Getting Burn Marks From Table Saw

Wiley's Woodworks

Wiley
Corporate Member
I'm getting way too many burn marks on hardwoods--white oak, ash, walnut, and even 3/4" plywood from my table saw. I've got a Powermatic 66 with a 5 hp motor and use a Forrest Woodworker II blade. I have no idea why this is happening. My usual suspects are:
  • I'm off on my feed speed. Do I speed up or slow down? Is there a way to "feel" for the correct feed speed?
  • The blade has gotten dull. How do I tell in my shop if the teeth need to be resharpened without shipping the blade off for weeks and maybe paying for a sharpening I don't need.
  • There is residue on the blade. I can't feel anything, but if there is what is the best cleaning method.
 

pcooper

Phillip Cooper
Corporate Member
I've had that problem too, and found it to be fence alignment and blade alignment to the miter slot. I have a lower end saw (craftsman) and had to do quite a lot of work on that to get the blade true to the miter slot, then align the rip fence properly. A good blade makes a difference too, but sounds like you have a good enough blade so long as it's sharp and not gummed up with residue. The only other thing I run in to is wood closing up on the blade after the cut, I use thin strips of wood to keep the kerf open when that happens because I don't have a splitter on my saw.
 

McRabbet

Rob
Corporate Member
Blade alignment is first priority, zero clearance insert is key and feed rate must be smooth and reasonably fast. I have a Forrest II blade as well but use a stabilizer plate on it to reduce any vibration. You should be able to detect a dull blade if the cut edges are not smooth.
 

Rwe2156

DrBob
Senior User
Clean it up first that is most likely it. Krud Kutter really works!!

If that doesn't do it, check the fence alignment. If yours has plastic adjusters they can wear.
 

Jeff

Jeff
Corporate Member
Is this something new? If so, you should clean the blade in mineral spirits using a toothbrush. Then maybe a sharpening by Forrest (about $27 for a 10" Woodworker II blade, turnaround time is about 7-10 days).).
 

JimD

Jim
Senior User
I also would check blade alignment. A simple way to do it is to use a combination square adjusted to just touch a blade tooth at the front and then check the clearance at the back. It should be the same or just a hair bigger at the back. Bigger in the front will produce the results you describe.

I use CMT's blade cleaner. I have a plastic lunch tray that is just the right size to hold the blade and let the cleaner soak for a bit. If there is a lot of buildup, I sometimes need to use a brass brush on the teeth.
 

Johnson

AD
Senior User
I soak my blade for 15-30 minutes in a metal tray with water and baking soda. Then I scrub off the gunk, spray the blade down and let it dry before using it again. This thread has reminded me that I need to do that again.
 

Wiley's Woodworks

Wiley
Corporate Member
Is this something recent? how old is your blade versus how long you’ve been experiencing the problem?
It's been coming on gradually. I bought the saw used with the current blade 2 years ago. Part of my frustration is that the scorching doesn't happen every time. I believe the thicker hardwood boards have the worst scorching.
 

JimD

Jim
Senior User
I've never used a Forest blade but I am very pleased by my Freud blades. I've tried others but gotten more consistently good results with Freud blades - and they are reasonable. I have a "fusion" on right now and ripped 3 inches deep repeatedly today with it (with my little 1.75hp PCS).
 

Brian Patterson

Bstrom
User
I've never used a Forest blade but I am very pleased by my Freud blades. I've tried others but gotten more consistently good results with Freud blades - and they are reasonable. I have a "fusion" on right now and ripped 3 inches deep repeatedly today with it (with my little 1.75hp PCS).
I’ve got one of their Glue Line blades on the TS,a rip model on the DeWalt RAS, their box joint set on another DeWalt RAS - and even a rip blade on my construction saw. Excellent values When properly used and the tool is aligned, etc. I check my cutting tools every time I use them avoid burn and out of square results.
 

Wiley's Woodworks

Wiley
Corporate Member
Progress Report: I made tremendous progress on solving my problem, thanks to excellent advice in this thread. Of all the things that could cause burn, a misaligned fence seems to be the problem. A properly aligned fence is angled ever so slightly until there is ~1/64" extra space between the fence and the back teeth when compared to the front teeth. My saw was set up exactly the opposite, and the result is that as a rip cut advances the board gets pinched against the blade at the rear, resulting in friction and burn marks.

It was quite a project, which included 2 phone calls to Powermatic customer service, who incidentally didn't know the adjustment solutions to their own equipment, but on my own I discovered there is an alignment adjustment on the rip fence. In succession I perfectly aligned the blade at 90`, perfectly aligned the miter gauge to the blade at 90`, realigned the rip fence to ~+1/64" front of blade to back of blade, and re-calibrated the ruler gauge off the front teeth. I still have to make some long and thick rip cuts in hardwood for proof it's fixed, but if I don't repost it's fixed.

I wouldn't have figured this out without the excellent advice I got through this forum. Thanks to all.
 

Rick_B

Rick
Corporate Member
No expert here for sure - I've always read/heard that the rear of the fence should be anywhere from dead on parallel or a few thousandths off set away from the blade. Seems like a 1/64 (.015") is a lot. Like I said no expert so it may be fine.

Rick
 

pcooper

Phillip Cooper
Corporate Member
I did a little quick math from my instructions that I got from Incra for my Incra fence, they said to use a folded dollar bill, which is 0.007", that is roughly 1/128. I increased mine to twice that which seems to be 1/64" or close (used two dollars folded last time) and on my saw that works. I'm not saying it fits everyone's needs, worked for me.
 

Willemjm

Willem
Corporate Member
I did a little quick math from my instructions that I got from Incra for my Incra fence, they said to use a folded dollar bill, which is 0.007", that is roughly 1/128. I increased mine to twice that which seems to be 1/64" or close (used two dollars folded last time) and on my saw that works. I'm not saying it fits everyone's needs, worked for me.
There is no rocket science here, no math formula, no one size fits all.

It is pretty simple. I was taught this by my dad 40 years ago.

The wider you can make the kerf and maintain a jointer quality cut with a perfectly smooth finish on the cut edges, the better. That setting dimension may be different for different blades, I normally set that up for my rip blade and then forget about it. In short, the wider the kerf with toe-out, the more forgiving your cut will be.

Too much toe-out and you will get tooth marks on the cut surface. The more toe out you set, the less chances of binding and burning and kick backs. The latter is technique though, if you feed wrong you can get a kick back irrespective of kerf width.

Toe-out also helps keeping the work piece against the fence.
 
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