I have retrofitted machines 4'x8' and up using 12 diametric pitch 20deg pressure angle, the 20 deg is considered to have a higher load bearing capacity then the 14-1/2.
Most CNC gantry tables I have been associated with all use some kind of tension arrangement to maintain pressure of the spur gear with the rack, mainly to remove any backlash. I have seen anything from gas filled (shock absorber type) to coil spring etc. I have had success using a product from Rosta that is originally intended as a motor mount belt tensioner. But If too much tension is applied, it leads to rapid spur gear wear.
Al
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CNC, Mechatronics Integration and Machine Design.
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E. |