BRIDGEPORT TABLE BIND

Currahee26 said:
Greetings,
I have a BP round ram knee mill. (M head) In pretty good shape actually, that i got for $500. I had to replace drawbar, some felt wipers and the spindle oiler wick. It had been lubricated with GREASE it nearly all its fittings so the cleaning process took a long time.
Now, the table works well from right to left, (starting full right and moving left) BUT when it gets half way in this travel the table binds so tightly it takes two hands to turn the cranks. Anyone have an idea why this is happening?
1. Will a two piece cross feed nut solve this? ( If so, can I just cut the current single piece nut in two?)
2. The gib had a very thin piece of tin spot welded to it when I took table apart to clean and OIL. (like some sort of a shim)
3. Can new table gibs be purchased?
Anyway, I'd like to get this fixed so I can use the whole table. I have a BP vice bolted down in the middle but have to move it for bigger projects!

Thanks all info and comments in advance.

Dave SO FLA
Click to expand...
DANG IT ALL!! I wrote the description BACKASSWARDS!! With the table starting FULL LEFT as you look at it, cranking it TO THE RIGHT< the bind starts about half way of full travel. It can be moved but takes two hands. UPDATE: with the gib COMPLETELY REMOVED, the bind improves but remains very tight in the final 12 inches of travel. My sincere apologies for my screw up in description of travel.
 
The former owner was a total screw up as he shimmed the front side of the gib. The table is bent and not worn on the ends. How long is the table? 36" or 42" You may consider making it a little better and sell it and buy something newer. You could buy a new gib but the table is probably screwed up. Once you get it moved and have the table off. As long as you at it pull the saddle off too. You can watch some You Tube shows and they will show you how to do it. write here again.
 
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Richard King 2 said:
The former owner was a total screw up as he shimmed the front side of the gib. The table is bent and not worn on the ends. How long is the table? 36" or 42" You may consider making it a little better and sell it and buy something newer. You could buy a new gib but the table is probably screwed up. Once you get it moved and have the table off. As long as you at it pull the saddle off too. You can watch some You Tube shows and they will show you how to do it. write here again.
Click to expand...

Bent? I have never heard of that happening, how is this possible? That is a big chunk of iron.
 
Richard King 2 said:
The former owner was a total screw up as he shimmed the front side of the gib. The table is bent and not worn on the ends. How long is the table? 36" or 42" You may consider making it a little better and sell it and buy something newer. You could buy a new gib but the table is probably screwed up. Once you get it moved and have the table off. As long as you at it pull the saddle off too. You can watch some You Tube shows and they will show you how to do it. write here again.
Click to expand...
I see your point. It acts EXACTLY like it is bent! Maybe it fell over or something a while ago. There are no obvious defects or repairs anywhere along its 36 inch length. As I only work on relatively small parts, I still get full use out of it. I just use the part that moves easily! It's adequate at this point but would be more so if it didn't bind. For $500 its serviceable to me. THANK YOU ALL SO MUCH FOR YOUR INPUT AND ADVICE!
 
Currahee26 said:
I see your point. It acts EXACTLY like it is bent! Maybe it fell over or something a while ago. There are no obvious defects or repairs anywhere along its 36 inch length. As I only work on relatively small parts, I still get full use out of it. I just use the part that moves easily! It's adequate at this point but would be more so if it didn't bind. For $500 its serviceable to me. THANK YOU ALL SO MUCH FOR YOUR INPUT AND ADVICE!
Click to expand...
(PS ill take the table off in the near future and photo the innards. Maybe something will pop up as a workable solution !! Dave
 
The tables get bent by wats called "Peened" by over tightening the T bolts and that stretches the Irion and that bends the table. Usually .005 to .010".

You can straighten them by peening the other side. I Just wrote about it on Facebook... Here is what I wrote.

1. I'm going to write my answer in sections as it will get long. The first time I heard about peening a table straight . I thought my god you have to be kidding. I was demoing the BIAX scrapers at the Chicago Tool Show IMTS and a fellow walked up to me and told me he was a rebuilder in IL and he then asked me if I peen Bridgeport table straight? Like I said I was appalled at the thought. I never used it and had my tables ground or planned to get rid of the bow. Over the years I figure tables average convex about .007"high on T slot side. I had always figured they got that way as the saddle is shorter and hung down and bent them. Then I met Archie Cheaba a Engineering professor. He told me that the table stretches or get pressure peened when the T-nuts get tightened in the middle of the table all the time.. I now figure that is true and a little nd to unsupported weight too.
2. When my kids were in their teens my wife told me I needed to stop traveling teaching classes as when I taught in Taiwan I would stay there for 90 days at a time. The wife said she needed help at home as my daughter who was probably 12 and my son was 15 were a handful plus they were into sports and my wife couldn't transport the on the same night, so I stopped traveling. Then I started to sell machine tools at a company called Midwestern Machinery and after a few years the owner of that company passed away and 3 of us bought the assets. We would go to auctions and buy old machines and do a refurbish on them. Then sell them. Many were Bridgeport's and the tables were bent. So being a part owner and wanting to save some money I started to straighten tables. I still didn't think peening was a good idea and tried a couple of other things first. I tried a 12 ton hydraulic jack and chains to try to pull them straight, parked a 10 ton forklift wheel on the table setting on 2 x 4's. Nothing worked. Then I finally tried peening the underside of the table.
3. I first would set the table right side up on 1 2 3 blocks on my granite table and made the far ends. Put the 1 2 3 blocks on the flats or directly on the ways. 4 corners of the table indicate as close to the same. Using a height gage and .001" indicator measure the bow. Then I would put the table on the cement floor laying on a 1/2 piece of plywood and using a 1" cold role punch I made and the one end a 1/2 radius point I used a 5 pound hammer and began to peen the bottom and the cross section ribbing under there. Being careful not to hit near the dovetails as I figured they would crack. I gradually hit it and put it back on the plate and remeasured it. The first few ones took a while as it was a learning curve. Eventually it would straighten up to .001" bow.
4.
I do not like the idea of laying it directly of the table T-slot s as it bends and you don't get a true reading. A fellow rebuider named Axel For's out in Utah who I met at an SME seminar I was speaking at told me he would run a T slot cutter in the table T-Slots to relieve the stress before he peened his tables. So many rebuilders use this method. I did a class in Denmark I think and Steven Isherwood an Englander living in Norway who came to the class peeded his table one time. He said he used a BFH and hit it hard. I was shocked he didn't break it...lol He said "you told me, hit it hard"....lol I also had Jan Sverre Haugjord do it in Norway, butit didn't work as he had the table on a cart and I figure it just bounced. The secret is to do it on a concrete floor or I suppose a HD steel welding table. Give it a try and tell the members how it worked. Steven said he concentrated in a 6" area in the middle of the table bottom.


5. Then Steven scraped the table straight. But in your situation you can probably leave it alone.
 
I was looking at the indentation on the gib. Almost looks as if he hammered in the gib when the lock was screwed in. The lock in front is a screw handle with a 50 degree angled stud under it. You maybe able to glue on some Turcite B on the wear side of the gib and that will help as it compresses and is self lubricating. I was going to wait to describe that until we saw more pictures. I was thinking you should lay the gib screws, gibs etc. on a table and take photo's so I or we can see if the correct screws are being used. The notch in the gib looks bent too..but we can fix that and you wont have to buy a new gib. Oh and check to see if the gib screws are straight,
 
Richard King 2 said:
The tables get bent by wats called "Peened" by over tightening the T bolts and that stretches the Irion and that bends the table. Usually .005 to .010".

You can straighten them by peening the other side. I Just wrote about it on Facebook... Here is what I wrote.

1. I'm going to write my answer in sections as it will get long. The first time I heard about peening a table straight . I thought my god you have to be kidding. I was demoing the BIAX scrapers at the Chicago Tool Show IMTS and a fellow walked up to me and told me he was a rebuilder in IL and he then asked me if I peen Bridgeport table straight? Like I said I was appalled at the thought. I never used it and had my tables ground or planned to get rid of the bow. Over the years I figure tables average convex about .007"high on T slot side. I had always figured they got that way as the saddle is shorter and hung down and bent them. Then I met Archie Cheaba a Engineering professor. He told me that the table stretches or get pressure peened when the T-nuts get tightened in the middle of the table all the time.. I now figure that is true and a little nd to unsupported weight too.
2. When my kids were in their teens my wife told me I needed to stop traveling teaching classes as when I taught in Taiwan I would stay there for 90 days at a time. The wife said she needed help at home as my daughter who was probably 12 and my son was 15 were a handful plus they were into sports and my wife couldn't transport the on the same night, so I stopped traveling. Then I started to sell machine tools at a company called Midwestern Machinery and after a few years the owner of that company passed away and 3 of us bought the assets. We would go to auctions and buy old machines and do a refurbish on them. Then sell them. Many were Bridgeport's and the tables were bent. So being a part owner and wanting to save some money I started to straighten tables. I still didn't think peening was a good idea and tried a couple of other things first. I tried a 12 ton hydraulic jack and chains to try to pull them straight, parked a 10 ton forklift wheel on the table setting on 2 x 4's. Nothing worked. Then I finally tried peening the underside of the table.
3. I first would set the table right side up on 1 2 3 blocks on my granite table and made the far ends. Put the 1 2 3 blocks on the flats or directly on the ways. 4 corners of the table indicate as close to the same. Using a height gage and .001" indicator measure the bow. Then I would put the table on the cement floor laying on a 1/2 piece of plywood and using a 1" cold role punch I made and the one end a 1/2 radius point I used a 5 pound hammer and began to peen the bottom and the cross section ribbing under there. Being careful not to hit near the dovetails as I figured they would crack. I gradually hit it and put it back on the plate and remeasured it. The first few ones took a while as it was a learning curve. Eventually it would straighten up to .001" bow.
4.
I do not like the idea of laying it directly of the table T-slot s as it bends and you don't get a true reading. A fellow rebuider named Axel For's out in Utah who I met at an SME seminar I was speaking at told me he would run a T slot cutter in the table T-Slots to relieve the stress before he peened his tables. So many rebuilders use this method. I did a class in Denmark I think and Steven Isherwood an Englander living in Norway who came to the class peeded his table one time. He said he used a BFH and hit it hard. I was shocked he didn't break it...lol He said "you told me, hit it hard"....lol I also had Jan Sverre Haugjord do it in Norway, butit didn't work as he had the table on a cart and I figure it just bounced. The secret is to do it on a concrete floor or I suppose a HD steel welding table. Give it a try and tell the members how it worked. Steven said he concentrated in a 6" area in the middle of the table bottom.


5. Then Steven scraped the table straight. But in your situation you can probably leave it alone.
Click to expand...
WOW!Great thread! As are the others. Thanks. I never considered a “ bent table” being “ bowed”. I was thinking the other axis, front to back and couldn’t imagine how that would occur without some massive accident. I doubt I have the skill or tools to measure bow, but maybe by turning table over I can see wear areas and get a clue from that. Thanks again! Dave. SOFL
 
Richard King 2 said:
I was looking at the indentation on the gib. Almost looks as if he hammered in the gib when the lock was screwed in. The lock in front is a screw handle with a 50 degree angled stud under it. You maybe able to glue on some Turcite B on the wear side of the gib and that will help as it compresses and is self lubricating. I was going to wait to describe that until we saw more pictures. I was thinking you should lay the gib screws, gibs etc. on a table and take photo's so I or we can see if the correct screws are being used. The notch in the gib looks bent too..but we can fix that and you wont have to buy a new gib. Oh and check to see if the gib screws are straight,
Click to expand...

Ok will do on the pics in the near future. Its being moved to a new shop and is prepped for movement now.

Does the table lock in the front also have a loose single ball bearing at the end of the screw, that presses on the angled stud? My (replacement) lock handle has a concave end that would receive and hold a ball bearing in place, so I put one in. Otherwise I dont think the lock threaded shaft is long enough to engage the angled stud that presses on the gib. (HMMMM i thinking, what if there is NO angled stud in the hole and the BALL bearing is pressing directly on the gib?? Hence that nasty groove in the gib??)
 
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