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Theorethical question

Started by kelLOGg, July 27, 2015, 12:12:39 PM

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kelLOGg

I've always wanted to know but never asked: why don't bandmill manufacturers make flat drive and idler wheels with flanges? Would the band run off the non flanged side? My metal cutting bandsaw has such wheels. It turns slower but the guide wheels on a sawmill are turning very fast and both make the band track well. We have loose belt drives, tight belt drives and crowned wheels but no flanged wheels. Just wondering...

Bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

deadfall

I would assume that what we have is not based on theory, but practice.  I'm sure everything has been tried and we have what works.  I can see a flange hammering a blade to death at sawmill speeds.  The physics of the blade always climbing back up to the center of the crown I find beautiful and fascinating.
W-M LT40HD -- Siding Attachment -- Lathe-Mizer -- Ancient PTO Buzz Saw

============================

Happy for no reason.

justallan1

I think you'd over-heat your bands causing them to fail prematurely from the friction of riding against a flange. On my EZ Jr my blade guides are basically what you are describing but with only a small percent of the pressure that you would have on a flanged bandwheel and with crowned bandwheels the bands are constantly wanting to center themselves on the highest point and away from the flange on the guide, therefore getting a little time to cool between every pass that it's in wood.
I'm not an engineer or anything, this is just my opinion on why it's done how it is. 8)

Andre

++2 to deadfall and justallan

Metal cutting is done at much slower speeds and you can get away with brute force type of designs.
There are metal cutting bandsaws where the blade leaves the wheel and is twisted 90 degrees going thru the guide and then on the other side of the material it gets a second 90 degree twist before going back around the wheels.
When the band is moving at 60 to 70 miles per hour things are much more dynamic and you have to work with the physics to get what you want and still have things hold together.
See ya
  Andre' B.

bandmiller2

Because large flanged wheels are not needed and it adds expense to the already expensive wheels. Bandmills started out with Vee sheves and belts only some of the expensive more commercial mills used steel wheels. Imagine what would happen if the band was pushed agenst the flange and climbed it. Would work but not really needed. Frank C.
A man armed with common sense is packing a big piece

kelLOGg

The band doesn't climb the roller guide flange but I guess that's because of the angle the band makes with the guide is so much greater than that with the wheel. Thanks for the input; I'm nor surprised it is a bad idea - just didn't know if it had ever been tried.
bob
Cook's MP-32, 20HP, 20' (modified w/ power feed, up/down, loader/turner)
DH kiln, CatClaw setter and sharpener, tandem trailer, log arch, tractor, thumb tacks

cutterboy

Quote from: kelLOGg on July 29, 2015, 06:34:18 AM
The band doesn't climb the roller guide flange

Oh, it can and will if the wheels and guides are not lined up properly.  I know ::)
To underestimate old men and old machines is the folly of youth. Frank C.

drobertson

Good question really, the way a I see it if the band is driven by some sort of cog or other driving devise I could see the use.  But the speed of the band wheels would surely create some wear and heat other wise.  If the saw blade is coming off or being deflected then there must be some kind of alignment issue taking place.   
only have a few chain saws I'm not suppose to use, but will at times, one dog Dolly, pretty good dog, just not sure what for yet,  working on getting the gardening back in order, and kinda thinking on maybe a small bbq bizz,  thinking about it,

bandmiller2

Crowned wide pulleys have be used for ages to drive machinery without flanges. Flanges are a crutch for poor alignment. Heacock feed works use a flanged pulley so the slack belt won't run off the pulley edge. Frank C.
A man armed with common sense is packing a big piece

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