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1st test-blade tracking problem

Started by ray299, June 19, 2016, 09:32:10 PM

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Ox

Yes.  A crowned wheel/tire will definitely help your blade stay on.  Hopefully you'll be able to find some donuts from the vehicle whose rims/tires you're using now and the backspacing will not be so different that you have to change everything around concerning your guides and such.  Just remember - you'll never get the huge tension with tires that you will with steel or pulley/belt bandwheels.  Tension until flutter goes away and leave it there.  It will take a bunch of fussing to get the right combination of tire pressure, alignment, etc. but once you're there you'll be golden.  Taking notes sometimes helps.
K.I.S.S. - Keep It Simple Stupid
Use it up, wear it out, make it do or do without
1989 GMC 3500 4x4 diesel dump and plow truck, 1964 Oliver 1600 Industrial with Parsons loader and backhoe, 1986 Zetor 5211, Cat's Claw sharpener, single tooth setter, homemade Linn Lumber 1900 style mill, old tools

gww

Ray
Your issue sounds like some that I had and that member Georgia88 also had.  My tires are pretty flat and I took an angle grinder and took a tiny bit of rubber off of it right where the teeth would ride in use.  I didn't work on it too hard though cause I believed with mine it was flex of the mill under tension.  If your blade cut good and then starts diving pretty quick, I would say the tire is taking out the set, if not diving after good cutting, I would say it is a flex issue.

Look here at replie #75 too see what georgia88 did to stop flex.

https://forestryforum.com/board/index.php/topic,88250.60.html

replie #468 shows a bad picture of how I added a brace to help with my mill flex.

https://forestryforum.com/board/index.php/topic,82695.460.html

I think georgia88 fix is much stronger then mine.

My wheels are out of ballance and bounce a bit but if my bearings on my blade guides are good and my blade is sharp it will cut perfect lumber.  I do find log stress gives me problims at times.  Hickory or maple and sometime sickomore.  I know it will cut good oak so know I can blame the loggs some of the time.

Hope this helps.
gww

Ps
Hi ox, ray, I would personally work on the stress before worrying about a tire switch.  You can figure out pretty easy if the tire is taking the set out of the blade after you get everything tracking and it may be as simple as an angle grinder if it is needed at all.  JMHO

gww

Ray
Even beefed up a bit I can not really scrunch my tires with the blade.  I also still have enough flex that I have to do the tracking of the blade with almost the tension I need to cut with and it will not run the same with the tension off.  You can get it where it will cut good and be repeatable between blade changes.  You do need to pay attention to the plane of the blade while getting it right.  The blade under tension needs to run paralel with your log bunks. 

Beefing it up while under tension will be the first start and with mine I could only go so far but it was far enough to cut really good and very consistant boards.

good luck
gww

Kbeitz

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

gww

If the tires have tread, the angle grinder will give you what you need cause a little grinding goes a long way and I think a small amount of crown goes a long way.  Still, You know you have flex cause you got it tracking untill you put it under tension.
gww

Ps I did cut good boards with mine before beefing it up a bit.  It was a double edge sword cause now my blade is a little harder to change.  The beefing over all did improve the cutting well enough to be worth it though and I gained a small amount of cutting speed.  Every little thing that helps even a small amount add up to quite a bit when put with everything else that helps. 

ray299

Quote from: Kbeitz on June 21, 2016, 12:36:01 PM
Learn why you need a crown.

https://woodgears.ca/bandsaw/crowned_pulleys.html
Thanks, but is it me or did he not explain the principle behind why it stays on the hump? I'll have to watch it a few more times... Something about stretching but I didn't really understand...

ray299

Quote from: gww on June 21, 2016, 01:08:10 PM
If the tires have tread, the angle grinder will give you what you need cause a little grinding goes a long way and I think a small amount of crown goes a long way.  Still, You know you have flex cause you got it tracking untill you put it under tension.
gww

Ps I did cut good boards with mine before beefing it up a bit.  It was a double edge sword cause now my blade is a little harder to change.  The beefing over all did improve the cutting well enough to be worth it though and I gained a small amount of cutting speed.  Every little thing that helps even a small amount add up to quite a bit when put with everything else that helps.
I guess I'm just not getting the concept of "flex"... I'm going to have to do some more reading...

Ljohnsaw

Quote from: ray299 on June 21, 2016, 06:47:15 PM
Quote from: Kbeitz on June 21, 2016, 12:36:01 PM
Learn why you need a crown.

https://woodgears.ca/bandsaw/crowned_pulleys.html
Thanks, but is it me or did he not explain the principle behind why it stays on the hump? I'll have to watch it a few more times... Something about stretching but I didn't really understand...
The side on the slightly large diameter of the wheel is pulled with greater tension.  It is easy to see on the rubberband, not so on your blade.  That stretching causes the band to arch in such a way that it will steer itself farther up the crown (as the wheel rotates) until the band is centered on the crown because the forces are equal on both sides.  If he took a shot down the length of the band, you would see it.  Suffice to say, crowned wheels have been used for a long time - they just work and you should follow that example.  Otherwise, you have to build in all sorts of backstops bearings to hold things in place.
Quote from: ray299 on June 21, 2016, 07:07:12 PM
Quote from: gww on June 21, 2016, 01:08:10 PM
If the tires have tread, the angle grinder will give you what you need cause a little grinding goes a long way and I think a small amount of crown goes a long way.  Still, You know you have flex cause you got it tracking untill you put it under tension.
gww

Ps I did cut good boards with mine before beefing it up a bit.  It was a double edge sword cause now my blade is a little harder to change.  The beefing over all did improve the cutting well enough to be worth it though and I gained a small amount of cutting speed.  Every little thing that helps even a small amount add up to quite a bit when put with everything else that helps.
I guess I'm just not getting the concept of "flex"... I'm going to have to do some more reading...

A tire, under load, will "flex".  That is, it will bend.  Look at your car.  The top of the wheel is round, where it hits the ground, it has a flat spot, right?  If you tighten your band too tight (for rubber tires), they will have to give, or bend, or "flex" because they can't push as hard as the band is pulling.  IF your band is making your tires look like a fat guy wearing a pair of too tight of a belt, you have too much tension (for the tires).  Either you need more air pressure or a more rigid wheel (not a car tire) to maintain that tension.  Or, just use less tension - you should get good cut results if everything else is set up correctly (including crown on your wheels).
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

gww

ray
Your words.  You said you had the blade staying on the wheels untill you put tension on the blade.  When You put tension on the blade the blade ran off the back of the wheel.  That means when you put it under pressure something changed.  That something is bending or flex of your mill.  If it was not flexing then nothing should change when you put it under tension.  Maby I am misunderstanding what is going on?
Good luck
gww

Ps
What ljohn said is not exactly what I mean.  You could crunch the tire and it would just mess your blade or tire up.  However if the head that holds the tire is flexing than the plane of the tire and wheel is changing and so the blade that did stay on won't cause the tire is not in the same plane it was in before you put tension on it.

gww

Ray
I am saying that I believe your frame is not strong enough for the pressure you put on it when you spread your wheels out to tighten the blade.
gww

gww

Ray
look at the picture in reply #3 here
https://forestryforum.com/board/index.php/topic,64720.0.html

and at the front of the mills here
http://kruppt.tripod.com//reworked/index.html

Hope this helps
gww

Kbeitz

My dad allways told me that a blade or belt will allways hunt for high ground.
Or on your wheels high crown.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

ray299

I think I'm getting crown now... based off all your comments, I thank you! That also means I was tracking it wrong to begin with which is why it kept popping off faster every time I tried to adjust it. I figured tilting the wheel in would make it track towards the front... but that actually puts more tension to the rear of the wheel (said from standing behind the saw head- rear and front being in front of the saw head) I've got a few things to try now.... I did have the blade spinning without tension... fingers crossed

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