Wrapped post processor for EMC2

Topics related to wrapped rotary machining in Aspire or VCarve Pro
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judedude
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Wrapped post processor for EMC2

Post by judedude »

I have just recently added a 4th axis rotary to my CNC router. I am using V-Carve Pro. Does anyone have a PP that can be used for EMC2? Any help would be appreciated :)

Greolt
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Re: Wrapped post processor for EMC2

Post by Greolt »

JudeDude

What PP are you presently using? What configuration is your machine? A axis rotating around X axis?

Greg

judedude
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Re: Wrapped post processor for EMC2

Post by judedude »

I am using the emc post in VCarve Pro 6. I have the rotary configured as an A axis in degrees. The rotary is parallel to the X axis so I would be wrapping the Y values. I tried to generate the G code using the emc post by it gave me X and Y values not the wrapped code I was expecting to see.:(

judedude
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Re: Wrapped post processor for EMC2

Post by judedude »

Some pictures of the rotary. I used part of a sherline lathe and a couple of timing pullys. I cut the stepper mount and baseplate on my CNC.
Attachments
rotary.jpg
rotary1.jpg

Greolt
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Re: Wrapped post processor for EMC2

Post by Greolt »

Try this PP. Based on the EMC2 one.

Test in the air before committing tooling.

Greg
Attachments
Emc2_Wrap YtoA_inch.pp
(3.04 KiB) Downloaded 437 times

judedude
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Re: Wrapped post processor for EMC2

Post by judedude »

Greg I ran the geometry thru the post processor. The G code created values for A from about -560 to -460. The rotary is set up for 360 degrees and it doesn't like negative values. I expected the output to be between 0 and 360. I could change the set up to cope with the negative numbers but i don't want the work to rotate one and 1/2 times to start. This might work if we subtracted 360 and made the numbers positive.

Greolt
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Re: Wrapped post processor for EMC2

Post by Greolt »

Negative values are as legitimate as positive. Depends where you set the origin.

Post the Vcarve file which is giving -560. I will take a look.

Greg

judedude
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Re: Wrapped post processor for EMC2

Post by judedude »

Greg you are right I corrected the rotary configuration. Now it runs. The G code does have areas without Z heights. The rotary is moving really slow at these points. I am looking at feed rates right now. The velocity and acceleration seemed OK in the configuration. I am using 1/2 stepping because Daves Hobby CNC board misses steps at 1/4 stepping with his current reduction.

judedude
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Re: Wrapped post processor for EMC2

Post by judedude »

Greg
I been at the EMC form trying to understand this behavior. Basically the velocity cutting on a small diameter is not the same as that velocity on a larger diameter. Is there anyway the PP can adjust the feed rate based upon the wrap diameter input into V Carve and use this feed rate for the rotary only milling moves.

Greolt
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Re: Wrapped post processor for EMC2

Post by Greolt »

judedude wrote: Is there anyway the PP can adjust the feed rate based upon the wrap diameter input into V Carve and use this feed rate for the rotary only milling moves.
Mach3 has an inbuilt feature to compensate the rotary axis feedrate, based on the diameter that the tool is cutting.

Shopbot code has the ability to scale an axis feedrate. Gcode does not.

I have no experience with EMC. Perhaps it has a similar feature as Mach. I can't help you much there.

Greg

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