GRBL rotary questions

Topics related to wrapped rotary machining in Aspire or VCarve Pro

GRBL rotary questions

Postby PhilJohnson » Tue Jan 15, 2019 9:24 pm

Hello. I'm about to finish my Rotary Demon build. I know conceptually what I need and how it works. I just need a little conformation and a few questions answered.

What I know
1. my rotary is a K11 100 with a 6:1 reduction.

2. I'm running my CNC DemonLTE controller which is a 3 driver version on my CNC Demon controller (TB6600 drivers). So I have only 3 axis. X, Y, Z.

3. I know this can be done because it already has been done on a GRBL based machine, just not as a dedicated machine like my design.

4. I will need to write a post processor for my machine (not to worried, I'm comfortable with that).

5. I will need to figure out my steps per mm for my rotary.

my questions.
1-3 are just statements to help you know where I am.

For 4:
In the post processor, I will have to make the output A convert to Y because my rotary is my Y axis. Is this correct and is there an example out there already?

For 5:
5a) my assumption is that once I have it set correctly, the jog distance should be degrees. As in I send G0 Y360, it should revolve 1 revolution exactly at rapid rate.
Is that correct?

5b) Also, then feed rate would be degrees per minute? So G1 Y360 F360 should take 1 minute to revolve around once. Is that correct?

Thanks in advance for your help!
my machine plans are here if you are interested.
http://www.designsbyphil.com/rotary-demon-cnc.html
Phil Johnson
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Re: GRBL rotary questions

Postby PhilJohnson » Tue Jan 15, 2019 10:10 pm

Or since my controller IS Y for the rotary, Do I even need a different post processor than my standard GRBL cnc machine? Does Vcarve output Y if I tell it to wrap around the Y in the project?

I will be using rotation center as my zero always.
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Re: GRBL rotary questions

Postby PhilJohnson » Wed Jan 16, 2019 4:08 pm

OK I think I am on to something for the post processor looking at the shopbot indexer post processor. Using that 1 triggers a secondary option Box when saving G code that has to do with changing the axis to degrees. The hurtle I see now is figuring out why it was saying a completely round model was wrapped around the cylinder a 114゚ instead of 360°.
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Re: GRBL rotary questions

Postby PhilJohnson » Wed Jan 16, 2019 7:39 pm

ok after talking to support and looking at videos, I believe I have it figured out. I should be able to get it to do exactly what I want.
My main issue was not having the ALONG X axis or Y axis correct. Once I figure that out, I'll be set. If anyone is interested, here is my post processor so far. I need to test and possibly adjust, but it's close.
Attachments
Rotary_Demon_inch_paj.pp
(4.08 KiB) Downloaded 68 times
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Re: GRBL rotary questions

Postby Rcnewcomb » Wed Jan 16, 2019 9:13 pm

I'm so used to reading rotary post processors with A and B moves it was a bit different to see XYZ moves.

I'm impressed that you put in ARC support.

I look forward to seeing some of your first projects on the rotary.
- Randall Newcomb
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Re: GRBL rotary questions

Postby PhilJohnson » Wed Jan 16, 2019 11:57 pm

I started with my current modified x-carve post processor. The arcs are already in that. I'm using the same grbl version. I can't wait to test!!
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Re: GRBL rotary questions

Postby PhilJohnson » Thu Jan 17, 2019 12:52 am

Anyone know what in the post processor triggers the secondary menu
Attachments
screen 1.png
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Re: GRBL rotary questions

Postby PhilJohnson » Thu Jan 17, 2019 2:43 pm

FYI I figured it out. The job orientation in vcarve must match the wrap orientation in the post processor to activate the rotary tool path saving dialog box.

When I am done tinkering I will have a post processor for a rotary CNC machine for GRBL.
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