spindle binding (I think) on BP mill

Thanks Ted. Yep, brand new sealed thrust & top bearings from H&W. I'm kicking myself for not chucking up the spindle in my lathe and measuring it before I put them on. I even thought about it but convinced myself I didn't need to. :rolleyes:

After cleaning up the grease problem & adjusting the head as best as I can I feel like I can run the machine as long as I keep it under 1000 rpm or so for short jobs. Above 1200 or so the ugly growl really starts to come out and gets really loud at high rpm. But that'll let me get some hobby project work done over the holiday & then I'll reach out to Barry.

I'll definitely update the thread. This has been a good learning experience and maybe others can benefit from what I'm discovering. I've sure learned a lot here!

-dave
 
diamond said:
I'll definitely update the thread. This has been a good learning experience and maybe others can benefit from what I'm discovering. I've sure learned a lot here!

-dave
Click to expand...

That's why we're all here... to learn and help others.

Only you can judge if running it can potentially damage something i.e. the spindle bearings, etc.. From what you are explaining it sounds like it would run better with the quill up high in the head and it would run worse the lower the quill goes (because the worse run out would be on the end of the splined shaft. So, if you do run it, take it easy...

Ted
 
Sorry for not getting back to update. Got distracted after the holidays.

I did make connection with Barry at H&W and was relieved to hear this is very common. Says about half the rebuilds he does he has to do some straightening of the upper shaft. Apparently it's quite soft. I haven't done it yet, been distracted elsewhere, but this gives me a lot of relief I won't be buying a new spindle. His method is to do it while in the head. He's got all kinds of mounts for holding heads on a bench to work on. I don't have a lot of room above my machine to work on it so I'm probably going just pull the spindle and do it on a press where I can indicate the shaft & dial it in. He said that should be fine.

I will update again on how that turns out when I get around to doing it.
 
Been very slow to update. Here is the end to this chapter in the story.

I pulled the spindle and checked the runout of the shaft by securing the thrust bearings to the table.
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It was even more bent than I first thought. Found the shaft was running out about .018 at the top. The good news is it seemed to be a simple bend, not a compound bend. Could measure about .007 just above the upper bearing but the high/low sides were consistent down the shaft. If that makes sense.
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Barry at H&W told me the shaft is really soft metal so I got the idea that I might try this setup below to straighten it vs. using a hydraulic press. I figured I could get more control. With the spindle shaft suspended between two 123 blocks, I used a piece of 4x4 against the ram & raised the knee with a dial indicator to monitor correction.
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I started out real gently. Only putting about .025 deflection by raising the knee. Then re-clamp the thrust bearings to the table and measure runout. Didn't budge. Then I went to .050 still nothing. Then .075 and the runout dropped a couple thou. Continuing with .025 increments I got to .125 and all of a sudden it was gone. In fact I overshot it by a few thousandths so I just bumped it on the other side (about .050 deflection) and the shaft is now running less than .002 measured down the length. It appears I didn't introduce any compound bend (which I was concerned about).

Never done this before so maybe I was being obsessive about getting it true. Barry says he just hits it with a mallet. lol. My approach of using the knee & ram as a press like this might make some folks cringe. It really didn't take much pressure on the knee elevation crank to get the shaft to move.

The good news is I put it back in and the machine is MUCH quieter now and the quill moves up and down without feeling that rubbing from the spindle shaft. Now that the shaft vibration noise isn't so loud I could start to hear other noises at high speed. Most notably a growl in high range coming from play in the bull gear shaft/vari-speed pulley shaft cogs. I've played with adjusting the hi/low engagement lever stop to put a little more upward pressure in high range and that seemed to make it go away.

I know these vary-speed heads are not known to be quiet. The belt alone makes quite a lot of noise I'm sure. For now I'm very happy with how it's running. Again I don't have a lot of experience with these machines to know but to my ear it sounds very quiet at most working speeds.

Thanks again to Ted and others who provided advice. Maybe my experience with this might help someone else out. I didn't find much in any discussions about straightening a spindle when I researched this.

Now it's on to installing the 3-axis DRO that just arrived! Lots of good threads on that. :)
 
Great news and that's using your head with what you have available to you to straighten the shaft! Yes, I'm sure that gave you much more control and it was good thinking. I'm sure it didn't damage anything... Yep, better than a mallet! :)

Good job!
Ted
 
Just curious - having a similar issue on a Bridgeport 2 where I work - pulsation in the quill handle as you travel up/down. However, it doesn't happen all the time. There is a new draw bar (maybe 2 months old), but it has a small wow in it. The old one has a a bit more of a wow, and exhibits even more pulsation, so pretty much was thinking that is the issue. I'll try ordering in another draw bar and see if that helps.

It's possible that the spindle got bent, as one of our techs was doing a tool change, and had the wrench on the draw bar, but snagged his loose floppy sleeve on the high/lo switch and sheared the draw bar off. Would this be enough to bend the spindle enough to cause this problem? It seems that the problem could have existed before this happened, but not quite sure about that.

In any case, I've tried a few tests, where I've clocked the spindle in different positions (using the keyway on the collets as my reference) and the problem seems better/worse depending where the the spindle clocking position is. It almost goes away in a certain position. As there is no consistency to the problem, I am considering different things to see what changes this issue (up til now, no one pays any attention to what position the spindle is in, they just rotate the collet until it inserts, etc.,.. Maybe this is a temporary work around?).

One more thing - after a lengthy milling project a couple of weeks back - the top of the drawbar was really warm. Never noticed this to happen previously. Didn't check the top of the cowl so unsure about whether the bearings were hot. Would that (bearings) be the typical cause of the heat buildup? Most of our jobs are pretty small, so this hasn't been noticed by anyone else, either.

In our area, none of us are machinists, pretty much casual users of the equipment as needed. So any thoughts or advice would be great.

Thanks,
Brad
 
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