band tensioning process Woodland Mills HM126

[John357]

I've struggled with this many times over the years, and usually after much fiddling, I'm able to get it right. But today I'm going to ask if anyone else has the same issues to better understand and improve my fiddling.  

I'm trying to understand what's happening behind the idler wheel and if something is wrong (more likely worn?) on my mill.   I'm the original owner and the mill is 2014.   I'm an occasional user but always at least a few logs each year, with many times 8 to 12 logs that I will process over 1 or 2 weeks time.  

With a new band I really back off the tensioner (about 6 full turns) to give me the most wiggle room on the idler wheel to be able to add the band.  At that time the wheel is really loose and can move in all the different dimensions.  I mean, the top of the wheel can tilt front to back and the sides of the wheel can tilt front to back too.  The whole wheel can move L to R.  Then when tensioning the band, I hold the wheel as close to planar as I can (planar with respect to the drive wheel) while turning up the tension.  Occasionally as I tighten, something inside snaps (not breaking but like slipping into place with a bang) and the wheel then is a little looser again.  I continue to tighten and the wheel gradually comes into plane.   I tighten to spec and it runs fine.   This doesn't always happen, and not if I only loosen the band a little to change it.   

Has anyone else experienced this "bang" and/or have any advice about it?

Thnx,

John

[WV Sawmiller]

   Sounds like a bad bearing to me. I don't know why it would snap into place and start working properly again.

[John357]

By loose I mean the whole wheel can move about an inch front to back, and L to R so I don't think its  a bearing.  It's a part of the adjustment system built in.  Also when I add tension the wheel first tilts in a little, then straightens out when I reach the specified tension.  

Makes me think I shouldn't back off tension too much when it's time to change blades.  But then I have difficulty adding the band.  

John

I did notice when making an adjustment to align the wheel that it seems to fit into some kind of a slot in the back, and the "bang" is it fitting into place.  

[btulloh]

Well, I have the same mill a couple years newer.  Your description and methodology sounds exactly like mine. I've never worked out a cure other than what you're doing. Exactly the same approach. It's a bit annoying but I never took it apart to see what's going on. It seems like something is interfering with the mechanics inside the housing, like a slight protrusion that catches on the axle when it's loosened to put the blade on the wheels. Sorry to say I haven't worked out a cure, I just do what you're doing and get back to sawing. I've thought about pulling it apart and look for what's interfering but . . . then I just back to sawing. 

[John357]

Btulloh,

Thanks for that, I was hoping you'd see this.  It's getting to a point that I don't want to get back on the mill.  :-\   

But it's so hard to let go some nice straight Pawlonia! so I'll get back on it.  

John

[btulloh]

Yeah, it's just one of those things.  For me, it has to get the point where I'd rather pull it apart than put up with, but so far I'm just putting up with. It could be design thing that's hard or impossible to correct. They've made a lot of changes and upgrades since you and  I bought ours. Did you update to the bellville washers from the polyurethane bushing?

[John357]

No, wasn't aware of an upgrade.  I did repalce the urethane one several years ago. 

John

[btulloh]

The urethane works fine until it starts deforming.  Mine started doing that way back and when talking to them they just sent me update parts for free. I was a bit past the warranty period, but not by a lot. It's just a stack of bellvile washers and a new spring. It changes the torque setting from 35 to 25. Doesn't affect the issue you posted about though. 

[bags]

Don't back it out so far. My old HM 130 will do the same if I back it off so the guts are flop'in around in there. The noise is the adjuster snap'in back into its seat once you put the tension to it.

[rusticretreater]

I have an HM130Max.  I agree with the above observations that it is likely your Belleville washer stack and components.  The adjuster runs off an acme screw.  I think that if you loosen it too much, something cants sideways and gets hung up.

I personally only loosen the adjuster enough to just slip the blade onto the wheels.  This keeps the blade from shifting/falling off while tightening up.

[alecs]

For mine, the snap/bang noise seemed to be that when I put the band on, with the wheel real loose as you describe it, the band would get stuck in the black plastic guide that sits under the follower wheel.  This is located where the arrow is pointing in the picture below.  This plastic guide has a slot in it that the yellow cover for the sliding blade support rides in.  So the blade is caught in that slot, and when you tighten up the tension, it eventually pops out and makes that noise.  I've started making sure that the band is not caught in that slot before setting the tension and haven't heard the noise since.

On a side note, I got a digital torque wrench adapter that you can set a torque setpoint on.  I pop this on a 1/2" breaker bar and have it preset to 22.5 ft-lb.  I just use that to set the tension and as soon as I hit the limit, it beeps, buzzes, and lights up.  If I am using a new blade, I will check the tension again after a few cuts.



  

[rusticretreater]

You have to take off the yellow extension cover to replace the blade.  If you pull the blade guide arm all the way out prior to installing the blade, the blade guide blocks will hold the blade up out of that groove in the plastic guide when you put the blade on.  Unfortunately, today I had the opportunity to confirm that this works.

[John357]

I think how Bags describes it is how it is for me.   There seems to be a seat inside that fits in place.   I was able to change a blade this weekend easily if I didn't back off the tension too much.  

[DanMc]

I have an older 126, sounds like the same vintage as yours.  Yes, there's a seat.  The shaft that the adjusting bolt presses on has a hole drilled in it, maybe 1/4" deep.  The adjusting bolt need to sit inside that hole.  If you loosen it up too much, the adjusting bolt can end up resting on the surface of the shaft and not in the hole.  Then something shifts after you've started to tension and it pops into the hole.  At that point, you lose some tension and the alignment changes.  

You can see this if you look up at the underside of the little housing that the adjusting bolts thread into.  

[DanMc]

I took a pic of mine.  I reduced the tension enough to cause it to drop out of the detent, so you can see it.  The wheel drops a little and the shaft goes up and then if you retension without having that bolt back in the detent, you'll have trouble.  It gave me fits one time when I changed blades and suddenly the alignment was way off.  

https://forestryforum.com/gallery/albums/userpics/44045/MillAdjuster.jpg