Blade Guard Alignment Issue

[DLB]

... If all your blades are of the same thickness, this is a one-and-done adjustment. But if your blades are of different thicknesses, you will need to make adjustments each time you switch between blades of different thicknesses. This is one reason I switched to using only Shopsmith-branded saw blades (rip, cross cut, combo) and stopped using my Forest WWII combo blade.

I don't do that. I know the book says the riving knife should be "centered on the blade." I use "anywhere within the kerf." So if I'm approximately centered on a thin kerf I'll be off center some with a standard kerf, but still within the kerf. Should I be worried?

- David

[John4337]

Two separate issues.

First, it is possible the riving knife part of the upper saw guard could get bent or twisted, in which case getting the riving knife properly aligned to the blade will be impossible until the riving knife is straightened/flattened/replaced.

Second, even with a straight/flat riving knife, care needs to be taken to ensure the adjustment screw on the back of the lower saw guard is adjusted so the riving knife is co-planar with the blade.

If all your blades are of the same thickness, this is a one-and-done adjustment. But if your blades are of different thicknesses, you will need to make adjustments each time you switch between blades of different thicknesses. This is one reason I switched to using only Shopsmith-branded saw blades (rip, cross cut, combo) and stopped using my Forest WWII combo blade.

Thanks, I’ve been massaging it and have it much closer that it was. I suspect it was bent/twisted when we moved. I’ll be looking at the adjustment on the lower guard today.

[John4337]

I wanted to thank everyone, some time in a vice working out the twist/bend and some work with that adjustment screw on the lower guard and its all lined up. Thanks again

John

[JPG]

Good News!

P.S. Thanks for the feed back.

[algale]

... If all your blades are of the same thickness, this is a one-and-done adjustment. But if your blades are of different thicknesses, you will need to make adjustments each time you switch between blades of different thicknesses. This is one reason I switched to using only Shopsmith-branded saw blades (rip, cross cut, combo) and stopped using my Forest WWII combo blade.

I don't do that. I know the book says the riving knife should be "centered on the blade." I use "anywhere within the kerf." So if I'm approximately centered on a thin kerf I'll be off center some with a standard kerf, but still within the kerf. Should I be worried?

- David

If you have to ask the question then I'd say follow the book. You don't want to get the answer by having a board flung back at you.

[DLB]

If you have to ask the question then I'd say follow the book. You don't want to get the answer by having a board flung back at you.

I did a bit of research in an attempt to get a good or consensus answer as to where, within in the kerf, is the proper location for a riving knife. No such luck. Opinions, occasionally supported by rationale, vary wildly. Even the primary purpose or proper terminology vary considerably.

One purpose, the primary purpose per Stumpy Nubs and an Axminster video, is to prevent material from contacting the blade body. As such it must be thicker than the blade body, thinner than the kerf, and sufficiently centered so that each face of the riving knife is outside the face of the body while inside the kerf. That proves difficult on the Mark, the riving knife is relatively thin. Typical thickness for the industry is 2.3 mm for for full kerf, the SS measures 1.90. Some suppliers offer a 2.0 mm thin kerf version, but IIUC they specify that it should only be used for thin kerf.


- David

[Matanuska]

Had a similar issue with my riving knife appearing to be bent but found it was actually being caused by the lower saw guard (which holds the riving knife) getting mounted at an angle. This was happening because although I had the adjustment screw set correctly to center the knife, the guard was cocked because the screw creates a standoff on only one side of the spindle leaving a gap on the other. I fixed this by putting a shim between the guard and the headstock. It’s cut from appropriately thick gasket material and goes all the around the spindle and adjustment screw and is flush with the top of the screw. I attached it to the saw guard using thin double sided tape and then trimmed to fit. Now I just push the guard firmly to the left when mounting it and everything lines up like it should.