band wheels - the great debate

[Tom]

In my mind, not being an engineer, I would consider the size of the logs I would want to cut.  Then I would consider the size of the lumber I wanted to produce and size of the cants I would be using.  Lastly I would consider the horsepower I would need to provide the production I wanted.

The Size of the log would help determine the width of the throat of the mill.  The distance between guides.   That helps with the design of the head but hasn't much to do with the size of the wheels.  If small wheels are used, a thinner stock of blade would have to be used to make the corner around the wheel.  The thinner the blade the less durable it becomes when relating to sharpness and the amount of horsepower it can stand.

The size of the cant will help determine the diameter of the wheel.  It's the vertical measurement between the bottom, cutting portion, of the blade and the top, returning portion, of the blade that allows you to process larger cants, make multiple cuts and provide a parallel top and bottom cut. (techniques learned quickly as you begin to saw.)

Thinner blades work better with small horsepower and smaller bandwheels.  there is less drag and kerfs can be made smaller.

If it were me, I wouldn't make a saw that wouldn't use .042 blades or thicker.  You get better service, especially with bark and dirt and knots and  holding and edge.

I used Woodmizer's LT40 for years and it was very successful in producing good lumber and handled cants in the 14" size regularly.  It doesn't sound, perhaps, that this is important until you need to split a 12" cant into two 6" ones.   Or drop the blade to the bottom of a 14" cant and take a 2x off of the bottom rather than the top to produce a 12" cant without releasing the hydraulic clamp and allowing the cant to move.  This allows you to produce a 12" cant with parallel sufaces rather than one straight and the other bowed.  That's important when you turn the cant 90° and begin cutting 12" wide stock. 

While blade life and bandwheel size are relative, I wouldn't be too concerned with it as long as I were staying in the realm of, already proven, sizes.  It's more important that you pay attention to the over-use of the blade,  keeping the blade sharp. trying to use clean material, lubricating the band and not overdriving the blade.

The existing band metallurgy is phenomenal.

[ronwood]

Tom,

I often wondered if the extra life that you would get with bigger band wheels having the same width cut as those with 19 in. band wheel would really save you any money considering the additional cost of the larger bands.  Does the life of the blade increase that much to make a difference? I not seen or read anything with regards to this.

Any thoughts.
Ron

[tcsmpsi]

The existing band metallurgy is phenomenal.

In using a lot of non-carbide cutting tools for a very long time,  I found/find it remarkable as to just how much actual cutting can be done with a bandmill blade.

I played hookie from work most of the day, yesterday, to get a bit further along in diminishing the stack of logs sitting.  Started out needing the regular maintenance and putting on a new blade.  

Just plain old bandwheels with belts in the groove.  The old blade was right where I put it, when I changed it out before.  Heck, I got my money's worth out of the blade.  If I just get it resharpened/set once, I would be ahead.  

The only real benefit that I can see that 'bigger is better' with the bandmill, would be to do bigger logs faster.  But, it would only be faster, production wise, if one had all the relevant bigger log handling equipment.

I found out yesterday, I don't really want to do anything bigger than 18-20", unless it is something special.  If I were going  to get in real production, where I was relative certain that I was going to be handling larger logs, I would go ahead a get a rig set up for that.  The one in my mind's eye, has 30" steel bandwheels, has all the hydraulic benefits and weighs in at about 3 tons.

My mill is set up with a 30" throat, and will do bigger logs than I am equipped to reasonably handle.   I get my overall fastest production in the 14-16" variety (handling, moving, loading, turning, cutting).  

Just keeping all the other equipment, vehicles, tools, property, etc., etc. maintained/repaired/modified takes enough of my time that I really couldn't begin to build a bandmill, though.  I think it pretty awesome that some do.  Quite an undertaking.   ;)

There certainly has been a great deal (debate?) of information on bandwheels and relative application brought forth in this thread.

Running my mill a bit, it didn't take me long to know where things had been calculated, analyzed, put together, run....then changed.   :D

[Tom]

I can't claim to have tested this.  But,....

I did buy a second sawmill with much larger wheels than my first sawmill.  As a result of the larger wheels the bands are much longer.  Since they are longer, there are more teeth to do the work over the first mill.  So, per band, I was cutting more wood. It's like having spare teeth.

I did get more life from my longer bands once I learned to operate the saw to maximise them.  I don't know if it was because of the extra length of the band or the big wheels.

I suspect it was more the length of the band.

You're still paying about the same per inch for the bands, regardless of size, so you would have to compare bf cut per inch of band and/or time of rotation per inch  of band  to make much of a scientific comparison.

I could get about 600 bf per sharpening (or less) to the small 13'2" band.
I get 800 to 1000 bf per sharpening (sometimes a little more) to the larger 17'4" band.

I usually got about 6 sharpenings per 13'2 band.
I usually get about 5-6 sharpenings per 17'4" band.

Just ballpark figures.  Sometimes I get a band that won't give up.  Sometimes (but seldom) I get a band that breaks before I get to sharpen it

While I know there are benefits to wheel size, band length, horsepower and other items of configuration,  I believe that the majority of us probably experience band longevity more by the way we utilize the band.   I'm pretty hard on them.  I'm known for saying things like "you can't saw any faster than you can remove the sawdust", "the band isn't a shear", "keep the teeth sharp", "use tall teeth", and things like that.  But, I don't baby them either.  The sawmill's purpose is to saw wood and I give it every chance I can to outdo itself from one board to the other.

On the other end of the spectrum are the people who pull their blades every 200 or 300 feet and resharpen them.  They clean and wax and polish and mechanic much more than I do.  I won't fault them for it.  Their mills may last much longer than mine chronologically.  I, on the other hand, bought my mill to wear it out. I want to saw wood, not baby a machine or be a mechanic.

I'll have to admit that I like the bigger wheels.  When operating heavy equipment, it's common to tense up and try to help it when it gets in a bind.  With larger wheels and more horsepower, you don't get the feeling, as much, that the saw is in a bind.

[sawhead]

This is the link for the homemade wheels homemade wheels 8)

[ronwood]

Tom,

Thanks for the input.

Ron

[Modat22]

thats the one I was talking about sawhead, thanks for posting that one. 

[Bibbyman]

Well,  I'm with you fellers. 

[Swede]

I´ve always been a mecanic but without any kind of education.  I´m also chronic curious.  ;D

Have tryed some other blades but been most lucky with Monkey-blades, T=0,039", W=1,25", P=1"
My wheels are Ø20" with V-belts SPB1600.
I can´t stop the blade whithout stoping the engine but have a breaker that drop the engine to idle when the kerf is done.
The engine is a Vanguard 18 HP. In a kerf not whider than 10-12" I think the blade is the weakest point, not the engine.
The guides has 2 ball-bearings (SKF 6201-2RS) +0,04 shims between, pulling the blade 5/16" down from the line between the wheels and 1 ball-bearing (the same) behind the blade.


People at Munkgors told me that theoretical the thickness of the blade should be 1/1000 of the wheel-Ø but it´s usaly not possible.

I pull the blades after 2-5 hrs. and sharpen them. After 3-7 sharpenings they begin to break. Some blades seems to live for ever. I never found that I need to set the blades, think it has to do with the teeth shape at the monkey-blades.

I´m sawing most softwood but also some birch, oak and other hardwood. Without any help 170Bf (or so) /Hr. 1" and 2" from logs Ø6-15" by 12-18´.

Swede.

[mike_van]

Swede, now that you brought that up, I remember from years ago, 1" dia. wheel for every thousand in blade thicknes - .042 blade should have  42" dia. band wheels. I haven't heard that mentioned in years. It would be interesting to see just how much longer a blade would last given those sizes.  'Till a 1 1/4" blade was sharpened down to 3/4" ??? The blade mfgs. wouldn't be happy -  >:(

[DragonsBane]

Alrighty,

The wooden bandwheels have definitely peaked my interest. What are the odds of catastrophic failure turning at about 700 RPM. I'd venture a guess if they were put together with a good epoxy they might hold up pretty well. Might be a bear to get balanced though. Might be worth a shot ;D

[bedway]

Ok,,im a little in the dark here. But for me thats nothing new! :D When you guys talk of putting a belt on sheves, is this belt loose fitting? That being the case how does the (loose) belt not slip while driveing the blade. This is being asked because im still formulating my build/buy plans for a saw. Im leaning towards building because of price and i have the skills. This forum is so additive, my wife swears i must be looking at porn ;D,,,,,,,,,,,,bedway

[Tom]

The belt is loose fitting and I guess it doesn't slip because of the pressure applied to the V of the pulley and the belt.   The belt isn't really pulling, it is a tire and is being ridden upon.   If tensions were too slight, I would think that the slippage would be betweent the blade and the belt (tire) rather than between the belt and the sheave. 

The sheave will wear after years of use, but, I think it is the continual movement of the belt in V and the sawdust involved that does it.

[logwalker]

I go down a size from factory specs and run them tight. I like the results and have found no drawbacks from doing so. Tom is right of course. The pressure from the band is pushing half of the belt into the groove as it rotates. LW

[Ironwood]

I know this has been a "dead" topic for a while, but I am trying 30" sheeves with the centers bored out and bearings installed. I will get some pics in the near future( the last wheel and shaft just came back last night from my machinist's place. The sheeves have a three groove profile. I am using a salvaged tensioner and adjuster from a big late model bandsaw that was in a fire. I sold the 36" wheels locally and will be setting up the wheels to the carriage soon. I am leaning toward a diesel 40'ish HP to drive it (that will need to wait $$$) but I will post some pics of the unit.

            Ironwood

[bandmiller2]

To get back to the origional question ,all three types of bandwheels will work well.It pretty much depends how much you want to spend and how professional you want your mill to look.I used 19" browning sheves with a tight belt.With .042 bands or thinner, band life will be good,with usable throat.Bigger bandwheel are better but not that much .If you can design your mill to use a standard legnth band mo better.I think ,myself ,its better to have a band running on rubber than steel, outhewise we'd have steel tires on our pickups.