Win a copy of The Ethical Meat Handbook this week in the Food Choices forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education skip experiences global resources the cider press projects digital market permies.com private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • r ranson
  • Nicole Alderman
  • Anne Miller
  • Pearl Sutton
  • James Freyr
  • Jocelyn Campbell
stewards:
  • Joylynn Hardesty
  • paul wheaton
  • Burra Maluca
garden masters:
  • Steve Thorn
  • Greg Martin
gardeners:
  • Jay Angler
  • Carla Burke
  • thomas rubino

Optimizing the cut on a bandsaw mill

 
pollinator
Posts: 1331
Location: Victoria BC
164
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

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?
 
pollinator
Posts: 291
116
solar wood heat
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator

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.
 
D Nikolls
pollinator
Posts: 1331
Location: Victoria BC
164
  • Likes 1
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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?
 
Posts: 140
27
  • Likes 2
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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.
 
Orin Raichart
pollinator
Posts: 291
116
solar wood heat
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
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
 
keep an eye out for scorpions and black widows. But the tiny ads are safe.
Natural Swimming Pool movie and eBook PLUS World Domination Gardening 3-DVD set - super combo!
https://permies.com/wiki/135800/Natural-Swimming-Pool-movie-eBook
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!