Ok, time to adjust the trunnions

[Jared Cuneo]

I've discovered that my wonky bevel cuts are caused by bad trunnion alignment and that I need to shim the rear trunnion on my Delta contractor saw. FYI, on my left tilt saw (fence to right of blade), the rear of the blade is closer to the fence at 45°.

Needless to say, I'm very nervous about this procedure as I understand this is a very tedious process.

Is there anything I can do to minimize the heartache? Any tips or pitfalls?

I plan on using some shaped aluminum coke can squares for shims. Also, my rough measurement (will take better readings tonight) looks to be about .01 out at 45°. Is there a way to take this error and calculate the needed shim size to minimize the trial and error?

Thanks to everyone for responding to my earlier thread and getting me this far.

JC

[Bart Leetch]

In one URL

Get them they really work.

http://www.in-lineindustries.com/saw_pals.html

[Tom Veatch]

The way I did it on my cabinet saw adapted to a contractor style saw is:

First make sure the 90 degree alignment is satisfactory and only the trunnion attach bolts at the required shim location are loose. Then tap in some thin, long tapered wedges between the trunnion and the table top at convenient points near the loosened attach bolts while checking the 45 degree alignment frequently. When the alignment is satisfactory, a feeler gauge between the trunnion and table top at the attach bolt location gives the thickness of shim required at that location.

I used steel arbor shims, but there's no reason that a stack of soda can shims wouldn't also work. You may need to use an extra thickness or two in order to compensate for compression when you tighten the attach bolts.

By only loosening the bolts at the shim locations, you reduce the chances of changing the 90 degree alignment. Although a PALS is great for the 90 degree alignment, I don't think they offer much help with the vertical shimming necessary for the 45 degree case.

You could calculate the thickness needed, but that would require some pretty precise trunnion geometry measurements that are probably not readily available without disassembling the saw.

The approach outlined above is pretty straighforward and goes fairly quickly. It got my cabinet saw to less than .001 TIR (measured with an Align-It setup off a Master Plate) in less than half an hour from start to finish..

[Anthony Whitesell]

There is math that can do it if you can take all the measures but I don't think it's worth the time. For this the PALS won't work. PALS work great at 90 degrees but have no effect at 45.

Here's something I tried and had some success with. Find the thread size of the trunion bolt (in my case 5/16-18). Back off the bolts equally and gently but frimly push the trunion down onto the bolt head and check the toe. If they are hex head bolts, I would suggest loosening the bolts one flat at a time. On a 5/16-18 bolt that equates to one-sixth of 18tpi (or [1/18]/6). That will help you get into the ballpark on what size shims you'll need.

I was ~0.035 off on a 1952 Craftsman and it took 12 flats (2 full revolutions) to get close. I use 2 0.062 washers as shims to bring in to ~-0.001. So don't be surprised if little changes have no effect. Would tried to find a variety of thicknees shims before you start.

If you use washers be sure you sand each side to make them flat and remove the burrs (washers are made using a punch process).