Good question Robert. I will often use a splined Z arc for entries into the material. I just created one in Vector and simulated it in Mach3 and the 3D arc file gave this warning "K word given for arc in xy plane on line #2". The spline arc file ran fine. It looks as if if doesn't, but maybe someone more experience in Mach/G-Code can shed further light.

(files in original Forum here)

Robert & Scott, the word "spline" in your posts confuses me. If you are asking if Mach3 can do straightforward helical motion, then the answer is "yes".

Don't use it myself, but often see the other guys discuss it. (Used for milling threads)

Gerald,
My question is based on doing the following.

If I set up a lathe on my PRT and use a side mounted router then I would just cut the curves on the X and Y plane. If I cut with the standard router mounted in the Z axis then I would cut along the Z and Y plane. As the ShopBot software can't recognize the radius in the Z plane I would have to use Vector to break the curved lines into straight segments. I was wondering if that was also true of the Mach 3?

I am not sure if I understand enough about radius tool paths in 3D.

Thanks,
Robert

Gerald, maybe it should be called an arc that has been interpolated in Vector (Change/Break/Interpolate) into segments. On the flip side, you can then take the result of that or any chain of segments and do a Arc/Spline to smooth it out by fitting arcs and splines (straight segments).

Isn't the helical motion for cutting threads or spiral down pocketing a "canned" cycle much like ShopBots CC or CP with spiral and bottom pass?

Here's another example more like what Robert explained above. One is in the XZ plane and one in the XY plane. The XZ one gives the error and the XY obviously runs normally. I don't fully understand why the K word gives an error in the XY plane when K is for Z axis offset for arcs.

Just for fun, what if you swapped the Y and Z cables, feeding Y moves to the Z and the Z for the Y. Hmmm...It's to late to wrap my mind around that tonight. http://www.mechmate.com/Forum/clipart/crazy.gif

Files in original Forum here

I think you gents are using the word "spline" for a polyline of straight line segments - I think a spline is a more complex thing.

When Vector's postprocessor gives you a lot of straight bits, it does not mean that this is what Mach3 wants. Mach3 uses the standard G2 code for circular or helical interpolation. Vector doesn't seem to recognise this?

An example of a flat circle in the X,Y plane:
G1 X0.0 Y1.0 Z0.0 F20.0 --go to X1.0, Y0.0 at a feed rate of 20 inches/minute
G2 X1.0 Y0.0 R1.0 --go in an arc from X0.0, Y1.0 to X1.0 Y0.0, with a radius of R=1.0

If you want a helical plunge of 1" then:
G1 X0.0 Y1.0 Z0.0 F20.0
G2 X1.0 Y0.0 Z-1.0 R1.0

The G2 command also works in the other planes, and it can work with R (radius) as above, or with I,J,K coordinates.

With a Google on G2 Helical, found this page that explains G2/G3 quite well. The helical bit is actually a minor, logical feature - see "3D Circular Interpolation" right near the end of the page. Makes one wonder why SB doesn't do it.

Thanks Gerald,
I need to spend some time reading up on G2 code. My questions stem around plans to build another machine leave me wondering about which software is best suited for the future. I presently go from Acad to Vector 9 (I have held off on upgrading Vector)and then ShopBot. I am more of an end user desigher and builder, lacking when it comes to grasping the best software solutions and all the programming details.

Thanks, Robert

Robert, we also go from AutoCad to Vector 9 and then to machine code (either ShopBot or G-Code). It doesn't bother us that Vector chops a curve into little straights because the file size is not an issue, and because we can specify the tolerance with which Vector does the chopping.

I think the time is fast approaching for AutoCad to give code directly - quite a few people are working on it. That's why we aren't investing more time into Vector.

Hi folks,
In order to help me think around this mach - sb issue, could one of you g code folk tell me if it is possible to use programming statements, if, or loups with interface, in a gcode file, in order to make it interactive?
I have several files of this sort, for morticing, tennoning and dovetailing, that I can just fill in the numbers and press go.

r/.

Some M-codes are standardised (eg. M3 always seems to be "start spindle clockwise") and cannot be user-defined. See more in this doc. The Mach3 guys seem to use M600's for their subroutines.

Ralph,
Another option would be to use the programming language of your choice to do the actual computations and then have that language generate G-code. That's the way that I wrote the doors program for the Shopbot. I started by entering all dimensions into a spreadsheet and then using 'C' to read the spreadsheet. The 'C' program computed the tool path using the data from the spreadsheet and then wrote shopbot code to SBP files. By doing that, I was only limited by 'C' and not by the commands available in Shopbot's language.

Gerald,
Unfortunately I don't know (aka have avoided like the plaque) VB. Is it the same as VBA? I'm a bit old to learn new languages (I'm struggling with Italian at present, having put Chinese on indefinite pause), unless they are seriously simple scripting like shopbot. I'll look into it, but I guess that whatever language you use, it must interact with windows.
Mike,
Trouble is, what I like to do is stand at the console next to my benchtop and put in the numbers as I go - sometimes 2 sets in succession for the same setup. Partfiles I build on a separate computer in my teeny office. I have a second horizontal motor on my Z for tennoning, horizontal pocketing etc, and I only use this with such interactives. To build partfiles for such a setup would be beyond most simple software and my teeny brain.

R.

Ralph, I'm out of my depth here! Looked at the Mach discussion forum a bit more and it would appear that VBA is also being used? Wonder if the actually language really matters - maybe Italian will do? http://www.mechmate.com/Forum/clipart/happy.gif

Thanks.
I only said VBA because it is included with wordperfect (my wp). Ill have a look.

ciao

(:

Ralph,
Using Google's "define: vba" feature, I found this:

VBA is "An abbreviation for Visual Basic for Applications, the official name of which is "Visual Basic, Applications Edition." VBA is Microsoft's common application programming (macro) language for Access, Excel, Project, and the Visual Basic programming environment."

Somewhere, way in the past, I looked at it for a few weeks when I was looking at various methods to connect to and extract data from databases.

Here is something that Art posted on his forum today:

"Shopbot camp was very interesting and has led to a few ideas and a few code
correction plans.....Seeing the shobot in operation gave me a few hints about a few things that need to be done.."

I was at the Kansas Camp and met Art. I would like to add "hold on to your hat" we have not seen anything yet. Mach3 Rocks! This group is motivated and full of ideas. I think Art spends over 12 hours a day working on his program. It is only going to get better for everyone.