Bridgeport table slop options

I read a few threads on the various symptoms and solutions for table slop so I'm relatively familiar with what's going on with mine. Typical older mill with worn ways and feed screws. I took the table apart to remove the hardened grease and familiarize myself with how everything ties together.

The feed nuts look like they were cut ~3/4 of the way through compared to the newer two piece design. Would there be any benefit to replacing the nuts and reusing the worn feed screws? Seems like it would be kind of pointless replacing one without the other, but maybe I haven't thought it through well.

Before I took the table apart I tightened up the gibs and found the typical tightness at the less worn ends with still a bit of slop in the middle of the X travel. Since I was still able to tighten the gib am I correct thinking there wouldn't be any benefit to try and shim them since the wear is uneven across the length of travel? So the only real remedy for tightening up the table slop in the middle would involve regrinding the ways? This machine is too old and underpowered (3/4hp) to warrant much investment so I'm just trying to find the most cost effective solution to get it performing a little better. I realize it may already be too far out to pasture for that.

It sounds like you have a handle on it. It really is a losing battle. If you tighten the gibbs for the center, then you fight the handles on the ends. Loosen them up and your middle goes sloppy. New screw and nuts will help the end play...but you can just as easily learn to use it as it is. Why put money into it?

Just plan on milling lighter cutting jobs to prevent chatter and live with it until a fresher mill comes along...or someone finds a cheaper way to repair old weighs.

Thanks for the confirmation. I had a feeling there probably wasn't much to be gained by taking it apart, at least I'm a little more familiar with how everything interacts and what to look for on the next one.

Just split the nuts into 2 pieces . That will give you more adjustment than the current setup without the cost of new parts. No east fix for Bridgeport ittus without grinding or scraping the ways.

JohnEvans said:

Just split the nuts into 2 pieces . That will give you more adjustment than the current setup without the cost of new parts. No east fix for Bridgeport ittus without grinding or scraping the ways.

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That's what I did on my BP. Cut the split in the nut all the way through and inserted a piece of felt to help hold oil. You can tighten up the nut a lot more when it's totally split (like the newer design).

My ways are worn as well, especially my Y axis. I tighten the gib where I use it the most (in the center of travel) and if I ever need to go to the extremes I simply loosen the gib up until the job is done and then retighten it again in the center. When you do this, if you have too much movement in the center of travel you can snug up the lock a little when in the middle of travel.

Ted


Ted

JohnEvans said:

Just split the nuts into 2 pieces . That will give you more adjustment than the current setup without the cost of new parts. No east fix for Bridgeport ittus without grinding or scraping the ways.

Click to expand...

Will do, thanks for the tip.

Splitting the nuts all the way is what I had to do on mine as well. most of the wear was on the nut, not the screw, but there was some wear on screw. I now try to use the ends of the table travel for most work. Why keep wearing out the most worn part when it is usually possible to do the work on the least worn area. Kind of depends on what size part you are doing...
The felt in the split to retain oil seems like a good idea

Well, I am now officially a member of the split nut crowd! It definitely helped with the backlash.

I'll have to live the floppy table until I can upgrade. It wasn't an issue for a lot of what I was doing until I tried face milling a 5"x20" chunk last week and saw how bad it was and how futile my adjustments were.

I never understood why everyone always seems to set the vice right in the middle of the table with the ram inline with the Y axis, that just wears out the middle of the table and leadscrew. Every time I put the vice on I swap which side of the table it's offset toward and swing the ram to the other side and re-tram.

Nmbmxer said:

Every time I put the vice on I swap which side of the table it's offset toward and swing the ram to the other side and re-tram.

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If you swing the ram over then wouldn’t the table stay in the middle of its travel? That seems to defeat the point of offsetting the vise. I have been using the vise on one end of my table, with the ram straight, thinking it would help even out the wear. Disadvantage I guess is the cantilevered table load on the dovetails.

Unless you are broke, buy new nuts. That was the best thing I ever did on my Bridgeport. Made a huge difference. Splitting the old nuts will help but not as much as new nuts.There is always some wear on the screw but most wear is on the nuts.

Superbowl said:

Unless you are broke, buy new nuts. That was the best thing I ever did on my Bridgeport. Made a huge difference. Splitting the old nuts will help but not as much as new nuts.There is always some wear on the screw but most wear is on the nuts.

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Good to know, makes sense that the brass nuts would have most of the wear. I don't mind replacing parts if I know there will be an improvement, I just didn't want throw away money chasing a fix that won't help. I've got everything back together and oiled. I'm a little surprised I was able to get some of the play out of the table adjusting the gibs after cleaning everything.

Rob F. said:

I now try to use the ends of the table travel for most work. Why keep wearing out the most worn part when it is usually possible to do the work on the least worn area.

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My weighs are not perfect, but decent, and that is exactly how I keep them that way. It's CNC, so there is no extra work on my part...I place every job far left or far right on the table. I have the limits marked. The middle still gets plenty of use as the CNC traverses it going to and from cuts.

I have also turned the lube way up, and I never start the machine cold without dabbing oil all over the weighs. I am amazed at how little friction a loose weigh has when you disconnect the drives. You can take that 150+lb table and, with a small push, watch it glide effortlessly from end to end when properly oiled! Tells me with proper lubrication, and keeping them clean (covers and frequent wipes), the weighs could last indefinitely. Dirt and lack of lube will kill them quickly.