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Author Topic: non repeating z moves  (Read 1327 times)

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non repeating z moves
« on: November 24, 2015, 02:11:21 AM »
hi

I'm having problems with the z accuracy on my router - its a basic 6040 chinese model but has been pretty useful so far.  Im running mach3 under xp and am using a usb interface

so I zero off the bit on the workpiece and then hit either ref all zero or zero x y and z manually ...

i then jog it up so I can snap my dust hood on -

I then press the goto zero button in mach 3 expecting the bit to go reliably back to the surface position

sometimes this works but sometimes the bit plunges a few mm into the part - eek ..

any idea what might be happening?

regards

keith

Offline Tweakie.CNC

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Re: non repeating z moves
« Reply #1 on: November 24, 2015, 02:20:24 AM »
Hi Keith,

Don't hit the Ref All Zero button - just zero the X, Y, Z manually - this should resolve your immediate problem.

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: non repeating z moves
« Reply #2 on: November 24, 2015, 05:55:18 AM »
thanks tweakle

so i just tried what you said - first and second time it returned to exactly the right spot after the arbitrary z jog, the next time i jogged up and hit the goto zero it plunged about a 8 mm into the stock.  at finish of the move the readout in mach still said z = 0

it then occurred to me that when jogging up that 3rd time i was hitting the limit of travel of the z -  and it must therefore be losing steps at that time - this does seems to be the cause of the sometimes error -- sounds right to you ?

cheers  keith


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Re: non repeating z moves
« Reply #3 on: November 24, 2015, 05:56:52 AM »
Sounds right to me  ;)

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: non repeating z moves
« Reply #4 on: November 24, 2015, 03:45:22 PM »
You can also setup "Soft limits" so it will not hit the hard-stops, given that the steppers not loose steps :-)
Re: non repeating z moves
« Reply #5 on: November 24, 2015, 06:07:23 PM »
good calll - many thanks1