This might be a little premature because I don’t have any preliminary design pics that I am ready to share, but I am working on a scratch build CNC mill design. The mill will be a weldment similar to what Dave DeCaussin made, but larger. I was poking at this idea before he posted his design, but his success confirmed the validity of this approach for me. This will be a long and slow process. I have three different weldment designs that I am working through and will evaluate based on rigidity and cost of the weldment. I am going to do a full analysis of the drive components and the structure, which I will post. I will also do some trades on component selection. After I finish the design, I am hoping that I will have the cash to move forward with it, but if not, I might try and kickstart it and see if I can get prices down through a group buy. If that doesn’t work, I will probably just post the drawings and see if anyone else wants to run with it.
I started down this road because of my BF20 conversion. It is painful to convert a mill to CNC that was designed to be a manual mill. I know I can do better with a scratch build; I am just not sure if it will be cheaper. My hope is the weldment I am designing will be as expensive as a new RF45 or close to it in price. I have looked at Tormach (Novakon is also an option). I like the machine and I will probably buy one before this is over, but I want more.
The machine I am working on will have linear rails throughout, a three HP up to five HP spindle motor, BT30 spindle, PDB, and if I can source one, an ATC. The travel for the mill will be somewhere between a Tormach and a Novakon. I am not sure what I will do for control software, but if I am working on that, then it is a good thing.
The first thing I am doing is working on some concepts and then I will start the mechanical/vibe analysis. After that, drawings and sending things out for quote. I have identified a few shops that specialize in machine fabrication and can manufacture the components from start to finish. All the mating surfaces will be ground.
One mistake I made on my BF20 build was not calculating the cost to finish the build, so for this build, I will do a complete price list down to wire and hardware.
I have found a good stand/enclosure is an important part of the design; I am going to make sure I spend time flushing this aspect of the design out. Also, the mounting points for the mill on the stand will be ground.
Finally, this should be fun; I enjoy doing design/analysis and this will help keep me sharp since I don't get to do it that often anymore.
Thanks for reading
Graham