to have band touch back of rollers or not?

[coastlogger]

Hey Im a new member and this is my first post. I have learned a bunch from you guys since finding forum a month or so ago.I have a locally mfgd("FGM") mill similar in config to a Norwood, have been cutting for my own use for 9 years with it, prior to that I had a Belsaw M14 for 20 years  geez that makes me OLD must be some mistake....Recently I upgraded to hydraulic feed, works SUPER,used a power steering pump belt driven off  my13 hp Honda,have a flow control to vary feed speed and a clutch to let chain sprocket freewheel so I can feed by hand if I want to OR gig back by pushing ( its a bit faster that way). Another mod I did was to upgrade my Norwood Dremel sharpener to a Harbour freight chain grinder mounted in place of the Dremel.Only just did this and first band cut VERY well so my hopes are high...well and truly tired of buying Dremel bits.
My big question is regarding whether to feed fast enough to force band back against back of rollers or not. I studied the thread from last May"band jumping out at end of cut" and there seems to be a few schools of thought on this.Basically in order to get my Honda working hard I need to push enough that blade is just starting to be up against back of rollers,if I back off enough to let it NOT do this my sawdust is mostly dust. I am cuttig 24" Fir with 10 degrees on teeth and 25 to 30 thou set,running WM bands 1.25 x.042.Im thinking of trying 8 degrees as I noticed when I went from 12 to 10 the saw seemed to feed itself better.Any advice on this would be muchly appreciated
CLGR

[Tom]

Opinion!

The blade has some "beam strength".  That is what keeps it rigid in the cut.  Without beam strength, the band is bent backwards and loses its ability to remain  horizontal.  It also is stressed and will begin to form cracks on the back of the body of the blade.

If the band is set up such that it is no more than 1/8 of an inch away from the shoulder on the back of the guide wheel, it will not ride on it while the band is not in the wood.  As soon as cutting pressure is applied against the log, the band will be pushed backwards against the shoulders of the guide wheel and gain support, which increases the "beam strength" of the band.  That is what the shoulder is designed to do.  That is also the rule when using a "thrust" roller, bearing or wheel as the support.  You don't want it touching the band when not in the cut.  When in the cut, you want it to give the band support.

You will find that a band set up this way, will last longer, cut quieter, cut faster, and cut more accurately than a band that relies only on its own beam strength.

It's also a reason that guides are kept close to the sides of the log or cant, usually within 3".

[old joe]

     That's what I love about this place.  I didn't know the guides were to be within 3" of the log or cant.   Thanks Tom.

Joe

[bandmiller2]

I think Florida Tom could explain quantum physics to a barn yard duck.I'am in awe of his abilities and cannot add a thing.Coastlogger welcome your with family here.I to went from circular to band now back to circular,the only milling I won't try is manual pit saw.Frank C.

[coastlogger]

Thanks Guys Ill try this, Ill sure get better production with more push.Another thought /question : when I recently switched from red streaks to WM bands I noticed band tracked about maybe 3/16 further ahead than before. I did not adjust anything now I think I will : question is to adjust guides(they should come ahead abt 1/4" to meet spec) or adjust wheels  I have the 19" belt pulleys and the BACK of the band is just ahead of back of pulley  maybe 1/16 at most.What do you think? Really appreceate the feedback. Ill get some pics on my gallery soon.
cstlgr

[Tom]

More importantly than the back of the wheel and band, the interest should be with the front of the band.   The gullet of the band should remain off of the wheel but not have more of the body of the band protruding beyond the wheel.  You lose support and  stability if the crown of the wheel (usually in the middle of the wheel's contact surface) is running on the back of the band.  The body of the band needs to, pretty much, be centered on the crown.   It's the crown that keeps the band on the wheel.  Do not allow the teeth to run on the wheel.  The pressure will take the set out of the inside teeth.

I would move the band backwards until the gullet was just in front of the wheel, then adjust the guides.   If you do it right, the teeth won't move back onto the wheel, under cutting pressure, when it moves backwards to the shoulder on the guide wheel.   It's difficult to say how much to move the band because not all bandwheels are the same size.

That's quite a compliment, bandmiller2.  Thanks.