4 th Axis with CNc toolkit

[Bubba]

Administrator,please relocate this to proper area if this one isn't proper. I simply don't have an idea where to place this. I know some would have other suggestions   .
Here it is my final result of creating continuous motion 4th axis toolpath Using CNC-Toolkit and Gmax. I been working on this thing for awhile  trying figure out how all this works together. It took time and effort because good manuals and any advice is hard to find on this subject . The pictures are in sequence to show progress.

This picture shows first step of importing converted STL to 3DS solid and align to proper axis (Gmax accept this format)  

[Bubba]

This pic is showing spline creation along X axis by the CNC-Toolkit script.

[Bubba]

 spline projection along X axis by the CNC-Toolkit script.

[Bubba]

Continuous motion 4th axis toolpath

[Bubba]

Post processed toolpath created by CNC-Toolkit and in Mach3.

[Bubba]

End product picture and possibly short video is coming.. soon.

[dh42]

Hello,

I have cut the topic and moved the discussion about CNc toolkit in related software.

++
David

[Bubba]

Thanks.

[Garyhlucas]

Now that I actually a machine with a real 4th axis (10" with an 8" six jaw chuck) it would be nice if CamBam supported a 4th axis.

[Bubba]

Certainly be nice. But, I think I found a solution I have lots true 4th axis work lineup and wrapper just won't cut it in my opinion. Some solid models I use needed to unwrapped and I don't have or know a way how to do this. Anyway if it be better way(by unwrapping solid) nobody would write a expensive software for rotational axis work.Thankfully I found this and it looks like it going to work for me. It is absolutely free, all it took is time and effort to understand it. I got long way to but I feel like I'm getting there. So If any one need help I certainly going to try provide some answers and solutions. Keeping in mind that principal of 4 axis machining I'm very familiar with, but,  the use of Gmax and CNC-Toolkit script is very new to me.

[Camden Blue]

I've been a fan of cnc toolkit for many years. The more you use it the more you realize just how powerful it is. The biggest flaw that I remember it having was it did not have automatic offsets for cutter diameter. For example to cut a simple circle pocket or square pocket with even a three axis machine required you to draw the circle or square smaller because the tool path followed the exact line drawn. It quickly grows complex even with simple text since you now have some lines needing to be offset inside and some lines being offset outside by half the cutter diameter. Getting a 3d tool path that's accurate without cutter comp would require a strange looking drawing in 3d. Maybe they fixed that since I used it last? With a very small engraver type tool that comes to a point will get you closer to what your after but it will not cut right in deeper sections where your tool has to cut farther away from it's tip since it's a v-cutter.

I had always hoped that someone would have taken the ball and ran with it once cnc toolkit went open source. But here we are years later and no further development has happened. Maybe it's simply a matter of letting today's current coders knowing the source code is out there. There's no point in re-inventing the wheel when a huge chunk of code has already been chiseled out of rock for you.

Cambam is great for what it does but I'm one who's also been waiting for the forth axis option. I too think a script to interface the two programs together may work but I also think if we could put the Cambam developer in the same room as the CNC Toolkit developer we would end up with a program that could do it all. It might mean sharing the profits with one another but the user base would grow so big that it might be worth it. I almost passed on a license for Cambam just because it did not have the 4th axis. There seems to be a huge jump in price once you move up to the 4th axis software.

For now I'd settle for an option to do 4th axis work the way Meshcam approaches it and that is to attack it like 3 axis work from more than one angle. Since Cambam can already generate 3 axis code, I think this option would be the easiest and cheapest to implement. 

[Bubba]

" The biggest flaw that I remember it having was it did not have automatic offsets for cutter diameter. For example to cut a simple circle pocket or square pocket with even a three axis machine required you to draw the circle or square smaller because the tool path followed the exact line drawn. It quickly grows complex even with simple text since you now have some lines needing to be offset inside and some lines being offset outside by half the cutter diameter. Getting a 3d tool path that's accurate without cutter comp would require a strange looking drawing in 3d."

That's what stopped me from pursuing anymore, because of the clumsy approach needed. After spending so much time trying to work right and not getting good result I simply given up..

[dave benson]

HI All
I have had a cursory look at the problem (still trying to add a cancel button to the collision detector) and I'm afraid I'm not multitasking so I'll look deeper when that's finished.
So what did I find, well the cnctoolkit uses "spline morphing" which is a 3D built in function of Gmax to make the roughing tool paths. This is akin to the lofting function in cad programs. This is the function that makes the tool paths by morphing  the stock shape into the work piece shape.
CB doesn't have this function so it has to be made first. This is not a trivial matter.
I cast around for a library to do this and OpenCv has it, But it may be difficult to integrate.
CB uses OpenGL from which a morphing function could be made, and I found a German  Uni site where they have done something similar for Images.
This is the site on the page about half way down you can see what I mean.
Look for B spline warping. Images
http://cg.cs.uni-bonn.de/project-pages/imogl/
If a library or function could be made from their work (It's Open Source) then you would be More than half way there.
I think this needs to be a collaborative work with at least two or more people working on it to make it happen quickly. There are other ways to get the job done (by slicing the work piece up, rotating 90 deg and applying a profile mop and then remapping the tool paths back to the correct position) This is not truly 4 Axis tool paths
in the strict sense of the meaning. But may be a quick alternative when all else fails!.
Dave

[EddyCurrent]

Just an idea that I've not fully thought through but might promote some other idea.

So you have a 3D model that you want to cut from a piece of stock. Instead of the warp idea, which I like the sound of by the way, what if the 3D model was just increaed in size then gradually reduced to form cut layers like onion skins ? It would have to be transformed in size for Z and Y only.
Not very efficient and would be slow I suspect.

[dave benson]

HI Eddy
Yes that's a good analogy onion skins, that's what the cnctoolkit doe's by spline morphing.
the work piece is increased in size by the depth of cut and splines are produced along it's surface at that depth
and then rinse and repeat until you get to the stock dimensions. This is a slow process and true 4th axis
machining optimises these further so that if you have a flat area on your work piece it doe's those like traditional tool paths to speed thing up . I've had a look at some youtube  videos of spurtcam among others
and watched how they programed the tool paths seems like they had a special mop where they added details to it much like we do for our various mops. I do like the idea of having a fourth axis and it would be fun to write some code for this for CB, But it's harder to do than it looks at first blush.
I wish I could get some "hands on"  use of 4th axis software to get a feel for it.
Dave