several years ago and I just removed it and never replaced it. I've never had a problem since. It also makes loading a collect or R8 shank much easier.
Its only purpose that I could find was to stop the collect or R8 from spinning while installing or removing. If your collect or R8 is spinning, you may have a thread problem which should be addressed.


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## RandyM (Feb 23, 2018)

Here is an article on how to do it.

http://www.machinerypartsdepot.com/page/487497676


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## Janderso (Mar 28, 2018)

My Bridgeport does not have it. There is just a hole there. I don't have any issues. It seems like a video I watched,the guy said he wondered why the collett locating pin is there?
My 2 cents.


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## Technical Ted (Mar 28, 2018)

I had a collet that would not go into my spindle without binding and luckily I thought to check the register diameter on the collet before doing anything with the key or keyway... it was almost 0.001" bigger than my other holders and collets. After some polishing in my lathe and getting it to the same size as my others it fit fine!

Just something to check,
Ted


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