Ripping woes.... bad technique?

[Augusto Orosco]

Long time since visiting, trying to get back in the saddle!

I have somewhat an open question, but looking for suggestions/ideas that may help me, if you don't mind.

I am a bit at a loss and frustrated. Since I got a Sawstop (3HP) a couple of years ago, I haven’t really asked much of it at all until yesterday. I needed to rip an 8/4 30” long piece of soft maple and the saw really struggled, to a point that I had to stop the saw as I was getting quite nervous having to push so hard.

Of course my first thought was that I was having alignment issues, so I checked and checked again, even made minor adjustments to the fence and checked the blade alignment. They are absolutely spot on (and I tried the fence to be absolutely parallel and then made it 1/64” wider at the end, as the manual suggests as an alternative). I used the splitter, and also tried with the the riving knife. I raised the tooths so the gullets show, and also tried with just the teeth showing. I even changed the blade (I have a fairly new WW-II, which is as good as it gets, but I even tried the stock Sawstop, which is inferior, but was 100% new). Yes, they are both 40 teeth hybrid cut… but honestly; the machine was struggling even with 1” test boards.


To be fair, even as the fence and blades were spot on, it felt to me that as I fed, the board started to pivot a bit (my stock had fresh edges and flat face from the jointer, though). I was also using a magna-board featherboard just *in front* (edited) the blade… and that actually felt like it was making things worse.


Right now, after all the adjustments, it has shown some minor improvements… but I can’t imagine I should struggle in pushing that hard with that 3HP monster and a good blade (not just the 8/4, but the 4/4... and no, the stock is not under a ton of stress and doesn't seem to be pinching anything more than normal.


So, any ideas what I am doing wrong? Look at the burn marks after forcing to finish the rip on the boards. And this is the second attempt… the first one burned much worse! Pushing them through was anything but fast. It was slow and had to push hard once the blade was fully engaged.

[Prashun Patel]

Do you still have trouble pushing through without either the blade guard or riving knife? That is, without ANY kind of splitter?

When I got mine, the RK was a little thicker than the blade I was using; I had to grind my rk down to accommodate the thinner kerf.

[John TenEyck]

The burn marks suggest the blade and fence aren't parallel, or the splitter/riving knife is pulling the wood into the side of the blade. On the other hand, taking so much force to push the wood through the blade suggests the splitter/riving knife is thicker than the blade or is pinching the wood against the fence.

John

[Malcolm McLeod]

... I was also using a magna-board weatherboard just behind the blade… and that actually felt like it was making things worse.
...


I assume this is a typo and you meant "feather-board", if so, I would never install it behind the blade. Whatever relief is created between the (now split) boards, the blade, and the fence will be compressed by the pressure from the feather-board.

If needed, I place mine right at the front of the blade - perhaps 0.75" to 1" overlap of the blade if necessary with small/short stock.

[Steve Demuth]

First, I assume you've verified that the blade is not dull or have damaged or misaligned teeth. If not, it's worth checking. Also verify that it's an appropriate blade for ripping.

Assuming those aren't issues, then as others have suggested, the thickness of the riving knife vis-a-vis the blade could be an issue.

But I would also check that the RV is not itself twisted or badly mounted. A riving knife pushing the stock into the fence could account for the tough cutting and the burning (by causing your pressure on the piece to rotate the stock into the blade's side). If the riving knife is the problem, BTW, you should be able to tell by when the resistance to cut appears. If the saw is cutting poorly even before you get the workpiece all the way through the blade, then it's likely the blade, not the knife.

One thing is for sure - you should be able to go through 8/4 soft maple with a 3HP saw and a good, sharp ripping blade like silk, unless the workpiece is a complete mess of reaction wood that is directly binding on the saw blade or riving knife.

[Mike Rambour]

can't help but I cut 8/4 maple and walnut with no issues when I made a large cutting board a few months ago and that was using the standard SawStop blade

[Augusto Orosco]

Sorry, I was a typo, and worse, I misspoke. Yes, it's a featherboard and it's positioned "behind" (as in, closer to me, before the board engages the blade).

My bad!

[Augusto Orosco]

Thanks guys. I will look further into the RK alignment. I checked earlier and I know it's thinner than the WW-II blade I am using, but perhaps it's not properly aligned as indeed that's where I start getting into trouble. I had hesitated to test without either the RK or a splitter, because I was nervous about kickback giving how hard I was pushing. But as I have checked both blade and fence for alignment, I think I will give that a go first as seems to be the easiest thing to check.

The blades I have tried are the stock Sawstop blade (which albeit not great was brand new) and the Forrest WW, which is not new, but barely has seen a few linear feet of action. Both are 40 teeth and rated as a combo, so I can also try a true ripping blade later.

Thanks for the help!

[Roger Feeley]

Try this.

1. Rip your 8/4 board so you take off just a tiny bit on left side (blade side). After you have ripped the board, we know that the board is properly sized for the blade. Move the board forward and back to see if it deflects the riving knife.This will test the alignment of the right side of the riving knife.
2. Now, lower the blade, move the fence to the left of the blade and repeat the test

If you see any deflection of the riving knife as the leading edge of the wood engages it, you will know if you have a problem.

Another simple test would be to remove the riving knife and rip a kerf partway through a piece of MDF. Is the kerf big enough for the riving knife?

To test blade alignment with the fence, just look at the saw marks. There should be roughly equal scratches from the front and back sides of the saw.

[Rod Sheridan]

Have you tried a ripping blade like a 24 tooth FTG grind?

8/4 is far too thick to rip with a 40 tooth blade.

Check your saw alignment as well.............Rod.

[Richard Coers]

Switch to a piece of plywood. The solid stock may have internal stresses and complicating the situation. Also I agree that a WWII is not a good ripping blade. How old is it and have you had it sharpened. It's not a thin kerf WWII is it?

[Doug Garson]

Sorry, I was a typo, and worse, I misspoke. Yes, it's a featherboard and it's positioned "behind" (as in, closer to me, before the board engages the blade).

My bad!
You are still misspeaking, a featherboard closer to you is normally referred to as "in front of" the blade. It's difficult to get good advice if people can't picture what you are doing because of incorrect terminology. With an underpowered saw (not your case), dropping the blade down and cutting half way thru then flipping end for end keeping the same face against the fence can prevent the saw from bogging down. You could try this w/o the riving knife.

[Augusto Orosco]

You are still misspeaking, a featherboard closer to you is normally referred to as "in front of" the blade. It's difficult to get good advice if people can't picture what you are doing because of incorrect terminology. With an underpowered saw (not your case), dropping the blade down and cutting half way thru then flipping end for end keeping the same face against the fence can prevent the saw from bogging down. You could try this w/o the riving knife.

You are correct, I was still misspeaking. Now corrected in original post. Sorry for the inconvenience.

[Andrew Seemann]

Check if the wood is flat after being ripped, or if it has any curve. If it is not completely flat, it may be that the wood has internal tension that is being relieved. Soft maple tends to be a stable wood (unlike hard maple), but like any wood, it can have differential moisture or, as noted above, tension wood in it. That can cause the wood to bind during the cut.

[Augusto Orosco]

Try this.

1. Rip your 8/4 board so you take off just a tiny bit on left side (blade side). After you have ripped the board, we know that the board is properly sized for the blade. Move the board forward and back to see if it deflects the riving knife.This will test the alignment of the right side of the riving knife.
2. Now, lower the blade, move the fence to the left of the blade and repeat the test

If you see any deflection of the riving knife as the leading edge of the wood engages it, you will know if you have a problem.

Another simple test would be to remove the riving knife and rip a kerf partway through a piece of MDF. Is the kerf big enough for the riving knife?

To test blade alignment with the fence, just look at the saw marks. There should be roughly equal scratches from the front and back sides of the saw.

Very helpful, will try that. Thank you!


Have you tried a ripping blade like a 24 tooth FTG grind?


8/4 is far too thick to rip with a 40 tooth blade.

Check your saw alignment as well.............Rod.

Thanks, Rod. I have a new 24 tooth Rip Blade lying around. I will try it, too. Although I would expect that my more pedestrian rips (4/4 rips) wouldn't have that problem


Switch to a piece of plywood. The solid stock may have internal stresses and complicating the situation. Also I agree that a WWII is not a good ripping blade. How old is it and have you had it sharpened. It's not a thin kerf WWII is it?

Upon experiencing the problem, I tried with other woods (including 4/4 hard maple). But haven't tried plywood, can try that, too. The WWII has seen little use and I don't see any damage to it. Probably have gone through less than 100 linear feet of wood (I use my bandsaw and hand tools more heavily than the saw). It's the WW-II thick kerf "for Sawstop Table Saws". 10", 40T.

[Matthew Hills]

Advice above on chekcing alignment is my first thought, as well.

I'd also recommend checking cleanliness of your blade -- your cutting will suffer a lot if pitch builds up on the blade.

Matt

[Doug Garson]

You are correct, I was still misspeaking. Now corrected in original post. Sorry for the inconvenience.
Not a problem, I had a poster in my office decades ago which read "Although you think you understood what you thought you heard me say what you don't realize is that what I said was not what I meant" . We all do it sometimes. :)

[Steve Jenkins]

Are you pressing down really hard as you push the board through? Try dropping the blade below the table with the saw off and push the board through as if you were ripping it. It may be that your table needs to be cleaned and waxed

[Jim Dwight]

My PCS has the 1.75hp motor and I've had some ripping issues with it but only when I used a full kerf blade. You shouldn't need thin kerf blades with a 3hp motor. But you might need a ripping blade. I rip 3 inch softwood with a Freud Fusion thin kerf on my smaller motor saw, however (40 teeth). But it has to be well behaved without nasty grain warping the wood as you cut. I have also had ripping issues with a 1 inch oak board that was closing up the kerf due to internal stress despite the riving knife. A wedge into the kerf stopped that. I am using the stock riving knife with thin kerf blades but you have to get it spaced just right to do that and I think I need to make a small adjustment. Sometimes I have to push harder than I should have to because the riving knife is pushing the board against the fence. This isn't a terrible thing but I will move it out a little to stop that. It is not a hard adjustment and if you are using full kerf blades it isn't hard to position the significantly thinner riving knife within the saw blade kerf. SawStop offers a thinner riving knife too but you should only use it with a thin kerf blade.

I've cut more thick softwood than hardwood with my PCS but I ripped legs for my bed out of cherry glueups that were 3 inch thick. The saw went through it relatively easily. I am not sure which blade I used but it was probably a full kerf ripping blade. Today I would use a thin kerf ripping blade on my saw unless I decided to just try the Fusion that is normally on it. It does surprisingly well.

If your saw is setup properly I would look hard at the kerf closing up on you. That's internal stress in the board. You want to rip oversize and then recut because the board won't be straight after cutting either. If it is more than just one board or an occasional board causing issues then it definitely suggests a setup issue with the saw. If I can rip 3 inch hardwood with my 1.75 hp PCS (and I can and have and will again) then you should definitely be able to do it with 3hp. But warping boards can still be an issue.

[Augusto Orosco]

I tried without the RF or splitter, on 4/4 hard maple. It was much better than before, but still felt some vibration at the beginning. I have a video link here. https://youtu.be/aoaOD0aZRKQ

At the end, I got some burn marks on the left side of the blade (farthest from the fence). The burn marks are always worst on the left side. But this was way easier than before and it doesn’t really show the struggles I have described. I will try later with 8/4 soft maple to test again and will try to record it to better illustrate, but I am out of jointed material now!

I am using the WW-II on the video (40T, combo). The dewalt I found unopened is a general use 32T, so it’s not the 20T ripping I thought... I don’t even know why I bought it.

Any suggestions for a ripping blade to buy next?

[Andrew Seemann]

Is the edge of the maple against the featherboard rough? That may be giving you a lot of drag. If that WWII blade is clean and sharp, it isn't the problem. I have one on my 3HP Unisaw, and I almost never take it off. It will rip 3" stock just fine. Soft maple has a high sugar content, so a little burning isn't uncommon.

Also, going too slow on a rip cut with high sugar woods like maple, cherry, or even oak, can allow the wood and blade to heat up and start burning. One it starts burning, it tends to get worse since everything wants to expand a little, messing up your clearances.

If the edge was rough, the table a little oxidized or in need of wax, you might be going slow enough with the 8/4 that the heat isn't being carried away by the chips, and that could cause a fair amount of burning.

A video of the 8/4 would definitely help diagnose the problem. If you are out of 8/4, try ripping a 2" piece of that 4/4 down the middle to "simulate" 8/4.

[Mike Wilkins]

The wood could still have some moisture in it and the kerf is closing in on the riving knife. I have been using a dedicated ripping blade a lot lately making cutting boards with no problems. I too occasionally get some push back when ripping but I chalk it up to stress in the wood just releasing as it's cut.

[Michael W. Clark]

Make sure the table is waxed. Even if the saw is aligned correctly, friction on the table makes it hard to push.

[Brian Tymchak]

From the video you provided, I think I hear the saw bogging down towards the end of the cut. A 3hp saw should sail thru 4/4 without skipping a beat. Have you pulled the 2 belts on the saw lately and cleaned or replaced them? Where I volunteered (until Covid came along) we had a SS that started to bog down cutting 3/4" melamine first thing in the morning after the weather started to cool off in the Fall. After running for 15 minutes or so it would be fine. We found that the belts had picked up quite a bit of dust and the cool weather I think contributed to belt slip. I've since wondered if this indicated a problem with the dust collection.

If the belts are slipping, the feed rate has to slow down, which is going to build heat in the cut and burn the high sugar woods.

[Daniel Smith]

The wood could still have some moisture in it and the kerf is closing in on the riving knife. I have been using a dedicated ripping blade a lot lately making cutting boards with no problems. I too occasionally get some push back when ripping but I chalk it up to stress in the wood just releasing as it's cut.

I've had issues with maple moving and pinching that I haven't seen in other species. Since I trust my saw is set up correctly, when I get resistance pushing a piece through a rip cut, I start watching the kerf to see if it is closing down.

[ChrisA Edwards]

You asked for blade recommendations, I use a Forrest WWII Thin Kerf 20T rip blade on my 3HP SawStop.

I also bought a thin kerf riving knife from SawStop for use with this blade.

Ripping with this blade is night and day difference than my normal WWII 40T Combo blade.

[Prashun Patel]

Looking at your video, I wouldn't call that a problem. Feeding maple through fairly slowly will result in that much burning routinely for me. You may also have the featherboard set a little tight.

Given that your problem reduced drastically once the RK was removed, my money is now on the thickness of the splitter relative to your blade being the issue.

As for blades, I use Freud blades from AMZN 24 or 30t and they work fine. I've used cheap blades too. They may not last as long as expensive ones, but they cut fine for a hobbyist, IMHO.

You can try ripping a couple pieces without the featherboard in place to be sure it's not your alignment.

[Jim Dwight]

Burning maple in my experience is a feed rate issue. Too slow, it burns. But which side you burn it on is an indication of where the friction is that is cause you to have difficulty feeding. If the side of board between the fence and the blade burns, the fence is likely tilted very slightly towards the blade. That would cause a feed rate issue too. Since you indicate it is the offcut side, I would look for a fence tilted a little too much away from the blade. That should not cause a feed issue however. It is a little hard to measure precisely enough, at least for me, but I use a good steel ruler to measure the distance from a blade tooth to the fence at the front and the back with the blade raised all the way. Distance should be the same or very slightly greater at the back. You could also try using dial calipers on the inside measurement side. Or you could just adjust the fence a little and see if it helps.

Your observation of lower feed effort without the riving knife indicates you need to move it a little away from the fence. That could be your biggest issue.

The best ripping blades have flat top grind. I like 24 teeth but if you have one with 32 teeth that has flat topped teeth, it should rip better than an all around blade. I have never used a Forest blade so I don't know anything about it's resistance to feeding on a deep rip but different blades are different in the pressure required.

[Johnny Barr]

The only time I've ever had a problem like this on my SS was when the timber is warped, particularly if its convex shape looking at it from the fence like this ..... )!

[Augusto Orosco]

I wish I could tell you what made the difference, but I am really not sure. I checked alignments again, made sure the splitter was properly positioned and that the blade was properly sized for it. Adjusted the fence again to make sure it was mostly parallel with just 1/64” wider towards the back to avoid pinching. Made sure the belts were clean and the table was smooth and didn’t need any wax. Also eased up on the feather board just a bit. Milled another piece on the jointer from the same 8/4 soft maple board that gave me trouble before and tried again. This time no issues, not even burn marks. I shot a video thinking I would show how hard it was to push and instead I just got a smooth ride even with the combo blade. One thing that felt different, though, was that the board was going straight and smoothly through the path. On the previous tries (including the other video with the 4/4), it felt that it wanted to tilt away. Not this time... everything went rather smoothly.

Anyway, I still have a 20 tooth rip blade coming in the mail tomorrow. Never hurts to have one around. Thank you all for all the help walking me through potential issues. Considering everything and making sure everything was done well, including technique, really helped. If the problem comes back again I will go through that checklist to troubleshoot... and likely bother you again. But now, albeit a bit puzzled, am happy with the end result.

The video: https://youtu.be/eCqsUN1JSxo

[johnny means]

I agree on using a proper ripping blade. 8\4 stock is a big ask for a combo blade. Combo blades are nothing but two bad blades for the price of one.

[Andrew Seemann]

It could have been one of the things, it could have been a combination, or it could have just been a board that was a SOB. Sometimes you get boards that are just fine on one side and chock full of tension on the other. Every species of wood I have ever used has had at least one board that refused to submit to standard woodworking operations. Either way, it sounds like your saw is much happier now.

A decent rip blade would be handy to have. I have a cheap thin kerf rip blade I use for when I do a lot of rough ripping or if I am a little suspicious of what I am cutting. I should break down and get a decent rip blade, but I get good enough results with the Forrest blade 90% of the time, plus I don't need to stop and change blades, so . . .

[Si Wood]

I would try ripping a different scrap board to eliminate the possibility that it is a lumber issue. Freshly dressed 8/4 stock, depending on storage environment should be done within a few days time depending on how much material your jointing off. If your issue still persists, check the alignment of the table top to the trunnion underneath. I have a cross slide attachment ( Excalibur ) that bolts to the side of the saw's cast top and when walking past it was knocked enought that the cast top twisted out of alignment to the trunnion. There should be 4 bolts securing the top to the saw cabinet or base with enough play in the holes to " square up " the top to the trunnion. The mitre slots to the blade BODY can be your reference point. If that checks out, then i would check the fence alignment and like mentioned, the RK to blade body ( maybe the knife is twisted a bit and pulling the lumber towards the blade )...my two and 1/2 cents