Small timing pulley and belts

[Amrad]

I'm looking for some small timing pulleys and belts, preferably ones that use a 3mm wide belt, the smallest I've found use 6mm belts. Does anyone know of a source of any that use 3mm belts? Thanks.

Regards,

Dave.

[AlanBeckett]

Dave,

They're easy enough to turn up.
You can buy Belting. I usually use the Plastic variety that you can join by heating.
What size?

Alan

[Amrad]

They're easy enough to turn up.
You can buy Belting. I usually use the Plastic variety that you can join by heating.
What size?

Hello Alan,

Thanks for your reply.

Well, I haven't found any! I need either one 10 teeth and one 30 teeth or one ten teeth and one fifty teeth pulleys, I haven't decided which yet. Can you point me in the right direction? Thanks.

Regards,

Dave.

[Yorkie]

From what you say Dave,  for a timing application you don't simply need pulleys and belting, but toothed pulleys and toothed belting to match.

The belting that Alan mentioned is very commonplace for such things as lathes - I use it on my  small Lorch-Schmidt  watchmakers' lathe. It's cheap, and as Alan says, you just cut it to length, heat the ends (I use a heated blade of a wallpaper scraper held in a vice), and press the ends together.

This stuff for example:

http://www.rdgtools.co.uk/acatalog/4mm-C...88009.html

But of course, that's only for normal 'V' pulleys where it's of no consequence if the belt happens to slip a little.

However, for a timing application, which is critical, it's a different matter altogether - we know what the consequences of a failed timing belt in a car engine are - it writes the engine off.

There are firms who will supply the belting that you need, and the toothed pulleys, but the pulleys are very expensive - EG: two pulleys and a belt will set you back about £100.

You don't say what application you need the pulleys and belts for or what your budget is, but I dare say this goes beyond the limit.

Anyway, for what it's worth, you might like to see if these are the sort of items you're searching for. The tooth pitch is 1.5mm, the belt width is 3mm:

http://www.ondrives.com/15gt-3-belt-15mm...belt-width

http://www.ondrives.com/15gt-blp-3-pulle...belt-width

The number on the pulley coding represents the number of teeth - for example, P48 = 48 teeth.

Hope that helps a bit.

(If that's no good, try a google search for 'toothed timing pulleys and belts' - that's how I found them).

Good luck in your quest.

[AlanBeckett]

There's also HPC - http://www.hpcgears.com/n/products/1.pul..._belts.php

Alan

[Yorkie]

Those prices look less eye watering Alan! 

[Amrad]

From what you say Dave,  for a timing application you don't simply need pulleys and belting, but toothed pulleys and toothed belting to match.

Hello David,

Thanks for your reply. Yes, that's exactly for what I've been looking.

The belting that Alan mentioned is very commonplace for such things as lathes - I use it on my  small Lorch-Schmidt  watchmakers' lathe. It's cheap, and as Alan says, you just cut it to length, heat the ends (I use a heated blade of a wallpaper scraper held in a vice), and press the ends together.

No, that wouldn't  do.

However, for a timing application, which is critical, it's a different matter altogether - we know what the consequences of a failed timing belt in a car engine are - it writes the engine off.

Indeed!

There are firms who will supply the belting that you need, and the toothed pulleys, but the pulleys are very expensive - EG: two pulleys and a belt will set you back about £100.

You don't say what application you need the pulleys and belts for or what your budget is, but I dare say this goes beyond the limit.

That's way above my budget!

You don't say what application you need the pulleys and belts for or what your budget is,
Anyway, for what it's worth, you might like to see if these are the sort of items you're searching for. The tooth pitch is 1.5mm, the belt width is 3mm:

That sounds like what I'm after but after a quick look at the link you gave, it seems that they don't have any ten-toothed pulleys and the prices of the ones I did see were higher than others I've seen.

I intend to make a T-Bar video fader, with these, the lever has a travel of between about 60 and 90 degrees, so the pulleys required would depend on that travel, and the travel of a standard pot, which is about 270 degrees.

For 90 degrees, it would be a ratio of 3:1 and for 60 degrees it would be a ratio of 4.5:1 (equiv: 45:10).

the number on the pulley coding represents the number of teeth - for example, P48 = 48 teeth.

Yes, I had gathered that!

(If that's no good, try a google search for 'toothed timing pulleys and belts' - that's how I found them).

I had been using only 'timing pulleys', so I'll give your suggestion a try and see what comes up.

Good luck in your quest.

Thanks.

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Alan,

Thanks for the link. It seems that I have to get their catalogue before I can see if they have anything that will do, they don't appear to list any details for them on their site.

Regards,

Dave.

[ppppenguin]

When I worked for Michael Cox Electronics ISTR we had special pots made for our faders with only 90 degrees of travel. The fader handle was connected directly to the pot shaft.

Assuming video isn't going directly through the pot which is usually not a good idea the easiest approach is simple mechanics and fix it in the electronics. In an analogue environment that simplly an opamp, a few resistors and a couple of preset posts to get the required voltage swing. In a digital environment it's probably easier to have a bit more resolution on the ADC and calibrate the pot digitally.

I think I disposed of all my Cox surplus assemblies some years ago but if you're interested I'll have a quick look for some faders.

[Joe]

It sounds like what you're after is similar to the stuff used in computer printers for moving the heads, though they would be too long and the one's I've seen are at least ¼" wide.

— Joe

[Amrad]

When I worked for Michael Cox Electronics ISTR we had special pots made for our faders with only 90 degrees of travel. The fader handle was connected directly to the pot shaft.

Assuming video isn't going directly through the pot which is usually not a good idea the easiest approach is simple mechanics and fix it in the electronics. In an analogue environment that simplly an opamp, a few resistors and a couple of preset posts to get the required voltage swing. In a digital environment it's probably easier to have a bit more resolution on the ADC and calibrate the pot digitally.

I think I disposed of all my Cox surplus assemblies some years ago but if you're interested I'll have a quick look for some faders.

Jeffrey,

You may recall that we have discussed this subject before and you have already looked to see if you still had any 'Cox' faders but didn't find any. Thanks for the offer, anyway.

No, the video isn't going directly through the pot!

I know you think the answer is to 'fix' the problem in the electronics but I would like to have a go at 'fixing' it with mechanics, anyway.

I didn't know Cox had special pots made for the job. Did they have a shorter track or were they just limited to 90 degrees rotation with a standard length track?

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Joe,

Yes, that is the sort of thing I'm after but as you say the belt would be much too long and I would prefer a narrower belt.

Regards,


Dave.