9' x 5' CNC Router Rack and Pinion Question

[joprinz]

I am designing a 9' x 5' CNC Router. I read in many posts here about the need for a support in case of ball screws longer than 5 Feet. Considering my design requires an axis which is 9 Feet long I'm considering using Rack and Pinion instead. However I am finding it hard to pick the right Racks and Pinions.

Here is my Machine Specs:

X-Axis : 5'
Y Axis : 9'
Gantry Type : Moving Gantry
Gantry weight : 75 Kg
Max speed of Axis Movement : 120 ipm
Each Axis using Two 15mm Linear Guides and 4 Carriages

I have come up with the following rack and pinion from Gudel.



I was wondering if the above rack and pinion is sufficient for my design.

The above Pinion has 20 Teeth. Can using a 30 Teeth Pinion help reduce vibrations at higher speeds?

Also can someone suggest commonly used rack and Pinion Specs when building longer axis machines?

Please Advice,

Thank You.

Joe

[ger21]

Originally Posted by joprinz Max speed of Axis Movement : 120 ipm

Imo, you should be designing for at least 500ipm. 120 ipm will be painfully slow with a 9ft axis.

[joprinz]

Thank you Gerry, for your suggestion. I am new into building bigger units like this one. I had built a 2' x 2' router and a 15" x 12" Mill earlier.You are right... with 120 ipm It will probably take about a Minute to jog from one end to another. Point Taken

Has anyone used 1.5 Module Racks with 20 teeth Pinions in their CNC Routers? Plz share your ideas regarding the gearing requirements for a 20 tooth 1.5 Module Pinion.


Joe

[blazedforever]

can someone explain what the modul measurement is?

[1000IPM]

This would work for what you are doing -

http://automotioncomponents.co.uk/se...pinion&x=0&y=0

[RICHARD ZASTROW]

Those roller rack & pinion systems are quite expensive. But, Gudel R&P systems are pricey as well.

You may consider mounting either system rack teeth side facing down to avoid fouling the rack teeth. Just a thought.

Dick Z

[Al_The_Man]

For a 110ft oxy/gas gantry I used Kohara products, these were supplied in Canada by Stock Drive Products. http://www.cadenas.de/catalog_pdf/khk.pdf
I used the SRF machine ground style of rack, these have countersunk mounting holes and machined ends for accurate butting up if required.
I installed the rack facing down and 28 tooth gear.
Gear SS2-28 and rack SRFD2-1500 (1,5metres/length).
Al.