CAMBAM and TinyG turing arcs into straight lines

Discussion of tinyG control platform
psppb
Posts: 38
Joined: Tue Jun 17, 2014 7:57 pm
Location: Mlwaukee, WI

CAMBAM and TinyG turing arcs into straight lines

Post by psppb » Fri Jan 23, 2015 3:10 am

Greetings.

It appears more problems are falling through the cracks. I designed a part on CAMBAM and ran it on my SO2. I looked at it with OpenSCAM and saw that it cut all the arcs as per CAMBAM commanded, I looked at the G code and there are in fact arcs inside the code (I, J commands). I then ran it on my machine. Two things happened. It moved the Zero 4 inches left (-X) so I had somehow -4,0 for my origin. THis did not show up on openSCAM and second of all the even more weird part was that it cut nothing but straight lines where it should have been cutting Arcs. VERY WEIRD. Has anyone Seen this? I am attaching three files. The first is the NC code CAMBAM created. The second is the $$ settings dump from the tinyG. PLease tell me there is something wrong with my settings. I am stumped on this one

I have no idea what is causing this? the code looked fine.

Please help!

Thanks

Bill
Attachments
tinyg_settins_Jan_22_15.txt
(9.21 KiB) Downloaded 45 times
Crate_two_nest_2.nc
(13.88 KiB) Downloaded 37 times
Bill

22" x 32" Shapeoko NEMA 23, ACME screw upgrade, DW660 Spindle with TinyG controller

AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

Re: CAMBAM and TinyG turing arcs into straight lines

Post by AlBorland » Fri Jan 23, 2015 4:18 pm

Hi,
the chordal tolerance $ct is set to a very high value on your tinyg, pretty sure that is the cause of your second problem. Normal value is 0.01mm, see also https://github.com/synthetos/TinyG/wiki ... -tolerance

The 4 inch offset could have been a WCS offset, but there are no offsets stored in the configuration, nor is there a G55 or something in the gcode. Might want to retest that, and if you have the offset again, look closer on which coordinate system is in effect (G54..G59 and/or G92). Which gcode sender are you using?
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

psppb
Posts: 38
Joined: Tue Jun 17, 2014 7:57 pm
Location: Mlwaukee, WI

Re: CAMBAM and TinyG turing arcs into straight lines

Post by psppb » Sat Jan 24, 2015 12:00 am

I am using TGFX. Thanks for the advice!

The coordinate system is G54 I believe.

Bill
Bill

22" x 32" Shapeoko NEMA 23, ACME screw upgrade, DW660 Spindle with TinyG controller

psppb
Posts: 38
Joined: Tue Jun 17, 2014 7:57 pm
Location: Mlwaukee, WI

Re: CAMBAM and TinyG turing arcs into straight lines

Post by psppb » Sat Jan 24, 2015 1:17 am

Correction I'm using G90

Code: Select all

( Made using CamBam - http://www.cambam.co.uk )
( Crate_two 1/22/2015 8:24:42 PM )
( T3 : 0.125 )
G20 G90 G64 G40
G0 Z0.125
( T3 : 0.125 )
T3 M6
( Profile1 )
G17
M3 S1000
G0 X5.4692 Y1.8607
Bill

22" x 32" Shapeoko NEMA 23, ACME screw upgrade, DW660 Spindle with TinyG controller

mristau
Posts: 27
Joined: Thu Nov 20, 2014 4:50 pm
Location: Northern Colorado
Contact:

Re: CAMBAM and TinyG turing arcs into straight lines

Post by mristau » Sun Feb 08, 2015 9:50 pm

Reply deleted. I see now that it was not appropriate in this thread. (Oops)
Last edited by mristau on Tue Feb 10, 2015 3:22 am, edited 1 time in total.
Build in progress: 1100x1100mm workarea using salvaged 45x45mm extrusions with Openrail, tinyG/435.10/v.0.97, NEMA 23s, belt drive XY, Acme Z, 400W PWM Spindle, lasercut 1/2" acrylic motor/wheel mount plates.

mristau
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Joined: Thu Nov 20, 2014 4:50 pm
Location: Northern Colorado
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Re: CAMBAM and TinyG turing arcs into straight lines

Post by mristau » Mon Feb 09, 2015 5:31 am

Reply deleted. I see now that it was not appropriate in this thread. (Oops)
Last edited by mristau on Tue Feb 10, 2015 3:22 am, edited 2 times in total.
Build in progress: 1100x1100mm workarea using salvaged 45x45mm extrusions with Openrail, tinyG/435.10/v.0.97, NEMA 23s, belt drive XY, Acme Z, 400W PWM Spindle, lasercut 1/2" acrylic motor/wheel mount plates.

WillAdams
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Re: CAMBAM and TinyG turing arcs into straight lines

Post by WillAdams » Mon Feb 09, 2015 11:31 am

List of G-codes w/ notes on what's supported or no: http://www.shapeoko.com/wiki/index.php/G-Code
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
Nomad 883 Pro #596 (bamboo)

cmcgrath5035
Posts: 61
Joined: Thu Oct 31, 2013 6:56 pm
Location: Florida, USA

Re: CAMBAM and TinyG turing arcs into straight lines

Post by cmcgrath5035 » Mon Feb 09, 2015 12:08 pm

The most current tinyG fw is 438.02, but installing that might compromise your use of tgFX.
Unclear if the issues fixed by 438.02 are relavent here.
You should plan too migrate away from tgFX, future tinyG builds will not be well supported by tgFX and there is not further development planned for tgFX

Why bother generating Gcode to 4 decimal places?
Makes for very large Gcode files, minimum actionable distances for SO2 are likely in the 0.02mm range.
Two decimal palces should be adequate.
I don't use CAMBAM, but understand from others that this precision is settable somewhere?
ShapeOko (V1) SN 1462
Dual 820mm Y, Double X, ACMEZ. V2 Motor Plates
TinyG V7 Controller; DUE and tinyGV9 test bed for tinyG2

cvoinescu
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Re: CAMBAM and TinyG turing arcs into straight lines

Post by cvoinescu » Mon Feb 09, 2015 12:27 pm

cmcgrath5035 wrote:Why bother generating Gcode to 4 decimal places?
Makes for very large Gcode files, minimum actionable distances for SO2 are likely in the 0.02mm range.
Two decimal palces should be adequate.
You need at least four decimals in inch mode and three in millimeter mode, regardless of the actual accuracy or resolution of the machine, because the "standard" (such as it is) says the arc endpoint for G2 and G3 should be on the circle determined by the current position and the center (I, J, and/or K) to within 0.0002" or 0.002 mm.
Proud owner of ShapeOko #709, eShapeOko #0, and of store.amberspyglass.co.uk

cmcgrath5035
Posts: 61
Joined: Thu Oct 31, 2013 6:56 pm
Location: Florida, USA

Re: CAMBAM and TinyG turing arcs into straight lines

Post by cmcgrath5035 » Mon Feb 09, 2015 12:48 pm

Code: Select all

You need at least four decimals in inch mode and three in millimeter mode, regardless of the actual accuracy or resolution of the machine, because the "standard" (such as it is) says the arc endpoint for G2 and G3 should be on the circle determined by the current position and the center (I, J, and/or K) to within 0.0002" or 0.002 mm.
Thanks, did not know that. I generally ony read the standard when something does not work.
Gcode generators that I use (with success) generally are two digits in mm mode.
I'll have to assume tinyG does some sort of best effort.
ShapeOko (V1) SN 1462
Dual 820mm Y, Double X, ACMEZ. V2 Motor Plates
TinyG V7 Controller; DUE and tinyGV9 test bed for tinyG2

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