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Bridgeport quill help

volvo 140140

Aluminum
Joined
Jan 8, 2018
Hi. I have read all the threads I find about this. Unfortunately, I do not find the answer I am looking for. I need help with my bridgeport, I have a problem with my quill becoming sluggish the last bit when it goes up in my head. The whole head is newly renovated with new berings and belts. Bering in the spindel is also new.

now to my problem as i said the last 25mm is sluggish when you return the quill last bit up in the head. I have tried to remove the set screw to the nose cap. it was not it but I noticed that if I release the noscap then it goes easily again.

So now to my question how much should the nos cap be tightened? what do you think can nose cap be defomed so that this cause the problem. is it a common problem? I did not see how this can happen because the nos cap is only too hold the autoside off the bearings. Can you screw it too tight so that makes the quill stiff.

Best regards

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Hi. I have read all the threads I find about this. Unfortunately, I do not find the answer I am looking for. I need help with my bridgeport, I have a problem with my quill becoming sluggish the last bit when it goes up in my head. The whole head is newly renovated with new berings and belts. Bering in the spindel is also new.

now to my problem as i said the last 25mm is sluggish when you return the quill last bit up in the head. I have tried to remove the set screw to the nose cap. it was not it but I noticed that if I release the noscap then it goes easily again.

So now to my question how much should the nos cap be tightened? what do you think can nose cap be defomed so that this cause the problem. is it a common problem? I did not see how this can happen because the nos cap is only too hold the autoside off the bearings. Can you screw it too tight so that makes the quill stiff.

Best regards

Skickat från min SM-N960F via Tapatalk

You can screw it on too tight and get increased resistance, it's deforming the bottom of the quill as you probably already know?
IIRC, it just needs to be snug, a little more than hand tight?

Kevin
 
You can screw it on too tight and get increased resistance, it's deforming the bottom of the quill as you probably already know?
IIRC, it just needs to be snug, a little more than hand tight?

Kevin

It's almost certainly an over-tightened nose cap, I did this when I was young and dumb.

Now that I'm old and dumb I'd find a new way to mess it up...
 
you may have overtightened it, BUT its important to note the quill on a Bridgeport type mill isn't supposed to "snap back up" like a drill press.

how "sluggish" is it? if it just needs a gentile push on the handle to return all the way, you are fine.

if you have to push with deliberate force, then something is wrong.

it should be neutral or near neutral with a chuck on the spindle (depending on size of chuck of course).
 
I have tried to remove the set screw to the nose cap. That was not it but I noticed that if I release the nose cap then it goes easily again.
1 So now to my question, how much should the nose cap be tightened?
2 What do you think, can the nose cap be deformed so that this is the cause the problem.
3 Is it a common problem?
4 I did not see how this can happen because the nose cap is only to hold the autoside off the bearings.
5 Can you screw it too tight so that makes the quill stiff?

Best regards

Skickat från min SM-N960F via Tapatalk

1 The purpose of the nose cap is to hold the bearing assembly against the counter bore/shoulder within the quill. This prevents the spindle assembly from "floating" up and down. A snug fit or just beyond "hand tight" should be sufficient.
The bearing assembly (Duplex Bearings) have a pre-load upon assembly. The nose cap does not affect this.

2 Yes! I have replaced nose caps that were out of round/egg shaped. The clue is when the nose cap does not screw all the way in easily.
Measure the O.D. of the nose cap for "out of round" dimensions. Bad threads can also cause distortion. Bad threads are usually caused by un-screwing the nose cap before backing off the set screw.

3 Not a common problem so it can be a missed diagnosis.

4 If the set screw is turned in too tight the nose cap and the quill will distort. That tiny set screw can exert a lot of point pressure.
The nose cap only needs to be screwed in to land the bearing assembly against the shoulder. The set screw screws into a pre-drilled hole in the nose cap applying just enough pressure to prevent the nose cap from coming loose.

5 Basically no, the cap will screw in to a dead stop. However, some people are really gifted at ....... things up!

Attached are some images including the original Bridgeport instructions for collet aligning screw replacement.
The diagram shows a 0.003" = 0.08mm gap when the nose cap is screwed all the way in. This is a factory value and may be different than what you measure. The important point is that the cap screws smooth and evenly all the way home and that there is a gap between the nose cap and the bottom of the quill. The gap tells you that the bearing assembly will not float in the bore.

If a new nose cap is purchased a new hole for the set screw needs to be located. This is so the set screw does not deform the threads.
This is an awkward task with the cap installed and usually leaves debris in the hole. There is also a risk for damaging the threads in the quill.
Spindle Nose Assembly Dwg.JPGCollet Screw Replacement.JPGSpindle Nose.JPG
Regards, John
 
Thanks for all the answer, I will check and see if I can release it a bit. I did notise that the nose cap not screw in easily all the way. It hade a few please that was thigter. But the last bit i can turning it by hand. Perhaps i need a replacement nose cap i will see.

Will test this as soon I can.

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jhruska pretty much covered it. When I replaced a spindle in the field I usually had to re-spot the nose cap with a number 7 drill so the setscrew would not protrude. Just beyond hand tight is all you need on the nose cap. remember, there is only 0.0003 to 0.0005 clearance between the quill and the quill housing. It doesn't take much distortion to cause binding. Another mistake is over tightening the 4 nuts on the front of the head, that will distort the quill housing as well.

Mr Bridgeport
 
Hi. I use a torque wrench to tightening the bolts to the head so there should be no problems. if I fix the the quill and it go easy. Would I need to buy a new nose cap thinking that if it a little stiff to screw in? or what do you think? Best regards

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Clean the threads on the quill I.D. and the nose cap O.D.
Toothbrush is the right size for a wire brush.

The head bolts, usually just snug for tramming the head to zero.
More than snug for milling.
Back them off and retest quill travel :D
John
 








 
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