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General Mach Discussion / Cutting a Circle - Figures don't add up!
« on: July 22, 2020, 11:42:32 AM »
Trying to get my head around G2 arc cutting, but the simulation shows that the circle diameter is not as designed.
Using an 8mm dia cutter - and therefore allowing a 4mm adjustment to the radius - the simulation shows that rather than cutting a 96.75mm dia pocket it will cut a 185.5mm dia ? whose radius is 92.75 -- so it's not even cutting 'double size'.
This is the code :
Lines N150 and N160 are commented out because, with them in, Mach3 complained that "R or IJK are all missing from N150" - which I also don't understand - I would expect to take the first cut then reduce the feed for a further 'plunge' and then do a second cut (where I & J would be specified). Ultimately there would be more cuts depending upon how deep I want the hole to be.
In the light of the Mach3 error message, can anyone suggest how the Z parameter can be specified in the same block as G2 and therefore create a helical cut getting deeper with each 'turn' and if such is possible how would the final depth the specified.
In case anyone thinks that the feeds and speeds are in error I should say that this would be cutting a hardwood such as Ash, Elm, Teak, Walnut -- etc.
Using an 8mm dia cutter - and therefore allowing a 4mm adjustment to the radius - the simulation shows that rather than cutting a 96.75mm dia pocket it will cut a 185.5mm dia ? whose radius is 92.75 -- so it's not even cutting 'double size'.
This is the code :
Code: [Select]
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O0000 (Bore large shallow hole.NC)
N10 (Author - JG - 22 July 2020)
N20 (for Denford MicroRouter Compact under Mach3 V2)
N30 (Thread Milling Ø100 x 3mm - bore = 96.75 - R= 48.375)
N40 ()
N45 (T3 D=8 Flat end-mill)
N50 (units mm)
N60 (X & Y 0 in MACHINE centre)
(X min = -200, X max +200)
(Y min = -100, Y Max = +100)
(Z 0 at top)
N100 G17 G21 G00 (set up XY Plane & Metric - fast traverse)
N110 X44.375 Y0 Z-50 (move XY & Z Determine Z by reference to work)
N120 S8000 M3 (set spindle speed & start spindle)
N130 F100 Z-52 (set feed rate & plunge into work 2mm)
N140 F200 G2 I-44.375 J0 (set feed rate, cut Circle about 0,0)
(N150 F100 Z-54) (set feed rate & plunge into work 2mm)
(N160 F200 G2 I-44.375 J0) (set feed rate, cut Circle about 0,0)
N1450 M05 (Turn spindle off)
N1500 G00 X0 Y0 Z0 (move tool at fast rate to 0 0 0)
N1510 M30 (Close Program)
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I've included all comments/annotations rather than just the working lines in case there is something that I simply have wrong in the basic understanding.Lines N150 and N160 are commented out because, with them in, Mach3 complained that "R or IJK are all missing from N150" - which I also don't understand - I would expect to take the first cut then reduce the feed for a further 'plunge' and then do a second cut (where I & J would be specified). Ultimately there would be more cuts depending upon how deep I want the hole to be.
In the light of the Mach3 error message, can anyone suggest how the Z parameter can be specified in the same block as G2 and therefore create a helical cut getting deeper with each 'turn' and if such is possible how would the final depth the specified.
In case anyone thinks that the feeds and speeds are in error I should say that this would be cutting a hardwood such as Ash, Elm, Teak, Walnut -- etc.