Hi just a quick hello as although i have been lurking doing research on here for a while this is my first post. I am in the process of designing a large 6m x 1m x 400 cnc. the main use will be for cutting foam but with the occasional job in wood and looking for around .5 - 1mm accuracy.

i have designed the frame which is to be a single sided cantilever design which is something i have seen used a number of times before in this application and due to the large block of foam will make life a lot easier getting them on to the machine

I have spoken to a number of companies recently and have been given a very mix opinion on what type of drive to use for the 16' long x axis. i will be using a aluminium profile for the frame and hywin rails.

Some of the people i have spoken to have said use rack and pinion as although i will have to join 3 x 2m pieces together and possibly harder to mount it will be a lot more accurate and the all so said that no mater how good a belt drive is over that distance accuracy is going to vary

The other people i have spoken to have said belt drive will be fine as cutting forces are relatively low and it will be a lot cheaper and simpler to set up. They did say some accuracy may need to be accounted for in setting up but the repeatability would still be accurate.

These people were also saying if i was to use rack and pinion that i would need some sort of way to reduce back lash. I have looked a a number of machines and from what i can see some do have mechanisms to reduce back lash and others don't.


Is there anyone on here how has any experience with belt drive over a large distance?

Would there be much saving in time and money in the long run using belt drive?

Do all rack and pinion on horizontal axis require anti back lash devices?

If anyone can offer any advice that would be much appreciated

many thanks charlie