Hi:
Sorry, Ive been a bit slow on this project, but this will likely take some time.
We have decided to simply upgrade the the table we currently have to work for us,
it does work well in most things, but cant do a small photo for example as the gantry will skew
too easily. So Im getting some new Tompson bearings for the linear rails on the X (or Y whatever.
)
SO first, we'll fix the skew, then we'll change the long axis drive system.
The problem with direct drive from a motor, is usually the gearing is too low. You want to aim for about 500 steps/mm,
, at 25Khz thats about 2inch per second, or 120IPM, not bad..but still slow. At 45Khz thats about 212IPM, which woudl be
much nicer. We'll work out some numbers as we get closer and choose the best compromise. The thing you need to worry
about with direct coupling, is the resolution. A 4inch diameter belt drive direct coupled, would give you only about 500 steps/inch,
which isnt very good. Hi speed, yes, but low resolution. That is the balance you need to look at.
Each person will have their own resolution/speed mix, but Ill probably end up driving this with a G100 or ncPod, so in the end speed
wont matter as much. ncPod does 75000, G100 does 4Mhz, so if I need more speed, Ill bump it up that way, in other words, Ill probably aim for
a reduction of quite a bit to make the servos go almost full out in rapid, thats the sweet point from my understanding of all the motor magic
involved. So if I can reduce the 2000-3000RPM down to 500IPM, Ill feel pretty good about it, and will use an appropriate speed pulse engine
to get the end required speed. Dont know if that answers your questions, but its the type of thing Id consider when it comes to motor coupling..
Soon, we'll begin to show what we did to kill the skew, and keep the gantry square, it may take two motors, but we'll try it with one for the sake
of simplicity..
Art
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