Bridgeport Leadscrew Problem....?

EmilioG

EmilioG

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Hi,

I would like to repair the BP 2j Variable speed mill where the leadscrew is very tight and hard to turn when it gets further away from the table towards myself. The handle gets very difficult to turn. It goes in toward the rear and gets easier to turn.

Can anyone with BP rebuild or repair experience diagnose this problem for me?
I know I will have to take it apart. What will this entail and what tools and parts will I probably need to buy? Thanks
 
Don't know about tools and parts. Maybe some one can help me here......I know the X axis had a split in the nut and a pinch bolt to adjust out the backlash. I don't recall if the Y axis does or not. If it does and some one has adjusted it to tighten up the back lash, the lead screw could be worn in the middle such that the screw works easy in the middle but binds in the nut on the ends. Another possibility is wear in the V ways for the saddle are loose in the middle and tight on the ends. The correction for this would be scraping away material to flatten 'and true the V ways. You might try to adjust the gib and see how it effects the motion. This could give you an indication of what to look for. I worked on a Gorton mill a few months ago that some one had added brass shims to the V ways to tighten up the play. It too would work fine in the middle motion and almost become impossible to move at the extremes of travel. I took out the brass shim stock and adjusted the Gib, it seemed better. I didn't cut any thing with it after that so don't know about the "proof in the pudding" so to speak. If the screw is loose, worn in the middle, I just happen to have one that I ran across today. It's a new screw from an acura turn that had been replaced by a ball screw for a CNC conversion. The acura turn is a BP copy, the screw might be the same.

Tim
 
I have a lot of free play in my x axis how do you go about tightening the split nut?
 
It's been a long time since I was in my machine under the table, It seems to me that you can run the table all the way one way and then tighten the screw with a long blade screw driver. I can look at my machine tomorrow when I get to the shop and see if it will jog my memory........ You might want to PM me to remind me to do it.

Tim
 
Another thought, if you have to take the table off the machine, it is heavy and remember it is a precision instrument, you don't want to drop it. Be prepared, engine hoist, crane etc.

Tim
 
thanks, would be nice to get some of the play out of the screw, but things are sure nice with the added DRO even with the play. on this old 1955 Bridgeport.
 
Ed ke6bnl said:
I have a lot of free play in my x axis how do you go about tightening the split nut?
Click to expand...

It depends on the nut you have. I have a Comet mill which is a BP clone. It had a locking screw I had to loosen, then I could led tighten the split nut. Othe instruction I seen was you had to remove the nut and finish a saw cut that sliced the nut in half. Then there was an adjustment screw to tighten it. I am sure there are some YouTube videos showing how to do that.

If your mill is old, I would suggest you remove the table and clean/inspect it. On mine I found plugged oil ports and lines, so only prat of the ways were getting oil. It isn't really that hard to remove the table
 
Yes. An overhaul is in order.
The bijur one shot is stuck as well.
Might be all plugged up.
Engine hoist?

Thanks to all.
 
I've been working on my newly acquired 1971 Bridgeport Variable Speed head and have found H & W Machinery to be most helpful. They have nearly everything (they have had everything I needed, but that's been limited) right in stock and their prices seem fair enough.
 
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