Belt Drive vs Rack & Pinion

[babinda01]

Hi,
I am building a CNC router about 4Meters x 1.5Meters.
I am thinking of using a toothed belt type of system as opposed to a rack and pinion system. I am wanting to use an open belt system, with the belt fixed at one end then passing around an idler, pinion and then another idler and then fixed at the other end as well(Omega drive). Has anyone used this type of system for a router? Any thoughts?

Regards
Andrew

[paulC]

Search for some of ynneb's posts he has built one and offered advice on other belt builds.
Apples built a very nice one.
Strange that they are Aussies too. Seems a popular concept down here.
Here is my thread on the subject
http://www.cnczone.com/forums/showthread.php?t=13905
Paul

[Greolt]

G'day Andrew. Still raining up there? Babinda has the highest rainfall in Australia I believe.

I thought about a belt system like you are describing.

When I priced all the pulleys, idlers, belts and anchor points I decided against it. Cheaper in the US of coarse.

You will still need to do a belt and pulleys reduction or gearbox. And still need to drive both sides of the X.

A drive shaft accross the gantry is possible, tying both sides together.

All belts stretch. Some more than others naturaly. Four meters is a lot of length. This is where it will show up.

I went with R&P with a belt reduction. I did so with reservations that I would be happy with the result. I am happy.

With the size of machine you are considering, definately look at the Mechmate. Even if only to get ideas.

http://www.mechmate.com/index.html

Keep us informed of what you decide and good luck

Greg

[babinda01]

Thanks for the info guys.
Greg, where did you get your rack and pinions from??

Regards
Andrew
PS Yes it is raining at the moment Greg.

[Greolt]

Andrew

I got them from TEA Transmisions http://www.tea.net.au/

They have Italian brand Chiaravalli

There is a company in Melbourne that produces it but they were expensive.

The size is "Module 1". I think you can get 1 or 2 metre lengths

I used 24 tooth pinion driven via a 4 to1 belt reduction. Best not to go smaller than 20 teeth

As I said I am very happy with the performance of the R&P so far.

Mechmate, EZrouter, Shopbot and others use it

Can you tell I am a fan of this type of drive.

I guess that if I had gone with belts I would be recomending them instead.

Greg