# Bridgeport J Head Spindle Bearings & Re Build...?



## EmilioG (Jun 4, 2015)

I recently worked with a shops J head BP mill, older, maybe circa 1970's.
I had trouble with milling and hole accuracy.  I know something is bad with
the spindle.  Just sensing that it is not running true or to spec, TIR.
I did not check with DTI but just looking at surface finish and hole quality I could
tell something is amiss.

Has anyone here ever rebuilt their BP spindle or had it done?
I've read lots of threads on the web about this problem and You Tube has a few
videos showing the process.

Can this job be done on site with all the parts and what else could be replaced while
the head is apart?  Is there a one stop shop that sells all BP parts? Is the BP manual
on rebuilding any good?  Thanks


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## Kernbigo (Jun 4, 2015)

I did years ago but you may be able to take up on the bearings i think they are angular contact


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## JimDawson (Jun 4, 2015)

You can try tightening the preload nuts in the top of the spindle (you have to pull the quill out to do this). Sometimes this works if the bearings are not too bad.  It got me through a big job I was working on at the time.  Then I sent the spindle out for rebuild and the 5 bearing upgrade when the job was completed.  A standard spindle rebuild is in the $600 range, add the 5 bearing upgrade for about $300 more.  In a pinch you could do the rebuild on your bench, but IMHO some things are best left to the experts who have the experience, proper tools, and testing equipment.  They will also re-grind the nose taper if needed.  Google Bridgeport spindle rebuild, and you will find a number of rebuilders in your area.  Send them the entire quill.  Normal turn around time is about a week.

You do not have to disassemble the head to remove the spindle, just drop the quill out the bottom.  If you remove the pinion shaft, the quill just drops out, literally, so make sure it is supported or locked.  It weighs about 30 lbs.  It normally takes about 15 minutes to remove the quill.  I normally tilt the head about 45 degrees to get clearance to remove the quill.  Remove the handle and return spring housing on the right.  Then remove the trip housing on the left, take out the hardware, and remove the screw in the end of the pinion shaft.  Then the shaft slides out to the right.

While the quill is out for rebuild, it's a good time to do a complete head tear down and replace the bearings, belts, brake shoes if needed, and do a general cleaning. I think total for the bearings in the head was about $50 or so, these are not precision bearings.


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## EmilioG (Jun 4, 2015)

Thank you.
See>
http://www.machinerypartsdepot.com/

This site shows re build kits and the most expensive is $340.00 with the sealed bearings.
The video shows how it's done which is do able.  We have all the tools.  It's for a J head step pulley BP.
The prices on this site are very good.  The only thing I may consider sending out is the nose taper for grinding.


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## EmilioG (Jun 4, 2015)

I think this job can be done in our shop with two people.
It would save a lot of money and we would take our time to do it right.


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## astjp2 (Jun 4, 2015)

You can drop in a cartridge that is the whole bearings and new spindle, check where you collets go in and see if there is a burr and also check your collets.  Tim


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## EmilioG (Jun 5, 2015)

When they say that (H&W) re grind the taper, what is it exactly that they do here?  Why would the spindle taper have to
be re ground?  Then there is the draw bar, that usually needs to be replaced also, Thanks


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## EmilioG (Jun 5, 2015)

Nevermind, I looked it up, the re grind work is done on the r8 taper to bring it back to tolerance.
This is done usually as part of the spindle re build.  is Wells Index still doing this work?


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## astjp2 (Jun 5, 2015)

The threads that retain the collet usually get jacked up bad when the air motor is left on too long because the operator thinks that it needs to be hammered tight and don't realize that the taper is what holds it solid.  Also there is the alignment key/pin that gets jacked up also.  You can contact Hardinge to get it done or there are a lot of spindle shops around.  I have one on the shelf at work for a series 1 and an easy trak that came from Hardinge a year or 2 ago and was about $1200 new.  Tim


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## EmilioG (Jun 5, 2015)

I believe the r8 taper is OK.  New bearings, draw bar,  collet alignment pin and screw should make everything right.


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## sd624 (Jun 5, 2015)

EmilioG said:


> Nevermind, I looked it up, the re grind work is done on the r8 taper to bring it back to tolerance.
> This is done usually as part of the spindle re build.  is Wells Index still doing this work?



Wells did mine a couple of years ago. Was fast and very nice to deal with. Don't know for sure if they are still doing them but I couldn't imagine why not. 


Sent from my iPad using Tapatalk


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## BigWeld (Jun 5, 2015)

The bearings are a high dollar item I was lucky and had some new old stock from Ebay, if the bearings have been spinning a lot then if it were me I would check the spacers are not damaged, they should be of equal length too. If you need to replace them too they aren't too bad price wise.


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## EmilioG (Jun 6, 2015)

could the spacers be re ground ?  I've seen the whole spindle assembly being sold for $600.  is that a good option if its in good shape
with new bearings?  I will contact a few places like H&W or Mills Index.  A complete tear down and all parts replacement (the really bad parts)
are probably in order; i.e. new collet pin, screws, bolts, washers, draw bar, belts,,,,, etc...
Thanks


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## astjp2 (Jun 6, 2015)

The drawbar is probably made by Kurt and is not part of the spindle.  Is $600 for a core or a rebuilt one?  All of the small parts are not that expensive, its the bearings and grinding if any is needed that costs the big money.  That is why I just bought a new one, then there is no question.  But we also build aircraft parts at work.  Tim


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## Uglydog (Jun 6, 2015)

Sidecar is one of our HM members. He specializes in rebuilding BP.
Consider soliciting his advice.

Daryl
MN


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## EmilioG (Jun 6, 2015)

Dorian makes good drawbars.


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