Don't know where I come up with some of this stuff, but anyways, here goes.
Beings that a blade tooth is set out a little on both sides, I wonder why the blade looses it's set. When I hit a nail it moves the set out farther, so you wood think as you saw the set wood get greater, but it does'nt. So if you could put a slight angle on the inside of the tooth, it wood keep the set out longer,maybe, I don't know, sounds good on paper, maybe not. :-/ :P Sometimes this pea brain of mine really rolls around in their.
EZ
My pea brain is rolling around now too. :) Let's see. :P
Perhaps looking at the blade teeth from the face would help determine the forces that encrease or decrease set.
The outside corner of the tooth is what does the cutting because it has been stuck out there in "harms way".
If a nail hits the corner of the tooth, it probably twists the tooth and the tooth gets pulled to the outside, encreasing (destroying) set.
Normal wear has the stress on the corner, point and face. Since the pressure is constant rather than an impact, perhaps it is pushing the tooth toward the straight up position which would cause it to lose set. Also the wear of the cutting corner would cause the loss of set.
Lenox makes a "Turbo" tooth that has an angle on it. Tim Cook of Cookssaw has a picture of one in his little newspaper but I can't determine what it is that they are trying to depict. I think that they are grinding the face at an angle.
Here are some diagrams from the knowledge base and prior posts about sharpening that show blade configuration.
(https://forestryforum.com/images/YaBBImages/userpics/bladeconfig00.jpg)
(https://forestryforum.com/images/YaBBImages/userpics/bladeconfig01.jpg)(https://forestryforum.com/images/YaBBImages/userpics/bladeconfig02.jpg)
Set - Sharpen / Sharpen - Set
Now without slow motion or stop motion high speed photographs we're just guessing but it's fun anyway, :D
Tom,
Yes that is what I mean by grinding a angle on the face, then the tooth should stay set longer, if you think about it. I called off work today to saw, but all I did is watch it rain. I been checking this post all day to see if any body answer yet. Thanks for answering, Tom, but I guess we still dont know about it yet.
Come on guys, we need more input, what do you think, Arkansawyer.
EZ
Well keep thinking, you might discover something. I think it is Dino that makes a sharpener that is advertised to alternate an angle on set teeth. I'll have to try to look it up later. :P
Looking at a blade......not off the mill as I don't have one of them in my office yet! But looking at a blade from my sazall I see what you guys are talking about but looking at a blade from the mill.......yes I have one in the office now, grabbed it out of the van! I'm thinking that the blade is tempered after its set? And in doing this the tips can't start bending outwards. Does that make sense?
Got a few other ideas but wanna see what you guys think about this.
Steve
I'm going to sit back and watch because I'm not sure I understand. :-/
If tempering the set wood make the difference, then why do ya loose the set. Next.
EZ
Come on Tom, be adventurous. ;D
EZ
I would think that tempering the set is just something that is done at the blade factory to make the tips stronger. Being the size that the tips are it seems natural for them to want to bend back into place and be flat like the blade.
As far as them wanting to bend outwards if you look at the blade you can see from the way its sharpened that it wants it to pull the set inwards.
Steve
I Don'T really think that you "lose" the set, as much as you lose the "sharpness" of the tip of the tooth. When I hit the first piece of metal, it was a glancing blow. I mic'ed it, and found the set off by only a couple of thousand's. The teeth on the other side were sharp, and the teeth that struck the metal were ROUNDED. The teeth are pretty tough to bend, so, I don't think you "lose" set. These are Suffolk blades and a file won't touch them !!
The set in the teeth is "worked out" of the blade as it goes around the band wheel. Try bending angle iron around a wheel. One side of the angle will have to stretch or the angle will have to be flattened out to bend. Because of the gullets, the teeth flatten out instead of stretching. If a blade is set by bending the tooth closer to the tip, the set will last longer. I usually have to reset my blades every second or third sharpening. I always set first and then sharpen.
Tom my pea brain thinks it is Simonds that has the Turbo tooth ;) I wouldnt know that either cept that I only use simonds red streak all the time. I know cookssaw says you can sharpen and set in either sequence but they recommend to set then sharpen, but I have wondered if going the other way would give the results EZ is talking about, DanG sounds interrestin.
I don't think the order in which you set and sharpen would make any difference. If I understand the turbo tooth right, it is the face that is alternately ground such that it isn't at 90 degrees to the direction of travel. The picture in Cooks paper was all I had to go on but that is how I saw it.
I set and then sharpen too. It saves me a lot of time from having to rub the burr off of the teeth. It is the way Woodmizer taught me years ago and it just stuck. If you look at the two drawings above you can see an exagerated example of each. If you set last then I think that you are changing the face grind because it twists the tooth a little. You are also moving the corner of the blade away from the wall of the kerf. I like to think that the left picture is what my blades look like.
Yesterday I sharpen a blade with a angle on the teeth, I use a angle grinder cause I dont have a blade sharpener. It took about an hour but I just wanted to try it. Today I put a barn beam on the mill(8 by 10 by 12 ft long. I'm pretty sure it was hickory, sawed 1x's, it sawed nice & EZ. The blade is still looking good, now I wish I had some more. Going to keep atrack of BF with this blade.
EZ
So that you can remember and judge against other blades, try to measure the angle and take pictures of what you did. Gullet depth, set, rake, tooth-back angle, tooth height, blade thickness and width all may make a difference in the long run.
Is the point of the tooth square or pointed? If there ends up being much difference is it because the face is ground at an angle or because the face is square and the point is ground to an angle.(this would happen if the back grind was angled rather than the face grind).
Photos will show gullet shapes and tooth to gullet transition angle shapes.
This might be interesting.
Tom,
As I said before I used a angle grinder. It was hard to use this cause of holding it by hand. I dont really know what degree of angle I put on, I just thought the angle I put on was good enough. The blade I used is a $15.00 1 1/4- .042, it was resharpen & set once. The guy sets at 19 degrees. When I put the angle on, I angle grinded the front of the tooth & the gullet, I did'nt touch the back of the tooth.
My puter camara is getting fix, they have had it for 4 months now, maybe I'll have to get a new one.
EZ
Could it be that as a blade gets dull the point of the teeth do not cut and as a result the teeth get deflected as they pass thru the wood? Eventually causing them to loose the set.
I use a 1 1/4 x0.042 blade with 7/8 tooth spacing and 10 degree hook. I have found that sawing fir that had the limbs broken resulting in dry knots, will take the set right out of a blade. The out side corners of the teeth were still sharp, so the cutting pressure of the knot was enough to bend the tooth toward the blade. On a log that is all green, there is no problem.
Saturday we sawed 640 bf of red oak with the blade that I angle sharpen. The blade is still cutting strong with good results. The logs are 10 & 12 inch dia that have been laying around a while. I can peel the bark off with the cant hook. I am sawing 5/8 thick x 5 inch wide boards. If I can get my wife out of bed this morning, I hopefully will finish this job up today. ;D
EZ
I'm going to take a stab at this.
According to a sharpener I had talked to, F_D is right. The pressure will cause the teeth to go back to neutral over use decreasing the set.
It is Dinasaw that has an alternating head on it's sharpener to put an angle on the tooth. It automatically changes through the range of left, centre, right or depending on what your configuration of rake? is.
I believe the teeth should be set first then sharpened. If you sharpen first and you have teeth that are out of set further than others then you will have a different angle of tooth when that moves out in line with the other sets. It would kind of be like having some teeth on a chainsaw, shorter or longer than others and only the longer ones will do the cutting. Not sure if that's a good example.
EZ - the way you sharpened it by hand is the way the Dino sharpener works I think giving the angled teeth.
Let me know if I'm way off or close.
I have cross cut saws and rip saws. They are ground the way they are for a reason.
Crosscut saws have an angle ground for cutting across the fibers to make the cut. (Like the saws all blade and EZ's angle cut blade. It is designed to slice the fibers into or cut across the grain.
Rip saws are flat across the tooth tip so they rip or chisel cut the fibers apart. The face cuts but the corners bear the most pressure. As the set increases so does the wear. This is why a ground and then set blades cuts smoother and last better. The whole face is cutting. When I need to make really fine and smooth cuts I put on a 0.055 re-sharp.
Hit a nail and you will notice that there is some metal cold welded to the inside of the tooth. I offten take a chainsaw file and starting in the gullet and pulling down and out at the same time and "clean" off the face of the tooth. A bad tooth I just flatten with needle nose pliers and 90% of the time I can still saw with the blade to finish the log with known hardware. I have done this up to 6 times in one log with one blade.
If you take a stump and stand it up inside and clamp it and saw across the grain you will notice the differance in a set/sharpened as to a sharpened/set blade in the smoothness of the cut and the sawdust. A set/sharpened (good rip grind) makes a rougher finish and long curley sawdust. A sharpened/set makes a smoother cut and fine sawdust. This is why I use new blades when cutting rounds.
The pressure is on the outside of the blade as is most of the wear. The blade bending around the wheels tends to bend the blade flat. There was a good article in "Sawmill & Woodlot" about hand saws and it told of the differance between rip and cross cut saw blades and it applies the same to band mills and circle blades. Just about all hand saws and circle blades for hand tools has a combination grind blades so the can cut across and with the grain (ie sawsall blade). I hope this is as clear as the lower Mississippi River.
ARKANSAWYER
(https://forestryforum.com/images/04_01_03/DSC00205FF.JPG)
Good explanation, Arky. NOW, is there a special way that you clamp the piece for "rounds"? What would keep the bottom of the piece from kicking out and ruining the blade?? We will be sawing table slabs from the Cypress sinkers and this is a real concern. I'm not real comfortable with the band mill yet. ::)
(https://forestryforum.com/images/YaBBImages/userpics/slice2.jpg)
Band mills are much more forgiving than circle mills when it comes to poor clamping. However, pieces can come loose and cause trouble. The band pulls the piece of wood toward the sawdust chute, so you need to support the wood on that side and run the clamp up against the bottom so it doesn't tip over. The pressure caused by the movement of the head is much lower but still need to be taken into account. I usually just clamp the pieces against a log stop and make the cut slowly so there isn't much pressure endways.
Ended up with 1200 bf on that job with the same blade, I have'nt touch the blade as far as resharpening or setting, still sawing strait boards. Pushing the carrage threw is the same as I started. I notice the saw dust seem to shoot strait out of the shoot, instead of going all over the place.
EZ
Ark-,
I don't under stand your sentence "as the set increases so does the wear" . Do you mean the that the wider set has more of the top(face) of the outside teeth cutting hence more wear?
When I hit iron and the points of the tooth is damage, I put a flat ground stone (no radii on edge) on the grinder and set it at a 20 degree angle. I grind off about .020 of the tip of the tooth, then I grind the face of the tooth. I loose a little of the gullet but the blade still cuts well.
Also please explain what "The pressure on the out side of the blade as is most of the wear". Do you mean that the bottom teeth that are cutting into the log wear faster than the teeth on top of the log.? I am not trying to nit-pick your posting, but would like to know in more detail the point you are making--Thanks.
Tom,
I ask my blade sharpener guy if he could sharpen a blade like the one I did, he has some kind of auto sharpener and said there was no setting for this kind of sharping. Right now I have sawn 1800 bf with this blade, without resharping. I wood like to find a setup to sharpen a blade with this angle I have on it before it breaks. Could you help me fine a sharpener that wood. Thanks
EZ
EZ,
check out the link below, I think that's what your looking for. I mentioned this one on page one of this post. I just ordered one and hopefully will show up next week. They have a listing of all their dealers, head office is Australia, for North America.
www.dinasaw.com.au
Yes,New Sawyer, that is the company I was referring to. Their MSA option is what I remember seeing on a video. This is the only small sharpener that I have ever seen that controls every position of the grinder head.
EZ, there are several band sawmill manufacturer's who are dealer for these grinders. I know of no blade maintenance companies that advertise a service like this.
D,
Yep! As more set is put on the blade the more of the tooth sticking out from center. When there is no set each tooth follows the one in front and takes a smaller bite of wood since the teeth in front keep it from biting too deep. When you set the teeth apart it cuts in a different path then the tooth in front of it so it gets to bite more wood. Still part of the tooth follows the path cut by the tooth in front of it and the out side half of the tooth cuts a new path. As set increases more and more of the tooth is exposed. If you have less spacing, say 3/4 instead of 7/8 or 1 inch then you have more teeth per foot of blade shareing the work and they have less stress per tooth but also have less bite so they may not remove as much wood per pass but make a smoother cut. A 1 inch has a bigger bite and rougher finish and more gullet to remove the wood so may cut faster but the teeth will suffer greater wear.
So if a tooth is sticking out from center it has a greater exposed cutting surface and it will be wearing more on the corner of the tooth. On my blades there is a tooth bent up then down, straight and back up again. So it is 2 5/8 inches from point to point that are facing the same way. The raker tooth does not hardly ever wear since it follows the cutting edge of the teeth in front of it. Look at your blade after you cut for a bit and you will notice that it is shinny on the points where it sticks out the farthest.
More set is neede on soft woods so they do not pinch the blade and you have to have some set or your blade will bet very hot dragging through the wood.
The article on hand saw blades was not in "Sawmill & Woodlot" but in "Timber Framing".
My hydralics hold the stumps very good and I have not lost one yet in the hundards that I have sawn. On some I have had to notch the bottom so that it would clamp good but the hydralics hold well.
ARKANSAWYER