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Old 19-07-2019, 09:02 PM
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5ash
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Alternative to a rubber drive belt

Having modified the mounting of an Orion electric focuser motor several times for several telescopes I’ve had to make rubber drive belts to fit each time. They’ve been made from strips of insertion rubber glued together or existing belts cut and rejoined using a strip of glued on rubber. Yesterday the glue failed on the recent one and it made me think of other ways to join the rubber strips. Velcro came to mind and was dismissed as its too thick and would not reliably bond. Then I remembered some very thin lightweight velcro tape I’ve used for plant ties. I cut a length angled at each end longer than the belt needed wrapped it around the motor drive wheel and focuser wheel and tightly joined the ends. Turned the motor on and it worked! Easy to make , easy to attach and cheap.

Philip
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Old 19-07-2019, 09:29 PM
Wavytone (Nick)
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Ah yes those things.. officeworks sells packs of these to tidy cables. Cheap as chips and as you say, flexible yet one side is quite ďgrippyĒ.
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Old 19-07-2019, 10:43 PM
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Hi Nick , itís similar to those cable ties but much lighter and thinner and a little bit narrower.Its designed for tying plants to stakes. Bought a couple of rolls of it on E bay from Guernsey in the Channel Islands.I originally purchased a small roll in the gardening department at Bunnings.
Regards philip
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Old 20-07-2019, 07:17 AM
RussellH
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Nice idea. A focusser is in my future once I get all the basics setup on my Bintel Newt. One of my outstanding questions is whether to try direct mount to the focusser shaft, or using a belt. A belt looks more attractive as I canít find a coupler to match the 4.2mm shaft of my focusser. I was going to try and shim it out to the 5mm hole on the coupler Iíve ordered. But doing a belt instead would get around the sizing issue, it just more complicated to setup initially.

Iím waiting for the focusser parts to arrive from Fleabay China, but I didnít order any pulley parts for the motor, just a flexible coupler. Do you need a toothed wheel on the motor shaft for this?
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Old 20-07-2019, 07:56 AM
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[QUOTE=RussellH.Do you need a toothed wheel on the motor shaft for this?[/QUOTE]
Hi Russel, my motor had a small~1.2 cm shaft attachment that I covered with a small strip of material used for making steps less slippery on the edge , works a treat. Comes in a roll you can buy in hardware..
Regards philip
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Old 20-07-2019, 08:04 AM
RussellH
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I know the stuff you mean. Wouldn’t that be very abrasive on the velcro though?

Also I see where your velcro overlaps itself, theres a step between the two ends of the material. Does this cause any jump in the focuser as it rolls over the motor shaft or the focus knob? I’m not sure how much tension is required to turn the focus knob I don’t have any gear to test myself yet. I wonder if cutting the velcro strip to the exact length to mate neatly at each end, and the throwing another piece on top as a joiner would be smoother?
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Old 20-07-2019, 01:03 PM
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Quote:
Originally Posted by RussellH View Post
I know the stuff you mean. Wouldnít that be very abrasive on the velcro though?

Also I see where your velcro overlaps itself, theres a step between the two ends of the material. Does this cause any jump in the focuser as it rolls over the motor shaft or the focus knob? Iím not sure how much tension is required to turn the focus knob I donít have any gear to test myself yet. I wonder if cutting the velcro strip to the exact length to mate neatly at each end, and the throwing another piece on top as a joiner would be smoother?
Hi Russel , the belt moves slowly so wear is minimal , anyway the Velcro is cheap to replace .A roll 5-10 meters long is about $5. The belt is quite thin , much thinner than normal Velcro, so overlap seems to present no problem. One piece makes it easier to adjust , however what you suggest will still work if you detect a problem in your setup.
Philip
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Old 20-07-2019, 01:05 PM
RussellH
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OK great. Now if only the seasnail mail would hurry up, I could do something with all this theory.
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