Surface plate question

[ErichKeane]

The contact area of the vise (reduced to the wire size) doesn't change the amount of friction keeping the part in the vise. It should not matter how thick a cut, it should hold the same as if you have full contact

 

[Flyinfool]

If your part is not square the first time you put it in the vice, (and it is most likely not square since you are trying to square it) you will still have only at best a single line of contact on one of the jaws, very possible only a single point of contact. Absolutely no different than using a piece of round stock on one side. By using round stock that is softer than the part you are machining it can deform to get more grip on the part.

 

[Cadillac]

Saw a good video about vise distortion and how to work around it. Video is by edge precision. He talks about how machinist had to overcome the problem with old style Bridgeport vises before the Kurt vise came to market. He shows how chucking a part off center in a brand new Kurt vise the deflection in the solid jaw and the moveable. He would get .002 difference on the jaws chucking a 123 block off center. He shows how to machine a part square without the worry of jaw deflection. Was a informative watch.

 

[finsruskw]

Messed with it again this AM and found the rear jaw lifts about .002 when tightened.
Found three bolts under each side of the movable table in the vise that were loose and tightened them snug to where it took a bit of torque
on the handle to tighten on the work piece.
So, therein was my problem from the get-go I think.

But, how much torque is too much, and how tight should these bolts be for repeated usage?
Again, this vise appears to be a no-name piece and was probably a cheap alternative to what ever was available back in the 80's when the mill was new. I might add. this is a one owner machine that came with all the original paperwork and was used in a small engine shop for balancing pistons. The ways all all appear ae as new.

 

[MrWhoopee]

Messed with it again this AM and found the rear jaw lifts about .002 when tightened.
Found three bolts under each side of the movable table in the vise that were loose and tightened them snug to where it took a bit of torque
on the handle to tighten on the work piece.
So, therein was my problem from the get-go I think.

But, how much torque is too much, and how tight should these bolts be for repeated usage?
Again, this vise appears to be a no-name piece and was probably a cheap alternative to what ever was available back in the 80's when the mill was new. I might add. this is a one owner machine that came with all the original paperwork and was used in a small engine shop for balancing pistons. The ways all all appear ae as new.

A picture of your vise would help immeasurably.

 

[MrWhoopee]

Saw a good video about vise distortion and how to work around it. Video is by edge precision. He talks about how machinist had to overcome the problem with old style Bridgeport vises before the Kurt vise came to market. He shows how chucking a part off center in a brand new Kurt vise the deflection in the solid jaw and the moveable. He would get .002 difference on the jaws chucking a 123 block off center. He shows how to machine a part square without the worry of jaw deflection. Was a informative watch.

A link to the video would help immeasurably

 

[macardoso]

I think this is what he was referring to.

 

[finsruskw]

Didn't have time to get back with it this afternoon but did snap a few pictures.

 

[MrWhoopee]

Didn't have time to get back with it this afternoon but did snap a few pictures.

That appears to be a Bridgeport style vise, which has a much greater tendency for moving jaw lift than the Kurt style vise. Those bolts should be as snug as possible while still allowing the jaw to move.

 

[finsruskw]

That appears to be a Bridgeport style vise, which has a much greater tendency for moving jaw lift than the Kurt style vise. Those bolts should be as snug as possible while still allowing the jaw to move. Are there more on the other side?

Yes, 3 on each side.
Going to give it another try in the morning, to make my paper weight even smaller!!