My Z randomly misses steps. seems to only do it on rapid Z retract, so then I lose my zero... amd BAM. Into part or table I go. Yes I do have my velocity and accel set pretty low.

Problem is it's not repeatable. it only happens when I'm 55minutes into a 1 hour job and it slams my $175 indexable cutter into the vise. Yeah me.

I've searched this board... and most of the time it's a mechanical issue. this isn't.... been down that road.

Would posting my XML help? Could switching to Sherline mode help? Does Kernel speed have any effect?

http://www.geckodrive.com/using-heds-encoders

I was thinking of trying this. This link shows what to do with the 320x, I'm using the older 320.

I found a 1uf 35v capacitor at Radio Shack... think this would be beneficial to me?

Hi Jonny,

Just my opinion…

Anything that reduces electrical noise and produces cleaner signals has to be good.

As you only seem to be having problems on the Z retract I would suggest that you reduce the Velocity and Acceleration on this axis until you find a 100% reliable setting.
(Just as an example my 100% reliable X and Y rapids are 4500mm/min @ 450mm/sec/sec whereas my Z rapids are only 1000mm/min @ 100mm/sec/sec – quite a large difference 1 : 4.5).

I don’t think you should ever assume that the issue is not of a mechanical nature, always consider all possibilities. 

Tweakie.