Optimizing the cut on a bandsaw mill

Orin Raichart wrote:afer using an lt40 woodmiser to cut the wood for my tiny house, I'm with Kyle, pushing the log seems more difficult. The woodmiser moves the bandsaw rather than the log.  Large sawmills usually move the log but their blades are solid circular blades rather than bandsaw blades and are more than 36" in diameter ....and have huge rotational momentum

if you push the log has to be flat straight or you will have to not only have a y-axis control but a y-axis control that will move up and down as you are actually cutting....otherwise your router cut will be of varying depths instead of a fixed depth...

...speed is going to be tricky. consider the bandsaw on the woodmiser....if I push the bandsaw too quickly, I get wavey cuts. if I push the bandsaw too slowly, I get wavey cuts  ....if I push it at the right speed, I get nice flat flush cuts and the same depths.

not sure why you want to move the log instead of the router, that takes more energy...but hey you can do it if you've got the time and money to make same depth cuts and you figure out the speed of the cuts

good luck!

Interesting. My thoroughly beat up and elderly little norwood cuts just fine at a dead crawl so far. Waviness comes solely from dull blades/going too fast, at least as far as I can tell..

Could this be a tension issue?

D Nikolls wrote:

Interesting. My thoroughly beat up and elderly little norwood cuts just fine at a dead crawl so far. Waviness comes solely from dull blades/going too fast, at least as far as I can tell..

Could this be a tension issue?

yes I did have tension issues....but if one thinks about it, the harder you push the bandsaw for speed, the more the blade will bend....too tight, and the blade breaks if I push it that hard

I am a novice when it comes to saw milling so you might have hit the nail on the head, because I did have to keep adjusting the tension...I did have a used blade at first too which I noticed helped straighten the cut when I changed to a new blade....also, I was cutting both douglas fir and oak on the same blade.

guess we should move this conversation to saw milling in order to avoid hijacking the OP's original question.

I suppose it's very possible that my success so far has to do with lack of oak! I'm mostly dealing with doug fir and cedar.

Causing breakage by going too fast makes sense intuitively.. Causing waviness by going too fast also makes sense, I think; the increased resistance seems like it would amplify any wander.

But having waviness increase from going too slow doesn't make much sense at first. The only explanation I've dreamed up so far is that the blade is too loose, but when the goldilocks pressure is applied the load on the blade from the teeth is simulating correct-ish tension?


Anyone more experienced care to chime in?

I have a woodmizer lt15. I saw mostly birch and spruce, with some poplar. I can’t think of any good reason to go slower than the saw will easily cut. You have to develop a feel for it. Too fast will bog the engine and cause a wavy cut, or break the blade. Too slow is wasting fuel and time, and may lead to saw marks on the lumber. A dull blade or improper tooth set or improper hook angle for the wood you are sawing will make wavy lumber. Improper gullet grind will leave sawdust in the cut which can heat the blade and cause wandering. In other words, always use a blade that is sharp and has the proper set.
You should not saw hardwood/frozen wood with the same blade you use for softwood. The angle of the tooth is critical. You can run 10 degrees as a good ‘in the middle’ blade, but if you saw a lot of ‘hard’ hardwood (poplar and beech are hardwood, but not ‘hard’) or frozen hardwood, use an 8 degree band. If all you saw is pine in the summer, you can use a 12 degree band, unless you hit lots of knots, then use a 10. Cedar is a difficult wood to saw on any mill, as it has fibers that can cause the blade to ‘pull’ sideways. You absolutely have to peel it or debark the cuts.

Tensioning your blade:
I’ve got this down to about 15 minutes. It is time WELL SPENT.
1. Remove blade guides–you CANNOT run this test if the band saw blade is restricted in any lateral movement.
2. Make sure tire/belt surfaces are in good condition–they cannot be hard, flattened out, cracked or brittle. On mills with loose fitting V-belts, replace them with the next size down so they are tight fitting. This will eliminate over 80% of the vibration in your mill and the blade. I learned this the hard way, by having the retaining bolt vibrate out of the idler wheel center.
3. Mount the blade on the machine and apply the tension to the band that the blade (not mill) manufacturer recommends (Woodmizer makes a tension gauge, so do others).
4. Close all covers for safety purposes. I admit I don’t do this, but it’s a good idea.
5. Start the machine, engage the clutch into the high speed cutting mode.
6. Stand Beside the mill, with your hand on the turn screw tensioner and your eyes on the band saw blade. Very slowly start detensioning by half turns at a time, keeping your eyes on the band saw blade. The object is to bring the tension of the blade down to a point that the blade starts to flutter. Go SLOW. It’s a small difference between flutter and coming off the guide wheels.
7. When you see the band start to flutter, you have found the tension baseline. Now start ADDING quarter turns of tension, SLOWLY, until the band stops fluttering and is running stable again. At this point ADD one-eight to one-quarter turn of tension.
8. You have now tensioned the blade correctly. Shut off the machine and put your guides back in place. You need to do this with every blade change. Again, it’s well worth a few minutes of time. Why ruin good lumber or a good blade?
9. ALWAYS DETENSION your blade after sawing (end of the day or long lunch). Since you do not know exactly where the proper tension is, it will be easier to remember if you take off 8 or 10 full turns of tension until the band is completely relaxed. Band saw blades, when warmed up from cutting, always stretch; and upon cooling shrink by tens of thousandths of an inch each cooling period. Therefore, blades, when left on the saw, over tension themselves and leave the memory of the two wheels in the steel of the band, which will cause cracking in the gullet. When you leave the band on your saw under tension, not only do you distort the crown and flatten out the tires (which makes them very hard), but you also place undue stress on your bearings and shafts. Believe it or not; you can, and will damage your wheel geometry sooner or later and considerably shorten bearing life. You are also crushing your tires or V-belts. This also applies to chainsaws! A long bar with a tight chain can lead to a bent crankshaft when the chain cools down and shrinks.

I love my mill, and the thin kerf, but all of the above illustrates why a bandsaw mill is a pain in the ass compared to a circle mill.

Thanks you guys!  All of this info gives me more to consider when I start having wave issues on the mill.   ...and thanks Julie for the tensioning guide: you had a bit more detail than the manual did

I have a Woodmizer(WM) lt35 Hydraulic with a 25 hp gas engine.  I am using WM 1.25 inch "double hard" blades of various types.  I cut around  35k board feet per year set and sharpen my own blades and have been using my sawmill for 4 years.

My 25 hp engine has more than enough power for my 24 inch max cut width.  How fast I can cut straight lumber is mostly about going just slow enough to ensure that enough sawdust is getting removed from the cut.  Mostly to judge the right forward movement speed for my saw I watch the sawdust coming out onto the ground.  I know exactly how much sawdust my blade can remove.  The harder the wood and or the wider the board the more sawdust you will make and therefore the slower you must cut.

If your blade is tentioned correctly, your blade has enough set and is razor sharp at the outer tips, your guide rolers are pushing the blade straight horizontal and your blade hook angle is not to agressive, then it's all about running fast enough to not get powder sawdust but slowly enough so the gullets can remove enough sawdust.

For softer wood I use WM 10 degree blades ( because the WM rep suckered me in to purchasing them) 10 degree bands can pull themselves into the cut to fast on harder wood, then the gullet overloads and sawdust packs around the band and causes more friction and pushes  the band up or down causing the cut to deflect up or down and ruin the board.

For realy hard wood or frozen wood I use WM 4 degree bands.

For hard wood and fastest cutting blade I use WM 747 blades.  These are awesome and are in my opinion the fastest longest cutting cheap blade.  They have a steeper back cut and larger gullet. Next time I am buying 1.5 inch blades because with the larger gullet the 1.5 inch 747 band has about the same width at the gullet as a 1.25 inch regular gullet band does and I am worried that my 1.25 inch 747 bands will be less strong as I sharpen them and they get more narrow.

Steeper back cut on the 747 keeps the tips sharp longer and on my mill how fast I can cut is all about the gullet size.  The limiting factor for cut speed is how quickly you can remove sawdust from the cut.  All of the standard WM blades have a small gullet and can not remove sawdust as fast as the blade can cut with my 25 hp engine so I have to cut slowly to keep the blade from over loading with sawdust.  But when cutting slowly your blade still wears out after the same amount of time, so you get less wood cut per blade and it takes longer.

If you are breaking bands you are probably cutting to fast and overloading the band with sawdust(may also cause the blade to deflect up or down), which causes excessive friction as the sawdust packs tightly around the band.  Or, possibly the gullet was not properly ground when the blade was resharpened and micro crack developed right in front of a tooth.


In the beginning when my saw was new, I had to fiddle with the tention.  My saw has a lever with a cam that presses up against a screw in a block of rubber.   I just pull the lever down to de tention and flip it up to tention.   I can set the tention by adjusting the screw when the lever is down.  Now, I very rarely touch the adjusting screw and do not have any problems maintaining proper tention for days at a time.  I think the lt35 and lt15 have a great blade tensioning system.  Probably better than silly Hydraulic tentioners that have to be cranked to tention them.  

If you are having to adjust your tention often, there's probably a problem with the way you have the machine set up, or you are not lubeing the blade.


If your blade keeps moving faster and slower or makes a little screaching sound it is to dull and you need to change it at the end of this cut.


It is important to lube your blade or it will overheat and you will lose tention.  Also, the blade makes a lowd noise like high pitched white noise if there is not enough lube.  If you are cutting through bark, especially dirty bark use extra lube to help keep the blade from dulling quickly from the sand and dirt trapped in the bark.

My saw came with a gravity fed single tube dripping water on the top of the blade.  I upgraded by adding the WM "lubemizer system".  It has a pump, a guide roler assembly with two spray nozzles and a small  control box with a on off switch and electric lube volume adjustment.  I now use 1/4 the lube and get 4 times better lubrication.

Water on the top of the blade only is ok but not great.   Spray nozzles on both sides works best, but a spray bottle with WD-40 or diesel works ok.  I now use diesel as my lube because I don't have to use mutch and my blade stays much cleaner and coated in diesel oil, which cuts way down on friction and prolongs blade life more than water or "water mixed with vegetable oil" (WMs tip).  A chainsaw uses oil lube to cut wood because water doesn't work as good.  Your bandsaw will thank you if you use small amounts of diesel to lube the blade a little bit every 10- 40 seconds.


De-tention your blade if you are not going to cut in the next 30 minutes.  When the saw cools down the saw band will shrink and tention will increase.  This will put a lot of pressure on the band weels and weel belts if your saw has well belts.  If the weel belts have pressure on them in the same spot for more than an hour or two the belts will be squished in the area under the band.  Then, if you use the saw the squished wheel bands will cause bad vibrations in the band and degrade cut quality for an hour or so until the belts expand back evenly.

If you are going to cut logs bigger than 25 inches in diameter often,  especially if you are going to cut 30-40 inch logs, I highly recommend getting a saw with a wide max cut capacity, bigger than my lt35s 24 inch cut width.  A wide cut capacity is needed for wide logs.  Especiallyon a Woodmizer, if youare goingto max out the max log diameteryou are goingto max out the blade width and spend half an hour cuttinga groovedown the log to allow your blade guideto clear. And, defiantly don't have a de-barker on a 24 inch cut capacity saw for big wood.  I had to remove my expensive de-barker because it didn't fit well at all with a 34 inch log on the deck and when your band gets stuck because it's not wide enough to cut the log and you have to cut a groove in the log to clear a path for the blade guide, if you have a de-barker, the debarker is right where you need to be working on the log with your chainsaw.

Hi Jason,

Welcome to Permies.

Welcome to permies Jason! I always enjoy hearing viewpoints and experiences of other bandsaw owners, especially if it’s woodmizer. Sounds like you have developed some practices that work well for your situation. I’m assuming you cut a lot of pine, or something with pitch, to need the diesel? That seems to be common with other mill owners I’ve talked with. I’ve never had to use it, and though I’m set up with a drip tank, I don’t even use water (and how is water supposed to mix with oil of any kind? WM actually said that??) or water/dawn detergent mix (which is what my woodmizer dealer suggests). But, I don’t mill ‘pitchy’ wood, as I cut my spruce this time of year, when it’s frozen. The birch and poplar don’t need lube at all, like most hardwoods. One thing you mentioned was a comparison to oil in chainsaws, but that’s to lube/cool the moving parts of the chain, not the teeth in the wood. If a band blade is getting hot, something else is wrong (feed rate, dull teeth, improper set, belt tension, blade tension, etc), as the water drip is not intended to cool the blade, only lubricate it to keep pitch from building up (which will also create friction and make it heat up). That’s why diesel works better, because it cuts the pitch, and you need less, vs water which needs to coat the blade to keep pitch from sticking.
I debark with a log wizard on a 45 cc saw. I not sure I understand how a water drip helps much with dirty bark, it seems like that would just make a muddy slurry? I do know any dirt is murder on a band blade, much worse than on a chainsaw chain. My $200 log wizard paid for itself quickly in longer blade life. Which model sharpener do you have?
I haven’t tried the turbo 747 blades yet but might next box. I’ve recently switched to 7 degree double hards for everything and am quite happy with those. I’d love to run 1.5s just to get the extra stiffness, but my little 15hp wouldn’t push those well I’m afraid. Good point about the deeper gullet though. Not many people consider that.
It’s a good time to be a mill owner. Sounds like lumber prices are headed up again this coming summer.

A quick question on a Diablo blade, ~12" circular on a chop saw.  I use this saw for cutting firewood down to size, but now as you can see I've bent one of the teeth.  It still works, but has more 'chatter' now as it passes through the wood. Would it be better to try to bend this tooth back into place or use a grinder to re-shape it to align back with the other teeth?  Thanks in advance for your advice!

John,

I also used the 12" Diablo blade to chop around 100 m3 of firewood - nothing beats this method and I'm still using the same blade.
I would grind the tooth. Bending can make it worse and with grinding you can get it planar with other teeth.