WM LT40 question

[delvis]

Hey folks,  I have a question about my LT40 sawhead power feed belt.  We try to stay on top of our mill's adjustments and maintenance needs but this one has me a little stumped.  Our mill is a regular LT40HD and not a super. 

The problem I have is with the belt that drives the sawhead back and forth.  There is not enough slot in the motor mount bracket to allow us to take the belt up as it stretches more.  We end up with a belt that is stretched too far to keep from slipping on the pulleys, but hardly worn out.  We are using the belts that Woodmizer sells so I know it is not an issue with using the wrong part.  I believe the size is 4280 and I know the next size down is a 4270 and that is too small to get on the pulleys even when it is slacked all the way off.

Has anyone else had this issue and what have you done about it.  Right now, we're looking at trying to make the slots bigger so we can actually put the smaller belt on and have the adjustment we need.

[Magicman]

Chances are your drive pulley is worn.  Yes, the pulley groves do wear and your belt could be resting on the bottom of the pulley instead of the sides.  If so, replace the pulley.

[Go-fer-wood]

I have had the same problem with mine 2013 LT40, the belt seams to have wear out prematurely. Just over a hundred hours ?????

[OneWithWood]

Is it possible you are tensioning the belt too much and causing the pre mature stretching?

[deadfall]

If the slot could be made longer and not interfere with something else, this seems a good fix.  So little wear should not mean tossing out a belt that would not break for years, just for lack of adjustment. I mean, how much tighter would it have to be to stop slipping?  Also, could a stud be fitted to the motor mount plate and a small ball bearing be fitted for an idler/tensioner? It wouldn't take much. 

Attn. Wood-Mizer:  Feel free to make any upgrades based on my musings.

[Magicman]

If there was anything wrong with the adjustment design, all of us would be having problems.  Either the belt is being stretched or the drive pulley is worn.

[drobertson]

Never a problem here, seems like there could be some sort of alignment issue? or an obstruction causing the excessive wear, hard to say without seeing.  Easy fix for sure once found, 

[JustinW_NZ]

I have the same problem, my pullys worn.
I just use shorter belt for now..
Tightens up within the slots fine then.
Cheers
Justin

[Ocklawahaboy]

I'm probably confusing the issue with common sense but shouldn't the durable item (pully) outlast the wear item (belt).   I know there is a possibility of many belts over time wearing out one pully but it still doesn't seen quite right.

[Dave Shepard]

If there was anything wrong with the adjustment design, all of us would be having problems.  Either the belt is being stretched or the drive pulley is worn.

I agree. No needed to reinvent something that has worked well for twenty years. Have you checked the bearings on that short shaft?

[POSTON WIDEHEAD]

I'll be learning from this post since I've never had a bit of trouble with what was described.

[Magicman]

Of course I am assuming that the lower bearing is not sloppy, but it could very well be.  Have you checked that power feed shaft and bearing?


 
Yes, they do wear out and the whole assembly may need replacing.

I know there is a possibility of many belts over time wearing out one pully but it still doesn't seen quite right.

Yes, the belts, over a period of time, will wear the pulley and allow the belt to ride on the bottom of the pulley instead of the sides.  When that happens there is no side grip and the wear accelerates.  You also run out of adjustment.

[MartyParsons]

Hello,
  Not much trouble seen here. I have seen this issue especially when the board return is used. It is just the belt being the weakest link. Replace the belt and do not over tighten. Keep an extra on hand. I always check the set screws on the large pulley every time I do a service on these mills. Most are loose. Constant forward and back loosen the screws. I put red lock tite on the screws.
I have seen a Gates Power belt ( green) work better than the original from WM. The Super mills have zero issues with this belt. NOt exactly sure why, but the super assembly is a lot different than the standard. This assembly has been used since 1995. I think. So there are many hours on this design. 
Hope this helps.

Marty

[deadfall]

I decided to take my belt cover off today for a look.  The belt looks old and worn but is still pulling okay.  I loosened one of the motor mount bolts to see how much slot was left.  It was almost used up, maybe a sixteenth left to go.  I think I will pick up a belt.  I will check those set screws when I change this out.  Not much room anywhere for that ball bearing idler idea I suggested.   

[DR Buck]

I had the same problem several years ago.  I also have the board return.  I was using a belt a month for a while.   Then I made a mod to extend the adjustment range.   I forget what I did exactly.   I'll have to look at it and  refresh my memory.   Haven't had a problem since.

[Brucer]

You don't want to overtighten your belt, but you also don't want it to get too loose. If it doesn't have enough tension, the belt will slip and then wear very quickly. Part of the problem with the standard LT40 is because the motor pulley is much smaller than it should be.

I go through a lot of these belts because I use a dragback (in a way WM never intended). I had a problem with over-tightening the mounting bolts and eventually stripping one of them out of the aluminum >:( motor end plate. Rather than get a new motor, I took it apart, drilled out the three end-plate holes, and retapped them to the next larger bolt size. This meant I had to widen the slots, so I made them longer while I was at it. Finally, because I didn't want to do it all over again, I bolted a small block of 1/2" keystock beside the motor housing (when it was fully retracted) with a jack screw in the keystock.

Now I just have to loosen the mounting bolts and use the jack screw to push the motor away from the drive pulley. When I've got the belt tension just right, I tighten the motor mounting bolts gently  .

[delvis]

I am going to check the drive pulley because that sounds like it may be the culprit.  We sawed without losing that drive belt for close to three years and all of a sudden we've gone through three belts in the past year.  Thanks for the advice folks as always.

[Magicman]

Apparently yours is different from mine, but also check the driven side.  On my shaft pictured above, the left end  bearing had seized and the inner race was slipping on the shaft which wore the nice groove in the shaft.  This created much slack to be adjusted out.  As I have mentioned a couple of times, be sure that the belt is riding on the drive pulley sides and not on the bottom.

[deadfall]

The left bearing would be the one subject to stress from belt tightness.  The right side in that pic is the one where the work is being done, and the load shifting each time the direction is reversed.  But the issue could have been many things.  Seeing that bit of rust, the bearing could have lost its seal and rusted inside.  I think I see some sprocket wear there too.  That issue could might have something to do with that million board feet thang. 

[Magicman]

Oh yes, there were many issues with those power feed components.  I have since replaced the entire assembly again.  Oh and when you replace the sprockets, also replace the chain.   ;D

[deadfall]

Your issue is clear, MM.  Too much sawing.  You just can't get yourself to stop at a million.

You've had more sawdust in your truck than I have had in all my piles.

I finally passed the halfway point in Cabin Addition.   I'll make it.  I will.  If you could build it, I can read it.

[Magicman]

 :P  That was a nice thing to say.