I am closing in on bringing my CNC router build to the finish line. That said, I am having a bit of an issue with motors stalling on my long axis, and on my Z. I abandoned the idea of using rack and pinion to drive my Y axis, and changed to twin 20mm ball screws, My stepper motors are Nema 34 878 oz inch. I thought they should be strong enough to handle the weight of the gantry and to lift the spindle. The X axis moves great. I can achieve a speed of 200 in/min without the motor bogging down, loosing steps, or just flat out stalling. I cannot say that about the Z axis and the Y axis motors. I can achieve only 75 in/min on both of these axis before the motors stall out, make a God awful noise, and fail to move the axis as I have commanded on the MDI or by continuous jog.
My gantry is very heavy, made of 0.750" aluminum, a huge extruded piece, and a hefty spindle. I am curious if my stepper motors are just not strong enough. I did find some Nema 34 1841 oz/in motors that are 5A per phase. I am curious for some insight from some more experienced CNC builders if it would be worth my investment to upgrade to the heavier torque motors, or should I just live with the slow movements? I have no idea what will happen when I finally get a router bit ripping through some hard wood. I can imagine that will only add to the load, and feed speed would need to be drastically decreased to handle it.
On a whim I thought that perhaps my linear rails mounted to the side of the extruded might not be the optimal thing, and I modified my gantry slightly to mount them to the top of the extruded rails along the Y axis. I really cannot tell that this made a difference and in hind sight my X axis is mounted along on the gantry beam much the same as the Y axis shown in the picture.
I am primarily building this CNC to manufacture some of my guitar necks and fingerboards, but as I am approaching retirement age I would also like to use it for other wood projects to generate some income. That said, I do not want to end up with 10 inches per minute feed rate.