I was ripping 1 1/2″ thick baltic birch (2 sheets laminated) on my TS tonight and was getting an awful edge. For one, there was a significant amount of burned areas. Second, despite having taken lots of time to make sure my blade and fence are aligned, plus using a magnetic featherboard, there were several times when the blade seemed to bite differently into the wood, leaving circular marks roughly 1/64″ deep. Also, despite trying to maintain an easy, steady feed rate, the blade seemed to bog down slightly, then ‘cough up’ some waste and the board would feed easy for a couple feet. I just put a new zero clearance plate in, and I can see where the blade has widened the clearance just slightly during this cut.
I’m using a Freud Diablo thin kerf combo blade (until I decide which blade I’m going to buy next). It’s not the most expensive blade, but it wasn’t that cheap, either. I don’t expect glass smooth, but I was hoping for better than this. What change is going to get me the most bang for the buck? A blade stabilizer? A new blade? Some kind of trick related to tweaking the heel in blade alignment? Or is this wood just super sensitive?
proje
Replies
Is this new behavior with this blade? Have you checked run out on your arbor (with blade removed)? I realize a lot of people on this forum swear by the thin kerf blades, but it may be that it's not the right solution for this application, or more specifically your combination of application and saw.
I run a full-kerf Forrest WW II and it cuts baltic birch 3/4" like butter, with a very clean edge, no burns.
wrudiger,
It's a fairly new blade and brand new Jet contractor's TS. I haven't checked arbor or arbor flange runout, but I did check blade runout with a dial indicator, and it's about 0.002" at the gullet. I don't have a fancy heel check jig, but I did clamp the dial indicator to my Incra miter gauge, which has a pretty snug fit to the table, and I got something like 0.002"-0.003" heel (can't remember which way).
I was in the store with full intentions of walking out with a WWII, and the guy talked me out of it, saying that the glue in plywood is murder on a blade, so I shouldn't put so much money into a blade I'm going to trash quickly. My next project is a wall of cabinets using red oak plywood and solid red oak for banding, rails & stiles.
Do you have a 30T or 40T blade? Which would you recommend?
proje
Proje,
I've run a lot of plywood, junk wood, etc. through the WW II and it's still almost as sharp as new. I have the 40T. If you are going to rip a lot of hardwood over 6/4 Forrest recommends the 30T.
Wayne
I have had similar problems nearly every time i've used a thin kerf blade. They get hot and warp in the cut, and do that weird stutter-step cut. What you might try is cutting slightly over size, then doing a second pass with the saw set exactly where you want. This will put less pressure on the blade and allow it to cool more readily. Just cut you roversize piece the dimension you want plus the kerf thickness, plus maybe 1/32 or 1/16"
I've gone back to all full kerf blades even though my saw is underpowered.
-Kit
I wondered if it was getting too hot... I touched the blade as soon as it stopped moving and it didn't feel warm at all. I also tried an initial cut oversize by 1/16", followed by a finish cut. Other than covering me head to toe in sawdust, it didn't yield any different results - still signs of burning on the edge. I didn't try leaving a sliver of waste (initial cut 1/8" oversize), although that probably would have kept a lot of the sawdust down.
I made these laminated pieces a few days ago when I cut the 3/4" baltic birch down to about 6" wide by 5' long. I don't recall having this issue when I cut the single sheet thickness.
proje
Proje,
I don't know if the same rules apply to plywood....but you did not mention what the tooth count was on the blade? its a bit dangerous, but raising the blade to full height may help with the burn marks.
Nothing wrong with thin blades. Never noticed them warping either.
Get some stabilizers. Rip 1/2 depth, then raise the blade and finish the cut. Burning usually indicates that you are moving too slow on the rip.
I think I will re-check all my alignments one more time. Also consider getting the WWII.
As far as rip speed goes, I also thought that I may be going a little too slow. But when I tried to increase the feed rate, the saw was not happy about that. Whining, groaning, lights dimming, blade slowing down, etc. I went back to the happy feed with burn marks...
Sounds like the fence isn't parallel to the blade, which is pinching the back of the blade against the plywood. It is also quite likely that the blade is gummed up with resin which will also cause burning. All other things being equal, a thin kerf blade that gets hot will warp more readily than a standard kerf blade which will add to your problems.
The guy in the store is basically wrong about the the glue in plywood ruining a blade. Glue is abrasive but a well made carbide tipped blade won't be damaged by sawing plywood.
John W.
I think that your problem is two fold. First, you are overtaxing your blade. A thin kerf blade does not have enough mass to dissipate the heat built up during a deep cut such as you are attempting. Go with a full kerf Freud or Forrest blade as suggested and that will help. I use Freud rip and combination blades as well as a Forrest WW@ with very good results. Second, I set the fence on my saw so that there is approximately 1/64" relief on the back side of the blade. So, my fence is SLIGHTLY out or parallel. That pretty much eliminates burns and kickbacks.
Good Luck!
John
Proje,
I suspect something seriously wrong with the blade you are using. The fact that you experienced the same problem just shaving 1/16" inch off the stock is very telling. Even with enough misalignment to cause problems during a deeper cut, that light cut should not have produced any problem. Of course, it helps to have the saw properly set up. And I do recommend setting the fence and blade as accurately parallel to the miter slots as possible.
I have cut hardwood plywood, MDF and particle board with economy-grade ($40-50) DeWalt and Freud thin kerf blades on a 1-1/2 hp contractors saw with absolutely smooth and clean, glue-line cuts resulting all day long. Not only do the abrasive elements in man-made material present little problem to a carbide-tipped blade, after months and months of use, there just doesn't seem to be any discernable wear. Each time I clean gum from the blade with alcohol, it just seems to perform as when it was new. I use 60 tooth blades and they treat the stock like proverbial butter.
I think you will find that a good blade - and the WWII is that - will end your problem.
VL
FWIW I found the same thing when my blade needed a cleaning. I am really surprised (as a brand newbie) how quickly the blade gums up, especially if cutting construction grade lumber or other resiny stuff. Plywood maybe??
if your teeth look not uniformally gray, or have brownish discolorations use some simple green and a brush and get that sucker clean.
If not, then forget what I said.
Easiest way to clean a TS blade: Pour 1/4" of household ammonia into the bottom of a 5-gal plastic bucket, drop the blade in (flat), leave overnight. Next morning all the resin is gone, no brushing needed. So easy you can do it every week! Just remember to do this outside the shop, so the ammonia doesn't attack any aluminum on your tools."Everything should be made as simple as possible, but no simpler." A. Einstein
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