Out of Touch for a Few Days
I just wanted to post a warning that I’ll be travelling until the 31st and may be without Internet access for part of that time. If you place an order or email me then my responses may be delayed for a little while. Sorry for the trouble.
Post Clarification
It’s been pointed out to me that my comment a few days ago, “I’ve just ended the dumbest event in MeshCAM development in a long time” sounded like I was criticizing the user for having an older CPU and expecting it to work forever. This is absolutely not what I meant. The dumb part was that I did not take the time to read the change log or this blog earlier in the debugging process. If I had, the whole thing could have been cleared up very quickly. Sorry for any misunderstanding.
Next Release Soon
I think I found the bug that has been holding back my next release. Some users may have seen crashing when using certain models with the new offset roughing. The crashes were repeatable but would come and go as the machining parameters were changed. The problem was in the third-party library I’ve been using but it was my fault- I changed a parameter (a floating point epsilon for the programmers out there) with the intention of making everything more robust. I obviously failed and have now put the parameter value closer to where it should be. Since I didn’t write the code I have had to spend time to learn about its behavior when given the complicated real-world data that MeshCAM generates. Overall it has still been better than writing in on my own but it’s not as drag-and-drop as I would have liked.
New GRZ Software Product
In a slight departure from MeshCAM related work, Apple has just made my latest project available in the iTunes app store, Aqua Match or http://www.grzmobile.com . If you have kids toddlers or preschoolers, and an iPhone or iPod Touch, then check it out and see if it’s something you might like. My three year old likes it quite a bit and I don’t think it’s because dad wrote it- he doesn’t seem impressed about that at all.
This is not a permanent departure from MeshCAM, just a diversion to get over some writers block. MeshCAM development will resume shortly with some new ideas I picked up from the iPhone game engine I used.
New Finishing Almost Done
Below is a shot of the almost-working finishing code. The big thing pictured below is that the threshold angle is now working (set to 20 degrees below)- I forgot that I would need to know the angle of contact with the cutter to determine the angle for both parallel and waterline finishing. This took another bunch of code and testing to get done. Also, the path linker turned out to be inadequate for the task and required a lot of changes to reduce the unneeded retracts. Luckily I’ve rewritten that so many times that it went really quickly.
Before I can release the new version I’ve got to add the code to find the correct forward step, the scallop height calculation that Randy mentioned, which should be no problem. Then I just need to make sure that mm/inch units are respected in the translation for the old ZMap code to the new code. These should both be pretty straight forward but there has been a lot of plumbing changed to get this code working so I’ll feel better after a lot of testing.
Filleted End Mills
I finally got the new code for filleted end mills working. I tried a number of ways to solve the line/torus intersection problem including one from an academic paper that seemed to just not work. I had hoped to solve the equations analytically but the math becomes unwieldy and round off errors due to floating point calculations make an iterative solution more accurate anyway. Below you can see an example of all of the work. It doesn’t look much different from a current toolpath and that’s a good thing. One difference though- this one takes every triangle in to account at each step. The current zmap-based approach can miss tiny features that fall between sampling points.
I just need to test the tapered filleted end mill and then I can move on to integrating it into the new finishing toolpath code.
Toolpath Update
The new ZMap-free finishing code is still in progress. I have only two types tool left to code, straight and tapered endmills with a corner radius. These are probably the most difficult because the math defining a torus is complicated.
If I can get this done within the next 3-4 days then I should be able to get the new finishing path done in the next few weeks. So far it’s not very fast but I haven’t had much time to dedicate to optimization. Hopefully any loss in speed will be more than offset by using less memory and only having to calculate the actual toolpath, not all the extra information that is currently calculated that is not directly part of the output path.