I warn you this tutorial it’s rather long and dry. Still, if you are interested in learning more about Tool-path Tiling then do continue. This first installment will focus on the Tool-path Tiling and how I am planning on using the technique to “Super Size” my new CNC. The more I thought about it the more complex it became. So for nothing else, I needed to document my ideas. If this helps someone else all the better.
Still patiently waiting for my new Onefinity CNC machine to arrive. Is it October yet?
In a previous post I explained why I went with the smaller machine when I put in my pre-order. Cost and space were the two big reasons. Still, I want to be able to work on larger pieces than the 16″X16″ work envelope the Machinist can cut. You can’t always get what you want. But if you think real hard maybe you can get what you need?
I created an overview of my project plans to Super Size my new CNC. The video give an brief introduction on Tool-path machining focused on how it relates to my plans. Further below there is a video from Vectric Software that describes the method in much more detail.
Since deciding on buying the new CNC I have been working on how larger pieces could be cut. Studying the unique design of the Onefinity machines with open frame rails and no attached base looks a little odd compared with most CNC machines. but the odd configuration with no attached base also opens up some unique mounting possibilities. Some of the product demos show the machine mounted vertically on a wall and it seems to work fine. I started to envision a way that could work and that gave me confidence in my buying decision.
Even if my Supersize plan doesn’t’ work the upgrade gives me a 80% increase in cutting area over my current micro CNC with it’s 6×8 cutting area.
Two Main Issues to Overcome
There are two areas each with their distinct set of issues to overcome coming up with the scheme.
- Technical – How to create tool paths with the smaller machine to handle larger pieces,
- Mechanical – How to configure the machine to handle the larger work.
Part I will focus on the technical issue mainly tool-path tile machining. To be honest tile machining is not new nor unique. It is used all the time by sign makers. I was aware of the technique but there was much I needed to learn. Probably because of my engineering background I needed to understand the technique in detail. I Keep mentioning that engineering is a series of trade-offs. Understanding those trade-offs allowed me to come up with a twist that will help me meet my design goals.
Before I get too far down the path we need to have a good understanding on how tool-path tile machining works. For those not familiar with the technique here is a good tutorial from Vectric explaining how it works much better than I could.
American Flag Example Project.
I found a quick STL model of an american flag cut in the shape of our country to use as an example project The 24×16 size is fairly typical for Flags and I scaled it to fit inside my 24×24 target size.
Following the Vectric video instructions I sliced up my 24×24 project into 16×16 tiles. I created a section grid that helps me keep things straight. Tile1 is a full 16×16 area while Tiles2-4 are only partial tiles. That is not a problem because tool-paths will only be generated were there are vectors. I could have chosen 8×8 tiles but that would mean keeping 9 sets of vectors and much more fiddling around with workpiece shifting. It always works out better to make use of your full work bed when you can.
I made a quick video demonstrating the cutting simulation done in Aspire if you pardon my voice over skills.
Problems with the Common Way of Tile Machining
So the Tiling technique works fine. But there are a few issues I am not satisfied with. First shifting the 24×24 board 16″ means you need 32″ of working space on the X and the Y. This kinda kills my intention of minimizing space.
Another problem is you end up overhanging a large percentage of your workspace off the cutting area. You would need to support the overhangs. The extreme case would be milling the Tile4 section of our example with a shift left and down of 16″. Almost all of the workpiece is off the table and it would be very hard to line up the registration. I think the bigger step shift the bigger chance of introducing errors.
To rehash the large shifting messes up my plans to minimize required space. It would mean a bigger workspace, A bigger enclosure and most importantly a bigger CNC support structure to solve yet another unmentioned problem. The Y Rails of the Onefinity sitting on the worktable gets in the way of larger boards. More on this in “Supersize” Part II dealing with the mechanical issues.
So yes I could carve larger projects but not satisfied I kept working the problems. I had to think of some kind of improvement in the process.