There are a ton of different cnc machining services out there nowadays that can do some amazing things. Depending on what kind of cnc machining service you want, you may want to consider the following things before going out and finding someone to get your cnc work done:
Preparing for a Quote
Make sure you have the right file formats and a good file export for a potential cnc company to look at. A great cnc machining service will not give you a definite quote on a file that is half finished. Even if they do, it can only really be a ball park figure. They will need to know exactly what material you want to be cut. They will also need to know if there is anything special you want done such as complex routing using a 5 axis machine or engraving using a cnc engraving machine.
Contact a handful of cnc machine shops to see just what they can offer you. See what their possible lead time will be. The lead time is how long the queue is, or how long it will take until they will even be able to start your project. This is why I always encourage people to contact early with a cad file as soon as possible to get in the queue of a cnc machine shop who may be busy.
The cnc machining center should also give you a solid indication of how long a typical project of your size should normally take and how much it will all cost. Of course this is really up to how well prepared you are and how good the cad file is that you give them for production and whether or not it involves broad routing or requires a more precision machining service.
Getting a Good Quote
To get a good quote, you need a great cad file. Make sure when you export a cad file for cnc, that you test it by reopening it in your own program, and if available, on a different program. Sometimes there are incompatibility issues, so make sure you talk to the cnc machining service to ensure that they will be able to take your file format, or have them specify at least two that they can take. That way if an export with one of the file formats does not work, then they have an alternate file that they can work with on the day.
There are many different cad/cam programs out there that will be able to give you a cnc file for routing, engraving or cutting. The top one I recommend for 2d work is AutoCAD. You can even get a free 30 day trial with them. Some fo the more solid 3d programs I have seen for cad/cam and cnc production are Inventor, Solidworks and Rhino. Concepts Unlimited is also a cheaper 3d program that I have used and recommended before, but does not have the power and stability of the other ones mentioned.
Always check with your cnc machining center to see what file formats they will take. Remember that every cnc machine service is different, so to get the ebst service, consult them first and do not just assume that everyone will take the same file formats.
Also, look for experience. See what kind of cnc machining training that your cnc technician has had and make sure to see actual physical examples of their work to judge the quality and craftsmanship that the cnc machine may be able to achieve for your project. Remember that photos are not enough, get some real samples!
Clear Communication for the Job – Communicating with CNC Machining Companies
Once you have a few different quotes, it is time to choose a winner. Obviously things like cost, and time are important. But something else I recommend looking into is the actual finish of the job. Make sure you see real physical samples of the surface finish to see what kind of finish you will get. Some routers provide a rougher finish, while others require no finishing at all when it rolls of the machine.
Some precision machining services can make things super small and can have tolerances that go down to a quarter of a millimeter with a cnc machine. I have encountered this with companies abroad, as local cnc machining companies tend to be very expensive when it comes to precision production cnc machining.
Also you will need to find out if you need 3 axis or 5 axis cnc machining. A 3 axis machine may be able to be used if you can split up different parts of the project and connect them together. You will probably need a 5 axis milling machine to make more complex shapes out of a single block of material. For 2d stuff, a 3 axis machine is sufficient enough.
I have had 3 axis machine technicians be very creative and split up a project, then rotate the actual project itself to achieve the same finish result as a 5 axis machine, but with only a 3 axis machine. This is also beneficial to the customer as getting time on a 3 axis machine is normally a lot cheaper than trying to get your project through 5 axis cnc machining. So depending on the axis and the cnc machine parts needed, this will sway the price up or down.
Let the cnc service know exactly what you want, before getting the project started. One of the things I like to do is include a separate file that includes the objects rendered in 3d and some basic dimensions and finishes. This is important especially if you are outsourcing the work overseas and you can not be there to oversee or describe what you want, so getting it down on paper visually makes sure that you will not get a job that does not match your initial specifications.
Getting the Final Product
Getting the final product is always exciting. But if you have done all of the steps outlined above, you should get exactly what you want. Paying a ton of money for something that you did not want can be terrible. While you can outsource the task, you must always keep tabs on it and explain exactly what you want. This is super important, in fact, it is so important, that you need to get it down in writing sometimes.
Make sure you specify an exact date for pick up and keep your fingers crossed that with all the hard work you have put into the cad file and with all the clear instructions, you should get exactly what you want.