Most "Stepper Drivers" are a mixture of analog and digital circuits that take two (or three) inputs from the controller."Step" and "Direction" (The third input that many have is an "Enable" input). XY should be faster as the table assembly is lighter, but may need to be kept slow enough to handle whatever I put on the table (say, a chunk of steel or similar). My dad had the random suggestion of using two parallel steppers to drive the tool head assembly (from opposite sides). in the code, it was running at approx 50% duty cycle. Tool head movement is slow but probably useable. also seem to be dealing with a fair bit of friction in a lot of this (was fine-tuning this).Ĭurrent total reduction Z is about 32:1 (2:1 from motor to the nut, and 16:1 due to the all-thread). was not able to accurately measure the torque needed to drive the gear (values too small to measure), but it is in the "rather stiff to drive with fingers" territory. I lowered it onto a scale (using an empty coffee can as an intermediate), tool head assembly is approx 17 lbs (8.5kg). Quadrature pulses are the basic pulse/rev count.įor driving the tool head-assembly in my CNC, I have ended up in initial tests using a fairly low RPM, as the stepper was having a hard time moving it all that fast/well. With Kflop + Kanalog add on, many of the ☑0vdc analogue controls available on ebay can be used.īTW, often seen misused, the correct term is Quadrature times four (or x1 or x2). Quality control can be obtained from Motion Control card such as galil or with system such as Kflop.
I have never been a fan of stepper motors in CNC applications, and when feedback is attempted, IMO you may as well use superior servo system. Modern CNC machines such as Fanuc and Mitsubishi typically now use 100K pulse/rev feedback resolution.
One of these shows when dual encoders are used for a system with high backlash, where the PID loop is spread between each feedback item to avoid oscillations, one on the motor, one on the final motion. One excellent source for servo's is the Instructional videos by Dr J.
Servo's now use a transconductance style (current mode) amplifier as opposed to older style velocity (voltage) controlled versions, one reason you do not see tach's on servo's any more. I try to use high quality motors such as Tamagawa, Aerotech etc. Without precise PID feedback down to the least input increment, which is the least possible command from the controller, then a BLDC servo motor which have a typical maximum pole count of 8 poles would be virtually useless without the PID loop.
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