First, I would like to say that the machine itself is the least of the expenses associated with owning/operating a CNC mill (or lathe). Once you commit, you will bleed money.
In January 2015, i jumped off that bridge and purchased a Fadal CNC mill with 30" x 16" x 19" travel. It has the footprint approximately that of a VW new Beetle.
Fortunately, skateboard parts are small. Why is this important? Once you delve into machining, it will change your life. You will find yourself doing things you never imagined, therefore you will continuously try to hold work well over the capacity of your machine. For me, I really needed to step up to the 40" x 20", which has the footprint of a crew cab dually. This takes up a lot of space in a 1000 square foot shop.
I consider my little 30" x 16" machine to be an entry-level production machine. My initial reservations to buying a CNC mill was, where do I keep it? The next was, how do I power it? My machine is 15 horsepower 220/440 3-phase. You will either need to rent in an industrial park and pay for 3-phase service or have a hell-of-a phase converter.
My initial reservations were the ongoing expenses of rent and utilities to operate it. In the grand scheme of things, rent and electrical are no joke, but they pale in comparison to the expenses of tooling your new machine. My first year, I spent approximately 75% of the cost of the machine on tool holders, cutting tools, and work holding. That doesn’t take into account measuring tools.
Yes, there are ways I could have saved money on tooling. If you are hobbying, you don’t need high-end carbide cutting tools, especially if you are cutting certain plastics and aluminum. You could get away with an ER collet set with just one collet chuck instead of individual CAT 40 tool holders for each size tool. That will also reduce your tool storage requirements.
To anyone who is hobbying or prototyping on a budget for a kick-start campaign, I would strongly recommend a Bridgeport style knee mill retrofit with CNC controls. This offers greater rigidity compared to the DIY CNCs with the versatility of a conventional mill. It is easy enough to run them off of a phase converter or even have the 3-phase motor rewound single phase so you can run them in your garage.
You will want to start with a mill that doesn’t have a lot of wear in the gibs. The ACME thread lead screws will need to be swapped for ball screws. There are numerous ways to perform the CNC retrofit, my favorite, when I last looked into retrofitting a conventional, was Favor. This is primarily for the way the Z axis servo mounts. It was the only one that didn’t require requalifying each time the head is indicated.
If you are looking for a more production orientated machine that you can actually manufacture on, a Haas mini-mill is a great option that can be factory configured single phase. I know several people running businesses out of their garage with these.
I have never been a fan of the benchtop machines. I have known a few people who have made a little extra money making small parts such as vape accessories and the like. They might work out for what you want to do. They aren’t for me.
Once you get to the point where you can start making chips, you are really only limited by your time, talent, and creativity. If you enjoy this sort of thing, it can be a life altering experience.
Let me know if I can help.
Cheers,
Joe