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Author Topic: Cut parts are wrong size, CNC knee mill problem  (Read 21315 times)

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #30 on: July 26, 2012, 01:44:07 PM »
Yes I agree with you on the tweaking, that's just masking the problem and probably wouldn't work.

Sebastian

Offline Hood

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #31 on: July 26, 2012, 01:57:20 PM »
Not that it matters but just a bit curious where you are as you seem to be setting in metric, code is metric but your cutter is imperial.

Hood
Re: Cut parts are wrong size, CNC knee mill problem
« Reply #32 on: July 26, 2012, 02:01:23 PM »
Canada eh! I grew up with the metric system, but all of the cutters are imperial and are generally produced in the states. Metric ones are possible but then it's hard to find metric collets etc... Just easier, cheaper and more selection in imperial cutters over here. Some machinists here work in imperial for travels, cuts etc... but that just doesn't make any sense to me.

Sebastian

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #33 on: July 26, 2012, 02:18:24 PM »
Ok makes sense now. We can get metric or imperial cutters here for the same costs but as I work in metric its normally metric cutters I use just makes it easier on my head ;D
Hood

Offline BR549

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #34 on: July 26, 2012, 04:16:41 PM »
HERE is "simple" Code for an inside circle AND an outside circle. It is setup for a 4"center line .

Not saying it is BUT there may be a problem within MACH3s conversion to metric Gcode on the G2/G3.

Art always said IF you are going to normally CUT metric then set the machine to metric as well.

IF that cuts correctly both ways then we will try a metric Gcode via Imperial machine.




(Filename: Circle_4x4)
( Plasma Shape WIZARD )
(Date Created: 07/26/12)
(Time Created: 3:54:49 PM)
G20 G17 G40 G54 G80 G90
G0 Z0.5
G0X0Y0
G0 Y2
M3
G4 P3
G1 X0 F20
G0 Z0.0
G3 X0 I2 Z-.050
G3 X0 I2
G0 Z0.5
M5
M30


(Filename: Circle_4x4)
( Plasma Shape WIZARD )
(Date Created: 07/26/12)
(Time Created: 3:54:49 PM)
G20 G17 G40 G54 G80 G90
G0 Z0.5
G0X0Y0
G0 Y2
M3
G4 P3
G1 X0 F20
G0 Z0.0
G2 X0 I2 Z-.050
G2 X0 I2
G0 Z0.5
M5
M30
« Last Edit: July 26, 2012, 04:18:17 PM by BR549 »

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #35 on: July 26, 2012, 05:04:16 PM »
Terry his machine is set to metric and code is metric, it was just he was buying imperial cutters and I was curious why.
Hood

Offline RICH

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #36 on: July 26, 2012, 05:45:07 PM »
Hmm,
The posted code in your reply #26 shows a change in the X value for the last circle to be cut by 0.1mm and thus increases the diameter
of one circle from a diameter of 34.2mm to 34.6mm. Additionaly that shifts the concentricity of the two diameters such that at 12 & 6
o'clock difference between is 0.1997, at 3 o'clock 0.1, and at 9 o'clock 0.3.

Now with a 12.7mm dia cutter you figure what the finished cut diameters would be but they will not be 30.
 ??? maybe I am missing something  ???
RICH

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #37 on: July 26, 2012, 05:52:23 PM »
Rich the 0.1 shift is the finish pass. So that is going round at a rad of 8.65 so dia of 17.3mm add to that the dia of the cutter (12.7mm) and the finished dia cut should be spot  on 30mm .

Hood

Offline BR549

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #38 on: July 26, 2012, 06:25:58 PM »
I had better find my glasses. (;-)

(;-) TP

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Re: Cut parts are wrong size, CNC knee mill problem
« Reply #39 on: July 26, 2012, 09:57:36 PM »
Thank you, thank you, Hood..... :)
I have tested and run a  backplotter on hundreds of files ( mill and lathe ) and never had it bomb once and on that simple one it was not interpreting the code correctly. 

Go figure......., ???
Now to get it fixed  :D
RICH