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Author Topic: Engraving around outside of a tube  (Read 8559 times)

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Offline birdbrain

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Re: Engraving around outside of a tube
« Reply #10 on: December 20, 2009, 12:13:12 PM »
why is "special" software needed for wrapping engraving gcode round a cylinder? just swap the Y code to the A code and as long as the steps per are set right - job done. Isn't it?
I have been considering doing this by running a search/replace on the g-code changing all instances of "Y" to "A". The only thing stopping me trying it is that the g-code certainly has G2 and G3 moves. I seem to remember reading in the Mach3 manual that G2/G3 are limited to the XY plane. Would it be OK to have G2/G3 in the XA "plane"?
Re: Engraving around outside of a tube
« Reply #11 on: December 20, 2009, 12:41:01 PM »
>why is "special" software needed for wrapping engraving gcode round a cylinder? just swap the Y code to the A code and as long as the steps per are set right - job done. Isn't it?

Depends on the job.  On some it will make no difference, for others the aspect ratios are really screwed up.  I engraved some deer around the outside of a ring for a deer-hunting buddy of mine.  Without adjustment for the circumference of the ring, the deer looked like dachshunds with antenna!

Bob @ BobsShop - Disclaimer for the benefit of the humane society - No deer were injured in the cutting of the ring!

Offline birdbrain

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Re: Engraving around outside of a tube
« Reply #12 on: December 20, 2009, 02:17:36 PM »
Would this work?
Take an existing g-code file and change it from cutting on the XY axis to cutting on the XA axis by replacing references to the "Y" axis with "A".
The A axis is rotational. It wraps around the X axis in place of linear Y axis.

e.g.
before replacing "Y" with "A",
G0 X10 Y10
G2 G91 X2 Y2 R3 F100

afer replacing "Y" with "A",
G0 X10 A10
G2 G91 X2 A2 R3 F100

Of course, I know that there will be scaling needed on the A axis. The point that I would like to know about is whether G2/G3 code can be used on XA axis as it can be on XY axis.

Offline stirling

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Re: Engraving around outside of a tube
« Reply #13 on: December 21, 2009, 04:37:58 AM »
If replacing Y with A in the code doesn't work because Mach doesn't like doing G2/G3 in the "XA" plane then just swap the settings in ports n pins so that the rotary axis is Y. As far as aspect ratio is concerned - that's what I meant above by get the steps per right.

Cheers

Ian

Offline birdbrain

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Re: Engraving around outside of a tube
« Reply #14 on: December 21, 2009, 10:32:35 AM »
If replacing Y with A in the code doesn't work because Mach doesn't like doing G2/G3 in the "XA" plane then just swap the settings in ports n pins so that the rotary axis is Y. As far as aspect ratio is concerned - that's what I meant above by get the steps per right.

Cheers

Ian

Would it be possible to change the port configuration automatically from within a g-code file, perhaps by running a macro or a vb script?

Offline Graham Waterworth

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Re: Engraving around outside of a tube
« Reply #15 on: December 21, 2009, 10:47:32 AM »
In most CAM systems you can output arcs as line segments then you have no G02/3's.

A better option is to do things right and get your CAM system to wrap/project the image over your cylinder, then output the code as X and A axis code.

Graham
Without engineers the world stops

Offline stirling

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Re: Engraving around outside of a tube
« Reply #16 on: December 21, 2009, 11:13:19 AM »
Hi Graham - whilst I appreciate what you're saying and would generally agree when you say - "do things right". It seems to me that software that "wraps" an image over a cylinder is just money for old rope. What does it do? It "rolls" the image and then your CAM generates gcode that effectively "unrols it" again. So we invest in CAD that can project round a cylinder and CAM that can generate 4th axis code and what do we end up with? same old code we could have created far simpler and at a fraction of the cost. Even "ace converter" could handle this one - well actually it would probably crash but...

Cheers

Ian

Offline ger21

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Re: Engraving around outside of a tube
« Reply #17 on: December 21, 2009, 11:27:08 AM »
I believe that CNC Wrapper converts the G2/G3's to linear moves automatically.You can spend $20 and let the software handle it for you, or you can spend hours of your time constantly switching setups to do workarounds that you don't have to do.
Gerry

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Offline stirling

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Re: Engraving around outside of a tube
« Reply #18 on: December 21, 2009, 11:39:07 AM »
Fair comment Gerry but its hardly hours is it? modifying your Y axis steps per and step and dir pin numbers should take about a minute at a push. You then save as a separate profile. One for linear Y one for rotary Y - job done and down the bar with your $20.

Now I'm out of here - I (now) know when its time to stop flogging a dead horse.  ;D

Cheers

Ian

Offline birdbrain

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Re: Engraving around outside of a tube
« Reply #19 on: December 21, 2009, 11:55:32 AM »
Fair comment Gerry but its hardly hours is it? modifying your Y axis steps per and step and dir pin numbers should take about a minute at a push. You then save as a separate profile. One for linear Y one for rotary Y - job done and down the bar with your $20....

Thanks, Stirling. That's what I want to do.
How do I get Mach3 to save and load different profiles??