ATC module for ER20 spindles

[dh42]

registration done ;)

++
David

[JohnHaine]

Daz, that's very cool! Could you show more of its workings please? Will you publish the design?

[needleworks]

I'd love to know what software you are running to achieve that ! eg, how do you get a 20k spindle to run slow enough to start the threading process of the collets ?

[Daz]

Hi JohnHaine, yes, I will share some more details. I have a nice slow-motion video of the impact mechanism in action. I will upload it to YouTube over the weekend.

Re your second question, I won't be sharing the detailed design, as I am making and selling the modules.

[Daz]

I'd love to know what software you are running to achieve that ! eg, how do you get a 20k spindle to run slow enough to start the threading process of the collets ?

I am running LinuxCNC with a Digital Dream EC300 controller that was originally for March3, but I have converted it to LinuxCNC with Remora firmware. I have 2.2Kw spindle that goes up to 24k RPM. I don't remember exactly the RPM resolution, but it is better than 50RPM around the 1k RPM range I am using it for tool changing. The inverter is Huanyang 220v 2.2kw. With this setup, I can run the spindle backwards and forwards, from I think around 300 RPM (I would have to confirm that) all the way up to 24k RPM. After moving from Mach3 to LinuxCNC, the setup is rock solid. I had lots of problems with Mach3.

[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.

[Daz]

I have done some more digging and since it is a DC motor, you will have completely different torque curve, with some significant torque available from the start. Theoretically many times higher to what I can get on my 2.2kw spindle at very low RPM, assuming your spindle DC power supply can handle it, it might actually work!

You would need to sort out the manual speed control and the reverse operation, but other than that, it should work.