60" Bar Sag

[SPM in King]

I have been working on a solution to a sagging bar. I have tossed the idea around with Bob, but came up with a slightly different solution (perhaps). I first removed the lower clamps, on both ends, from the Granberg mill. I then drilled and tapped the upper clamps for a 3/8 - 16 bolt. After bolting the bar into the upper clams, I adjusted the uprights and got it all as true as possible. I then made some "Coke can" shims to use between the upper bar clamp and the bar (see pics). 4 layers of a Coke can seems to be right. This puts pressure on the top of the bar, on the power head side of the clamp, which, in turn, moves the center of the bar up. This reduced the sag to zero.

Not sure if this will work. Let me know if this has been tried before. Please shoot holes in the design.

Thanks, Steve.

 

[BobL]

Yep similar things have been tried with some success.

But I would not just jam bits of coke can in like you have - if they come loose while cutting - well . . . . . I guess you can work it out from there.

The pieces of metal need to be firmly attached to the clamps or arranged so they cannot come out due to vibe etc. One setup I have seen is used tapered milled steel pressure plates that clip over the existing clamp jaws with the taper adjusted to suit bar length and remove the sag. Another method used an 2" steel arm welded to at right angles to the outside top of the clamp. A bolt threaded through the arm and down onto the bar was used to provide leverage to lift the bar in the middle

Eventually this method can wear a contact groove into the bar and wears the clamp pad unevenly but if the pressure plate is wide enough the wear will be light and should last for the life of the bar. Another guy I know who tried this said it ended up bending his mill uprights but I think he had other problems with a bent mill to start with. Some say it will bend the bar but somehow I doubt it.

Sorry I didn't mention this method in my earlier communications with you about this
Definitely worth a shot I'd say.

 

[Woodsurfer]

Has anyone tried bending their bar? Put say a 1" or 2" arch in it so that in the mill it sags down to the dead flat condition. I know its a crazy idea! Just throwing it out there...

 

[mtngun]

Has anyone tried bending their bar? Put say a 1" or 2" arch in it so that in the mill it sags down to the dead flat condition.

Then you wouldn't be able to flip the bar.