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Author Topic: New user, confused by feed and plunge rates  (Read 4863 times)

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New user, confused by feed and plunge rates
« on: January 02, 2014, 05:35:20 AM »
I bought/registered MillWizard today, having taken a step into CNC over Christmas, and wanting a SIMPLE utility to allow GCode to be quickly and easily created.

I've created a project to cut a rectangular shape from a piece of perspex, thinking that I'd created suitable feed and plunge settings (800mm/min, 60mm/min, respectively). What happens with the generated g-code is that the feed rate is set correctly for the plunge, but never set again for the x/y feed, resulting in a very slow x/y feed into the work (which, with perspex, is likely to burn the stock material). G-Code extract given below with the plunge feed-rate highlighted (*****) :-

(MillWizard 1.0.13)

Any clue as to what I'm doing wrong?

Code: [Select]
(***New File Started***)
(created by NFS Mill, V4)
(New File Started 01/02/14 09:42:40)
(posted for Perspex3mm )
(Strategy:  As Entered)
(Rapid height: 1.0000  Clearance height: 1.0000 )
G98 G80 G17 G90 G54 G64 G91.1

G21 G90
(***New Tool Selected***)
(ToolNum: 02  Diameter: 2.3825  )
(Feed: 800.0000  SFM: 168.0000  Plunge: 60.0000  ChipLoad: 0.0318  )
M06 T2 (Green CornCob)
G43 H2
M03 S16843
(***Cut Rectangle***)
(Xorign: 0.0000  Yorign: 0.0000  Length 200.0000  Width: 160.0000  CorR: 0.3000  InOut: 01  )
(Ztop: 0.0000  Zdepth: -2.9000  Zstep: 1.0000 )
(will make  3.9000  cuts of:  1.0000 )
G00 Z1.0000
X0.3000 Y162.6208
G01 Z-1.0000 F60.00             (*************** FEED SET HERE ****************)
G03 X-0.8913 Y161.1913 I1.1671 J-0.2385
G01 X200.8913
G02 X201.1913 Y160.8913 I0.0000 J-0.3000
G01 Y-0.8913
G02 X200.8913 Y-1.1913 I-0.3000 J-0.0000
G01 X-0.8913
G02 X-1.1913 Y-0.8913 I-0.0000 J0.3000
G01 Y160.8913
G02 X-0.8913 Y161.1913 I0.3000 J0.0000
G03 X0.3000 Y162.6208 I0.0241 J1.1910
G01 Z-2.0000
Re: New user, confused by feed and plunge rates
« Reply #1 on: January 02, 2014, 08:15:19 AM »
Please save and post here a job file, that way I can see exactly what entries you made.
Re: New user, confused by feed and plunge rates
« Reply #2 on: January 02, 2014, 08:26:43 AM »
Job file attached (hopefully... 2nd attempt)
Re: New user, confused by feed and plunge rates
« Reply #3 on: January 02, 2014, 08:31:09 AM »
Hmm, I can't see the attachment even though the forum software confirmed it's attached. In any case, the content of the job file is

Code: [Select]

1|1|Job|C:\Program Files\NFS_Mill\ToolTable\baseplate.tap|Perspex3mm|5|260.0000|325.0000|550.0000|750.0000||1| As Entered|1|1.0000|1.0000|C:\Program Files\NFS_Mill\ToolTable\Doddy.wtl|30000.0000|800.0000|60.0000
2|1|TOOL|2|2.3825|0.0938|0|4|2|168.0000|0.0238|22445.0000|800.0000|60.0000|0|0|0.0000|Green CornCob

with the wtl content:-

Code: [Select]

1|Orange CornCob|0.1250|4|0|0.0000|0
2|Green CornCob|0.0938|4|2|0.0000|0

Re: New user, confused by feed and plunge rates
« Reply #4 on: January 02, 2014, 11:07:22 AM »
Ok, looks like a bug when you do a plunge cut instead of a ramp into the work. If you change the ramp angle on the tool settings to something like 5 it all works fine.

I will have to find this one and fix it and make a new release. That will take at least a few days.

I notice you are using Rapid Height and Clearance as the same value. Do you understand that Rapid is the height above all clamps where rapid moves are allowed. Clearance is the height that a plunge will stop moving at rapid speed and switch to plunge rate. It is also the height to raise the tool between passes. Using the same value is OK, just not using one of the wizard features.
Re: New user, confused by feed and plunge rates
« Reply #5 on: January 02, 2014, 11:39:21 AM »
Re. workaround - thanks - I'll give that a try (a quick look at the generated g-code looks good).

Re. rapid/clearance heights - thanks for the info... that'll probably save a few cutting bits, although I'm still in the what-am-i-doing phase, it's probably a good idea to get into good habits earlier, than later.

Many thanks.