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Band setting and curvature

Started by kelLOGg, May 30, 2012, 11:27:15 AM

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kelLOGg

I have begun checking my setter zero by zeroing on the gullet rather frequently during setting and using compressed air for cleaning the setter. When I flip the band to set the other side frequently I have noticed that the zero is way off – sometimes more than 0.005" – which is more than the variation I observe in the same-side measurements. If the band is flat how can this be? ... maybe the band is not flat! Maybe I have curvature. I put a straightedge with a light behind it across the band and I could see a sliver of light in the middle on one side and slivers of light at the edges on the other side. So I do have curvature. Maybe the problem with curvature is that you cannot get an accurate set. Has anyone else observed different zero settings upon flipping the band?

An obvious (and expensive) solution is to roll the band which is a controversial topic in this forum but my recent observation convinces me that a flat band will give a more accurate set and I think everyone can agree that that is a good thing.

Zeroing on the gullet gives a set relative to the band and if the band has curvature the wood will "see" an inaccurate set. What about using ground flat stock for zeroing? (I know some FFers use this.) For a band with curvature the set would be accurate as "seen" by the wood but inaccurate relative to the band body. Would this be a way to avoid buying a band roller?

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

Chuck White

I use a piece of metal that I got when I bought my sharpener and setter from Cook's.

The metal is about the same as a piece of bandsaw blade before the teeth are cut in it.  It's about 2"x 8".

I check it and flip the piece over and check it again.

I also do a check once in a while using the raker tooth.
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

ely

i agree with chuck. i also will say that without my band roller i would have thrown alot of bands away by now.

bandmiller2

Bob,I've had little trouble with curved band bodies probibly due to the lack of tension on my homebuilt mill.Its my belief curve is put into the bands by too much tension over crowned wheels,probibly steel crowned don't have enough crown to affect it.What do you have for band wheels?An interesting experiment would be to take a band with known curve turn it inside out and put it on your mill tensioned up and run it a wile,if the curve is removed or reversed you'd know for sure what caused it. Possibly flatter belts on your wheels or less tension. Frank C.
A man armed with common sense is packing a big piece

customsawyer

I have no science to back this up but from the hundreds of bands I have run, I feel like the curving of the band is caused by the fact that everything that is done to or with a band is done to the leading edge. This makes the leading edge get just a little bit longer than the back of the blade thus causing the curve in the blade.  The reason that the roller works is that it is used in the back 1/3 of the band body. This elongates the back of the blade just a tad which make the band flat. I use a raker tooth for zeroing out my setter.
Two LT70s, Nyle L200 kiln, 4 head Pinheiro planer, 30" double surface Cantek planer, Lucas dedicated slabber, Slabmizer, and enough rolling stock and chainsaws to keep it all running.
www.thecustomsawyer.com

Banjo picker

I don't know about the curavature thing, but I have thought a bout it ...and it seems folks are running wider bands over wheels that were ment to be used with a smaller band, logic would seem to point that a distortation would occur.

But I have had a problem with the set much as you have discribed...I finally took the dial indicator off and took the back off of it...and found it had a little broken piece inside that was causing problems ...I ordered a Starrett ..put that on ..and have not had any more problems...Does your indicator ever seem to hang up by not wanting to go back to 0 when no pressure is applied to it...If it is acting up in any way it may be the problem...Just trying to help..Banjo
Never explain, your friends don't need it, and your enemies won't believe you any way.

kelLOGg

Frank, I think flipping the band and running it as such would reverse the curvature. My understanding of a band running around a wheel is that it curves away from the wheel. Sorta anti-intuitive but I remember this effect from a demonstration on the web but with a short search I could not relocate it. So I guess your idea is to flip the band and use the mill itself as a band roller. I do have crowned steel wheels but Tim Cook says it happens with all wheels.

Custom, I think setting on the raker is fine if the band is flat. You have a roller so flatness is assured. Are you saying the band roller operates only on the back third of the band body and that flattens the whole band? I've started setting with flat ground stock. I'll see what my experience is.

Banjo, I have seen my dial indicator stick but only after weeks of non-use and not since I keep it lubed (WD40) and under plastic to keep dust off of it.

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

bandmiller2

If you have a Harbor Freight store anywhere near look at some of their sheet metal tools,some of them could be easily modified for band rolling, for cheap.I've never really had any problems and get long band life so I taint going to mess with something that isn't broken. Frank C.
A man armed with common sense is packing a big piece

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