Post Processing for tapping is strange.

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1350519287
Posts: 22
Joined: Mon May 19, 2014 1:05 pm

Post Processing for tapping is strange.

Post by 1350519287 »

I'm having problems with setting up the post processor for applications that use an imperial mill but have to do metric tapping.
LinuxCNC uses G31.1. The stock post processor with VisualCAM has only EMC Inch

If we're using the inch post processor then a 6mmx1.0 tap should do a 20mm deep hole like this right?
N6 G31.1 X1.5748 Y0.3937 Z-0.7874 K0.0394

And if we're using a metric post processor then
N6 G31.1 X40. Y10. Z-20. K1.

Mixing metric taps with imperial post processor creates weird values where the 6x1mm tap has
N6 G31.1 X1.5748 Y0.3937 Z-0.787 K25.4001

I can see that the tap pitch in imperial has to be 0.0394" per rev. So what needs to be set into the config file so it creates the correct value?
1350519287
Posts: 22
Joined: Mon May 19, 2014 1:05 pm

Re: Post Processing for tapping is strange.

Post by 1350519287 »

Seems the metric and imperial don't mix well and descriptions can be confusing.
Seems to generate the code below, the pitch of the thread which usually means the distance moved in one turn in this case is TPI and has to be set to 25.4 TPI.
Googling thread pitch
https://www.google.com/search?client=f ... ead+pitch

So in case anyone is confused like I was hopefully this will help.
John

Code: Select all

%
N1 G17 G20 G40 G90
( BEGIN TOOL LIST )
( TOOL 1 - Tap6x1mm - DESC: 0.2360 DIA, 3 FLUTE,  HSS MAT )
( ENDOF TOOL LIST )
(Clockwise Tap)
N2 T1 M06 G43
N3 S100 M3
N4 G0 Z1.25
N5 X1.5748 Y0.3937
N6 G33.1 X1.5748 Y0.3937 Z-0.787 K0.0394
N7 G80
N8 G0 Z1.25
N9 T0 M06 G49
N10 M30
%
Attachments
Tap6x1mm.jpg
Tap6x1mm.jpg (233.51 KiB) Viewed 4026 times
EMC_Inch_Setting.jpg
EMC_Inch_Setting.jpg (241.29 KiB) Viewed 4026 times
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