bandmill power

[okie]

I have been looking at some small comercial bandmills and noticed that in general the smaller "hobby mills" have really small engines on them, the Hudson oscar 18 comes with a stock 6.5 hp and the Woodmizer lt 10 comes with an 8 hp. Is this enough for someone who saws in their spare time with no need for massive production? Is this enough to pull the band through hardwoods without bogging down too much. I was just wondering because I have noticed that it is a common school of thought on here that you need 18 hp or better. Just curious.

[Tom]

I asked that question when I bought my tractor and the wise old salesman told me that the little one would do most of the same things that the big ones do, it just takes longer.  I guess the same applies to the little sawmills.   I wouldn't be happy with anything under 20 horses, but, I cut my teeth on a 24 horse bandmill.   You can bog all of them if you try.

You will find that the smaller engines don't get the best wear and longivity out of your blades.  They don't have the oomph to take advantage of most tooth designs.  It's like having 200 mph tires on a Geo.  They last just as long as a 100 mph tire but you still can't go more than 60 mph.  They work though.

[Chris Burchfield]

I've seen the Baker, Norwood and Woodmizer mills operate just fine with the smaller engines. I suspect each was engineered with the smaller engines in mind for optimum efficiency. Pine, Oak and Cedar on species up to about 16" in diameter for the logs. Hope this helps.

[okie]

Thanks guys. Tell me, what is a yooper ???

[thecfarm]

I have a 18hp Honda on my mill.Kinda big for it,but I did not want to work a 8hp motor when it's in the 90's.Would not do it much good.If you don't need the power than don't use it,but if you don't have the power,than it's hard to use it.It does a very nice job.I don't regert the extra money it cost.I would do it again.

[cptbob06]

Here in Michigan a yooper is someone who lives in the Upper Peninsula or U.P. We that live in the Lower Penisula are commonly called trolls because we live under the bridge(Mackinac Bridge). Also if you live in the U.P. you have to finish each sentence with eh.

[jpgreen]

Does that mean if you live out west you would be called a "wiener"?..  ??? ... :D

[jrokusek]

My homemade mill has a 13 HP Chinese copy of the Honda engine.  Someone told me it probably has closer to 11 HP.  It would be nice to have more power, but as a hobbyist I can live with it.  Like Tom said, it just takes longer. 

Jim

[tomboysawyer]

Having had a 13hp Norwood and upgrading to an 18hp on my custom cantilevered mill, I can say there is a huge difference.

I can drive bigger blades and everything goes faster.

On the Norwood I cut some 10,000 bf of EWP and it did a fine, albeit relatively slow job. Then I put a 16' long ash on it and for a 4" wide cut not only did it take about 10 minutes to walk the log, I couldn't get a non-wavy cut to save my life.

Honestly, I'd like a little more power than the 18 because I still go slower than I'd like. But for now it will do. The 18hp cuts straight and true and green ash as fast as pine cut on the 13hp Norwood.

[tomboysawyer]

Does that mean if you live out west you would be called a "wiener"?..  ??? ... :D

True story. My niece, Hannah, lives in Texas with my parents (Oma and Opa). They were traveling to Kansas to visit my brother. They have friends and family in Florida, Pennsylvania and us in Vermont. This is one of those "traveling in the car kids come up with questions" things.

Hannah: "Opa, what to you call someone from Kansas?"
Opa: "Kansans"
Hannah: "What about Texas?"
Opa: "Texans"
Hannah: "Forida?"
Opa: "Floridians"
Hannah: "Pennsylvania?"
Opa: "Pennsylvanians."
Hannah: "So then do you call people from Vermont 'vermins'?"

No kidding! From the mouths of babes.

[jpgreen]

.... ;D

[Tom Sawyer]

Far be it from me to disagree with Tom, but in my experience I run out of blade capacity to remove the sawdust from the cut long before I run out of power from my 51hp Cat.  Maybe I need to try a different blade ??? ???

[sawguy21]

 :D :D :D :D tomboysawyer, I would think you would get to a point of diminishing returns when adding too much power to a small mill. Pushing it hard will expose the weak link and lead to expensive repairs.

[ladylake]

Far be it from me to disagree with Tom, but in my experience I run out of blade capacity to remove the sawdust from the cut long before I run out of power from my 51hp Cat.  Maybe I need to try a different blade ??? ???

51 hp cat maybe a 6" blade with 2" gullets to use that much power.  I just replaced my 27hp Kohler with a 28hp Isuzu diesel. It cuts about twice as fast and straighter as it doesn't slow down.    Steve

[jgoodhart]

When I built my band mill I had a 5 hp brigs on it and the blade speed around 4,200 fpm. It cut ok on smaller logs 18" and smaller anything larger was real slow going. The other problem was blade wear or lack of, blades still plenty sharp just to dull for the engine to pull it. Stuck a 20 hp Kohler on the mill and changed the blade speed to 5,500 fpm and life is good, cuts straighter, smoother and a whole lot faster.

[Tom]

OK, Im going say something that has no science to back it up,  I'm saying it because it is the only way I know of to describe what I feel is a way to determine the limits of a blade as to the limits of horsepower.  I think Ladylake is tongue in cheek. :D

Assumption #1 :  a tooth is 3/8" tall
assumption #2 :  Each horse utilizes 1/64th of the length of the tooth.
sawing advancement controls the depth of the cut of the tooth. Speed of blade remains the same.

The 3/8ths tooth has the equivelant of 27/64's in it.

If all this is true, then:

a 5 horse motor will utilize 5/64's of the tip of the blade. That's a thin curl.
a 10 horse motor will utilize 10/64ths before it gets too deep and bogs the motor.
a 20 horse motor will utilize 20/64ths before it gets too deep and bogs the motor, but it is getting close enough to the gullet that the curl is beginning to have trouble filling the gullet.
a 27 horse motor uses the entire tooth but is on the verge of bogging with the tooth that deep,  It might actually cut faster if advancement is slowed so that only half of the tooth is being used.  The blade will be cutting as if driven with a 10 or 15 horse but there will be reserve to power the tooth on through difficult spots that may bog the smaller engine.

A 50 horse motor will utilize 50/64ths of a tooth.  The problem is that there aren't 50/64ths available.  So, the blade actually maxed out at somewhere between 20 and 27 horses.  If the 50 horse wants maximum efficiency, it needs a different blade with a taller tooth, deeper gullet and probaby heavier back and thickness to withstand the stresses.

Now, I know this can be shot full of holes, but it's the picture that I'm trying to draw rather than give a science lesson.

Why does a band not last through as many board feet on a 5 horse saw as on a 20 horse saw before needing sharpening?  It 's because it is removing a much thinner curl on each pass.  An anology would be a sawyer sawing 1/2 inch boards rather than 1 inch boards, but charging by the board foot.  That's twice the sawing for the same amount of money.

A band on a small motor might last longer than one on a big motor before breaking because it is not under as much stress.  If you are counting the number of sharpenings you get to a band, it might look like the band on the smaller motor is better.

You have to look at the amount of lumber produced in a given amount of time to determine the efficiency of the band.

The same band on a 50 horse motor may break during the first usage, but, if it produced 5 times the lumber in 1/4 the amount of time then not being able to sharpen it might be a plus.

That is why each operation  is so different.  Not only is the hardware different, but the operators are driving the hardware at dfferent rates as well as sawing different materials.  When you find a good blade, it might not be good for someone else.  Even when someone tells you that their blade or sawmill is better than yours, you need to prove it to yourself.

[TexasTimbers]

I am not much differnet on not being able to back it up with imperical data, just gut feelings. My expericne with bandmills was first with a 23HP Briggs on a Norwood. That engine would not bog down but the cluctch would start slipping if you pushed too fast. I would not want less power than that 23 HP though. I have a 42HP diesel now and I have never bogged it down either but man is there a difference.
I rarely broke blades with the 23HP Birggsl, but I have broken 2 today, getting in a hurry trying to get as much cut before the thunderstorms arrived, with the big diesel. I think alot of it has to do with the blades though. I just never did break as mnany blades with the 23HP as I do with the big diesel.

So to answer your question directly Okie I would get as many HP as I could afford to get. Anything less than 20ish is going to be slower and the further away from that your get the slower it will be.

[eamassey]

Tom has it right.  For any bandsaw blade, or other saw, cutter, former, etc--- we could develop a performance curve by horsepower.  This curve would show that when you are underpowered, you get great benefits by upping the horsepower.  But as you keep increasing horsepower, the gains get less and less (the point of diminishing returns), and finally you get no gain.  Also, as you increase horsepower, you start on another curve - the curve of unintended negative consequences.  A typical 1-1/4 x .042" bandsaw blade has a limit where additional horsepower does not help much, my guess would be about 32 horsepower- gasoline engine basis. This is a guess based on limited experience.  If you have a lot more horsepower than that,  it will take a thicker (helps some) or wider-and-thicker (helps more) blade to take advantage of that horsepower.  Any blade upsize must be supported by adequate wheels, bearings, etc, to be effective.
EAMassey 

[jpgreen]

Interesting thread.

I wonder at what point does diminishing performance kick in as I'm running the same pulley that was on the Onan 24hp with my 27hp Kawasaki. Pineywoods went to a different pulley with his Kawa and likes it.

I wondering how much faster I can push the blade speed, and still keep up the torque? There's got to be an optimum formula for these Woodmizers.  I need a tach to see what's going on.  The mill's doing a good job, but I think it can do better.

[TexasTimbers]

Maybe the excess HP extends engine life to a degree. ???

[jpgreen]

Engine rules of thumb I've always followed:

Never run an engine at peak power.  Back down an 1/8th or more.
Never shut down hot.  Always cool down for a few minuets, and warm up when cold.
Rig a low idle linkage cable for engines that start at a fixed high operating RPM.
Regular oil changes.

I"ve got engines that don't know they should have died a long time ago..