Schaublin 125-CNC retrofit.

Thanks guys.

As long as the current motor is in there, the CVT will stay. If that motor dies, I'd have to replace the CVT, as that original motor has an extended length shaft for it.
Making a tool to cut the poly-vee groves is no problem, that is what the Clarkson is for. Actually I already made one for the Poly-Vee of the mini lathe.

Good points.  I'd forgotten that the CVT can only change gear whill running. That will complicate the control logic a bit.
The back gear is pneumatically actuated, and will be controlled though the Festo CPV and 7i84.

I dont see any point further complicating it with the two additional contactors necessary to bring in the 8 pole windings. Whether the motor runs at half frequency or on 8 poles, the speed is the same and the power is approx halved right? I dont have space for those contactors, and would be nearly guranteed to blow up the VFD by swithcing it's output by mistake.

I need to look at Andy's back gear + VFD to see how he inhibits back gear selection during CSS cuts.
Mark

Hi Mark
Have been enjoying your new conversion journey , and a big thank you for all the videos an discussions .
Wondered if you have considered space requirement  of a VFD with output -input filters + external resistor .  Input filter to keep family an neighbors happy when Dad is in the basement .  CSS turning may exceed the VFDs speed drop duty cycle thus requiring a external  load dump resistor + fan .
My thinking is that a external VFD power supply could be a multi use feature, but it is your Schaublin sand box .
Bob

 

Hi Bob,
Indeed I haven't considered the space for an input filter. I am adding an output  line reactor based on Ralphs suggestion. Might have space for an input filter beside it.

Braking resisters are only necessary if you use the VFD for braking, an I have an electro mechanical brake in the gearbox for that. While theoretically you could need a braking resister if doing a CSS outwards cut, fast enough that the cutting forces are insufficient to act as the braking load, I think that is a somewhat unlikely case in my home shop. I will never run this machine anywhere near the performance limits, as I dont have production pressure.

Mark
 

Less done this week than hoped, but enough for a short video update...


Mark

In the comments section to this video I am getting a few comments like...

The line reactor is for the input side of the VFD to improve its powerfactor. For the output you will need a LC-filter also called Sinusfilter or dU dT filter. A reactor alone will do almost nothing to flatten out the PWM voltage spikes of the VFD.
or
A line reactor is not the suitable device for that. Thats why its called a line reactor, it is for the mains side of the VFD to improve its power factor. For the motor side you want to use a LC filter often times called a sine wave filter. They will smooth out the PWM mess coming out of the VFD to a sinusoidal voltage and protecting the windings.

Yeahhhhh about that......
I am getting sick and tired of "experts" that never ever read a single users manual, let alone an actual book about electronics.
Manual, if any of those who told you that would have bothered to read them, it is always mentioned that outputs go to motor, nothing else can be between drive and motor, some have even info for when using longer cabling.
Sorry but i did see the video, and thought about it, and decided to keep my "fingers" shut!
Shame on me.