ATC module for ER20 spindles

[JohnHaine]

Well I could be interested except I use ER16 on my mill.

[Daz]

Well I could be interested except I use ER16 on my mill.

It is very straightforward to modify the ATC module for ER16. Just a simple change to one part, and I would be happy to do it.

The main challenge will be around the torque your spindle can generate. This is mostly a problem for the unlocking step where the spindle needs to overcome the module's initial resistance from the standstill. In case of my spindle, and with the current module setup, I had to increase the acceleration setting on the VFD to give the spindle a bit more torque, as it was stalling from time to time.

If you could let me know your spindle model, I can check its specs and let you know if it would work.

[JohnHaine]

I have a Novamill which uses a DC commutator motor, about 375W. Max speed is 5000 rpm. At the moment I only have manual speed control and no reversing so that would need to be added. The table is also quite small so at the most only room for 2 modules - what size are they?

[Daz]

The module external dimensions are: 95mm X 95mm footprint, and 88mm height.

Checking your spindle, I am afraid you most likely won't have enough torque to operate it. I might consider making a lower torque version in the future, but I will need to modify some internals.

[JohnHaine]

Thanks for the extra information Daz. If the motor could generate the torque it would need a very different controller, the current one is KBE thermistor type. Something that would generate stall current at low volts would be needed, and anyway as it's a PM motor it might be field limited. Also the height would severely restrict me and my table is only 125mm wide! Shame it's a very nice concept.

[magicniner]

Thanks for the extra information Daz. If the motor could generate the torque it would need a very different controller, the current one is KBE thermistor type. Something that would generate stall current at low volts would be needed, and anyway as it's a PM motor it might be field limited. Also the height would severely restrict me and my table is only 125mm wide! Shame it's a very nice concept.

The whole point of an Impact Driver Mechanism is that it isn't reliant on motor torque, it releases the drive in response to pre-settable torque demand, allowing the spindle to accelerate, it then uses spindle system angular momentum against a braking mass to apply the required torque, repeatedly.

[JohnHaine]

The whole point of an Impact Driver Mechanism is that it isn't reliant on motor torque, it releases the drive in response to pre-settable torque demand, allowing the spindle to accelerate, it then uses spindle system angular momentum against a braking mass to apply the required torque, repeatedly.

That's true when tightening but loosening is a different matter as the spindle will be stationary.