Replies

1. 
   hdgis1 | May 03, 2009 10:00pm | #1

   It is interesting what advice saw blade manufactures give concerning the proper setting of their blades. Just went through a Freud training session and they suggested that the blade be set considerably lower - 1/4 above wood. I tend to stick with this as I would rather knick a finger than take it off. I find that one of the best things you can do to avoid burning is to reduce the number of teeth on the blade and adjust your feed rate accordingly. This is all assuming that the fence is either parallel to blade or canted out on out feed end. I usually don't go much more than a 1/32 for that. Ultimately, burning and such take a back seat to safety in my book.

   Chris

2. 
   SteveSchoene | May 03, 2009 10:00pm | #2

   This is an area where trade-offs exist.  Setting the blade so it clears the wood by only a small amount reduces the severity of injury if your hand slips over the blade, while the board you are cutting is still their.  I'm not sure how common that sort of injury is.  

   But, when the blade is low, any contact of wood with the rear of the blade will occur where there is a relatively large vector trying to push the wood toward the operator, where with the blade set high the force has a larger up direction. 

     I usually set the blade high enough so that the bottom of the gullet clears by a bit, not the tip of the blade.  I think that helps clear sawdust and reduces heating.  And, if I were having a burning problem, even with a clean sharp blade and properly set fence, I wouldn't have a big problem raising the blade further, because in that situation I would be more conscious of the risk and avoid that kind of accident. 

   A 1/16th toe out on the fence seems a bit much to me, though it would be better than any amount of toe-in. 

    

1. 
   DaveinPa | May 04, 2009 01:13am | #6

   "I usually set the blade high enough so that the bottom of the gullet clears by a bit, not the tip of the blade. I think that helps clear sawdust and reduces heating. And, if I were having a burning problem, even with a clean sharp blade and properly set fence"Correct on blade height but I cut with a 24 tooth blade. This reduces the blade from over heating and "burning" during the cut.

1. 
   SteveSchoene | May 04, 2009 04:07am | #7

   One can hardly argue with using a proper rip blade when ripping.   

3. 
   roc | May 03, 2009 10:09pm | #3

   Yes there are times you want the blade high. Prevents burning and preserves life of blade. There is greater chance of kick back. Probably best to do this in plywood but not solid wood. I seem to be the last one to ask since I don't use a tablesaw but rarely. I have spent allot of time learning how though and have had great results.

   Here is a book I recommend

   http://www.amazon.com/Accurate-Table-Saw-Cambium-Handbook/dp/0964399954/ref=sr_1_3?ie=UTF8&s=booksqid=1241375906&sr=1-3

   If at all possible use the guard when blade is way up there.
   Rather than "misalign" fence for ripping solid wood use an auxiliary short fence or an adjustable fence that does not extend all the way across the table; the high end Delta is one example.

   Here is a quote from that book:
   p 70
   Raising the blade until the gullets clear the top of the workpiece will eliminate overheating and flutter, but the cut might not be the cleanest possible one. The cleanest and most efficient cutting occurs with the blade raised to its maximum height. However, having that much blade exposed above the workpiece might make you nervous.

   The correct blade height is somewhere in between. For the cleanest cut, raise the blade; it if rattles you. lower it.

   Then he says: Every saw cut requires a guard. If you find yourself unable to cover the exposed blade, don't proceed. Find another way to get the job done.
   end quote

   Also a very sharp, very high quality blade is a revelation. I keep some blades just for nice cuts for when it counts. Keep 'em all sharp though.

   roc

   Give me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )

   
   

   ---

   Edited 5/3/2009 3:14 pm by roc

4. 
   RonInOttawa | May 03, 2009 10:43pm | #4

   I've also been nailed by kickback. Both took place with my old, underpowered 1 HP Craftsman tablesaw. Only one of them resulted in blood loss but both made a lasting impression on me! I left the red spray pattern on my shop ceiling as a reminder that my "Stupid switch" can turn on at any moment.

   I now have a 5HP Unisaw with a Bies fence. There is enough power there to kill me if I have a stupid moment, so I've taken a few precautions. I now uses a Bies splitter for every cut possible to make with a splitter. I also use an adjustable half-fence that mounts over my Bies and stops just past the front teeth on the blade. I always set the blade so that the gullets just clear the top surface of the wood being cut. I still have all ten fingers and I haven't had any surprises since I implemented the changes.

   My other pieces of safety advice is to never let your hands get within 6" of the blade, always use a sharp blade and always use push sticks if at all possible.

   Regards,

   Ron

5. 
   KeithNewton | May 04, 2009 12:32am | #5

   There are a few more things besides blade height that can cause burning that you might consider.

   Number of teeth in the cut at one time, power of motor, tip geometry, and feed rate, not to mention sharpness, or stresses in the wood. So for a blade rep to jump in with an answer like that without having all of the givens would lead me to ask how much time he has had in front of a saw before he got this job.

   One of the most common mistakes that I see new woodworkers make is feeding too slowly. If you are ripping, you should have either a rip or combination blade, and feed fast enough that each tooth take a large enough chip, that the chip takes the heat out with it.

   If you feed too slowly, the wood heats up, causing any moisture to turn to steam. The steam has the plenty of the VOCs in it which condense on the blade, and quickly build up on the sides filling up the side clearance on the blade, causing more friction, which causes more than normal heating, etc.

   I am not accusing you of being guilty of this, but if you don't hear any drop of the RPMs of the motor, it could be likely.

   However, before the pounce on brigade jumps in here. Let me also state, that I am not saying to feed as fast as you can either. One must learn to listen to the tools, and be sensitive to the sounds they make, then use that feedback to guide your actions. Always inspect the work, and be willing to try different things.

   While raising the blade up high for ripping, may allow for fewer teeth to be in the cut at once, those teeth are cutting the wood at the hardest angle of attack, which is 90º across the end-grain. I am not so sure that that is better than more teeth cutting at a lower angle.

   I hope you find something here that helps. Easy answers are not always the right ones.

6. 
   SARGEgrinder47 | May 04, 2009 04:55am | #8

   With the exception of cross-cuts where I do only raise the blade so the bottom of the gullet is just above the wood.. I raise the blade all the way to the top then back off about 1/16". The front cutting teeth are coming down at a more acute angle that way and push the stock down.

   I use a 20 T or 24 T (depending on wood thickness) for all ripping and 40 T blades for cross-cutting. I use the "short fence that does not extend beyond center blade. My fence does not have to be "toed out" because their is no fence beyond the final point of the sever to interfere with the stock. With the short fence... that area becomes a "free zone" so to speak. Wood cannot rebound on the fence and back into the rear rising teeth if there is no fence back there.

   Does it scare me to raise the blade all the way? Absolutely not as I use a splitter.. a crown guard mounted on top of it and a plastic splitter completely covers the blade. I also use push sticks and I will not perform any operation on the TS where my hand has to be closer than 6"-8" of the spinning blade.

   So.. I totally agree with the reps that told you to run it high to prevent burn.. toe out slightly if you use a long fence (never toe in as it will cause burn and probably kick-back).. To add to that I can think of no reason you should not use a splitter.. riving knife and an over-head shield with the exception of a few non-through cuts. I sold my dado set and do them with a router and T square which is safer to do IMO and blind dadoes (which is my most common) are a PITA with a dado set as you are going to have to do some chiseling for sure and registration of end of cut is close to impossible as you can't see the stop line with the cut being under the board.

   So... me for one agrees with those reps as long as certain other things are taken care of first....

   Good luck...

   Sarge..

   
7. 
   cowtown | May 04, 2009 06:18am | #9

   I don't think that there is one simple answer to this queSTION.

   Every different type of saw blade is configured differently, every machine has different run-out, different HP, every set-up is different, some less precise than others.

    

   Moreover every material is different; even to the differences within the same species- reaction wood, case hardening(from the kiln), etc.

    

   Even the same sawblade with differing degrees of dullness couild function differently even cutting the same stock.

   Even within the realm of machining metal, where stock consistancy is much greater than wood, the numerous table s of best cutting speeds, best cutting angles etc are alwways prefaced by the "guideline" terminology.

    

   anyway, that's all my pea brain can figure out.

    

   Eric

    

8. 
   bones | May 04, 2009 08:30pm | #10

   I've seen reccomendations all over the place from just above to the bottom of the gullet.  I've also heard of the offset the fence stuff.  My reccomendation would be try different things and see if any improve.  For me, I tend to put my forrest blade just above the tooth out so that I can minimize heat(heard that helps somewhere don't know if its fact but makes since in theory)  I don't know if that works but it was reccomended some time and I tried and have never had a problem.  I don't offset the fence it just seems odd to me.  I have mine dead parallel.  I think the important part is that.  I use the microjig splitter and with the splitter adjusted so a few thou kick to the scrap side. It helped.  I found burn has been more related to my speed than anything and I love cherry and it burns easy.  I will push a sample piece through just to get the feed rate right (would love a power feeder)  then cut.  Thats just me.  I'd love just a rip blade, but I use forrest, so my combo does well and I'm lazy all the blade changing (just kidding).  Good luck.

   Government's view of the economy could be summed up in a few short phrases:
   If it moves, tax it. If it keeps moving, regulate it.
   And if it stops moving, subsidize it.
   
9. 
   stantheman | May 04, 2009 10:19pm | #11

   Can someone summarize the difference in the physics/geometry of the cutting process between the two approaches?  That is, is the difference only a trade-off between safety and potential burning due to heat build-up, or is there a significant difference in the quality of the cut surfaces due to the angle of  attack of the blade ?

   I use a short fence (thanks to this forum), but have burning issues (sorry) when my splitter is out of alignment with blade.  I never have understood why toe-out is recommended as it seems like keeping the workpiece in contact with the fence would result in a bowed cut as you near the end of the cut. 

1. 
   SARGEgrinder47 | May 05, 2009 12:02am | #12

   If the rear is toed out and the wood is not tension wood.. the stock that has already been severed won't touch the fence. The only concern you have with touching the fence is the stock that rides it going into the cut. The rear portion of the fence has no bearing as the stock is always severed before the middle of the blade.

   If the fence is toed in.. the already severed stock will be pushed into the splitter.. riving knife and if it flexs at all you get burn and worst... possible kick-back if the wood touches the dangerous rear rising tooth. So... you either have the fence dead parallel or toe it sligthly out if you run a long fence. If you run a short fence you are only concerned with parallel before the center middle tooth as a fence beyond that point serves no purpose.

   Sarge..

1. 
   stantheman | May 05, 2009 05:19pm | #14

   Sarge, Thanks for the explanation.  But if the toe is out, the whole fence is at a (slight) angle, correct?  So as the head-end (last part to be cut) of the workpiece is moving down the fence, it moves at an angle too, doesn't it? THe result of which would be a slight curve towards the end of the cut.   This is what I think I used to see on my set-up - my long fence used to self-adjust to toe out.  I have heard some say that once the cut starts, the blade itself acts as the guide so that it is not necessary to keep the head end of the workpiece in contact with the fence. Even if true, there is still some room for the workpiece to move.

   Sorry for the hi-jack. I would still like to see the original question answered - which is best, high or low position.  THere must be a science-based answer to it, not just personal preference.  If it is just a safety issue, then which way is really safer?

1. 
   SARGEgrinder47 | May 05, 2009 06:30pm | #15

   I have to agree about the toe out giving the overall cut some degree of in-consistency even though if I used a long fence I would not toe out more than a 1/32". I don't think that would affect a rip cut that much as I rip proud and go to the jointer to take 1/16" off each side anyway. But for those that feel that their blade gives glue ready off the TS it could be a slight annoyance.

   But.. I dis-agree adamantly about once the cut starts.. it guides itself. I have had 5 twisting kick-backs over the years. All with plywood.. all because in-attention on my part let the ply stray from dead-on registration of the edge of ply to the fence. Guide itself my *ss would be my reply. The blade will guide it until it hits those rear teeth and then fate guides it whichever direction the saw twist and launches it IMO.

   As far as safety.. a high blade is no more concern than low blade if.. if... you use a shield. I personally believe that the manufacturers real reason for suggesting low blade is the fact that most don't use any shield.. many don't even use a splitter.. and many perform operations that will take their hands way to close to the blade in lieu of push-sticks.. etc. So.. liability becomes an issue when reccomendations are made to run low.

   As far as which is best for cutting.. heat build up.. etc. I don't run mine high because I flipped a coin but because I have been both directions and I know which gives the best cut with the least chance of problems as long... as long as you use protective gaurds. And for those that don't use protective guards.. push-sticks.. etc..... the Sawstop with a brake should be included in a future budget before it's too late.

   That's muy opionion and I'm sticking with it... :>)

   Sarge..

   Edited 5/5/2009 11:32 am ET by SARGEgrinder47

1. 
   stantheman | May 05, 2009 07:17pm | #16

   Thanks Sarge.  I switched to short fence after your and RJ's dissertations a few year.  I like the idea of the teeth moving downward being safer with blade high -makes sense to me.

2. 
   SARGEgrinder47 | May 05, 2009 10:00pm | #17

   Just be sure to keep that guard on. I do lower it on certain cross-cuts as I have an Infinity Super General with 30* ATB and side grind that is like a Freud Fusion. It leaves a basically burnished finish but it will burn wood raised to high. Other than that the high is standard for me.. I lowered my crown guard so that when I raised the blade full height, it acutually cut a channel in the bottom of the hickory crown gaurd. So.. with my blade raised high the upper teeth are inside the wooden crown guard.

   As for safety.. probably the safest way would to be lower the blade under the TS insert. A little difficulty with the cut but... safe as you can get unless you don't even turn the saw on. ha.. ha... ha..ha..ha..

   Just kidding of course...

   Sarge..

10. 
    JohnWW | May 05, 2009 02:50am | #13

    Nobody has mentioned what I look at first: the condition of the blade. A dirty, dull, or the wrong kind of blade will all lead to burning and are by far the most common causes of the problem.

    A dirty blade is especially likely to cause burning and is easily fixed by soaking the blade in Simple Green and then scrubbing it with a stiff plastic or brass brush. Carbide eventually chips and dulls and eventually needs sharpening and, even with no other adjustments to a saw, just switching over to a true rip blade will almost always reduce the burning.

    If you have a good quality fence it should be dead parallel to the blade. Also, some woods, like maple, just burn more easily than others.

    John White
    Shop Manager for FWW, 1998-2006