Powermatic help needed

[Lee Schierer]

Where I work they have a Powermatic 12" Table Saw, Cabinet type, Model 71 Ser No. 1-4758 that is out of alignment by about .020" front to rear on the blade to the miter slots. Under the table there are two trunnions front and rear with 2 bolts each up into the bottom of the table. On each side of the trunnion are jacking screws. So after loosening all four bolts 1/2-1 turn and backing off the jacking screws on the side where we are trying to move toward, we cannot move the trunnions (front or rear) at all. The jacking screws feel so tight that they feel like they might break if we twist any harder. What am I missing? We can't see any other bolts. Anyone have a similar aged saw that has done an alignment?

Also, does anyone have a manual or instructions on how to repalce the arbor bearings and belts on this saw. It has a 3 Hp 3 Ph motor with three drive belts.

[Robert Reece]

Is that a cabinet saw? On my cabinet saw, the cast iron top just removes with four bolts. So you loosen three of them slightly, then give the table a little wack to move it relative to the blade.

[Lee Schierer]

It is a cabinet saw, but the trunnions hang from the underside of the cast iron top.

[george wilson]

The Delta Unisaw also works by loosening the top. The blade stays still.

[David Christopher]

Lee, it sounds like you need to loosen up the trunion bolts a little more and maybe even tap the trunion a few times to get it broke loose and then use the jam nuts

[CPeter James]

On some saws that are constructed this way, the trunions are pinned in place after they are aligned at the factory. Check to see if there are some pins through the trunion into the table. This is the way that Darra/James did theirs.

CPeter

[Stephen Musial]

Here's the owners manual from OWWM http://owwm.com/pubs/655/809.pdf

[Lee Schierer]

Well after consulting the manual and doing a bit of disassembly we discovered that all three belts were shot, two of the trunnion mounting screws were badly damaged and the raise lower linkage was broken. We also noted that the arbor bearings were shot. So we disassembled the saw, replaced the two bearings (about $30 each), found new bolts (7/16-14, which isn't all that common) and elongated the holes in the trunnion castings by .020. Surprisingly everything came apart pretty easily and no parts were damaged.

We reassembled everything today and in less than 30 minutes we had the blade aligned within .0015 after everything was tightened down. We even managed to fix the raise lower mechanism which had not worked on this saw for over 20 years. I used my Beall Tilt box to get the blade perfectly square to the table.

With a freshly sharpened blade (we also ordered a new plastic cutting blade), they will be making cuts either later today or tomorrow. So for under $200 in parts they have a like new saw.

Thanks one and all for all the help.