Software Files for CNC

[Chris Parks]

Being totally ignorant of CNC is there one universal file type that everyone uses? I need to get some prototypes converted to a file system and then look for someone to make the components. What is the minimum run that makes commercial CNC use viable?

[Phil Thien]

Most places that will run your parts would probably prefer good CAD to g-code. With good CAD, creating the g-code is somewhat trivial.

Minimum runs, well, there is probably no hard and fast rule. If you're dealing with a guy with a ShopBot in his garage, a minimum might be one. If you're dealing with a high-volume place and milling aluminum, they'll provide an estimate (hopefully) that makes it clear where the sweet spot starts. Qty. 1 will be as expensive as getting qty. 10, and qty. 100 will have a much lower per-part cost. You'll be able to decide from the quote where the vendor needs to be in order to be competitive.

I'd start talking to the CNC outfits early-on to determine what they want for CAD, and get a feeling for how cooperative they tend to be. I know a large industrial place that does mostly automotive work and I think most would imagine they'd turn small jobs away, but they don't. And I know small outfits that act like they are only looking for large contracts and are pretty worthless. So ask around and start talking to estimators at these places.

[Art Mann]

I have seen the ".DXF" file format used more than any other as an exchange format between various CNC platforms and applications.

[Kevin L. Waldron]

Dxf is probably the most generic for Autocad based systems but not necessarily the better files or most used across the world of CNC. More involved 3D cad files for CNC would probably be better served with STEP - STP, IGES, SAT, 3DM, SLDPRT and several others......

There is a difference in whether you want STL files or nurbs style files or DWG/DXF files etc. You will need to determine the scope of the work you intend to do.... cabinet parts or say rocket engine parts it will make a huge difference in the software you use..... (We personally don't like STL and find them difficult to modify the actual parts where the part/s have a lots of fluid motion in the shapes. It can be done.. we just find it much more of a hassle. )

Blessings, in your search.

Kevin

[Chris Parks]

This is a new world to me so advice is appreciated. I have designed a simple adjuster with two moving parts sitting in a fixed body so to me it is a fairly simple thing. I guess I have to prototype it in metal or on a 3D printer and let someone do the files from that. I expect it will be produced in China to keep costs down and I do not want them to see the whole assembly in one piece so they can duplicate it even if they knew what it was. I have been ripped off once before on a design that is now sold worldwide so I am being cautious this time and not involving anyone else. It will supersede the first design and make it redundant and that person is going to be very unhappy which will make me happy. Last time someone was brought into the project and they took my basic idea and changed it to get around my patents that I held, lesson learned.

This time I am taking it from having the idea to retailing it via the web and getting the thing from the concept to the metal is a new experience for someone who knows nothing about manufacturing but I do have some web retail experience which will help. If anyone has advice on the best way to go about the transfer of design to manufacturing I would very much appreciate it.

[Dan Hintz]

Word of warning... if it's sold or manufactured in China and the idea is worth money, expect it to be copied, patents or no patents. Even in the States, if a larger company can get away with copying your design, many will... they know you won't have the legal backing to support a lawsuit.

[Chris Parks]

That's exactly why I would break up the production and do the assembly myself, the Chinese have no regard for intellectual property as I have found out from others that have been burned by them. My intention is to get the parts made in separate batches as I have the contacts to spread the production between different plants. I doubt that even if it was all made at the same time anyone would guess what it was as this design is totally different and has never been seen before in use by anyone but me. Once it is on the market that is another thing and we will see if anyone else decides to compete. The history of the hobby involved suggests that competition has not occurred so I might be safe. I would never patent anything again, it is a fruitless exercise and just puts money in lawyer's pockets as the patent is only good if you have the money to stop others using it by going to court.