Control system for Harrison M250 CNC

[Chaz]

Cheers - those VFDs look like great value. Do you have a link for the guy selling encoders? The minimum recommended spec is 8000p/r (seems excessive?) and even the 2000p/r ones I've found are in the hundreds of quid.

https://www.ebay.co.uk/itm/Hengstler...EAAOSwySlaJSLx

[AdrianW]

https://www.ebay.co.uk/itm/Hengstler...EAAOSwySlaJSLx

I was looking at that earlier - the listing isn't very helpful as it only quotes the P/N and not the code that gives the spec - zooming in on the photo it looks like it's a D/500 which from the datasheets I've seen give it a 500 counts per rev, which is well under the minimum spec. for the Acorn.

I checked the resolution a 2000 count encoder would give assuming a workpiece of 250mm diameter, and it's about 0.4mm, so having 2000 as a minimum spec. doesn't seem that unreasonable.