Bandwheel Diamenter Question???

[Lumber Grader]

I have the opportunity to buy a fully manual portable sawmill with 24 or 25 inch band wheels with a v groove belt, (Not solid steel wheels.),  that is powered by a 25 HP Honda Gas Engine. This was special ordered by the customer, as the standard mill comes with 19" wheels and a 25 hp Honda Gas Engine. I think I can probably use 1 1/2" bands, as opposed to 1 1/4" inch bands, due to the larger band wheels. I think I should probably get a more sharpenings out of 1 1/2 inch bands, but was wondering if I should expect better feed speed through the log and more production at the end of each day?  I guess what I am asking is how much difference in production should I expect, due to the larger band wheels on this manual mill???? Would greatly appreciate hearing from all the fine folks at Forestry Forum and Happy Thanksgiving to you and your family and God Bless Yall Richly!

[rwepinetree]

I have been told the bigger wheel the longer life your bands have. they don't bend as much as the smaller wheels .

[red oaks lumber]

x2

[Lumber Grader]

Thanks for the replies. I am aware that the larger diameter of the band wheel, the longer the life of the band, because a larger diameter wheel does not flex the band as much a smaller diameter band wheel does.  I also know that the larger diameter band wheel you have, the wider and thicker the band saw blade can be. What I am really wondering is what will this do to production??? How much more production, if any more,  should I expect to get on the same mill with 19" wheels and a 25 HP Honda Gas Engine, as opposed to a 24" or 25" band wheel with a 1 1/2" band saw blade using the same 25 HP Honda Gas Engine?  I realize that with a manual mill, a lot of your time is spent loading and turning, edging, stacking, etc. and not as much time in the cut, as a hydraulic mill.   I am mostly wondering if the feed speed through the log is going to be increased enough to make much difference in production at the end of every day.  I appreciate each and every response. Have a very Happy Thanksgiving and God Bless you and Family.  We all have MUCH to be thankful for!!!

[Den-Den]

There should be an improvement in feed rate while making wide cuts due to the wider blade.  At the end of the day, any difference will not be significant.

[Ljohnsaw]

There should be an improvement in feed rate while making wide cuts due to the wider blade.  At the end of the day, any difference will not be significant.

I'm just pulling numbers out of the air, but since you will have the same motor that was pushing the 1.25 band, maybe you would cut 10% faster because of the stiffer blade (you can push it faster) before dogging the motor.  Now, figure how much of your time is actually with the blade in the log?  Maybe 10% of your time working (between loading/offloading/flipping/etc)??  So that comes out to a 1% increase in throughput - not significant.

[Ianab]

Mill is only going to cut as fast as the lowest component allows. So putting a 100 hp engine in place of the the 24 wont cut much faster, as the band cant hold the enough tension to utilise the extra power. Likewise putting a larger band on, and leaving the 24 hp engine, you wont have the power to cut much faster.

Now a large band, with the larger wheels, and more tension, would allow you to use the power of the larger engine, and hence cut faster. But you soon get to the stage where the mill is no longer affordable or portable.

[longtime lurker]

The bigger the wheel, the gentler the radius of curve the band is required to travel. Small wheels force the band to track around a tighter curve which results in more metal fatigue and reduced band life.

Okay, I got all that. Makes sense to me. So here's another question for y'all because I know nothing much about bandmills and it's not too off topic...

Why not fit a third wheel? Like a triangle shape with the third wheel mounted higher and in the middle of the other two...

To my mind this would give a longer band, hence more teeth so sharpening intervals would be extended. And it would also reduce the degree of arc the band was pushed into as it went around the wheels from 180 degrees to 120 degrees, equating to less metal fatigue and longer band life. Works on a cat dozer... :D

Just curious is all

[Banjo picker]

Those nice big wheels make for longer bands which cost more.  Also cost goes up when you go from a 1 1/4 to a 1 1/2....If I were running a manual mill I would want 1 1/4 blades on 19" wheels.  And if building one I would want to make sure it would be the same size as a very common mill....like a woodmizer 28 or 40.  My wheels are 26 inches and the bands are 17' 1" and they cost about $30.00 .... bigger is only sometimes better.  Banjo

[bandmiller2]

As a general rule larger bandwheels are a plus if your band is traveling at the proper feet per min. if they were just installed on a mill belted for 19" they will probably have too high a band speed. A band run too fast or too slow will not cut properly. A third bandwheel will serve no usefull purpose and only exasperate band flex failure. I can't comment on 1 1/4" bands as all I've ever used are 1 1/2". I would have the owner and yourself run his mill, if everything works and it cuts well, buy it if the price is reasonable. Frank C.

[mikeb1079]

from what i've read you run higher tension and have greater beam strength with 1 1/2". this allows for faster feed rates, but from what others have said on here you really need a higher hp mill (say 40hp or greater) to take advantage of this.  my understanding is that they're useful in a "high production" setting...and such a setting is not the realm of a manual mill.   ;)

personally i'd stay with the 1 1/4" on a 25hp manual mill.   

[Brad_S.]

It is not the size of the band wheel that determines what width band you should run, it is the size of the guide rollers.

If you have rollers meant for a 1.25" blade and use a 1.5 blade, the overhang will be severe and you may get rising and falling action from the blade.

If the roller is 1.5 and you run a 1.25, there is a good chance the teeth will hit the guide wheel and take the set out of them, causing the blade to dive.

[york]

Hi all,link to some tech.stuff.......

http://www.lenoxtools.com/Guides/LENOX%20Guide%20to%20Band%20Sawing.pdf

[Lumber Grader]

Thanks folks for all the wisdom I got from your replies. I really thank you all and hope today was a great day with family and friends and you took the time to thank our Heavenly Father, from whom all of our blessings come from. Thanks again to all!