table saw troubleshooting

[Alex Robertson]

Hi all,
I've run into some problems ripping boards on my table saw, and am hoping I could get some advice. It was most noticeable yesterday ripping some 8/4 oak, but has occurred with softer wood as well. In harder wood, the blade starts to bind, and it seems as if the boards end up cupping towards the blade. In softer wood, the blade just powers through the wood, doesn't end up binding, but the resulting boards are still warped - in all cases, the boards seem to warp "around" the blade - I hope that makes sense. Seems like a potentially dangerous situation, as well as a waste of wood! My best guess right now is that either the saw is out of alignment or the fence needs to be upgraded (the tail of the fence seems able to flex under pressure - as much as a quarter inch left/right).
I use a Delta 10" contractor saw with the rip fence that came with the saw, and a dedicated rip blade, which still seems pretty sharp. I just ordered a dial indicator to test the alignment, runout, parallelism, etc of the system, but it hasn't arrived yet. I'm considering getting a higher-end fence system, but I'm hesitant to spend $200 or more if that's not the problem. I know a band saw would probably be the better choice for what I'm doing, but I don't have one at this point. I'm certainly not a high end woodworker, but I would like my boards to come out flat!
Any help or advice would be much appreciated - thanks.

Alex

[scott spencer]

The blade andfence alignment are really important...best to get the blade within +/- 0.003" of the miter slot, then align the fence as close to the miter slot as possible....it's ok to allow a "toe out" (away from the blade) at the tail end of the fence about the thickness of a folded dollar bill. You didn't mention using a splitter, which is also an important aspect. If you're not using one, try it. If you are, make sure it's also aligned with the blade well.

Does the fence flex under the pressure of feeding wood? There's a big difference between grabbing the tail and actually ripping wood...the pressure from wood tends to be much lighter than pulling on the fence to check deflection. If it's flexing 1/4" from wood, it's probably a good idea to get rid of it. Before trashing it though, get it aligned, and try clamping the back end to the table during a cut.

Make sure your blade is decent quality, sharp, and clean. It's also a good idea to flatten and straighten your wood prior to ripping (jointer/planer work best), and make sure it's sufficiently dry.

[Jason Beam]

Do go through all the setup steps, but that may not be the problem. Wood moves after you cut it - even properly seasoned wood will move sometimes. There are internal stresses that get released as soon as you slice into it and sometimes the boards just curve on ya.

Make sure your splitter is on the saw - this is exactly the kind of stuff the splitter is designed account for and help prevent an unsafe kickback situation.

[Howard Acheson]

What exactly is you "dedicated rip blade"?

You don't need anything fancy to align your saw. Here is the low tech, low cost way to align a tablesaw that I learned maybe forty years ago and taught to my students for years.

Make 3/4 x 3/4 x 12" hardwood stick. Drill a hole somewhat centered in one end and insert a brass #8 x 1" round head fine thread machine screw about half way. UNPLUG THE SAW. Raise the blade completely up. Clamp this board in your miter gauge (if you determine that there is some slop in your slot to miter gauge, use a playing card to take up the slop) so the screw head just about touches the blade at the front. Now rotate the blade by hand and determine which tooth is the closest. Adjust the screw in or out until it just touches this tooth. Mark this tooth. Rotate the blade so the tooth is now at the back of the table and move the miter gauge/stick assembly to the back and see if it touches the marked tooth to the same extent. If it doesn't, adjust the trunnion (if a contractor saw) or the tabletop (if a cabinet saw) until it does.

For a contractor saw, first use a small c-clamp on the rear trunnion and cradle to keep the assembly from moving. Then loosen the two rear trunnion bolts and one front trunnion bolt. Slightly loosen the other front trunnion bolt and use a stick to tap the trunnion until the blade and screw lightly touch. The blade does not move directly around the center so you will need to repeatedly go back to the front of the blade, readjust the screw, and then again measure the back. Be sure to check after tightening the trunnion as the trunnion frequently moves when being tightened.

For cabinet saws, loosen the bolts that hold the tabletop and tap one corner until things come into alignment.

The same adjustment gauge can be used to set the fence parallel to the miter slot. Slide the miter gauge to the front of the table and move the fence over to the screw head and insert a playing card between the screw head and the fence just so you can move the card as it touches both the fence and the screw head. Now move the miter gauge to the back of the table and see if you have the same feel when you insert the card. I like my fence absolutely parallel--if you want to have a slight opening to the fence, you can easily estimate the opening by adding a thickness of paper to the card.

I always show my students with a dial gauge that their adjustments are within .001 - .002.

You can also use the same gauge to measure blade runout by using a $5.00 feeler gauge.

Finally, after you are satisfied with the above adjustments, check the position of the splitter to make sure it is exactly in line with the blade.

Bottom line, there is no need to spend more than the $0.05 for the brass screw.

[Stephen Edwards]

Howie,

You're my kinda guy! I'm gonna try your method first on my Ridgid contractor saw. Thanks for the technique.

[Dale Lesak]

Dose this happen on all your cut or just some of them? sounds like it might just be wood tension when cutting. IF the ends of the wood close up that's what happening. when I see this happening I'll stop the cut and re saw the cut to make the saw kerf wider untie it doesn't close up any more. the wood will still be warped and about all you can do with it is use it for small projects after squaring it up and letting it set a week or two to see if it has quite moving