roundel325 wrote: ↑Fri Dec 18, 2020 3:59 pm
I'd prefer to buy something off the shelf rather than a scratch build. The whole mechanism would have to spin so I'm not sure how it could be wired. And it would need to have no backlash. Do you know of such a thing available to fit motor shafts?
I have seen a pneumatic clutch mechanism that took a servo motor and coupled it to the 3 phase spindle motor by way of the FAN side of the motor on a TEFC motor. Dave DeCaussin former Owner of FADAL took this approach with his small lathe when he was experimenting with his C axis.
I will see if I can find info on the pneumatic clutch.
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We can't "SEE" what you see...
Mesa, AZ
I've been thinking about this. Using Spur gears between the Spindle and Motor, and use an air cylinder to pivot the motor to engage the gears. This would eliminate almost all the backlash. But an overload could push the gears apart. To get everything lined up for engagement the easiest way I can think of this Is you need a VFD with Feedback so that it can be used to orientate the motor. Now if you are running a 1:1 Timing belt you can use the Index pulse off the motor. If not you'll have to use the Index pulse off the spindle encoder. I'm just starting up a new lathe project and plan on playing with spindle orientation based off the spindle encoder instead of the motor encoder.
Apologies from the start for not having time to read through the entire post, but couple of quick points since this is very similar to what I'm setting up.
- DMM does have a special firmware to allow swapping from speed mode to analog mode via gcode on the fly
1) This firmware uses different pins versus the standard firmware for reversing in analog mode
2) DMM sux about telling people everything when they buy it, there is a release notes pdf posted on my build thread
3) There is a different version of the programming software required for use with this firmware
- On the Z pulse deal. The encoder output DB9 from DYN4 has z/z- a/a- b/b- which the acorn uses via it's DB9 for position/direction and RPM
1) The DYN4 DB9 also has ZRI- / ZRI + too for use in homing that can be passed over to the Acorn DB25 - different circuit from the Acorn DB9
Anyway, saw the title and thought I'd post a few details that may or may not help. The encoder info is the same on both firmware versions.