Re: Need Opinions on Z Axis Design
Don't forget tool length. Often people model the spindle and forget there is something actually sticking out from the spindle nose.
The rails on gantry carriage vs rails on Z plate debate usually forgets about the fact you actually have a tool with length.
I have rails on the gantry carriage, because this allows me to move the spindle up above the gantry.
This keeps the gantry as low as possible.
With rails on the Z plate it is likely stiffer with Z all the way up, if you only analyse the Z axis. However to get the same functional travel, the gantry must be higher which compromises stiffness of the whole gantry.
Z travel needs to be:
Longest tool bit you want to use plus clearance to get over the thickest part you want to cut.
E.g. 100mm long tool, wanting to cut full 100mm thick part. Z travel must be >200mm. Gantry clearnance must be >100mm.
Consider all the shortest tool you will want to use and whether you can reach the spoilboard / fixture (though it is often possible to use spacers to raise workpieces up if needed).
7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)