Bandmill Blades

[Tom]

To preface this post, I want to say that this is what I've learned not what I've created.  A little discovery along the way perhaps but the basics have been around for a long time.

To get on the same foot with everybody,  I've labeled the profile of a blade, like most of us use, with the titles of the parts.


There are 3 grinds used when configuring a tooth and you will hear this nomenclature time and time again. The "face grind" is the flattening of the face and minimal material is removed.  The "back grind" is grinding the back of the tooth and not only determines the tooth's height but is where most of the sharpening of the point takes place.  The last is the grinding of the gullet and is called "gumming" or "gumming out".  Gumming designs the venturi that removes the sawdust but also removes the beginning of stress cracks that would eventually break the blade.

The pitch references the distance between teeth.  When you hear of 3/4, 7/8 or 1 inch pitch,  they are referring to tooth spacing.

The point is formed by the grinding of the back and the grinding of the face. In 3 dimension, it is a wide edge, with a horizontal top and composes the three cutting edges of the blade.  The outside corners of the set teeth are responsible for most of the cutting.  The raker cleans the kerf.

The face is flat and should be formed at a 90 degree angle to the travel of the blade.  It's longitudinal angle (from the point to the gullet) provides the "rake" (lean) of the tooth.  A heavy rake will drive the point into the wood whereas a lesser rake will shave the wood.  The harder the wood, the less the rake.  The angle will optimally be from 13 degrees to as little as 8 degrees with most commercially available blades having a rake of 10-11 degrees.  When grinding the face, a minimal amount of material should be removed.  

The gullet is that part of the tooth that lies between the face of one tooth and the back of the next tooth. It performs a function other than to connect the teeth.  It's design is such that the shavings from the point can slide into the gullet, without packing, and be carried out of the cut.  A blade will cut no faster than it can expell the sawdust and that is the gullet's job.

There should be a gently sloping transition from the face of the tooth to the gullet and the gullet should be smoothly ground.  Too sharp of a transition allows the body to bend at that point and fatigue.  It should be deep enough that the tooth is at least 3/16ths high from the point to the beginning of the transition.  

The Back of the tooth controls the height of the tooth. The steeper the angle, the taller the tooth.  The bulk of the sharpening of the tooth takes place on the back.

These are two characterizations of set teeth as seen from in front of the tooth and looking down the blade.  There is a right-set, a raker behind and a left-set behind that.  The drawing on the left has been set and then sharpened.  The drawing on the right has been sharpened and then set.

 
The teeth are bent (set) such that they will cut a path (kerf) through the wood that will leave the body of the blade free from friction.  The kerf also helps to guide the blade in a straight line.  When a tooth is set, the face is pushed out of square and just barely touching it with the stone, when sharpening,  will bring it back to square.

Bandmill  blades are generally configured with a tooth set to the right, a tooth set to the left and a tooth left straight (in the same plane as the body)

Preferably, only the upper half of the tooth is set and it is bent to 1/2 of the body's thickness.  This allows the teeth to cut a kerf twice the thickness of the body of the blade.

The wider the set, the more material must be removed and the more horsepower it takes to perform the operation.  In softwoods like pine and cypress a more agressive tooth pattern can be used.  In Oak, Maple and frozen wood, a lesser aggressivness is desired.  Too much rake causes "chatter".  Too much set leaves sawdust in the kerf.

[L. Wakefield]

   And this nomencalture is appropriate with a blade that is all of one piece, right- like especially a bandsaw blade but it could be a hacksaw blade too- but not specially a chainsaw chain?   lw

[Tom]

That's right LW.  A chainsaw has no set. I guess it has a gullet after a fashion, but I don't know the nomenclature nor the technicalities of sharpening a chain.  I do with them what I've been told and it works but I would be afraid of leading someone astray if I were to try to expain it.

Some circle saws and some bandsaws don't follow this example I have offered.   They use swaged teeth rather than set teeth.  That means that the tooth has been "mashed" to widen its face to produce a kerf wider than the body of the blade.  I don't know how to do that either but timberbeast and Jeff and Ron Wenrich talked about it on a thread a few months ago.

My experience with these blades is limited to thin kerf bandmill/bandsaw blades with raker and skip tooth blades sized 1" thru 2" and pitches of 3/4" thru 1".  There are smaller and larger blades that would fit this example but I've not used them.

Some hacksaw blades use a set called a "wave set".  Rather than set each tooth (they're small) the manufacturer bends the tooth edge of the blade into a wave form which opens the kerf wide enough for the body of the blade to pass.

[L. Wakefield]

   Oh man, can't you see  me now? 'Hemlock Stones, the great defective..' with my little magnifying glass, approaching all the saw blades around for evidence of these types of set... I have old bandsaw blades from my industrial boltcutter doobie thing that is currently defunct on the front porch (it did some time as a meat-cutting saw..) then hacksaws dating back to 'before the flood' (I ain't sayin WHICH flood)- a WEIRD saw that if it were a little different would be a keyhole saw but as it is I'm DanG-ed if I know what to call it. Some of these may have the evidence obscured by a protective coating of iron oxide aka 'rust'. I do have one swordfish 'sword' but it's organic so it doesn't really count... I'll get back to ya.. lw

[JoeyLowe]

Bandmill blades can sure be a confusing topic for a novice like myself.  I've owned and used large bandsaws for several years so I'm pretty sure there are some similarities between these and the bandmills.

I finally figured out some of the problems that I was having.  Too much blade lube, wrong kind of blade lube; wrong size tires, possibly wrong tires altogether; too much blade tension, not enought blade tension; improper blade tracking, guide problems.  I'm sure you get my point.  I've read just about everything I kind on the subject and there are sure alot of different camps out there.

At present, I just ordered the orange urethane tires from Suffolk Machine along with 5 blades designed to cut softwood better.  (1 1/4" wide, 7/8" something or other, .042 thickness).  Supposedly gives more air needed by the softwood to work right ;D ;D ;D  The fella that owned the mill before me used a mixture of diesel and bar chain oil to lube the blade.  He also used one B56 and one orange urethane tire.  I did put the B57 tires on and performance improved over the hodgepodge that was place, but according to one source I read, the B57 tires will slap the blades until they break.  I read somewhere that a good idea would be to keep the blades off of the mill when not in use and coiled soaking in a mixture of diesel/oil.  When ready to use, wipe off and install.  Then use the occasional water/pinesol lube to keep the blade clean.  Supposedly if you just use the water/pinesol, the blades will rust and break.  Geez, there is too much to remember. ??? ??? ??? ???

I do know this, when you call Suffolk Machine to oreder blades/tires, they will also try to sell you their video, their blade guide systems, their tooth setter and their blade sharpner.  Talk about being overwhelmed.  SO MUCH TO LEARN. 8)

[Tom]

Yep, there are experts at every turn of the road that will tell you that your manufacturer is doing everything wrong. Talk about "hard sell", I've met a few in my time.

It's real easy to allow yourself to become overwhelmed.  To not be overwhelmed try this.  Operate the mill like Woodmizer tells you to and use the recommended parts.  When you have sawed long enough to decide they are wrong about something then you can change. You have to do it their way before you can say another way is better.

I use B57 belts and have for years.  They don't break my blades.  I have used water and a little soap sometimes for a blade lub and find that it works just fine and cost practically nothing.  Almost everywhere I go I can find water. I have used woodmizer blades when they had square gullets and then round gullets and have used a Suffolk blade and simonds Red Streaks and Lenox and they all cut wood. I have favorites but it's got nothing to do with a bunch of technical gobbledy gook.

I don't keep my blades in oil, Heck, they wear out before I get a chance to worry about whether they might get too rusty.  I think that some of these folks with recomendations for things like that must not be sawing.  I don't take my blade off of the mill till it's dull because it work most every day.

I've heard all kinds of weird tales about waxing mills and polishing blades and.............  I'de rather be sawing wood.  Maybe my mill doesn't look as spiffy as some of those other mills but I bought it to wear it out not to show it off.

Contrary to popular belief, if your blade isn't sawing wood then your working for free or not working at all.

[woodmills1]

i have been cutting red oak for a post and beam job part time since the first of the year.  so far i have 120 hours invested, a little under half of that time was for harvesting the trees from our forest.  in the 60 or 70 hours of cutting i have sharpened the 8 blades i have been rotating but not done any setting.  these blades were new and then used through 3 sharpenings on pine before i started this oak cut. so far they have performed flawlessly.  because the product is posts and beams which are to be used off of the mill, i use one blade to open the log and size the cants to 2 inches over finish, set the cants aside untill the first blade gets dull, then resize the cants to finish with a fresh blade.  most pieces are 8x8, 5x7, and 4x6. the product shows nice surface and is square along its length to within a sixteenth of an inch.  i use woodmizer .045 with B56 belts and baroil/deisel.  when i finish in a week or two i will check the set and post back results.

[Tom]

I had an experience once that reinforced my desire to use water as a blade lube.

My saw quit cutting straight and I couldn't keep the blade on the wheels. I called WoodMizer and, right out of the chute, they ask if I had put any petroleum products like diesel on the blade.  No, I hadn't.  Well they weren't sure what was causing the problem but asked that I keep in touch.

I had to take my knife and cut the belts off of the wheels.  Boy, what a job.  Then I remembered that my water container had broken and I replaced it with a 5 gal bucket that had been used for hydraulic oil and diesel.  I hadn't cleaned it out when I put it on the tower and that's when my problem began.  I called Wood Mizer back and explained.

I was told that I had probably found the problem.  When petroleum products get on rubber products, they cause them to swell and in time will deteriorate them.  

I have made sure that I stayed away from petroleum products as blade lube ever since.  Some may use them successfully but I'm not going to try to "fix what aint broke".  :D

I figure that there are other things on the mill that a petroleum product may not be too good for as well, like, the exterior of hydraulic hoses and drive belts and my band brake, etc.

I guess that is what makes this occupation an art as much as a science.

[JoeyLowe]

   I agree with you guys as for the mountains of information and some misinformation.  I have both new and used Woodmizer blades and B57 tires as well as a used B56 tire.  I just ordered the Suffolk blades and the orange urethane tires. I figure that which ever way I settle, having the same kind of tires on both wheels will be a much needed improvement.

Question:  Are the sharpener and setter worth the extra investment or should I just send them in to be sharpened?

Question: The blade guides that Suffolk is selling support the blade from both sides.  Has anyone tried these guides on their Woodmizer?  What wwas the outcome?

[Tom]

Joey,

I go through 3 blades daily with my woodmizer in a production atmosphere and sometimes as many as 6.  That's $20 a day that I put back into my pocket by sharpening my own blades. (I don't buy that labor thing 'cause my spare time is mine to do with as I please) It takes me about an hour to maintain a day's worth of blades.  I usually pile them up and do them when it fits my schedule.

It's also handy to be able to sharpen your own blades when you get into nails, dirty logs or difficult wood and are running out of blades. Overnighting a box of new blades can get into your pocket.

I have also been able to experiment with different hooks and sets on various woods. I find it fun and entertaining but wouldn't go so far as to get fanatical about it.

I have found that I can sharpen a blade pretty good and use my abilities to judge whether someone else is doing a good job or not.  I figure that I need to know how the blade works to be able to tell whether the other fellow knows what he is doing.  It helps to be able to diagnose problems as well.  Most of the time when you have problems with your saw, it is the blade or the alignment.

Over the years I have been please that the sharpener and setter have given me independence from someone else's schedule.  It has made me a little money sharpening other sawyers blades.  I mean "little" because I wouldn't want to do it as a business.  I have done it for others because they were over a barrel and had run out of blades. (exactly what I was talking about when I mentioned my "Independence")

I have two Wood Mizer blade maintenance kits now.  One is destined to be put on my truck and taken to the job when I can get a round :D "tuit"

[Frank_Pender]

I am sure glad I do not have to learn all that stuff.  I have knock out teeth ( not in my head either 8)) .

[woodmills1]

i sit firmly in the sharpen your own camp, first for the dollars saved and second for the timing.  i can sharpen a days worth of blades while i sip coffee and read the posts here between 5 and 7:30AM.  the auto sharpener is that good.  setting is another story.  if the blades haven't hit any thing it is not too bad, but wow it gets tedious when the teeth arent uniform from a metal hit.  i was always going to try the suffolk dual setter but am waiting to hear more from other owners.  as for blade lube i am going on the fourth year using bar oil/deisel and my belts last as long as with water.  in fact the B56 last way longer than the B57 used to though as i said before they are hard to put on and i do cut them off as they are impossible to stretch off.

[cut2size]

I use the suffolk setter and think that it is well worth the cost.  It takes a little over two minutes to set a blade for my woodmizer.  I use the orange belts with bar oil and diesel on one of my mills and b57 belts and water on the other.  The oil-diesel mix makes blades look new(no pitch).  It takes so little mix to clean the blade that I have never heard anyone say that the lumber smelled bad and I have never seen any lumber stained as a result.  The orange belts do not degrade because of the petroleum and I will probably use them when my b57 belts wear out on the other mill.  When I cut white pine I don't use water because it seems to make the blade hydroplane in the cut.  I just give the blade a good bath after the cant is sawn.
David

[Gordon]

Great information guys thanks! Tom I'd say a couple of these posts are perfect for the knowledge base. What do you think? Keep it coming I"m learning new stuff everyday. :P

I also agree with Tom on the if she isn't runnin she anit makin me money!

Gordon

[Papa Dave]

Tom, I would like to sharpen my blades, but do not want to spend a fortune on a sharpener. What kind of machine do you use.

Since I built my mill and it works fine, I guess I could build a sharpener.

By the way, I have used both the oil and diesel solution and water and found that they both worked to keep the pitch off of the blade, but the blade wanted to come off of the wheel with the oil and I have not had any problem with water. I think I will stick with the water. ;D

[JoeyLowe]

   Called Woodmizer today to discuss the many nuances of bandwheel tires and blades.  According to Rod at Woodmizer, the B57 is designed (and patented) to fit loose.  3/4 of the tire should fit snuck with other 1/4 loose so that it can flap against the blade to knock off any sawdust that might accrue on the belts/blade, thus extending the life of the belts.  No glue is required to keep the belts in place.

I also ordered info on balde sharpeners and tooth setters from both Woodmizer and Suffolk Machine.  I would love to hear from owners of each. ;D

[Tom]

Joey, Check out Cooks accuset also.

Papa Dave, I don't think that copying a sharpener that has all the correct design features would be any great shakes for someone who is decent fabricator.  The important thing is that everything lines up exactly and that the materials will last in a water bath.  If you can't cut out a cam then they can be purchased from most anybody.  You need cams that will fit the tooth design of your blade.

I have two Woodmizer sharpeners and like them.  I also have two Woodmizer setters and favor any setter with a dial indicator over one that has no measuring device.  I've not seen Suffolk's sharpener but I have see Dino's and don't care for it as much as the ones I have. I like Cook's and, if I live long enough to wear these two woodmizers out, may get one.  Moon's has an interesting design and I would like to see one in real life.

[Mountain Guardian]

I read here back a few posts up that chainsaw chains do not have any set to them, actually they do.  I tend to keep sharpening and using my chains until they are basically little nubs, but I have found as I get too far down you also lose much of your set and have little to sometimes no clearance between the chain kerf and the bar width, which can become a real bear.  It took me a while to catch onto that, I was thinking at first it might be due to some teeth that got so small they actually broke off, but when I studied my old chain to new chains I realized that I had no offset on the teeth beings they had been filed back so far over time.  I was able to bend my teeth out a bit on that old chain missing teeth and all and get it to still cut.  Nothing like getting a full year of heavy use out of a chainsaw chain.  Every time I take an old chain in to the guy at the saw shop he just shakes his head..... lol....

I am currently studying how to set my blades, this study has brought back an old memory from when I worked at Homestead Log Homes, they had me cutting the end cuts on the logs with a box cut so that you could fit two logs together and get a perfect 90 degree finish corner on them when fit together.

The bandsaw that they had me using was running a 4 inch blade, wayyyy too much for the little machine it was on.  I was having a heck of a time getting those cuts done, it was binding and smoking constantly as I was trying to use it and getting a straight line was basically impossible.  Luckily you did not have to get a perfect straight line for it to work on the wall, but it was still bugging me.

I finally noticed that there was no offset on the teeth at all and that was why it was binding so much trying to cut.  I ran the blade through manually and bent every other tooth just a bit to the outside alternating back and forth with a pair of pliers and a vice grips.  That thing cut like a champ after that, it stopped binding up and stopped smoking and I was able to actually cut a pretty straight line.  Apparently no one had thought of doing that before and they just kept buying new blades.