Any web resources on timing belts?

[themos]

I'm thinking of making a new motorised focuser and I'd like to use "timing belts" and pulleys as they seem to be widely used in precision applications. Does anyone have a handy list of web resources I could use to find out how to build a system with these?

I have found this so far:

Buy Power Transmission Components and other Mechanical Components parts | RS Components

I'm thinking that a 2.5 mm pitch, 10mm wide belt should be appropriate but what do you think?

[yesyes]

I've bought some pulleys and belts from Motionco for my motor focuser. They also have a handy Centre Distance Calculator to calculate belt size for given pulley sizes and distances.

motionco_Pulleys & Belts_Aluminium MXL Timing Pulleys_Buy Online

[themos]

Thanks! Do you have any recommendations on minimum number of teeth for the driving pulley, ratios, belt width or pitch?

[yesyes]

Not really. This was the first time I used timing belts / pulleys. I just went with the MXL standard. No idea if there are more different standards.

My focuser has roughly 2:1 ratio (32 teeth on the stepper and 60 teeth on the focuser shaft). I started with 32 / 48 teeth but the stepper didn't have enough torque. Replacing the 48 teeth pulley with a 60 teeth one fixed that.

I found the main concern was that the stepper shaft is 5mm diameter but the smaller pulleys have only bores for 3 or 4mm shafts. So I had to drill it up to 5mm which would have left a lot of metal for the grub screw on pulleys smaller than 32 teeth. If your stepper has a smaller shaft, you can use smaller pulleys.

Here is my web page describing my motor focuser build, if you're interested.

yesyes DIY and astro :: Motor Focuser

[Gina]

A remote electric focusser is yet another project on my ToDo list Little timing belts look just the thing

[themos]

Your stuff looks great! You're doing microstepping, yes?

[Gina]

Your Arduino based focusser looks rather too complicated to me Chris But maybe it isn't as complicated as it looks...

[malc-c]

If you google MXL timing belts or pulleys you'll find loads of hits including those already mentioned

[yesyes]

Your stuff looks great! You're doing microstepping, yes?

Yes, 8 microsteps per step. But it's the EasyDriver circuit taking care of that. No need to account for that in the software apart from the max number of steps.

[yesyes]

Your Arduino based focusser looks rather too complicated to me Chris But maybe it isn't as complicated as it looks...

It's not. With your experience you should be able to do that. If not, we're here to help.. ;-)

The most difficult task in making a DIY motor focuser is, in my opinion, sorting out the mechanics of mounting that motor onto the focuser. You'd need to to that anyway, regardless of how you drive the motor.

The rest is explained step-by-step in the SGL Focuser Getting Started Guide that I wrote. (attached)

SGL_Focuser_Getting Started.pdf

[Gina]

Thanks Chris I think I could manage that I'll check out the options later but using already tested stuff saves time and "reinventing the wheel"