TimberKing 1220 Drive Belt Jump...cause? fix?

[jander3]

I just started milling with a new TimberKing 1220.  I have the tracking and cutting dialed in so the lumber is square and consistent.    However, I started to throw the drive belt.  This occurs when bringing the machine up to cutting speed (even when I try to bring it up to speed slowly). Seems like the clutch engages and the belt jumps around and then gets thrown.  I've been running the saw blade tension at the mark that was provided by the factory.  When I backed the tension off somewhat, this reduced the jumping quite a bit and I have not thrown the belt at the reduced tension.   The saw cut fine once up to speed.

Any ideas on causes? Or fixes? 

Specific question:

1. What tension should I run the saw at?  Is there a rule of thumb? Torque spec? Etc?

2.  With an electric clutch, I would think the machine should engage smoothly.  Any adjustments suggested?

3. Other items I should check or adjust that will help the drive belt engage a little smoother?

[fishpharmer]

Jander,
I have no experience with TK, all I can tell you is what it sounds like to me.  On my band mill when I tighten the tension a lot it torques the frame ever so slightly.  The belt on mine is engaged manually and is somewhat independent from the slight change the strong tension causes.  So its not really causing any alignment problems.  You may have a slightly different situation.

I am thinking maybe when you have the tension tight there is enough "twist" to throw things out of line a bit.  Therefore throwing the belt.  When you let off the tension its closer to "perfect" alignment, so belt stays put.  Maybe take the belt off and use a straight edge to determine if this is occurring when you have different levels of tension.  I would call TK first thing tomorrow and see what they say.

Hope that helps a little.
Fish

[SamB]

If the blade is tracking properly, I'd be checking the alignment between the engine and the drive wheel. Check the spacing on the slotted holes for the engine mount bolts and make sure the engine isn't cocked a little more to one side than the other. I've found a good tool for tensioning the drive belt is a nylon ratchet strap.

[bandmiller2]

Jon,are your drive belts tight enough and aligned,many times you can put a straight edge from pulley to pulley to check alignment.Your electric clutch will either be in or out ,solenoid will snap it in.Are your guards around the belts adjusted right mayby adjust closer to the belts will keep them from jumping ship.Frank C.

[jander3]

Thanks, appreciate the feedback.  Next time out, I plan on checking the alignment between the motor and the band wheel as I did not look at this. Talked with TimberKing tech rep today; he was very helpful.  At this point, I'm thinking the backing off of the blade tension was not related to no longer throwing the belt (as at the same time I was also a little easier on the throttle).   It is also clear that the electric clutch is not going to engage smooth as silk on this type of machine.  I'm betting that the motor is just a bit misaligned and that is likely causing my problem.   I will probably add a little tension to the drive belt for good measure. 

Hopefully, I will get back to the Stump Ranch this weekend and check out the alignment.  I will let you know how it works.

Oh, yeah. Man, do I really like the machine.  Heavy duty, cuts true, everything looks straightforward (as in I can fix and adjust things as needed I adjusted the tracking and all rollers...not because it was needed, just wanted to make sure I understood how things worked).    Over the weekend, I had chance to cut some larger logs (18" diameter instead of the 8"-10" diameter logs I've been practicing on) and the saw just ripped through the logs.  It didn't take long and I had a nice pile of Red Oak lumber.   There is no comparison to my chainsaw mill.   I cut my cabin sub-floor with a chainsaw mill...two weekends of back-breaking work. With the TK 1220, I could cut this amount of flooring in a couple hours without breaking a sweat.   

Now, if I can calibrate my eyeball to the scale a little better, I will be in great shape.  I want every 1" board to be dead on 1".  Looks like it will take some practice as 1 out 10 boards tend to be either a little shy or a little heavy (clearly operator error).

[jander3]

The belt issue is resolved...

As Sam B suggested, I loosened up the motor mount bolts and installed a truck strap to put a little more tension on the belt drive.  Tighted up the motor mounts and the mill no longer throws the belt.

[1938farmall]

jander,  my tk1600 sawhead looks just like your 1220.  if mounted a fixed idler(not spring loaded) on the slack side of the belt and it cured the belt jumping.  the electric clutch is very quick.  al