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Shop Improvements #2: Why your SawStop riving knife still isnt aligned

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Blog entry by Sarit posted 10-25-2017 06:38 PM 1599 reads 0 times favorited 7 comments Add to Favorites Watch
« Part 1: My love hate relationship with pegboard Part 2 of Shop Improvements series no next part

My SawStop PCS tablesaw has a pretty fussy riving knife adjustment system. You have to crank the blade up to check alignment and then crank it back down to be able to adjust the bolts and of course every time you tighten the bolts you move the knife out of alignment. So back and forth you go crank, loosen, align, crank, tighten, crank, loosen, align,... Then once you’ve got it just right, and you crank the blade back down to a reasonable height to cut some 3/4” plywood the knife seems out of alignment. What gives!?

Turns out that the knife holder isn’t exactly tilted in the same plane as the saw blade. It’s off by the slightest half of a degree. That doesn’t sound like much, but when the difference between the kerf and the riving knife is measured in .001”, that’s huge. If you have this problem it will seem like either you have to push harder to push the workpiece past the riving knife or the workpiece seems to want to drift away from the fence and cause burns along the cut. I had the latter problem. SawStop surprisingly has no mechanism to adjust the tilt. What I did to fix this was to add a couple of pieces of tape as shims to tilt the knife in the opposing direction as in the photos below.



7 comments so far

View RobS888's profile

RobS888

2413 posts in 1870 days


#1 posted 10-25-2017 08:28 PM

I did the same with the blade guard. 2 layers of blue tape.

-- I always suspected many gun nuts were afraid of something, just never thought popcorn was on the list.

View Redoak49's profile

Redoak49

3283 posts in 2013 days


#2 posted 10-25-2017 08:33 PM

Interesting… mine is right on

View Sarit's profile

Sarit

549 posts in 3164 days


#3 posted 10-25-2017 08:45 PM

The difference was quite small, but became much more apparent when I switched to a thin kerf blade.

View pintodeluxe's profile

pintodeluxe

5705 posts in 2838 days


#4 posted 10-26-2017 05:53 PM

Hmm, I’ve really enjoyed the riving knife on mine. I often remark how nice the adjustments are, with toothed bars for some of the adjustments so things stay parallel. I see you’re using the chrome thin kerf riving knife. What is the kerf of the teeth on the blade your using? The reason I ask is the blade should be slightly thinner than the riving knife so it doesn’t hang up. Some of my blades are too thick to use with the chrome riving knife, even some thin kerf blades.

I have both the standard and thin kerf riving knife, and use them both depending on the blade width. The clamp tension needs to be adjusted slightly when I switch, but that is an easy tool-free procedure.

Is your riving knife dead flat?

Was this a problem for you when the blade was tilted, straight, or both?

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Bigrock's profile

Bigrock

292 posts in 2987 days


#5 posted 10-26-2017 07:48 PM

I have the PROF. Saw Stop and don’t have the problem. It is about 3 years old.
Have you talked to Saw Stop people, they may have a lot better answer or fix?

View Sarit's profile

Sarit

549 posts in 3164 days


#6 posted 10-26-2017 09:25 PM

pintodeluxe, Did you mean to say “the blade should be slightly thicker than the riving knife”?

I got the PCS a few months after they came out with it (several years ago). Last time I asked them about the plywood faces of my fence delaminating and they said it was out of warranty so I had to buy new ones. Not sure if I want to go through the hassle of contacting them since the tape is working for now.

I don’t know exactly the kerf thickness, but it is definitely thicker than the riving knife itself since I can line up a straight edge with 2 teeth on the blade and see that there’s a little gap between the riving knife and the straight edge on both sides of the blade. The gap is there when the blade is in the highest position, when I crank it down the gap opens up on one side and disappears on the other side (pushing the straight edge so it doesn’t contact one of the teeth anymore).

I don’t think the knife is bent since both the knife and the one w/ the blade cover are both misaligned by the same amount in the same direction.

The problem definitely occurs w/ the blade straight up. I didn’t try with it tilted, but I would suspect that its the same since the riving knife angle is cast into the carriage that holds the blade arbor and brake.

View pintodeluxe's profile

pintodeluxe

5705 posts in 2838 days


#7 posted 10-31-2017 06:01 PM

^^^ Sarit, yes, thanks for the correction.

Mine will give me imperfect cuts if the blade is too thick or too thin, but using a blade thinner than the riving knife really won’t work. The suggested blade thickness range printed on the riving knife has been a good guide for me.

All the best.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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