8mm Forum: Slipping projector belts

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Posted by Gary Lee Hammond (Member # 5888) on June 15, 2017, 03:56 PM:

I just got 2 new belts for an Elmo ST600. The belt on the take up reel/spool is slipping. Is there a belt dressing that would eliminate the slipping? I've pulled off the cover on the arm and the gears work freely as does the shaft the pulley is on. Once a few feet of film is on the takeup it start to slip. Thanks!

Posted by Bryan Chernick (Member # 1998) on June 15, 2017, 05:23 PM:

I use a product called Roller Rejuvenator on my turntable's rubber drive wheel when it starts slipping. It works pretty good for that application.

Roller Rejuvenator

I have used Belt conditioner in industrial applications but not on a projector.

Belt Conditioner

Posted by Mathew James (Member # 4581) on June 15, 2017, 05:28 PM:

Hi Gary,
Welcome to the forum!

Normally, these belts do not nor should slip. If they do, my first thought would be regarding the type of belts and where you got them. You really want the square OEM type for the elmos.

if the belts turn out to be good, then i would look to make sure the top reel holder is not cracked.
https://shop.van-eck.net/PP-0062.html?_globalsearch=pp-0062
(see pics at link to see where to check)

A slipping clutch is also possible and can be tightened should it not be the other above options.

Someone else may have an idea as well...

Posted by Phil Slater (Member # 2388) on June 16, 2017, 12:58 PM:

Hi Gary,
Strangely enough, I had the exact same problem recently. The top belt was slipping resulting in the take up reel not turning, resulting in an ever growing pile of film on the floor. I ordered a set of belts from a company that does replacements via ebay, put them both on and the problem was still there. I think the belt is slightly too big.

I decided to try wrapping something around one of the shafts to give the belt something to grip onto and also make it tighter. First I tried a thin elastic band, the smallest I could find which still needed wrapping round about 3 times - this didn't work, it still slipped. Then I tried cutting a thin strip of masking tape and wrapping it around - this didn't work either, still too slippy. Finally I tried cutting a thin strip from a roll of double sided foam, the sort that is used to stick plastic hooks to the wall, and wrapping that around one of the shafts - this has so far worked, although it hasn't had a proper test yet, with a full take up reel.

An unauthodox solution I know, and it may not last, but I couldn't think of anything else.

Posted by Bryan Chernick (Member # 1998) on June 17, 2017, 01:03 AM:

Could the slipping belt be a symptom of another problem, like something needing lubrication?

Posted by Tom Photiou (Member # 130) on June 17, 2017, 06:10 AM:

if the belts slip its often oil or grease in the "V" of the pulleys that the belt fits into, try cleaning these out first, then clean the belts before refitting.
Just use a good de-greasing cleaner and get it right into the pulleys pitch or groove.

Posted by Gary Lee Hammond (Member # 5888) on June 17, 2017, 07:16 PM:

Thanks to all of you for your ideas. I did clean the pulleys before putting on the new belt with alcohol and q tips. I also disassembled the takeup arm and checked the gears and clutch. I'm thinking like Phil Slater that the belt might be too short as we may have ordered from the same ebay seller. My seller has offered to send me a shorter one although I mentioned to him Matthew's comment about the originals being square which was on mine but stretched out. Hopefully the shorter one will work.

Posted by Phil Slater (Member # 2388) on June 18, 2017, 03:03 PM:

Gary, please could you let me know if your replacement belt works. My solution seems to be working for now with the foam on both sides, but I would rather have a better belt.

Posted by Adrian Winchester (Member # 248) on June 18, 2017, 03:37 PM:

I've had the same problem now and again. I think once giving a belt a clean with washing up liquid and warm water, followed by drying without handling helped, even though there was no sign of the belt being even slightly greasy.

However, there IS a product called Belt Grip - I have an aerosol of it, having heard about it years ago from Bill Parsons. It now seems to generally be called Belt Slip, which seems odd as it helps to prevent slipping! It makes the surface of the belt sticky and therefore makes it grip better. It has proved very useful with at least two problem belts I've had, on Eiki 16mm projectors, including one motor belt that kept falling off! But it could mask another problem, so I'd generally try to rule out other issues, and then check that all looks fine once it has been applied. I'd be reasonably optimistic it would rectify Phil's problem, if that isn't a too little tension issue.

It used to be hard to find and expensive, but here's a reasonably-priced example on ebay: www.ebay.co.uk/itm/Pma-Belt-Slip-Aerosol -Lubricant-Maintenance-Spray-500ml-/262497944047?hash=item3d1e18c1ef:g:KN0AAOSwGIRXbqgB

Incidentally, I've had one or two Elmos where the 'official' square belts produced terrible rattling and I had to switch to 'wrong' round belts to avoid this!

Posted by Tom Photiou (Member # 130) on June 18, 2017, 03:50 PM:

could i ask where the new belts are from?
a belt only has o be too big by 1 or 2mm's and you wont stop it slipping. i replaced one on our ST180 and when the machine was hot i noticed a "chinging" sound. when i took the cover off i noticed that the rewind belt was drooping enough to keep bouncing off the shutter. We recently got another new one from a different source and its at least 2/3mm's smaller and now works fine. That first belt had only done a few hours worth of films.
It would be ideal if anyone on here has any official belt sizes for various models. [Wink]

Posted by Gary Lee Hammond (Member # 5888) on June 29, 2017, 04:59 PM:

Phil Slater: I got the replacement belt, not sure exactly how much shorter from my ebay supplier here in California. He went out of his way and sent me another at no cost. Before I put it on and opened up the back again I tried the original one he has sent and to my surprise, no slipping yet. Puzzling, all I can imagine is the belt needed some conditioning?

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