Rebuilding gantry type Suregrave engraver - advice needed!

[GordonB]

Just a quick response to JAZZCNC, thanks very much indeed, plenty to digest there but I think I'd go for the AXBB board, looks like it would do what I want and the cost is offset by the lower cost of the software, about £80 less than Mach 3 I think. For stepper drivers I was considering these, partly for cost, partly because they have decent reviews, and they will easily cope with 36V 2.8A/phase supply to the steppers, which is what they are rated at.
https://www.amazon.co.uk/TB6600-Step...p_pl_dp_2&th=1

The power supply within the existing engraver controller is a large toroidal transformer with a rectification and smoothing circuit board. I've checked the outputs and it provides 36V for the steppers, 5V for controllers etc, and 24V for the spindle. All works fine and I don't see any need to use anything else. I'll post a photo tomorrow.

The spindle spec sheet is shown below, the one installed is 24V brushed dc, but it's rated at 17.4A. Needs a PWM controller I presume but I'm not sure what to go for. There might be a PWM circuit in the existing controller but I think it's part of the stepper driver board, which is completely unmarked as to what each connection is, which is a bit of a bummer as I might have been able to use it. From my discussions with Mervyn White at Microwhite (he's a Suregrave guru) the main controller boards were somewhat unreliable and not capable of being repaired. More tomorrow!