let's talk about flat (not leather) drive belts

there is plenty of info and discussion of flat leather drive belts for older
machinery - but very little on the care/feeding of the synthetic flat drive
belts used on newer machines.
I've been trying to keep the traverse belt on my Abene mill from jumping off
at the slightest provocvation - it's a flat GATES belt that is inside the
body of the machine - to get to it, I have to remove the cover over the
relays and then loosen and swing the relay board aside and reach into the
bowels of the mill and put the belt back on - so it's a pain in the neck -
not at all like just putting the belt back on an old time lathe.
I've tried tightening it - I can't make it any tighter - the motor mounts to
the opposite side of the mill and is held in place with four bolts through
slots in the motor base (vertical) - there is nothing to pry on, and anyway
the belt seems pretty tight.
I did finally decide that oil on the belt might not be a good thing, so I
sprayed brake cleaner onto the belt and the pullies - that seemed to help
quite a bit - but I doubt that it's a permanent solution.
so today's discussion topic (this can't be the only device with this kind of
belt) - is - care/treatment/tensioning/ etc of these synthetic flat belts -
Oh, yes, I do have the manual, and it's in several languages but it says
nothing about the belt other than providing a part number.
Reply to
William Noble
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That is right. Oil is not what they want (or need). They want precise alignment and a slightly (0.1mm or so) belly-shaped wheel to run on.
Nick
Reply to
Nick Mueller
The most likely cause is that the pulleys are slightly mis-aligned. You can try adjusting the motor position (that's why the slots) or possibly adding a couple shims.
Also, flat belt pulleys should have a bit of a crown to them (the greater the crown, the more tolerant they are of mis-alignment).
However, one of the nice things about a flat belt is that it will come off if it is over-stressed, hopefully before something breaks. So, is it possible that the machine is turning way too hard?
Another possibility (rare) is that the belt has stretched unevenly so that one side is a tad looser than the other. Try reversing the belt and see if it tends to come off the other side of the pulleys.
Cleaning the oil, etc., off the belt is a good thing. Did you try putting some belt dressing on it?
Just a few random thoughts...
Jerry
Reply to
Jerry Foster
Don't do it. It works by softening the rubber. I have worked on cars where instead of getting a belt adjusted the owner has used cans of dressing, making a nasty mess under the hood and ruining every bit of rubber under the hood. Clean it and align it. Soaps like Castrol Superclean and Simple Green will do well, but they are bad for Aluminum if not flushed out of the cracks.
Reply to
Stupendous Man
Agreed! Been there done that.
In the limited space the only way to make the belt really tight is to adjust the motor with the belt off and then roll the belt on.
I'm sure.
I agree there. The manuals have a rather peculiar mix of either nothing you need to know, slight hints at other things, and completely skipping important stuff. It took me several hours to figure out how to change mine from 440 to 220 (had trouble finding the change over leads for the main motor).
Reply to
Wayne Cook
You have that belt on TOO tight. Tighten just enough to prevent slip.
Reply to
phillipeprice
I don't think the belt is on too tight - what happens ( watched) is that the traverse encounters a stiffer than normal place (for example, raising the table at all), so the belt stops - this is because the motor pulley is smaller than the pulley entering the gearbox that drives the traverse, so there is less surface for friction on the motor pulley - anyway, the belt stops, the motor keeps running, and the belt just slides off the pulley.
the pulleys are properly cronwned - as nick said "belly shaped" - I think the problem is the oil, and maybe the age of the belt - I have no particular reason to believe that the belt has been replaced since the mill was new in 1970.
Wayne C - have you changed seals in the traverse gearbox? -- if yes, worth doing???
others - generically - glazed belt? versus new?
big giant snip -----------
Reply to
William Noble
I put some water-based valve lapping compound on sepentine automotive belts occasionally to break the glaze on the pulleys. Sand on the roads here in winter turns to dust and embeds in belts.
Reply to
Stupendous Man
We used a poly V belt (serpentine engine belt) flipped to run on the back side to replace the belt on mine.
I've not had the gear box out of mine yet. I need to since the rapid traverse clutch is iffy as to whether it will engage or not.
Reply to
Wayne Cook
Gunner making notes as he schemes on getting his Abene home.
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Reply to
Gunner Asch
I used to service equipment with a similar flat belt. They would go "bad" I didn't beleive it... At first. Get a new belt, and problem solved. No amount of tighter, looser, flipping of belts, or aligning would fix it, once the belt got out of whack. New belt, solved. YMMV. Good luck.
Reply to
Half-Nutz

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