BP J-Head spindle nose cap stuck

kopeck · Nov 16, 2020

Hi,

So like a lot of BPs out there my "Key Screw" is sheared off. I order a replacement, watched a video and thought to my self this is going to be an easy job.

Well my cap is stuck. The set screw is out, I can't tell you what's going on but it wont budge. I even bent the spanner pin tool I had trying to get it to go. The holes were pretty buggered before I started so I'm thinking the PO had the same problem. I did try some light tapping on the spanner tool to see if some shocking would help...no joy.

Any ideas? I guess I could put a pipe wrench on there and buy a new cap.

Oh and I am turning it the right way (I did see some imports were left handed threads but this is a good old 1960s BP).

K

JohnEvans · Nov 16, 2020

Check and see if there is another set screw in the hole where you removed the first one.

kopeck · Nov 17, 2020

I did get it off...frustration got the best of me.

There wasn't another screw, I did think of that too.

I did use the pipe wrench. I figured the cap was buggered anyway. I have no clue what was holding it back but once broke free it unscrewed by hand. It looks like it had the clearance in place too so I'm not really sure what was going on.

The pipe wrench left a very light mark, I can dress it and no one will no any different. It kind of matches everything else on the mill. :-)

K

Nmbmxer · Nov 17, 2020

I can't remember the last time I used a mill with the key in place. Never had a problem.

kopeck · Nov 17, 2020

I have a collet that the thread hangs up on. If I remember to make sure I back the drawbar out 3/4 of the way before I break it loose it's not an issue but I don't always remember to do that. The key will solve that issue.

It's only that single collet and the key was less that a new collet. :-)

I have tried to fix the collet, not sure what's up with it.

K

kopeck · Nov 17, 2020

After a closer look it seem this was an aftermarket peice anyway. The two really buggered holes were not me, I couldn't even use them, the other two, well I might have fouled on of them, hard to say at this point.

K

kopeck · Nov 19, 2020

So now a question.

By spec I'm supposed to tighten the spindle nose cap until theres .003 gap between the cap and the quill. I've also read this is non-critical and there's some variation to be had in that number.

Well my cap stop turning with about .030 clearance. The spindle is bound at that point, if I back the cap off a quarter turn everything seems OK, the spindle runs with out any binding, run out etc but .030 is a huge difference between .003 that I've read BP asks for.

I didn't measure the gap before I took it off but from the looks of things the cap is back were it began.

Is this something I should be worried about?

K

seagiant · Nov 23, 2020

Hi,
Saw this!

How to Replace a Collet Aligning Screw on a Bridgeport Milling Machine – Blue Chip Machine Shop

moonlight machine · Nov 23, 2020

kopeck said:
Hi,

So like a lot of BPs out there my "Key Screw" is sheared off. I order a replacement, watched a video and thought to my self this is going to be an easy job.

Well my cap is stuck. The set screw is out, I can't tell you what's going on but it wont budge. I even bent the spanner pin tool I had trying to get it to go. The holes were pretty buggered before I started so I'm thinking the PO had the same problem. I did try some light tapping on the spanner tool to see if some shocking would help...no joy.

Any ideas? I guess I could put a pipe wrench on there and buy a new cap.

Oh and I am turning it the right way (I did see some imports were left handed threads but this is a good old 1960s BP).

K

My idea is to throw the new key in the trash bin. My BP has not had one since about 1979,and its just fine.

moonlight machine · Nov 23, 2020

kopeck said:
I have a collet that the thread hangs up on. If I remember to make sure I back the drawbar out 3/4 of the way before I break it loose it's not an issue but I don't always remember to do that. The key will solve that issue.

It's only that single collet and the key was less that a new collet. :-)

I have tried to fix the collet, not sure what's up with it.

K

Just run a tap through it and if you really want to get fancy clean the thread on the drawbar as well. A few drops of oil will help as well. it's not really rocket science.

gbent · Nov 24, 2020

The purpose of the gap is to insure the spindle bearings are captured tightly in the quill. The size of the gap doesn't really matter, but there must be a gap. If you think its to large, remove the cap and face the surface that presses against the outer race of the bearings by .025.

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