Take Up Belt Replacement

[Steve Kraus]

In my screening room we have always used yellow Rounthane with seldom any issues over many years. We normally run 20 min reels but I may put up a 6K once in a while.

Now I have a belt breakage issue. Probably a combination of age and embrittlement from lack of use since going digital. They typically break at the connector. Given my success over many years maybe I should just order new Rounthane and make sure the flanges on the connectors are sufficiently dulled. And maybe put a little crimp to keep them from rotating and slicing through the belt. (Thank you Steve G.)

But some have advised getting V belts. I wouldn't mind but I'd have to figure out which. I have two different take-up arms, perhaps because back in the day Cineplex Odeon used the room to try out different equipment.

This is a long shot but did anyone save any info about which belt to use with each kind of soundhead and take-up arm combination? One envisions a little black book!

Both soundheads are Simplex 5-Stars. Machine 1 has what I think is a Kelmar, cast type. Machine 2 has what may be a Ballantyne arm and there is an idler pulley which can be used to control tension.
LSSRproj1takeup.jpg LSSRproj2takeup.jpg

[John Eickhof]

the dark arm is a SPECO brand, not a kelmar, the other one is a BALCO. take the belts off and go to an appliance store or commercial HVAC store, buy 'fractional horse power belts that match the length, usually a 5/16" width is perfect, automotive belts will not suffice. or you can find correct belts by length online. they will have instructions on measuring. yes v belts work great however they will stretch and slip if they get oil on them. I stock rounthane if you decide to go that way. use a 2L OR 3L size belt.

[Mark Gulbrandsen]

Just go to Graingers... They have every belt under the sun! V-belt, or O-thane is fine...but O-thane is certainly more adjustable, since you don't appear to have belt tensioner pulleys on either arm

[Steve Kraus]

Thanks. I knew it was a long shot but I thought someone might recall which belt for which arm / SH combination. Go to Grainger and ask for what? Also, why Othane not Rounthane?

The Ballantyne arm does have an adjustable tension roller.

[Steve Guttag]

The potential sizes are many. We had a chart for some magazine/soundhead combinations but you'd be amazed even within a brand how many variations there could be. With reel arms, you have to consider that the angle of the arm is an unknown and the pivot point versus belt pulley will change the length needed. Additionally, the need to miss other objects in extreme angles will affect it yet more. I dislike roundthane, my self. it takes a set too easily, becomes brittle and, overall, doesn't grip well. So, you have the friction of the clutch and the belt to consider. I prefer V-belts. They last longer and do a better job of transferring the power to the takeup. I consider roundthane temporary, at best.

If you really want roundthane (or the industrial equivalent). Here is a link to the clear version (they also have it in orange):

https://www.mscdirect.com/product/details/35364850
The barbed connector:
https://www.mscdirect.com/product/details/35364918

[Mark Gulbrandsen]

Note that Othane and Roundthane are more or less the same thing, although Othane is a bit less expensive. Graingers sells Othane. But what Steve says is also true, that it can set up from sitting. Even on the Dailies projectors, Othane was fine because we were running no more than 1000 foot reels, and basically running every day. So the belts didn't get a chance to take on a set shape. plus at the end of the job they were dismantled to be moved out. Anyway, never had a single issue with the Othane.

[Steve Kraus]

Mark, typically just 1000’ max but with the R8 setup we were spinning two take ups!

In the end I’ll probably just buy more something-thane as it worked fine for many years. But if I did decide to try V belts is there a lookup table to get the size? I know what 5/16th is on Rounthane but not on a V belt like inner or outer width. It does need to drop into the pulley and then as it curves around the sides will try to bulge out which is what grips. I do have the lengths of the Rounthane measured.

[Steve Guttag]

Take up belts are from the 3L family. A 3L460 normally works with a 5-Star to a Kelmar 7000 series takeup. Now, if you have some old belt, even roundthane, you can use that to measure the length and then get a suitable 3Lxxx belt.

I'm not saying that roundthane doesn't have a place and it changes direction better than a "V" (contorted paths). I get it for portable applications but for standard takes ups, I'll take V-belts everytime.

[Mark Gulbrandsen]

Mark, typically just 1000’ max but with the R8 setup we were spinning two take ups!

In the end I’ll probably just buy more something-thane as it worked fine for many years. But if I did decide to try V belts is there a lookup table to get the size? I know what 5/16th is on Rounthane but not on a V belt like inner or outer width. It does need to drop into the pulley and then as it curves around the sides will try to bulge out which is what grips. I do have the lengths of the Rounthane measured.

Well, only the picture take up had a 180 degree wrap because it was out front. The mag was something like 110 degrees give or take with the belt in it's triangular shape. At any rate there was never an issue. Since I only serviced a couple locations that had take up arms and two machines running double or hour reels, those also used Othane. And yes they had spare belts kept in the booth that were swapped out every year or so. Those were some old crap that stayed in until digital came along.

[Steve Kraus]

A followup.

I measured the Rounthane and bought 3L belts of the same sizes. Alas, they were both too short as I neglected to take into account that the Rounthane is a bit stretched when in position. I ordered an inch longer. Final differences were achieved with a slight change in the arm angle on the SPECO -- which was a better angle for running a 6K anyway and a bit of adjustment on that idler roller on the Ballantyne arm. So for the record in case someone is searching for this info, Simplex 5 Star to SPECO arm was 3L450, Simplex 5 Star to Ballantyne arm with idler was 3L480.

I repurposed the incorrect belts to a temporary setup of a Century SA / R8 I did at home recently with one belt for the Wolk rewind station I set up and the other as my initial takeup. That is, until I set up for unmarried twin take ups for which I ordered a 3L720.