8mm Forum: Strange belt problem

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Posted by Adrian Winchester (Member # 248) on May 22, 2006, 06:13 AM:

If anyone is an expert on belts, I'd welcome a comment on this strange problem. I've recently been making use of a Elmo ST-600D, which I had not used for about 9 years. It previously worked fine, but the square motor belt soon broke after I started using it again. I managed to obtain the right Elmo square belt to replace it, and it fitted the pulleys perfectly. However, before long the projector became very noisy and I discovered that the belt was not remaining 'flat' between the pulleys on one side, and all the noise was coming from some sort of vibration that resulted from this. The belt had definitely been applied properly, with no twists in it. I tried moving the position of the lower pulley, but nothing completely cured the excess noise, so I moved it back to where it was initially, in line with the upper pulley. I then tried replacing the belt with a fairly cheap round one that I'd bought as a spare some time ago, and all the noise immediately disappeared.

It seems very odd that the correct Elmo square belt should be so problematic, so I wondered if anyone has ever experienced anything similar, or heard of evidence of a belt that looks perfectly normal turning out to be faulty in some way?

Posted by Kevin Faulkner (Member # 6) on May 22, 2006, 07:38 AM:

Adrian, I have seen this sort of thing with the GS and the V belt for the main drive.
It seems to me that some of these belts seem to be too stiff resulting in this extra noise.
What I do is to apply a very slight smear of grease to the belt surfaces but not enough to make it slip. This generally quietens it down and allows the belt to wear in.

On the GS's now I use a round section rubber belt and this makes the machines run really quiet jus as you have found. If your happy with the round belt then carry on using it.

Kev.

Posted by Adrian Winchester (Member # 248) on May 22, 2006, 09:39 AM:

Thanks for the suggestion, Kev. I'm sure that with some belts, on some projectors, there's good reason to have something more sophisticated than a plain round belt, but there seems to be others where there's no obvious improvement in performance, so you wonder what the rationale was.

Posted by Tony Milman (Member # 7) on May 22, 2006, 12:58 PM:

I have found that the buckle on my belt tends to make a clanging sound as it goes around. Tried the grease but to no avail [Big Grin]

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