Earthing?

[Edward]

Thank you Dean, for the clear advice and for the warning about the transformer! I've learned so much from this forum.

A metal enclosure it will be, more expensive, but worth it.

I think I will try the cheapo prox sensors first, as I am more interested in them acting as limit switches, at least at this stage. I'll keep you posted.

Oh, a last question unrelated to this. What is the average or expected backlash on bog standard ballscrews C7, chinese. My backlash is between 0.045mm and 0.054mm for each axis, i.e. including the bearings, etc. Is that reasonable?

Edward

[JAZZCNC]

I think I will try the cheapo prox sensors first, as I am more interested in them acting as limit switches, at least at this stage. I'll keep you posted.

They will be fine but bit of advise Fit Home switches ASAP. Infact if I could only choose one it would be Home every time. Far more usful than Limits and can use Softlimits to put you one until Limits are fitted.

Oh, a last question unrelated to this. What is the average or expected backlash on bog standard ballscrews C7, chinese. My backlash is between 0.045mm and 0.054mm for each axis, i.e. including the bearings, etc. Is that reasonable?

Edward

About good as it gets for Chinese C7. Acceptabe or not again depends on usage. For Router yes more than enough. For Mill then might want to chase higher but again depends on what your doing and prepared to accept.!

Didn't see you say what type of machine.?

[Edward]

Hi Dean,
Yes, I can designate them as Home or limit switches, or both. I think Mach3 works similarly. With Kflop for instance, you assign a Home button to execute a C file for homing that basically reads the sensors as home switches, homes the machine, then pulls off a little, zeros the coordinates and then turns the sensors into limit switches.

The mill is a Sieg2.7 conversion, which is just a little smaller than an X3, but with better Y range and I think a similar brushless motor, 750W. It's massively better than the SX2 in every sense, for those who want to know. I haven't actually cut anything with it yet, though everything moves as expected. I want to get the electronics in a box to get them away from the muck. In terms of accuracy, well, I am not expecting great miracles, but it's as neat as one can do...for the money spent. We shall see what the pieces look like, the time it takes to produce them and so on, it's my first foray into CNC.

I have been playing with the backlash compensation, and it's pretty unbelievable what software can do! The compensation happens in milliseconds, and using a dial gauge, the backlash "removal" is bang on. I don't know how good it will be in real life, cutting a circle, changing direction, for example.

Edward

[JAZZCNC]

I have been playing with the backlash compensation, and it's pretty unbelievable what software can do! The compensation happens in milliseconds, and using a dial gauge, the backlash "removal" is bang on. I don't know how good it will be in real life, cutting a circle, changing direction, for example.

Backlash Comp is a fudge at best, better if can remove any slop.! . . Not seen one yet that will get of rid the chatter. . .Lol

[Robin Hewitt]

If you have tight Gibb strips then you have backlash. No Gibb's then what you have is slop

If you have a circuit going through a hole in a metal box, I suggest you make sure that both wires go through the same hole.

[Clive S]

If you have a circuit going through a hole in a metal box, I suggest you make sure that both wires go through the same hole.

Is that because you will get a ground loop

[Robin Hewitt]

I cannot pretend to understand metal boxes and the strange things that happen when you drill holes and run wires through them. Putting the whole circuit through a single hole sounds like a good idea, balance things out, like an earth leakage trip.

OTOH, sounding like a good idea is not always enough. Recently there was a lovely picture doing the rounds of a plated steel nut and bolt holding an earth loop to a copper bus bar. Should have used copper, they used to use copper nuts and bolts in that golden age of understanding when I were a lad. In the picture dissimilar metals had formed a thermocouple. The earth loop probably only gave a fraction of a Volt but the current was enough to heat the nut red hot