Spindle removal on J head

[jmhoying]

My Millport (Bridgeport J head clone) has run out on the spindle and it feels like it has a more than normal movement when you rock an accessory (like a drill chuck) back and forth. I want to check if the bearings are bad, so I thought I'd drop the spindle out. I removed the lower spindle nut and tapped lightly on the top of the spindle. It dropped about an inch and exposed the lower bearing, but it stopped there and seems to be hung up on something. I wasn't planning on removed the whole quill, but is that the preferred method?

Thanks,
Jack

 

[jmhoying]

Here is a video of the spindle wear, just to give you an idea of what I'm dealing with.

[video=youtube;so0MUEr1IgA]http://www.youtube.com/watch?v=so0MUEr1IgA[/video]

Jack

 

[Calibre]

I'm hoping there will be follow up pictures or videos on this project.

Thanks.

 

[sd624]

My Millport (Bridgeport J head clone) has run out on the spindle and it feels like it has a more than normal movement when you rock an accessory (like a drill chuck) back and forth. I want to check if the bearings are bad, so I thought I'd drop the spindle out. I removed the lower spindle nut and tapped lightly on the top of the spindle. It dropped about an inch and exposed the lower bearing, but it stopped there and seems to be hung up on something. I wasn't planning on removed the whole quill, but is that the preferred method?

Thanks,
Jack

Yup Jack that's how you do it. Just tap a little harder.

 

[jmhoying]

Yup Jack that's how you do it. Just tap a little harder.

With the Bridgeport clones, apparently the depth gauge attachment bolt onto the quill extends into the body of the quill, which is where my upper bearing of the spindle was hanging up. Once I backed up the bolt a bit, the spindle came out pretty easily. (I had help with this from a member on another forum). What I found is that the outside bearing spacer was worn and loose. The machine re-builder I talked to said that this is fairly common on well used machines and as long as the bearings feel good, it's worth a try to grind the center spacer down to match the outside spacer (or even a few tenths less) to get a proper pre-load on the bearings. He said he has had good luck in fixing spindles this way. It's definitely worth a try, as I'm not out anything if I don't get an improvement. I'll do the repair and report how it goes.

Jack

 

[sd624]

With the Bridgeport clones, apparently the depth gauge attachment bolt onto the quill extends into the body of the quill, which is where my upper bearing of the spindle was hanging up. Once I backed up the bolt a bit, the spindle came out pretty easily. (I had help with this from a member on another forum). What I found is that the outside bearing spacer was worn and loose. The machine re-builder I talked to said that this is fairly common on well used machines and as long as the bearings feel good, it's worth a try to grind the center spacer down to match the outside spacer (or even a few tenths less) to get a proper pre-load on the bearings. He said he has had good luck in fixing spindles this way. It's definitely worth a try, as I'm not out anything if I don't get an improvement. I'll do***ent the repair and report how it goes.

Jack

Clone??? LOL I wonder how I missed that? It's only in the first sentence of your post.

 

[Rennkafer]

My clone (Rutlands/Long Chang LC-1) came apart just like a BP. So looks like some clones are closer to BP than others. Mine even has standard threads everywhere I've looked so far. My mill came as kind of an unassembled "kit" and so I've replaced some missing parts with OEM BP parts and they've all worked/threaded properly.

 

[jmhoying]

Here are some findings on my repair.
I had a 6" piece of 2 1/2" OD, 3/8" wall tubing that fit perfectly over the spindle nose to push against the dust collar for removing the bearings. The bearings were a tight fit, but they did come off. From what I can tell, there was no wear on the outside bearing spacer. It was actually minutely taller than the inside spacer. The bearings felt fine and when viewing with a ground straight edge, the interior and outer races were very flat. I cleaned, greased and reassembled the unit and the outer spacer is now tight in the assembly. Maybe the nut wasn't as tight as I thought it was when I took it apart? (the locking washer was engaged in one of the notches in the nut)

The bearings were marked "Germany SKF 7207 B", which I think means that these are not the highest quality bearings that you can get.

I installed the spindle back into the mill this morning and I do have quite a bit of improvement (after another fix). Just like a few members mentioned earlier on this and other forums, the nose cap nut did indeed bottom out on the quill before tightening against the outer bearing race. I measured both places and I needed to remove almost .001 just to make it flush. I took .004 off the hub of the nose nut and that seemed about perfect when I tightened it up. I didn't have time to do a lot of testing, but I did put a 1/4" collet and ground dowel in it for a quick measurement. As you can see in the previous video in this thread, I had .010 run-out, but now it was slightly less than .001. I'm quite happy with the improvement. I probably have lower quality bearings and this is about as good as I can get at this time. This is actually a pretty easy project to do, so other than the expense of buying new bearings, I wouldn't have any second thoughts about doing the repair.

Thanks for all the help,
Jack