Smooth-cutting rip blade burns cherry

[Jules Dominguez]

I just purchased a couple of Freud 10" "Industrial" grade sawblades - one for crosscuts and one for ripping. The crosscut blade, which is labelled as the "ultimate cutoff saw" or something to that effect, makes an excellent smooth crosscut. I'm very pleased with it.
The rip blade is a 1/8" 30-tooth "GLUELINE", and I can't rip cherry without burning it.
I checked fence and blade parallellism and opened it up a little, but that didn't help. The blade was set about 1/4" clear above the workpiece. I made several rips on three different cherry boards from my scrap pile and the blade burned all of them. I ripped a piece of pine 2x4 and a piece of oak with the same settings and got no burn. I changed the blade to a Freud Industrial combination blade, and re-ripped the cherry, with no burns.
I used push sticks without hold-downs or featherboards on some of the cuts, and two Grip-Tite magnetic featherboards (mounted on the fence) on other cuts, and none of that changed the results. I think I eliminated the saw (Delta contractor), parallelism with the fence, and my technique as being the problem, although I'm open to suggestions.
I've read posts indicating people have had similar problems with the Forrest WW 2, which is a high-end blade. The answer may be that the smoother-cutting blades just aren't suited to ripping cherry.
I know that cherry burns easily, but the results I'm getting with the Freud aren't acceptable and my plan at this point is to return the blade and go back to using a combination blade. Any suggestions or comments?

[Jim W. White]

While less safe, the blade would cool better if it was raised higher so more of it was exposed above the workpeice.

Cherry is tough to rip without some burning; sounds like the combo blade was serving you well though, perhaps you should go back to that.

..Jim W

[Jules Dominguez]

I'll give it a try. The combo blade occasionally burns cherry, but not a big problem. My reason for trying the Glueline is that the combo blade frequently requires handplane or scraper work to remove some of the deeper sawmarks from the ripped edge. I was hoping to eliminate that. And the Glueline may well do it, for woods other than cherry. Problem is, most of my projects use cherry.

[Roger Hergenrader]

Jules:

If you are getting deep saw marks in the ripped edge, it would appear to me that your blade and fence are not parrallel to one another.
Roger

[Tom Jones III]

I also recently bought both blades you did. This is my first experience with dedicated use blades. Like you, I found the crosscut blade to be excellent. Also like you, I found the rip blade to burn very easily.

First, a very important question, where on the wood is it burning? I seem to be burning consistently over the entire board, but a little more in the middle and back half of the wood.

I've got a PM 66, the fence is a few thousand off parallel, setup according to the book Mastering Woodworking Tools. The rip blade burns in mahogany, walnut, cherry and oak. Just to be sure that it was the blade, I put my very dull Freud combo blade back on and gave it a try, no burn.

I've made several observations about the Freud glue line rip:
* On the blade, it says it is for a max. of 1" thick!
* It does not burn as much if you raise the blade so that the gullets are about 1/16" out of the wood. Raising it more than this does not seem to help.
* The only way I can get it to not burn, and this is not foolproof, is to push the board *much* faster than I did when using the combo blade.
* This blade carries much more sawdust onto the table top than the combo blade did. Possibly this is because the glue line rip is a full 1/8" kerf and the combo is a thin kerf?
* The crosscut blade cuts oak veneered plywood great. I've never seen plywood cut so fine.

All in all, unless I learn how to make this glue line rip effective, I wish I had never spent the $180 to get two dedicated blades and I should have stuck with the $50 Freud combo blade.

[Jules Dominguez]

"Deep" is relative, Roger. The deepest sawcuts left by the combo blade aren't so deep that you can see a gap between two boards clamped up for gluing (unless I screw up pushing the board through, which sometimes happens), but they're deep enough to make me want to take them out before gluing. The fence and blade are as parallel as I can measure using a good steel rule and magnifying glass.
If it were possible to get a totally smooth rip cut on a contractor saw with a combo blade there would certainly be less of a market for jointers and the high end super smooth cutting rip blades.
Burning is another issue. It smells bad, looks bad, may interfere with a good glue joint for all I know, and you certainly can't leave burn marks on edges that will be exposed.

[Butch Hayes]

I too bought those same blades. Like you, I burn cherry with the guleline rip blade. Conversely, my combo blade left marks that had to be cleaned up with every wood. The cross cut blade is now on the RAS, where it shares cutting time with the dado. For now, when ripping, I'll stick with cleaning the burn marks off the cherry and having perfect cuts on wood that doesn't burn so easily.
btw, I got the blades without the red coating. Which ones did you get? It may be that the coated blades don't burn as much.

[JayStPeter]

Cherry is initially difficult to work with because of the burn. While I don't specifically know about the Freud rip blade and cherry, there is usually a feed rate for a blade that will keep cherry from burning. With wood like pine, slowing down the feed rate will often produce a smoother cut surface. With cherry, it will burn. Feather boards and hold downs are useful devices when pushing cherry through the saw so you can concentrate on getting it through quickly. Another thing I do is precut my parts before final ripping. That way you're pushing through smaller boards which are easy to feed without stopping and getting a burn. It takes a little effort, but is a lot better than sanding burn marks off.

Jay

[Jim Becker]

Woods with a lot of "sugar" in them (Cherry, Maple) tend to burn from heat created by friction between the cutter and the wood. This is exacerbated when there is an alignment problem on the tool. Raising the blade higher can help as it makes each cutter (tooth) contact the wood for less time as it passes through the materal. But if burning still occurs, cutting 1/32" proud and then taking a 1/32" pass through the jointer (or using a jointer plane with a fence by hand) will deal with the issue and leave a good surface for gluing.

[Doug Shepard]

I've got the same Freud cutoff as you. My Freud rip blade is the 24 tooth red blade and not the Glue-Line Rip though. I've been pretty satisfied with both, but if anything's going to burn it's going to be cherry (and maybe slightly on maple too). Like others mentioned, speeding up the feed rate with cherry should help stop most of it. I think this is one application that benefits from having the fence be a few thousandths out of parallel (slightly wider at the back) too. Using outfeed rollers that are even a hair out of perpendicular to your blade can also cause the wood to pull in slightly toward the blade and burn. I pretty much just follow the same routine as Jim now - cut just a hair wide, then clean up the edge with the jointer or plane.

[Doug Jones from Oregon]

I too have the Glue-Line rip blade installed on my table saw set up just for ripping. One huge advantage of the power feed is that you don't have the momentary pause when ripping long stock for had repositioning. I ripped probably 500 feet of cherry a few days ago with no burning.

Speed and constant flow are the trick on a properly adjusted saw.

Doug

[Jules Dominguez]

Tom, my blade burns cherry pretty much the whole length of the cut, and more so where I slow down in changing hands.

Doug, sounds like you get great results with a power feeder. I don't have one and don't even know what the costs and other ramifications of installing one would be. And, I don't think a blade sold off the shelf without any stated stipulations should require the use of special equipment in order to perform satisfactorily.

Speeding up the cut to avoid burning is something I'm not going to do, as I think that would invite mistakes and safety problems.

As a matter of additional information, I had made a zero clearance insert just before using the new blade, and made the initial saw kerf cut with it. When I switched back to the combo blade, it was a tighter fit, and I had to almost force the insert down onto the blade. I assume this is is because the GLUELINE is made to tighter tolerances to achieve the smoother cut, and produces a slightly narrower kerf.

I think what this all means is that the GLUELINE creates more friction than regular, non-super-smooth-cut blades and that the additional heat generated is just enough to push the high sugar woods (credit to you for providing that fact, Jim) over the line to the point of charring.

Thanks for the input, everybody.

[Jules Dominguez]

Butch, my blades are all coated, including the combo blade.

[Doug Jones from Oregon]

Jules...a power feed on a table saw is not for everyone. Along with being a costly accessory, $500-$1000 (I would not recommend the .25hp for a table saw), they are heavy to put on and take off when you only have one saw. And, they do restrict your cutting when installed, especially cross cutting.

As for the different size kerf between blades, I don't know that there is a standard set for this, and I've found variance in most of my blades.

Sounds like you would be better off returning the rip blade and trading for an extra combo blade, and I would bet that Freud will stand behind their product.

[Howard Acheson]

>>> The fence and blade are as parallel as I can measure using a good steel rule and magnifying glass.

That may be part of the problem. That's a pretty gross way to align your saw. Here is the low tech, low cost way to align a tablesaw that I learned maybe forty years ago and teach to my students now.

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 wood 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.

[Howard Acheson]

The only way I can get it to not burn, and this is not foolproof, is to push the board *much* faster than I did when using the combo blade

Decicated rip blades are designed to cut faster. The deeper gullets remove sawdust a lot faster.

Here is some info from Freud about the height of the blade.

QUOTE
I feel this one has been rehashed a few times but I must interject again that if you are using the correct Freud blade for the application, the blade should be set so that 1/2 of a tooth is protruding through the material. So, if you are cutting 3" thick material with a 10" blade, the blade would be at full height. The idea is to have 3-5 teeth in the cut when ripping and 5-7 for crosscut and manmade materials. If you cannot acheive this and keep the blade at 1/2 tooth height, you have the wrong blade for the application.

------------------
Charles M
Freud, Inc.
CLOSE QUOTE

[Dennis McDonaugh]

Its been my experience that all smooth cutting blades burn more than rougher blades. Cherry and maple are particularly bad. Kinda goes with the territory because they physics that make them cut smoothly also make them likely to burn because they contact the wood longer.

[Steve Clardy]

I never run over 40 tooth blades, and Cherry still burns where I hesitate, changing hands, etc.
Hard maples about as bad.

[CPeter James]

I use an oak splitter that is 0.130" with a Ridge Carbide blade or a Forrest WWII that are 0.125". The splitter is centered on the blade. It opens up the cut just a little and it seems to help. I use a lot of red oak and like maple and cherry, it is prone to burning.

CPeter

[Jules Dominguez]

Gee, Howie, you're a real silver-tongued rascal. My methods are gross, are they? :) Actually, I hadn't set out to align the saw, I was just making a quick check to see if the fence was forcing the wood against the blade on the way out, and I don't think it was, based on my "gross" measurement. After reading all the responses in this thread, I'll stand on my last post - the problem is ripping cherry with a smooth-cut blade.

And thanks for the alignment tip. I like them "low-tech and practical".

[Greg Mann]

Gee, Howie, you're a real silver-tongued rascal. My methods are gross, are they? :) Actually, I hadn't set out to align the saw, I was just making a quick check to see if the fence was forcing the wood against the blade on the way out, and I don't think it was, based on my "gross" measurement. After reading all the responses in this thread, I'll stand on my last post - the problem is ripping cherry with a smooth-cut blade.

And thanks for the alignment tip. I like them "low-tech and practical".

The easiest way to tell if the blade is burning when cutting or trailing is to look at the pattern to see which way the arcs match up. If it is burning when initially cutting, the alignment of the fence is not the culprit. If it is burning as it passes the trailing edge then it certainly could be fence alignment that is contributing. Ultimately, perfect alignment may still not solve the problem. Those woods that burn easily need more clearance gound behind the cutting edge, which will tend to leave a little more evidence of the saw cut. But even here, very true running blades with more clearance can produce smooth, uniform surfaces without producing the heat that results in the burn. My guess is that many combo blades have more relief in their grinds, resulting in less burn. If they are running true on a stable arbor they can also provide stunning finishes, and, since they cut more freely with less heat, they will allow us to feed slower and still get away with it. When we search for the holy grail in a glueline rip, manufacturers try to give it to us by altering the grind with flatter sides on the teeth. This gives us a wiping action, but, with more carbide in contact with the cut surface, we get more heat. It starts to produce the same kind of frustration we feel when we don't know whether we should use a longer or shorter club to get on the green. Since I see more books about golf than woodworking I suspect no one has a foolproof system to answer that question either.

Greg

[Chris Padilla]

Assuming everything is good and sharp and blade is parallel to the fence, I've always gotten less burning by pushing the wood thorugh the blade faster. A good dedicated 24-tooth ripping blade does the trick. I use CMT for all my TS blades.

If I have burning on the first rip, I'll push the wood harder next time and I normally have no problems after that.