I’ve been playing with tablesaws for a lot of years now, and always thought that you should keep the blade, whether ripping or crosscutting, just above the wood, the less showing the better.
I belong to a woodcarving list and an Aussie, a professional joiner by trade, said that he was taught, as an apprentice, to keep the blade high to avoid kickback and prevent burning the wood. I can see the point of both, but still, don’t recall that being discussed in most articles on tablesaws.
How does everyone do it? how much blade do you expose and why?
The assumption is that all your safety guards are in place, etc….
Thanks,
Vic H
Replies
The "less showing the better" is the finger-saving approach, but doesn't always produce the best cut. One of the threads I posted several weeks ago touched on this subject in passing, with some input from Sgian, which I appreciated. I generally set the blade 1/4" or so above the stock (teeth + a fraction of an inch). However, if I want to relieve some of the cutting stress on the saw and the blade, I set it higher so that there's less of the blade in the cut. Setting the blade higher will also enable the teeth to enter at a more direct angle and can produce a cleaner cut in some instances.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
The general rule of Thumb is set the blade with the height of the teeth above the material being cut,, Really what Forest Girl just said in her post...
Tooldoc
Vic,
For Freud blades we recommend 1/2 of the carbide tip protruding above the material. If you have the correct blade for the application this will yield the ideal of 3-5 teeth working in the cut when ripping or 5-7 teeth for crosscuts and manmade materials. The geometry of the tooth in the cut is also a factor of having the correct blade. Generally speaking, for ripping the hook angle of the blade will be 15-20° or higher. Crosscut blades should be 10-15° and for laminated or veneered stuff the hook should be around 0° or less. If you want to feel safer in your woodworking always do the following:
Use blades with kickback reducing designs, use the guards and splitter, pay attention to what's happening with the saw and the material and wear safety glasses.
That's just the short list. Consult the saw owner's manual for a detailed list. The warnings found in the manual can seem over done, but I assure you that they come directly from lawsuits over injuries and are valid concerns to anyone using the equipment.
Charles M,
Freud, Inc.
Thanks for the reply. Coming from a blade manufacturer (who makes the blade that is sitting on my saw now) that makes me feel better that I haven't been doing something wrong all these years! I have been a woodworker (Hobbiest) since I was young enough to see the top of dad's workbench. Started using the tablesaw in my early teens, etc. I still have all my fingers intact and tend to be overly cautious with tools, all for a good reason! I was truly surprised at the idea that someone would have been taught to run their blade full up, that just doesn't seem like the best approach. May I quote your comments on the carving list? Having an expert opinion helps settle a lot of discussions!
Thanks, Vic H
You are welcome to share this. It's all public info.
The misconceptions about blade height are many and varied. I've seen magazine articles that tout raising the blade to expose a full gullet, purportedly to allow for chip ejection, while missing the fact that the chips are made by the leading teeth and are ejected under the material.
Charles M
Freud, inc.
Charles, one reason I suspect the high set blade for ripping is popular, particularly in the US, is the rather common practice of using table saws without any guards. The thought of the user is probably that the near vertical chopping front teeth are safer than a near horizontal angle of attack because they tend to drive the piece being cut tighter on to the table. That argument rather fails to address what's going on with the complementary near vertical rising rear teeth, especially if a piece either pinches or bows after the cut. No doubt you've seen plenty of arguments put forward that support such usage, coupled with a long fixed rip fence of the Biesemeyer pattern? I guess, being European myself, and trained in table saw usage typical of that continent I've never lost the habit of using a riving knife, crown guard, and short rip fence, with the blade height generally set on the low side. Each to their own I guess. Slainte.Website
"For Freud blades we recommend 1/2 of the carbide tip protruding above the material. If you have the correct blade for the application this will yield the ideal of 3-5 teeth working in the cut when ripping or 5-7 teeth for crosscuts and manmade materials."
I surely would like to hear a justification for your above statement ! ! ! I do not see how the amount of carbide showing is in any way correlated to the number of teeth in the cut. I am also intrigued about this notion of a necessary number of teeth in the cut. I see it with bandsaw blades and now you are apparently suggesting something similar for round saws. WHY?
In another posting within this thread, you seem to indicate that gullet capacity is important. Based on what I have learned, I do not see gullet capacity to be a factor with most saw blades unless power feeds are employed. As far as I am concerned, with most sawblade purchases, individuals are buying more teeth than they really need (at least regarding anything remotely related to gullet capacity).
I am very pleased that a company representitive is participating in this forum. Their essential presence is something that has been missing.
I look forward to your response and continuing participation.
The gullet size and proper tooth count are directly related and are the same issue for circular saw blades as for bandsaw blades. Ideally you'd use as many teeth as possible for every cut. The problem with that is that once the gullet is full of chips the tooth can't cut. The ranges I gave of teeth in the cut are derived from the optimum tooth count for proper chip ejection. In ripping applications you make long curls of wood that roll up in the gullet and require more space than the smaller chips made when crosscutting. Thus the need for less teeth when ripping. The higher number will produce the cleanest cut and the lower number will produce a faster cut. If you use more teeth than in those ranges you will experience burning and a slower cut because the gullet becomes loaded and the teeth rub the material instead of cutting (this also leads to premature dulling and excessive heat which can damage the carbide). If you use less teeth the cut quality will suffer. So if you have selected the proper Freud blade for the intended application, when you raise the blade to 1/2 tooth height you will find that there are 3-5 teeth in the material for ripping or 5-7 teeth for crosscutting.
Charles M
Freud, Inc.
Your advise for only 1/2 tooth above the material doesn't always play in the world of less than flat materials and less than perfect feeding. It can be real nervewracking to get part way thru a cut and find your blade is not clearing the top of the material. I adjust my blade height according to what produces the best cut in the material I am using. I do tend to run my blades on the high side, usually up to equal the thickness of material being cut over the top. For the record I have a Biesemeyer overhead guard and the pop in splitter which is about as close as you can get to a riving knife on an American saw.
Scott
Scott's Sharpening
"The gullet size and proper tooth count are directly related and are the same issue for circular saw blades as for bandsaw blades."
I believe that gullet capacity and tooth count (pitch) are INDIRECTLY related because as gullet depth increases (necessary for gullet volume) tooth strength is greatly diminished.
"Ideally you'd use as many teeth as possible for every cut."
I disagree with this statement. The power necessary to saw lumber must overcome two forces -- the actual cutting forces required to produce the chip and the rubbing forces of the tooth passing through the kerf. Koch in his publication Wood Machining indicates that rubbing forces exceed cutting forces. Thus more teeth relates to more rubbing forces which generate more heat which equates to more wear (dulling), besides requiring more power.
"The problem with that is that once the gullet is full of chips the tooth can't cut. The ranges I gave of teeth in the cut are derived from the optimum tooth count for proper chip ejection."
It takes an incredibly high feed rate in extremely thick stock to overfill a gullet. When that actually occurs cutting ceases but more likely the saw will loose tension (round saws) or leading edge strain (band saws) and begin to snake. If I needed to, I would use a factor of between 0.5 - 0.6 for gullet capacity vis a vis chip volume to insure that gullet capacity was not exceeded. However, before I get to that, I would more likely consider the ratio of bite/feed as to pitch/blade speed. Based on most hand fed operation, feed speed is so small that bite is extremely minimal. This produces a lot of very fine shavings that tend to spill from the gullet rather than being retained. The reality is that too many teeth produce too fine of a chip.
"In ripping applications you make long curls of wood that roll up in the gullet and require more space than the smaller chips made when crosscutting. Thus the need for less teeth when ripping. The higher number will produce the cleanest cut and the lower number will produce a faster cut.
If you use more teeth than in those ranges you will experience burning and a slower cut because the gullet becomes loaded and the teeth rub the material instead of cutting (this also leads to premature dulling and excessive heat which can damage the carbide). If you use less teeth the cut quality will suffer."
None of that makes any sense to me with the exception that excessive heat leads to excessive wear. More teeth do not equate to gullet loading unless you have got very small gullets. And I contend that it is almost impossible to overfeed saws with high teeth counts. The fines produced will spill before they are likely to be retained and pack the gullet. I see no correlation between clean cuts and number of teeth. I do not know what information you are citing regarding fast cuts to low (sawtooth) numbers especially if feed speed and blade speed remain constant.
"So if you have selected the proper Freud blade for the intended application, when you raise the blade to 1/2 tooth height you will find that there are 3-5 teeth in the material for ripping or 5-7 teeth for crosscutting."
I still don’t know how you came to this conclusion. You somehow are attempting to correlate pitch to depth of cut (arc distance of the cut) and I don’t see it. For example, were I to rip 8/4 stock, by your example, I should have a blade with a tooth count that is half the number that I would use for 4/4 stock. If my standard (4/4) rip blade is 24 tooth, that would mean that for 8/4 material I should go to a 12 tooth blade (so as to retain the 3-5 teeth in the material value). This does not make one bit of sense! Where do bite and feed speed enter into blade parameter choices?
Please clarify!!!
Stan,
It's been a long week and to lighten myself up some, what do you think blade tension has to do with all of this? lol
Don
Well ............... improper tension, too much heat and things all of a sudden go goofy. The object is to be cool !!!
Do something to celebrate the equinox !! Know any pagans?
I've always read, and practiced, the same, Vic. But at the last WW show I attended, the demonstrator from Forrest was ripping a 2"+ block of cherry about 30" long, ripping 1/8"- slabs off using a smallish contractor's saw and, one of their blades, obviously. Two things he claimed would reduce or practially eliminate saw marks were to set the outfeed side of the fence a few thou further away from the blade and, if buring was a problem, *raise* the blade.
I certainly don't feel comfy with the blade any higher than it has to be to make the cut, that's for sure.
[email protected]
Dennis,
The Forrest rep illustrated my point about having the correct blade for the application. The blade he was using had 40 teeth which is too many for ripping 2" stock. By raising the blade you can reduce the number of teeth in the cut which might be thought to make the blade okay for the application, but a 40 tooth blade has smaller gullets than the 24 tooth blade that I would recommend so it would be less efficient at chip removal. This would lead to a slower rip and more wear on the blade.
Charles M
Freud, Inc.
> ....40 teeth which is too many for ripping 2" stock.
Others have said it before, I'll say it again: What a great place to hang out and learn. Being a weekend woodbutcher I've never given much thought to blade design, geometry, etc., with respect to the difference between ripping and crosscutting. Thanks for another installment in my continuing education.
Dennis in Bellevue WA
[email protected]
Charles, I had a discussion with someone in Forrest's tech department last year about using their blades for ripping. I was told that the 40 tooth blade is not intended for ripping hard stock much over 1" thick. If the application was for ripping over 1" then their 30 tooth blade would be a better choice. It would cut faster and cooler thereby reducing the tendency to burn hardwoods like Cherry and Maple.
But, he also confirmed that raising the 40 tooth blade would reduce the number of teeth in the cut and the teeth would be in the cut less thereby reducing heat.
Dennis, safety is an attitude, an approach to working, not heavy reliance on guards and other devices. I don't mean to be harsh, it's really not my nature, but some very salient facts need to be mentioned.
As an EMT, I was first on the scene when a hobby woodworker took off 3-1/2 fingers (a diagonal cut) with a tabletop Ryobi 8". The patient later became a friend and I followed his progress of healing after successful reattachment of the digits. He does pretty well now, but not as good as he was before the accident. He's never touched a tablesaw since that time.
I myself, in a moment of extreme stupidity, once stuck my left forefinger into a powered down but still spinning router bit (mounted in a table). "Gee, I wish I hadn't done that, I said to myself," as I contemplated the bloody fingertip. The finger is fine now (my right little finger that my kid slammed in the car door a few years later bothers me more), but it still is troublesome when I try, and I do mean try, to play my guitar.
There are times that the guards have to come off, or where the blade needs to be raised high, to do some specific task. Even with all the guards in place, some exposure will be there, and unless you can feel comfortable with it, perhaps photography would be a better hobby.
Planning the task ahead, knowing just how you will accomplish it, even doing a dry run with the machine off, will set up your thinking, adjust your attitude to that of safety, to that of a precisely calculated risk.
We risk every day. Many people are killed crossing the street or commuting to or from work. To me, the risk inherent in woodworking is more than balanced by the feeling of accomplishment resulting from a well built project, be it a simple jig or a fine piece of furniture, but that choice is up to each individual.
Safe tablesawing!
Dennis, safety is an attitude, an approach to working, not heavy reliance on guards and other devices.
I agree. I think one thing that has helped me retain all my appendages without secondary attachment proceedures is that I maintain a very, I mean VERY healthy respect to how much damage these machines could do to me if I don't pay attention to what I'm doing. Not implying that I'm afraid of them. And I appreciate your suggestion of walking through a process prior to the actual ... process. When I got my band saw, never having used one before, I would (and sometimes still do) walk myself through the cut befor I even plug in the machine. I've only had to back the blade out a cut a couple times to recognize this would be a good idea.
Man, I shudder to think about some of the stories I've heard. Over in the Breaktime forum there's a thread about some guy that cut off his hand and had it stitched back on. I'll pass on that one.
Dennis in Bellevue WA
[email protected]
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