When do you know your TS blade is dull?

[Brian Sommers]

I haven't had my TS very long but I had at one time been putting a lot of plywood through it and I've been reading how that gums up the blade.

From the very beginning I put a Freud 80 tooth in there and it was going great. About last month I was ripping a bunch of 2x6 and 2x4's taking off that rounded edge and I noticed I really had to push quite hard. I then switched to the default Dewalt 24 tooth blade and I have to say I haven't switched back, it's going much better for all cuts, I find it plenty smooth for what I do.

I have to say, I'm surprised. Is my 80 tooth dull already? Maybe I'm feeding stuff through to quickly on my 80.. All I know is that I really like how quick and fast the 24 is.

I thought that isn't supposed to leave a good smooth cut, but I find it does.

[Mark Gibney]

Is the 80 tooth a cross-cut blade? - as you know this might explain why it was slow ripping the 2x4s. For sure a rip blade is just so much easier to rip with than a combo blade, but I still switch back to a combo for sheet goods.

[Gerry Grzadzinski]

You shouldn't be ripping anything with an 80 tooth blade.
Ripping should be done with 24-40 tooth blades, or combination blades.
There's a reason they make so many different types of blades. Ideally, you should always use the proper blade for the job at hand.

It's also important to clean your blades. Clean blades will run cooler and last longer.

[Ben Rivel]

You shouldn't be ripping anything with an 80 tooth blade.
Ripping should be done with 24-40 tooth blades, or combination blades.
There's a reason they make so many different types of blades. Ideally, you should always use the proper blade for the job at hand.

It's also important to clean your blades. Clean blades will run cooler and last longer.
Right here.

[Brian Sommers]

ahhh.. never thought to check about ripping/xcutting, etc

thanks for that.

[John Blazy]

To kindof answer the original question - I use a magnifier, (or take my glasses off) and look for light reflecting (light source directly over top of the cutting edge) off the dull, rounded edge. Carbide will slightly round over the cutting edge of each tooth, and will be somewhat visible - moreso on really dull blades. A freshly sharpened blade will NOT reflect light on the very edge. Same trick to use on any cutting tool, from router bits to kitchen knives, etc.

BTW, any well sharpened blade will cut pretty smooth for the first few cuts (answering why you were impressed with the smooth cut from the 24 tooth blade). I would never put a 60 or 80 tooth blade on for ripping anything. Although I think my thin kerf ATB is a 60 tooth, and since its thin kerf, I use it as my general purpose blade.

Best thing I ever got was a bunch of used diamond blades that my neighbor thought I could use to cut glass. WAAYY too fine, til I realized that they were about 400 grit diamond for sharpening carbide. I made a magnetic hold down jig for holding a saw blade with a sliding slot to bring the inside face of each tooth in for the diamond blade to hone the inside face, and haven't sent blades out for sharpening in about ten years. Only takes five minutes to face a 60 tooth blade, and its insanely sharp. Easy to adjust for any hook angle.

[Roger Feeley]

You develop a feel for each combination of blade+material+operation. If you find yourself pushing too hard, it's time to sharpen.
If you weren't burning wood and are now, it's either time to sharpen or clean the pitch off.

I always buy blades in pairs (except stacked dado sets). I don't have to stop work to wait for a blade to come back from being sharpened. I just switch blades and continue. It make me much more likely to keep a sharp blade on the saw. A sharper blade means less pushing and less danger.

[Mark Gibney]

Can you post some pics of this sharpening set-up? Sounds interesting.

[Chris Padilla]

One thing to keep in mind when you pick yourself up a ripping blade: push the wood through a bit faster than you normally would. If you don't, odds are decent you'll burn the edge. Burning is also an indication of a dull blade. Even with a scary sharp blade and good technique, cherry and maple can still burn a bit on you...sands off pretty well. Ideally, you should have at least 2 blades but I'll push it to 3: ripping (20-30ish teeth), crosscut blade (60-80ish teeth), and a general purpose (40-60ish teeth). For nice plywood/melamine/particleboard, the crosscut will give you splinter-free cuts and sharp edges (BTW, "ripping" plywood with this blade should work fine, too). To cut general plywood, MDF, other, the general purpose can work. To rip hardwood: the ripping blade. You can certainly branch out from there where you have your group of NICE blades and then your group of CUT EVERYTHING ELSE blades.

[John Blazy]

Here are pics of the sharpening system. I don't know where to get these blades (diamond blade is on right side of 1st pic below with bushing), but if anyone wants to do this, just google Norton diamond 400 or 600 grit blades with 1" arbor. I made my own bushing to reduce 1" to 5/8". Well worth it, even if these blades cost 200 + bucks. I have sharpened my blades at least 100 times since setting this up ten years ago.

The white magnetic plate on left side of first pic has a sliding center for the 5/8" DIA blade arbor. Just position the plate on the table according to hook angle (matching the carbide face grind angle) and radius + distance for pulling the blade out of the diamond blade path to the next tooth. I give each tooth a few rubs on the spinning diamond blade and it re-faces with a fresh edge real nice. I have removed as much as .006 or so in a few seconds to remove a chip, although you cant take too much off to lower the cutting edge from all the others, which isn't as drastic as top grinding.

336795336796

Here is the blade in the sliding center that slides fore and aft: In case you didn't get it, you need to make a sliding center, you cant buy it. Real easy - I used 1/8" FRP, cut the dovetail slide in it, added the magnet backing, and machined the aluminum center into the dovetailed slot. It slides with the blade, keeping common center.
336797

[Tom M King]

Sound and feel of the cut.

[Rick Fisher]

My ripping blade is 24 teeth .. Its messy when used for crosscutting ..

[scott spencer]

Read up on using the right blade (http://lumberjocks.com/knotscott/blog/12395)

There are a lot of factors involved, but the general rule of thumb is lower tooth count equates to a faster more efficient cut that's easier on the motor, but rougher. High tooth count equates to a smoother cut but with more heat and resistance, burning, etc. 24T blades with a steep hook angle are ideal for thicker ripping. 80T blades are generally best for crosscuts and ply.

It's also worth noting that all blades aren't created equal. Avoid most of the cheap junkers and stick with Freud, Forrest, Infinity, Amana Tools, Ridge Carbide, Tenryu, Popular Tools, World's Best, Irwin Marples, Diablo, DW Precision Trim seris, Guhdo, Leitz, Delta Industrial, CMT Industrial, etc. I typically avoid Avanti/Avanti Pro, Ryobi, Workforce, HF, Oldham contractor, DW construction series, Skil, Vermont American, Irwin Marathon and Classic series, most Craftsman, and other off names offered by the homecenters.

[Erik Loza]

Sound and feel of the cut.

This ^^^...

I can tell the moment I walk into a shop, how their blade is. Dull blade makes a gnarly, thrashy sound. Just listen to any of the Safety Speed Cuts or RAS's in your neighborhood Lowe's or HD. Those blades are probably as old as the machines, themselves. Sharp blade is a nice, clean whine and hiss.

Erik

[David Kumm]

When you get into the table saw world, located a good sharpening service early on. there is a huge difference in quality and technique when it comes to sharpening. I've been lucky in having both Leitz and Gladu shops nearby and have used forrest and Woodworkers toolworks as well. Night and day compared to a local guy who does it part time. Dave

[Earl McLain]

Read up on using the right blade (http://lumberjocks.com/knotscott/blog/12395)

There are a lot of factors involved, but the general rule of thumb is lower tooth count equates to a faster more efficient cut that's easier on the motor, but rougher. High tooth count equates to a smoother cut but with more heat and resistance, burning, etc. 24T blades with a steep hook angle are ideal for thicker ripping. 80T blades are generally best for crosscuts and ply.

It's also worth noting that all blades aren't created equal. Avoid most of the cheap junkers and stick with Freud, Forrest, Infinity, Amana Tools, Ridge Carbide, Tenryu, Popular Tools, World's Best, Irwin Marples, Diablo, DW Precision Trim seris, Guhdo, Leitz, Delta Industrial, CMT Industrial, etc. I typically avoid Avanti/Avanti Pro, Ryobi, Workforce, HF, Oldham contractor, DW construction series, Skil, Vermont American, Irwin Marathon and Classic series, most Craftsman, and other off names offered by the homecenters.

Glad to see Popular Tools on your list Scott. I was nervous about trying them a few months ago, but figured if Tom Walz (Carbide Processors) was selling them they had a chance. If the 2 i picked up for my 7 1/4" circular saw are any indication, they may be a pretty good value for the money.

To the OP's question--it's been said a few times already, but i don't think i would judge the sharpness/dullness of a dirty blade. And i'll not judge a blade that i'm using improperly--if the tooth count and grind aren't right for what i'm doing, it's not the blade's fault. My current favorites for the TS are an Amana 610600 (60 tooth, ATB, 10 deg hook) for cross cut, Forrest WW2 40 tooth for light rips/quick cross cut, Freud Industrial 24 tooth for heavier rips, with a Tenryu Gold 40 tooth ATB as a decent alternative to the Forrest. Have been running an Amana 60 tooth TCG on my RAS with outstanding results in cross cutting/mitering, and usually either the Forrest or Tenryu mentioned above for ripping on the RAS.

I think i change blades more often than i change underwear, and changing one helps to prevent the NEED to change the other!!

earl

[Robert Engel]

When you get into the table saw world, located a good sharpening service early on. there is a huge difference in quality and technique when it comes to sharpening. I've been lucky in having both Leitz and Gladu shops nearby and have used forrest and Woodworkers toolworks as well. Night and day compared to a local guy who does it part time. DaveThis is very true excellent advice.

The two biggest ways you know the blade is dull is increased feed pressure and poor quality cuts.
You can also simply look at the teeth as a blade gets dull it gets hotter and the wood resins accumulate on the teeth, often resulting in burns, too.

To the OP: from the question you have asked, I suggest you check into some basics of using a TS because I would question your overall knowledge level on using a dangerous power tool like this.

There are too many guys with TS's in the garage and they do not know how to operate the machine safely.