Hi,
I'm running the ESS with a C25 BoB, 5v. I think it would be beneficial to run a 12v or 24v system to mitigate signal interference.
No, if you choose the impedance levels correctly then the noise performance is IDENTICAL between 5, 12, 24V systems....it all comes down
to Signal-to-Noise Ratio....not voltage level.
My mini-mill which I operated for seven years had a 5V BoB and 5v signaling. My new build mill, in service for about six months now, uses Delta
servos, which use 24V signaling as is common with industrial gear, thus I made my BoB 24V also, excepting the Step/Dir outputs which are
5V differential for higher signal speeds. My choice to use 24V signaling is not about noise performance, its about having a clear and consistent
design throughout supported by a wide range of suitable electronic and electromechanical parts.
I looked at the MB3, its a well thought out design and a quality build and deserves its high reputation. If using the MB3 you are perforce limited
to the design choices CNCRoom have made. When I designed my BoB I could have exactly what I wanted and absolutely nothing I didn't.....no
compromises. My own BoB has been working great....but like all designs it can be improved.
I have found that I can make a better PWM circuit than my existing circuit. When I get around to making the new circuit it will be within 1% of
linear with duty cycle whereas my current circuit is linear within 7.5%.
About a fortnight ago I discovered that the circuit (2 dual channel OP-amps per axis) I used for generating the differential Step/Dir signals
while fine with my Delta servos is just a little to noisy for Step/Dir of my Allen Bradley servo used for my heavy duty spindle motor.
I have redesigned the BoB so that the differential Step/Dir signals are generated by a new generation line driver IC.....with considerably better
characteristics than my previous home-brew attempt. The ICs are $11.00NZD each, I require three of them, which is a little more than I like
paying for analogue ICs, but they look the part. I ordered them 10 days ago and they turned up yesterday from the UK, freight free.
My mill is working perfectly well with my existing BoB....so I'm in no great hurry to build another....but will get around to it in the next few weeks.
I want to be able to use my Allen Bradley servo spindle motor in Step/Dir position mode so that I can use it for rigid tapping. I've used it for rigid tapping
on my mini-mill a dozen or so times over the previous two years since I built the spindle. I have only just started to make the changes necessary
to have the same functionality with my new mill which lead to the discovery of the noise shortcoming of my first BoB design.
Would you like to share a picture of your BoB? Do you sell them?
I'll take some photos of them, they are split into two boards. Given that I have design improvements to make to both of them...no I haven't sold any,
but may do. They are hand-made and hand soldered which makes them a labor of love rather than a profit making exercise. I could post
the design files if you wish to make your own, although it might pay to wait until I have the GenII boards made, tested and in service before
copying what I have done!.
Would cost to get it from the states and add a whole other level of ugly to the control panel.
My ESS, BoBs and power supplies are screwed to a plastic chopping board, they are about the right size and cheap source of plastic. So when I say
that my control system is 'breadboarded'....I bloody well mean it. I have another breadboard that has the single board PC and its power supply,
yet another breadboard that has the three Delta servo drives, the AC distribution buses and EMI filter and yet another breadboard for the VFD and
Allen Bradley servo drive for both spindles. You might laugh, and to be fair its pretty untidy......but better than my mini mill. When I built that
I just nailed the various boards and things to a piece of MDF, promising to go back and do it properly later. Seven years later and its still the same. There
is nothing more permanent than a temporary solution.
Craig