Band Wheel Size?

[WyMan]

I was reading the thread on steel vs aluminum band wheels.  A question I have had is diameter of wheels and how much that really affects performance.  Different mill manufacturers claim their mill is superior to others because the wheels are a couple of inches larger.

Does anyone have experience with different diameter wheels they would care to share?

Thanks

[Tom]

All other things being equal, a larger wheel will provide longer band service than a smaller wheel because the band is longer.  That doesn't equate to more economy because the analogy is about the same as saying your truck gets more miles to the tank than my truck.  I still may be gettin more miles to the gallon but your tank is twice as big as mine. :-/

Bands are metal and metal fatigues as it bends.  The metal bends more on small wheels than large wheel so I guess the life of the metal, before it breaks, is greater on a big wheel.

A big wheel  may provide more distance between wheels and more height to the throat than small wheels, so a larger mill with a bigger engine may be able to take advantage of it and cut larger stock, where a smaller mill may not.

Larger wheels may be easier to balance than small wheels but I'm just guessing.

[KURT_STURZ]

Tom is correct about longer blade life on bigger wheels. But bigger wheels are more difficult to keep in adjustment. They will tend to need more alignment to keep them from throwing blades as compared to their smaller relatives.

[Will_Johnson]

Larger band wheels will give longer blade life, both because (as Tom pointed out) there's more band there so each tooth is cutting less and because there's less strain on the blade from bending.

But keep in mind your junior high geometry: as diameter increases, circumference increases at a greater rate.  So blades are disproportinately longer, which means they're disproportionately more expensive.

Whether the added expense is worth it is a question too complex for me!  

My company, TimberKing, makes three mills with 19" wheels and one with 25" wheels.  So I guess you could say we're hedging our bets on this question.

[Bro. Noble]

Welcome Will,

It's nice to have people that make the machinery involved.  It's good for everyone when you know what kind of problems and needs the guys using the machinery have.

We got guys that are involved in making and selling Mobile Diminsion, Swing Blades and Band saws here.  They don't post a lot but seem to be there when we need them.

Concerning band wheel size,  there seems to be more types of blades available for the larger wheels.  Can anyone explain the difference in flex back and hard back blades and wheel sizes that are appropriate for each?

Noble

[Bibbyman]

Welcome to the Forum Will,

I'm so happy with my small wheels I see no reason to change.  But I've given some thought to larger wheels.  Looks to me like when you go larger wheels,  you'd have to make the sawhead much bigger to get the same opening width wise.  Bigger head means more support structure and weight, bulk and so on.  

All this leads to MORE POWER needed to justify the bigger machine.  Then you'll want a wider and thicker blade to make use of the more power.  The more you upscale,  the more you loose the benefit of the nimble - cost effective thin-kerf sawmill that made them popular in the first place.

Larger wheels may be justified in the production "headrig" like the Wood-Mizer LT300 and resaw applications where production is $$.  But for Mom and Pop weekend sawyers, small wheels with industry standard blades is about right.

[D._Frederick]

Noble,
The flex back blades are made from a carbon steel alloy, the teeth tips are flame hardened. This type blade will give longer life before it cracks and breaks on the smaller diameter band wheels. The hard back blades have the whole blade hardened and will give the best life on larger diameter band wheels. The blade being hardened has a greater tensile strength and will not stretch as much as the flex back blade. This means that the feed rate can be faster.

[Bro. Noble]

D_F, Thanks,

That sounds logical.  Do you know the minimum wheel size that would be desirable for the hard backed blades?

Noble

[solidwoods]

I think a person will get more performance/longevity from a blade by sharpening it when it starts to show that is dulling.  As it gets dull it takes a little more feed pressure to run, causing more blade stress. You will be running blades that are in their prime sharpness (better feed rates).
Sharpening removes hairline cracks that contribute to breakage.  There is a balance to achieve between running the full sharpness out of the blade and not sharpening too much

I voted for purchasing sharpening equip because:
When you have your own sharpener,  a whole bunch of problems will go away.  Setting up the mill basics is easy (engine run,no slip to wheels,blade true,guides set,cut) but the poor guy at the front of the show is: The blade.
When you sharpen your own blades,  you will learn how to tune it to run sweet on your machine.  As soon as it shows a sign of dull, take it off.  You will get better WPH (wood per hour) by running blades in the prime of there sharpness.  Cost is low for you to sharpen.  You could take a few customers blade sharpening, like I do.  Or put someone on the machine on piece work pay.
JIM

[WyMan]

By Golly!  The responses have been a wealth of information.  Thank you all.  As with all things, it appears there are economies of scale.  Too small of band wheels and you can't cut a thick enough cant  :D  -have to have some fun  ;D  and too large and it takes too much motor to turn then.

Will, I appreciate your coming in and offering a candid response from a builder.

It sounds like there is probably a "best" size of bandwheel, motor etc. for a certain size of tree being cut this based on cut width, cant height etc.  But if I read it well, a bigger bandwheel is not better just because it is bigger.

Having run a push (manual) mill for more hours than I want to remember, I can address the sharpening comments.  Yes, a newly sharpened blade works better.  However, even as important is the set.  I spent considerable time sharpening blades when I could have been cutting - and the cutting is what makes the money.  So, for my vote, I will send them out to someone who will sharpen and set each time.  Just my $.02.