Christoph Posted September 20, 2014 Report Share Posted September 20, 2014 Hello all, I made my first experience with cutting a thick Sapele board. I started a 19' boat, actually a Caledonia yawl. One of the very first things you have to do in that process is cutting stacks of wooden strips for the inner an outer stem laminations. I decided to use Sapele for the stems so I got a 3x6" x 7' Sapele board to cut the laminations for the forward inner and outer stem. The board was slightly twisted and curved. I planted one face of the board with a hand plane and then used my planner to finish both sides. I used a power planer to take out the curved shape on one side. I then ripped the board on the table saw in 21/4" wide pieces to cut the stripes (3/16") for the laminations. I used a new Freud thin kerf (40T) saw blade on a SawStop contractor saw. After approx. 3' into the cut, push the board got harder and harder, finally impossible. I stopped the saw to check what was going on. What I found was that approx. 2' behind the riving knife the kerf disappeared, basically closed. I took a piece of scrap wood with almost the same thickness like the saw blade and put it in the kerf to keep the kerf open. I then restarted the saw and was able to finish the cut. This was a kind of scary experience and most likely I disregard a bunch of safety rules, however, what else could I have done to finish the cut? In addition, when I checked the resulting 2/14" board I found that it was slightly curved along the cutting face. How could that happen? What can I do better/different to avoid such situations? Thanks Chris Quote Link to comment Share on other sites More sharing options...
Popular Post Eric. Posted September 20, 2014 Popular Post Report Share Posted September 20, 2014 I'll just say it...get a bandsaw. Table saws are not the correct tool for resawing. A lotta this going around lately. 6 Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted September 20, 2014 Report Share Posted September 20, 2014 Kiki is right, a bandsaw is much better suited to that job. What you experienced sounds like the result of internal stress in the wood. This can be the result of uneven forces during growth, like a leaning tree trunk, or boards cut from branches. It can also result from poor drying practices that allow the interior moisture to remain higher than the surface moisture content. In either case, sawing the board apart allows those stresses to act upon two smaller pieces. Closing of the kerf is probably the most common symptom. This will still happen if you use a bandsaw, you just won't have the danger of kickback occurring. You may find that you still need a wedge to hold the kerf open. 1 Quote Link to comment Share on other sites More sharing options...
..Kev Posted September 20, 2014 Report Share Posted September 20, 2014 Dangerous cut indeed and why the bandsaw is being suggested. Quote Link to comment Share on other sites More sharing options...
Boatworks Today Posted September 20, 2014 Report Share Posted September 20, 2014 All things considered with the cutting, the stem is looking good! Quote Link to comment Share on other sites More sharing options...
Christoph Posted September 20, 2014 Author Report Share Posted September 20, 2014 Hello all, thanks for you answers and the advice. I think I forgot to mention that I had this issue only when I rip-cut the board the first time. The second cut went pretty normal. Cutting the lams from the resulting 21/4 x3" was not an issue at all. I certainly thought about using the bandsaw. However I could not imagine how to handle and cut such a heavy board on my 14" bandsaw. Cutting the lams on the band saw, although the blade is thinner, would need additional planing of of each laminate. Cutting them on the table saw gives a very smooth surface on either side of the stripe, so no additional planing or sanding necessary and maybe less material loss. In retrospective I can remember that one side of the board after planing was much brighter than the other one. Could it be possible that the board was a mix from heartwood and sapwood? Could that explain the stress in the board? Indeed the riving knife has almost the same thickness like the thin kerf saw blade, together with the closing of the kerf it caused the binding. I will reconsider to use my bandsaw, for the next board of almost the same size, laminations for the aft stem. But then I will need some kind of outfeed table, probably not easy to realize. Quote Link to comment Share on other sites More sharing options...
Barron Posted September 20, 2014 Report Share Posted September 20, 2014 I think the reasons are described above. I have cut a 10' board in half, then ripped the halves and had one half with no movement and the other half that moved quite a bit. While a band saw would leave a rough surface, a power planner will clean it up fast. The Garden Chair project on Fine Woodworkings site or the Morris Chair in the Guild both have great tips on cutting thin laminations. Roller stands at either end make managing long boards on a band saw easy. Quote Link to comment Share on other sites More sharing options...
woodbutcher74 Posted September 21, 2014 Report Share Posted September 21, 2014 I had this happen when I was cutting some hard maple. Check your fence. I found that my fence was out of alignment. The fence was angled ever so slightly toward the blade, causing it to wedge between the fence and blade. Very dangerous situation Could also explain the curve you talked about. With that being said and the size of your project I would rig some way to use the bandsaw. Quote Link to comment Share on other sites More sharing options...
Byrdie Posted September 21, 2014 Report Share Posted September 21, 2014 The only thing I would add is that since you were doing a bent lamination that basically changed the shape of the wood you may not have need to do so much flattening prior to ripping the stock. You need a flat surface for gluing. I might have made my rips a tad thicker and then surfaced the strips on my planner afterward rather than spent quite as much time surfacing the rough stock. Your method of wedging the plank as you ripped it is a successful tried and true one but as mentioned several times, a bandsaw is the better tool for resawing. Quote Link to comment Share on other sites More sharing options...
Christoph Posted September 22, 2014 Author Report Share Posted September 22, 2014 Hello all, @woodbutcher My fence and my saw blade are perfectly aligned. I recently did that, when I figured out that they weren't while cutting some hard maple, walnut and purple heart for those cutting boards. And... if I am going to cut some serious stuff, not for every piece of plywood or 2X4 .... I check my saw blade for being exact 90 degree to the table. @Master Poster Basically you are right, no need for flattening prior to ripping the stuff, however it is a nice exercise to improves those skills on big boards. Quote Link to comment Share on other sites More sharing options...
Stampy Posted October 5, 2014 Report Share Posted October 5, 2014 Also consider that with a thin kerf blade they have a greater tendency to heat up and the result is the blade warping and twisting. The blade ends up taking out more material than the blade is capable of getting rid of and hence binding. I'd love to take credit for this info but it came from the guy who owns the shop where I get my blades sharpened. After that conversation my thin kerf blades are collecting dust instead of making it. Buy a band saw. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted October 5, 2014 Report Share Posted October 5, 2014 Also consider that with a thin kerf blade they have a greater tendency to heat up and the result is the blade warping and twisting. The blade ends up taking out more material than the blade is capable of getting rid of and hence binding. I'd love to take credit for this info but it came from the guy who owns the shop where I get my blades sharpened. After that conversation my thin kerf blades are collecting dust instead of making it. Buy a band saw. This lumps all thin kerf blades into one narrow category and makes claims that I cannot support through long experience with thin kerf blades. For sure evaluate the performance of the blade when given a task, but to set these blades aside as always inappropriate is just following a preference. Quote Link to comment Share on other sites More sharing options...
Indy Cindy Posted October 5, 2014 Report Share Posted October 5, 2014 I will reconsider to use my bandsaw, for the next board of almost the same size, laminations for the aft stem. But then I will need some kind of outfeed table, probably not easy to realize. I got this for long boards at the bandsaw. http://www.homedepot.com/p/Workforce-43-in-Steel-Roller-Stand-with-Edge-Guide-5-Pack-AC43/202530462 Reviews are mixed, but I like mine and have no problems. I have also found it useful for wide boards on the bandsaw, i.e. plywood. I also use it for long boards at the miter saw. One great feature is it folds up easily and tucks away when not needed. And the price is right. Quote Link to comment Share on other sites More sharing options...
Coop Posted October 7, 2014 Report Share Posted October 7, 2014 I got this for long boards at the bandsaw. http://www.homedepot.com/p/Workforce-43-in-Steel-Roller-Stand-with-Edge-Guide-5-Pack-AC43/202530462 Cindy, You use this on your band saw at 43"? I have one similar (well not really; it's made by Ridgid and it's sort of a tilt table also folds up) and it will not reach the top of the table on my BS. My Griz 14" saw is on a mobile cart that raises it up and extra 2" or so. Wish it wasn't quiet as high. Quote Link to comment Share on other sites More sharing options...
Indy Cindy Posted October 7, 2014 Report Share Posted October 7, 2014 I got this for long boards at the bandsaw. http://www.homedepot.com/p/Workforce-43-in-Steel-Roller-Stand-with-Edge-Guide-5-Pack-AC43/202530462 Cindy, You use this on your band saw at 43"? I have one similar (well not really; it's made by Ridgid and it's sort of a tilt table also folds up) and it will not reach the top of the table on my BS. My Griz 14" saw is on a mobile cart that raises it up and extra 2" or so. Wish it wasn't quiet as high. I just measured it and it barely makes it. My Griz on mobile cart is 43 3/4 inches high and I can just get the roller stand to raise to that height. Quote Link to comment Share on other sites More sharing options...
Dave H Posted October 7, 2014 Report Share Posted October 7, 2014 I have the same issue cindy my band saw is on a mobile base, so I built a little box to elevate the flip top stand that I use. I use this combo with my drill press also. 1 Quote Link to comment Share on other sites More sharing options...
Stampy Posted October 8, 2014 Report Share Posted October 8, 2014 This lumps all thin kerf blades into one narrow category and makes claims that I cannot support through long experience with thin kerf blades. For sure evaluate the performance of the blade when given a task, but to set these blades aside as always inappropriate is just following a preference. Hmmm... just passing on what I thought would be helpful....moving on. Quote Link to comment Share on other sites More sharing options...
Mike M Posted October 8, 2014 Report Share Posted October 8, 2014 Doesn't Sawstop offer different thickness riving knives for thin and full kerf blades? My powermatic 2000 has an accessory knife for use with thin kerf blades. The standard knife that came with the saw is too thick for a thin blade and would bind.. Quote Link to comment Share on other sites More sharing options...
BobInAustin Posted October 8, 2014 Report Share Posted October 8, 2014 Sure sounds like just internal stress in the wood. Happened to me a lot when ripping SYP 2x10s in half for my workbench top. Some of them had so much stress that they actually split apart before the saw blade finished the cut. Popped a little wedge in the kerf and they move right on through. Quote Link to comment Share on other sites More sharing options...
RPCV_Woodworker Posted October 8, 2014 Report Share Posted October 8, 2014 Important note on using the bandsaw: blade choice matters! You could get one of the fancy Resaw Kings by Laguna and, with a properly tuned machine, barely need to plane at all. -OR- there is always the woodslicer from highland, which is about 1/3 the cost. I've read a few articles comparing them, but I've never tried the Laguna, so the jury is still out for me. Either way, get a good new blade with no more than 3-4 teeth per inch and it'll go much better. Quote Link to comment Share on other sites More sharing options...
Llama Posted October 8, 2014 Report Share Posted October 8, 2014 Just adding to the above post... I use a 5/8" laguna shear force blade and it's fantastic. Obviously not as nice or smooth as the resaw King blade, but for $25 or so it is certainly worth a look. Quote Link to comment Share on other sites More sharing options...
phinds Posted October 9, 2014 Report Share Posted October 9, 2014 I agree completely with those who have already suggested internal stress in the wood in this particular case. I have seen sapele have severe cases of that and your description of the large piece as starting out with what are obviously drying defects makes it a sure thing in my mind that the problem was at least as much with the wood as with your setup. That's not to suggest that your setup was ideal, but don't blame it all on using a circular saw instead of a bandsaw. Quote Link to comment Share on other sites More sharing options...
Snaslund Posted October 10, 2014 Report Share Posted October 10, 2014 For ripping hardwoods i use a dual technique. I used the bandsaw to rip about 1/8" oversize. Next i use the tablesaw to rip again, but now i either have no cutoff or one so thin that it cannot pinch down hard on the blade. The tablesaw cleans up the bandsaw marks and ensures i have parallel edges. My 1.5 Hp with a good Forrest blade can handle 8/4 oak when nothing is grabbing at the blade. Yep, its two steps instead of one but its faster then one ripping operation on the tablesaw and then a trip to the ER. It's also allowed me to do some big stuff like a roubo bench with only a contractor saw. I think all rips other than engineered sheet goods should be done on the bandsaw if at all possible. Even with the safety gear on a contractor saw, a rip that goes wrong it a board that substantial is going to break something or someone. Quote Link to comment Share on other sites More sharing options...
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