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Author Topic: accuracy  (Read 1733 times)

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accuracy
« on: January 06, 2013, 04:35:30 AM »
I am CNCing a sx2 mill and have an annoying problem with accuracy.
The mill has been roughly converted using the stock metric screws.
A pice of work marked out for 3 holes and punched then put into vice.
The punch marks are roughly at the points of a triangle on the face of the work.

Mach 3 steps has been set using a digital calliper mounted to the mill using brackets
Same calliper for marking the work
Check the callipers against a micrometer.
Check gibs.
I'm using the blue screen for mach3 as it has a touch off gadget.
I have mounted a 2mm drill ( isolated from the mill with shrink rap) in the collet then touched off the work left and front and zeroed the DROs.
Using the MDI screen entered the x y coordinates + 1mm for half the diameter of the touch off tool.
tool  moves but is short from the punch mark  in both the x and the y.

Calliper mounted to the table confirms the DROs movement and distance.
 manually jog the tool to the punch mark Read the DROs repeat for all the punch marks.
On average   The y is 1.2680 short and the x is 0.7 short
Manually set 0 x and y  from the left and fount of the work In case it's back lash  retest SAME.
up grade the machine with 1605 ball screws nuts and mounts.
Re calibrate machine for the modifications using the same callipers.
Repeat all of the above and it's the SAME.
Wifey is packing bags dogs are hiding in bedroom.
I'm missing something !!!!!!!!!!!!!


 



 
Re: accuracy
« Reply #1 on: January 06, 2013, 04:53:17 AM »
Problem sorted the probe is 2 mm + the insulation so need an offset of 1.5 and the drill is not quit 2mm it's just under.
Helps writing things down.
Dam wife's unpacking.