LT40 Blade Guide Assembly, Drive Side

[dad2nine]

Was sawing up some white oak, things were going fine, then... The engine stopped, like the blade got caught on something. I disengaged the clutch and fired the motor back up, ok that was strange, I thought. Maybe I hit some trash, so I backed the blade out and inspected the log, no trash.?.?.?. So I got to looking around the saw head and lo and behold the entire blade guide assembly was loose...

I backed the tension off the blade and sure enough the EZ-Glide wear material was missing (just a hollow square space in the block, where the EZ-Wear material should be) and the entire blade guide assembly was loose. Out came the wrenches... after some poking around, I discovered the two allen screws with lock nuts that are used to adjust and secure the blade guide shaft, would not tighten up,  the shaft threads were stripped. I checked the idle side and everything was nice and tight.

Granted I just got this mill, bought it used with 77 hours on it, but I find it very odd the threads were pulled out of blade guide mount. I don't think I was doing anything wrong or was I? Anyone else had this problem? Anything I can do to prevent it from happening again? It really took me by surprise... to say the least!

Called Wood Mizer and ordered a new set of EZ-Glide blocks and a blade guide shaft and a 15 pack of blades. Should be up and running again soon... I hope  :

[Percy]

Bummer about the failure. I have had the blade guides come loose every so often. A good practice is to check them for loosness every time you change a blade. If you are already doing that, then it musta been the shock of that EZ glide thingie getting jammmed and stripping the threads. Them allen head locking/adjusting bolts are a royal pain. I have replaced them with stainless capscrews in the positions where it doesnt interfere with cutting width/thickness. Are you gonna have to weld a new mounting block on the mill??
Anyhow, good luck with the repairs and happy sawing.... ;D

[onionman]

What year is your mill?
I had a similar thing happen to both sides of my 03 lt40.the 2 adj screws for the blade guide
mounting block kept breaking drive side twice ,idle side once..1st time there was only 44 hours on the (new to me ) mill. 2ond time I think there was around 60 hrs on the mill.
Are these the screws that stripped on yours or did 2 of the 4 screws that hold on the blade guide strip?
Onion

[dad2nine]

Onionman, it's an 04.

According to the parts manual it's, "Shaft, Blade Guide Mount - part # 035427" it's the threads that are stripped, (fine thread), the two hardened set screws will lock nuts are fine. I suppose I could tap it out a little larger, or hela coil it, but needed blades and a pair of EZ-Glide blocks, so I just ordered it instead. It was $12.95, so hardly worth the effort to tap or hela coil.

Was thinking about dumping the set screws and just putting in a long enough hardened bolt, I could still use the lock bolts to adjust the roller guide up and down, which is what the set screws with lock bolts do anyways.

My thoughts were, surely I'm not the first person this happened too. Maybe there's a good way to "beef it up" somehow. I'm really interested how others dwelt with and corrected it.

I guess once I install the new blade guide mount, I'll have to re-adjust the roller guide position (up / down), which I've never done before, so any advice there would really help...

Thanks

[jpgreen]

THis may or may not be a help with your situation, but one of my favorite things to do is apply Permatex Formagasket 2B "Non Hardening" to threads on any bolt I don't want vibrating loose.

It works like gangbusters, and unlike locktight, it is easy to loosen, and doesn't need to be perfectly clean. I have never had a bolt vibrate loose.

I use it exclusively for essembling engines and on gaskets and never use silicon.  Permatex will not leak on you.  The old timers followed this rule. Then silicon started being used, and for most sealant applications is inferior in my experience.

[BBTom]

I have had those setscrews break.  I guessed that a chunk was accelerated by the blade to just above terminal velocity by the time it struck the guide.  I just dug out the brokeoff piece and put it back together. 

I also had a problem with that guide getting so it was a bit loose after 2500 hours, so it got replaced during the platinum service.

[onionman]

I t part # 035408 block assy that was causing my problems.The o4 may have the beefed up version already on it.
Onion

[dad2nine]

it's this piece



jpgreen Thanks for the tip, I'll be sure to going to pick up some Permatex Formagasket 2B "Non Hardening"  for when I reassemble.

[jpgreen]

It maybe the "2A", but it's the non hardening one in the tube.  You can get it everywhere.

I use it for all kinds of stuff.  Have a bolt that you need to stay put in an extended socket to get in a hard to reach place? Put some on the head of the bolt and it won't fall out of the socket on you.

On the road with a bad thermostat? Pull it out, and Permatex both side of the broken gasket, and you're back in business.

Coat threads on gas and oil fittings, and they won't leak cause gas and oil doesn't bother permatex.

Looking for a good rub for your steak BBQ?...   :D

[woodbowl]

..... apply Permatex Formagasket 2B "Non Hardening" to threads on any bolt I don't want vibrating loose.

JP, is that the permatex red ATV or the blue?

When you break a bolt loose that has been in the weather and rusted, does it kinda "break easy"? Not really easy, but can you tell that it's different than a bolt that is rusted over?

[jpgreen]

OK I double checked cause I get the numbers mixed up sometimes.

It is Permatex Form-a-gasket 2B "non hardening" in the white tube.  It's black goo.

It's NOT blue- red- atv or silicon.. 

[Tom]

I did  have reason to remove those same bolts from the guides on my 1990 model.  I remember being confused when I put it back together because the hole was threaded all the way through and the bolts didn't go all the way through.  I couldn't figure out how deep to run the bolts.  Then it occurred to me that the bolts met in the center and actually formed a single bolt.  It made sense because that adjustment is done by the movement of the nuts on each side, not the movement of the bolt.

I can see how those bolts would work loose if not jammed against each other in the middle of the block. What is to keep them from moving but the nut.  It is being used for adjustment and all the tension is on the threads.

I can also see how too much tension on the threads can be cause by jamming the two bolts in the center with too much force.

On one of my guides, I can't remember why, I created a piece of all-thread by cutting the threaded portion of a stainless bolt off and running it all of the way through the block.  It never caused me any trouble, though not having a way to hold the bolt sometimes made adjusting the nuts difficult.  I just used a pair of vice grips on the threads of the bolt and was always a little concerned that I would "bugger" them enough as to make removal of the bolt difficult.

I could see another problem with using a through bolt.  If the bolt got bent, removal would also be difficult.   It is a solution if the shorter bolts aren't available.

Now I see the positive points of using two bolts, jammed together in the middle of the block.  If properly jammed it always gives you a better means of removal, a way of holding the bolt to adjust the nut, and a relief from the problems of trying to remove a bent "through" bolt.

The solution is to jam the bolts but do it with finesse' so as to not overstress the threads.

[dad2nine]

Tom - thanks for your reply, very informative. I agree with you "The solution is to jam the bolts but do it with finesse' so as to not overstress the threads." Seeing it's a fine thread, I'll have to be careful to try and get the two bolts to meet in the middle of the block and not "gorilla torque" em.

After I get it fixed and if it fails again I think I'll tap it out to a corse thread and do what you did... with a single bolt and two nuts.


BTW - what prevents the guides from moving side to side? the two bolts with the locking nuts are for up and down adjustment but what about side to side, mine it's doing that too...

Thanks

[Tom]

the two bolts with the locking nuts are for up and down adjustment

Don't say it like that.   :D   Those aren't locking nuts.  They are adjustment nuts and hold the front of the guide in a floating position inside of the housing.  The housing shouldn't allow side to side movement.


The side to side movement and the tilt are adjusted by the bolts in the block on the rear of the guide,  to the far left in your drawing.  In this instance, it is the bolt that does the adjusting and the nuts are truly lock nuts.   These bolts push against the back end of the guide's shaft and adjust the guide by floating the adjustment shaft inside of the opening in the block.

[dad2nine]

The housing shouldn't allow side to side movement.

There is surely side to side movement... Sounds like I also may need to order (Block Weldment, Roller Guide Adjuster - part # 035408) too.  >:(

Eventhough with so few hours on the mill, I wouldn't think so many parts should go bad. I did buy it used and I suppose I'll have to fix what the previous owner didn't.

Thanks again Tom, your a wealth of information

[Tom]

Check the side bolts on the far back of the guides (those on the far left of your drawing) and see if they are not in contact with the shaft.  they may have backed out or never been tightened properly.  It would be easy for someone to not understand how the adjustments work. 

The shaft, at the front, is square and fits in a rectangular hole that is supposed to be tight on each side and only allow movement up and down with the nuts.

The shaft at the back is round, with a knob on the back, and is supposed to be able to be moved in all directions by the bolts.  If the side to side, in the back, is adjusted first and then the tilt(top/bottom) is adjusted, the shaft may have been moved away from the side bolts.  It's hard to explain but easy to see once you start making the adjustment. 

You might find yourself tweeking each, until you reach the proper adjustment, just to be able to keep them tight on the shaft.  The parts may be OK.

[dad2nine]

The shaft is defiantly tight where the 4 bolts hold it in place at the back (round part). Side to side movement is coming from where the shaft (square part) and the block weldment, mate.

I took it apart today and noticed someone had crammed some lock tight (blue) in shaft threads that are stripped.

If I were a betting man, I would bet at one time, one of the two "adjustment nuts" worked its way loose and wasn't noticed right away. Over time the block weldment worked its way loose enough to cause wear to the block weldment and the shaft to allow for the side to side movement. The previous owner must have tried to stop the side to side movement by over tightening the adjustment nuts. In doing so, stripped the thread out of the shaft, so out came the lock tight, well the result is, the mess I now have to make right.

I'll rebuild the Blade Guide Assembly with a new shaft, block weldment and EZ glide block and make it right again.

This and a broken reset switch is all I've found wrong with the mill so far, considering what I paid for the mill, I'm still very much pleased indeed.

Thanks again Tom for all your help, its help and experience like yours, is the reason I'm glad I joined this forum.

[Tom]

I would either shim that opening so that the shaft would be a little tighter or maybe hit it with a hammer and tighten it a little.  It doesn't have to be immovable, though that would be nice.  Then I would either use it or save it for a spare.

You will find, with experience, that the basic design of the mill isn't rocket science.  It's much more like building with rough cut lumber than putting the insides in a wrist watch.  What is important is learning what is being accomplished by a part and making it do the job.  All of the adjustments they have allowed are there to let you put your blade dead on even if the parts are worn or you are operating in the swamp instead of inside of a building.

[dad2nine]

Tom, you were right again! The side wall of the block weldment was bent out. This is what cased the side to side to side movement. A couple of whacks with a 3LB hammer on the anvil did the trick. Hope you know , You just saved me a few bucks ;D. Thought I would have enough steel left in the shaft, to tap 3/8 corse, but nothing doing. I don't really want to go any bigger, the walls are pretty thin the way it is. And anways the shaft is also bent just a little. Figured I could bring it in to allignment with the four adjustment bolts on back, if tapping worked, which it didn't. So I'll just have to wait till my WM order comes in, with the new shaft...

[sparks]

DAD2NINE, were these parts warranted? If not give me a call or email me. There is a block upgrade we have for th drive side breaking screws.    Thanks

[dad2nine]

Sparks, that's mighty nice of you to chime in. I bought the mill used and it's an 04, doubt it's anything under warranty. But would be interested in the block upgrade, the screws didn't break, but stripped the threads right out of the shaft and bent the shaft a little. I highly doubt this is a design flaw as I'm sure it was cased by the EZ-wear material breaking loose from the EZ-wear block. It must have lifted up and got jammed under the blade. There is nothing left on the EZ-wear block but a square where the EZ-wear material should be. It was there when I replaced the blade , now it's gone ???

I'll shoot you an email...

Thanks again

[jpgreen]

Tell em' ya just bought it but the dog ate your paperwork D29..  ;D

[dad2nine]

Being the skin flint I am, I fixed it. I hela-coiled the stripped threads in the shaft. Worked out better than I thought it would too. Put two 3/8" x 16 coils in, one from each side and 1 1/2" cap screws with "adjusting nuts". Just for grins I gorilla torqued the cap bolts to see if it would hold much too my suprise, They did. ;D

I put the blade guide back on the mill and lined everything up the best I could. I adjusted both blade guides down about an 1/8" from where the blade is norally would parallel with the wheels, now the blade rides on the blade guide rollers nice and tight. Removed both EZ Guide wear blocks from the blade, head tilt seemed fine, and re-adjusted the height scale since it was off about a 1/4" after all was said and done.

Lessons learned:

1) There are a lot of smart folks on this site, willing to help. All you gotta do is ask...
2) I need to learn more about my mill.
3) Have fun...

Thanks everyone, the black goo works great too...

I'm still a little conserned I may have the blade guides jacked down on the blade a bit far, perhaps someone could ease my conserns?

[jpgreen]

I just spent part of the day tearing down my blade guides.  Had to heat them DanG near cherry read to get the bolts out.. :

Some of them stripped, but it was the threads on the bolts, so I re-tapped the holes. Put in new bearings and guide rollers.

Well I guess this is a good way to learn about your mill. I don't even know how to run it, and I'm rebuilding the whole thing..   :D

[BBTom]

When WoodMizer Techs set up a mill they put 1/4" deflection in the blade with the guides.  I think 1/8" will work just fine. You should not be concerned.