When I lent my services to a collegue who was working on a film about 12 years ago, I was introduced to the world of cnc. I remember watching this huge machining centre milling out a slab of mdf and turning it into a fantastic set of gears. I knew that it would have taken me hours to achieve the same thing with traditional power tools. I decided then that I would invest in a cnc router for my own business Oxenham Design. At that time I could turn on a computer, but even to check email seemed like a crazy set of operations. I persevered and learned every piece of relevant software I could get my hands on. I am now fortunate enough to be using Vectric's ASPIRE software, and Techno cnc routers, which has helped us to create some amazing projects, both in part, or in full. I thought that this blog would be a great place to share "behind the scenes" adventures with the software, materials and equipment we use, as well as the projects we build.

Monday, 5 January 2015

Toolpathing in Aspire, the l-o-o-o-ng hard way!

First off, I hope everyone had an amazing holiday season, and Jody and I truly hope that the arrival of 2015 brings amazing things for everyone!!

We had a few NDA projects over the holidays, and a couple that weren't. So I thought I would get started with the couple that we're allowed to share.

The first one was what should have been a simple one, but progressively took more time than I had planned on. Hey, it can happen!

A neighbor a few units down from us does major renovations, for some pretty big custom properties.
He had contacted us in hopes that we could match his custom trim profiles for a series of arched top windows in a huge house he was building.

"Sure, should be pretty quick" I thought out-loud...............

I took his trim profile, traced it onto a sheet of paper, and scanned it into the computer, and adjusted it for some minor differences. This clearly would be made from 2 pieces, as the machined out waste would be way too much!

I tackled this this project in the usual way. I swept my profile along the 2 rails that match the window opening, then set up a 3d offset machining strategy, so the cutter would machine along the length of the trim, hopefully giving me a wonderful piece of custom trim, that will match exactly to all the other trim that already exists.

 Here's where it pretty much fell apart for me!

Due to the X and Y size of the window trim, versus it's relative skinny width, versus the resolution of Aspire on an entire 4X8 sheet of MDF, it didn't come out very well. On a 4X8 sheet, with the maximum 50X resolution (the highest Aspire reaches) it put a voxel pixel at around 1/16th of an inch. So couple that, with a .125" cutter, and you get a relatively rough piece of trim. Add to that, the long 3d machine time of multiple pieces of trim, and it all boils down to finding a better way to deal with this. The estimated machine time, including cutter changes, was 6 hours a sheet. PFFF.......

Aint nobody got tahm for dat!

So I was forced to re-think the process. I decided to go with many, many, many, single profile toolpaths, at the varying heights required.
So the above image was my self-torture test. Each circle represents the .125" ballnose cutter, and the vertical lines are the .025" stepover. These were originally laid out in Corel, as I still find I'm faster at some portions of vector work in it. But the actual offsetting of the vectors for the all the trim profiles, was done in Aspire, because that portion was faster in it.
This was the vector-jenga-mess I ended up with! Then it was just a matter of assigning each vector to a separate profiling toolpath, with the cut depths based of the first image above. The good news is I was able to re-purpose all the toolpaths for each successive piece of trim. Then I just saved all 27 profile cuts, for each piece, to one toolpath file.

WAAAY more computer time than I had first anticipated, but it got the machine time down to 45 minutes a sheet, and the trim was flawless!


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