G93 question

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Phil
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G93 question

Post by Phil »

I just watched the video for the latest, 9.5, version of Aspire. Love the text improvements. The video showed the dramatic improvement of the G93 helical post processor, in the video the helical post processor was demonstrated as a separate post processor.
Is the G93 incorporated into the existing post processor? I don't see a separate helical post processor for the Shopbot toolpaths.

Thanks,

Phil

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Re: G93 question

Post by ger21 »

G93 is Inverse time mode, not helical moves.
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Re: G93 question

Post by IslaWW »

ShopBot does not support G93 (inverse time) mode
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Re: G93 question

Post by Phil »

What would it take for Shopbot to support G93? Is this a big, difficult deal? I have no programming experience so I don't know if this is easy or impossible.

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Re: G93 question

Post by ger21 »

I'll defer to Gary, but my guess is impossible. Unless Shopbot wants to add support for it in their control software. Which would probably be a huge undertaking.
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Re: G93 question

Post by IslaWW »

Phil...
I answered this on the SB forum. I am with Gerry, there is no need to add this to the legacy versions of the software with a new one out soon.

Having helped a bit to initiate the G93 for rotary, I am thinking you may be thinking it does more than it actually does. Inverse time mode simply uses the angular vector length to calculate the feeds for a given vector. Based on my experience, even tho it will produce very accurate and consistent feeds, in most cases it may simply slow the cut down from what you have been using
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Re: G93 question

Post by IslaWW »

To possibly reduce confusion with others that read this thread, here is what was posted to Phil's question on the SB forum:

Phil...
You are confusing the helical G2/G3 arcs with the G93. When using the spiral ramped option on a circle, the output is vastly different between the two. (G2/3 or points) In the existing version, a series of points, literally thousands of them are output and in the newer helical version it will only take a few, depending on actual numbers of passes required to cut to the required depth.

As far as I know right now, along with the G93, ShopBot does not support this feature either, as they do not support GCode arcs with Z depth change. They never have. In actuality, the fact that they do not may be the reason that the "thousands of points" version exists in the first place. GCode controllers, for the most part have had this feature all along.

Having or not having this feature should not affect you in any way, unless you have an outdated computer with little or no RAM. On the vast majority of todays control computers those "thousands of lines" will execute flawlessly
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Re: G93 question

Post by ger21 »

IslaWW wrote:
As far as I know right now, along with the G93, ShopBot does not support this feature either, as they do not support GCode arcs with Z depth change. They never have.
I just happened to notice in the Shopot Command Reference that it can indeed do helical arcs (They call it a spiral).

To verify, I installed the ShopBot Control software and tested the code below.


M2, 2,2
CG, , 2, 2, -1, 0.0000, T, -1, -.5,,,, 3
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Re: G93 question

Post by IslaWW »

Gerry...
From the fill-in sheet or the MDI, you can interpolate a circle with the CG or CP commands. That has always worked.

If you look at the attached PDF, you can see that the "Plunge" parameter is a relative distance of negative Z depth change per repetition, or revolution. So even tho your code would work for the first pass, most normal postP's would not output an "incremental" or relative Z change per revolution, they would be outputting the absolute depth of the Z at the end of that revolution. So there are a few cases where it would work, but it is another example of how unintended consequences can pop up when varying from accepted standards.

That said, ShopBot is one of the controllers that for the most part can cut the segmented spiral code that Vectric has long output. I say for the most part, because the start/stop are a bit wonky due to some issues with their ramp (accel, etc) settings. Look at this video at 00:35 and 00:51 to see (and hear) the obvious slowdowns: (toolpathed with Vectric, spiral ramp selected)


http://www.shopbottools.com/ShopBotDocs ... ComRef.pdf
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Re: G93 question

Post by ger21 »

All I was saying was that Shopbot does support helical arcs, which you said they didn't.

Of course, you'd need a proper post to use it.
So even tho your code would work for the first pass, most normal postP's would not output an "incremental" or relative Z change per revolution, they would be outputting the absolute depth of the Z at the end of that revolution.
It's really no different than standard g-code helical arcs, so it should be simple to do.
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Re: G93 question

Post by IslaWW »

Ill be standing by for that solution! :D

Maybe I should clarify. Due to some idiosyncrasies, ShopBot control will not support Gcode arcs with other than incremental Z parameters. This was designed for and works well in a on off or hand coding situation. Not so much when using a cad cam program which would normally output Z position at end of the arc execution.

So, if you were to modify a postP, it would work properly on the first revolution when Z ref is at the surface. Very few, if any other cases would work properly. Unless you can find a post processor that will output the "Z Change" per revolution
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Re: G93 question

Post by ger21 »

Man, Shopbot code is strange... :?

I didn't quite follow you, so I had to do some testing.
Once I figured out how to keep it from retracting to Z zero after each move, I see what you are saying about the incremental moves.

Thanks, you may have just saved me several hours of work. Or cost me several more hours, I'm not sure yet... :D
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Re: G93 question

Post by IslaWW »

Gerry..
ShopBot says they are coming out with a new controller soon that runs Gcode. Of course, as usual, they have been saying that for a few years. There is currently an ongoing "lively" discussion on this on their forum: http://www.talkshopbot.com/forum/showth ... dification
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Re: G93 question

Post by gkas »

IslaWW wrote:Gerry..
ShopBot says they are coming out with a new controller soon that runs Gcode. Of course, as usual, they have been saying that for a few years. There is currently an ongoing "lively" discussion on this on their forum: http://www.talkshopbot.com/forum/showth ... dification
Gary, thanks for the link. It's a good read (not finished yet). I'm a retired Systems Software Engineer. I choked when I read that the SB3 software was written in Visual Basic. Nobody in his right mind would do that for control software. No wonder there are com problems, etc. Sounds like something that was developed in a garage by an aspiring programmer. Certainly not a systems developer.

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