I'm a novice searching for my first machine. I'm looking at a jhead series one bridgeport 9x32. When you crank the table out towards the ends, it gets really tight. Is this a sign that it has been tightened to allow for the wear in the middle and won't go out to the ends anymore? In short, is it worn to the point of needing trued up? How do I decide if a machine needs attention in this area so I can judge what I would pay for it or if I would buy it?
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judging table wear on used mills
- Thread starter LEEQ
- Start date
I would say, thinking out loud the weight of the table and all the surface area of the ways I dont think
I''d worry much about it. I probably would loosen the gib and find a happy spot, and then a lot of
operations the table either / or will be locked anyways. I maybe off line, but I think of this little end
mill,drill,boring head, whatever -v/s- the mass weight of the machine. In fact I do not own anything
that does not have some kind of quirk in it. Then it could only be a clump of old cold tar grease stuff.
I''d worry much about it. I probably would loosen the gib and find a happy spot, and then a lot of
operations the table either / or will be locked anyways. I maybe off line, but I think of this little end
mill,drill,boring head, whatever -v/s- the mass weight of the machine. In fact I do not own anything
that does not have some kind of quirk in it. Then it could only be a clump of old cold tar grease stuff.
More then likely its the wear on the dovetail ways and gib is to tight in middle s the others have said or the ends are super dirty with crud. Bridgeport has a adjustable feed nuts and can be adjusted. The older machines have a brass nut with a cross slot milled 1/2 thru the nut and it can be tightened to squeeze the threads closer together. On the table (X) axis you look in under the table with a flashlight on the left side and you will see a slotted screw that is held in by a small jam screw. That screw also holds the nut into the screw bracket. But when you have to much backlash you can use a square shafted screw driver with a wrench (spanner) to help tighten that screw. You can access the Saddle (Y) brass screw by removing the 4 cap screws holding the front feed screw bracket. No need to loosen anything else. Before removing them, crank the saddle near you and lock the saddle clamp left side or put a 2 x 10 behind the saddle and then remove the screws and then crank the handle to the right, that will push the bracket off the roll pins and it will come out. Remove the feed screw carefully when it get out near the end the brass thread can get burred up near the front end. Look in hole and loosen the small slotted lock screw and again use a square shafted screw driver and tighten the screw approx 1/8 turn and lock small screw and carefully screw in the feed screw again. On newer machines they have 2 brass nuts that basically are adjust the same way. Another thing is the gib adjustment bolt slot is broken off and when you move the table to the right and it gets tight that could be the problem. If you move to the left it would get loose, but the table would get super loose.
I think after buying a good book I can make repairs. I'm not sure about fixing excess wear. I might take the worn parts to someone to adress way wear, or not make the purchase. I'm thinking some pb might not hurt to help clean up/ free up the table. If not, it's beyond me to diagnose the cause of this without studying some good drawings so I can understand Richards advice. What would it cost to have this trued up/ scraped if it's worn in the middle? Who close to KCMO does this sort of thing?