You have now finished your DIY CNC router, or you went out and bought one. You've been waiting years for this. and now it has finally happened. But by now your girl friend is jealous because you don't spend enough time with her, or worse your wife is pissed off over all the money you have spent on this funky looking contraption. You think to yourself I'll show her, I'll go out to the shop or the basement and I'll make a thingumabob that will really impress her. But first you check the internet to see how the big boys do it, just to find a small handful of cheesy G-Code files that are compatible with your CNC router software. Even after weeks and weeks of searching you can't find anything that will impress your lady or your neighbors, now what?
Let me tell you that your not alone. I've been in the business for more than 15 years and I have heard it all. In this article I will explain all the ins and outs that the big boys use. All their tips and tricks that they wont tell you.
Forget the G-Code, this is just a waste of time. In this day and age you need to think like the big boys do. Your end file WILL be G-Code, however you don't need to know anything about it. The Big Boys will have a 3D modeler design and draw the 3D image, once its drawn they will convert this to a file type like .STL then load that into a CAM program that can generate G-Code for the type of CNC router software they use. I know this sounds complicating, but I will show you a few shortcuts.
Unless you need a VERY specific 3D image you wont need to draw much of anything. There is a website that you can purchase the 3D Reliefs (3D Images for CNC routers) from.
Your router spindle motor collet, needs to be able to accept Dremel bits. I can't stress enough on this. I don't care how you do it, just do it. Unless you are making huge signs or pieces you will need to use Dremel bits. This is because the smaller the piece, the smaller the cavities will be, and unless you have super small bits, all those small details wont show. Dremel bits are cheap, tried and true replacements for those very expensive bits that the Big Boys use.
The CNC router control program that I suggest is Mach3 CNC. The CAD/CAM software that I suggest is Artcam. This is a remarkable piece of software that you can't do without. This program will be able to export the G-Code to your CNC router program. But don't be fooled, It will do a thousand things more than just that.
Let's look into Artcam a bit more here. You first Purchase a few 3D Reliefs from a website, then you will load and scale this into Artcam, then you will choose tool paths, and in tool paths you will need to create three to four tool paths with different size bits. Your first bit will more than likely be 1/2 inch to 3/8 inch ball nose depending on the size of the model you will be making. then down to 1/4 inch ball nose, then down to 1/8 inch ball nose then down to around a 106 Dremel bit. You will need to configure each bit in the tool bit database. The step over percentage is rather tricky, I have found that around 9% is my sweet spot. It's a bit slow, but I don't have to sand so much, but I save this small step over for just the Dremel bit, the others can be around 40%. And unless your router and bits are like superman you will more than likely have a feed rate of around 100 inches per minute. less than 40 will burn up your bits. more than 200 will start to chip up wood and cause cavities. With more expensive bits, the faster you can go, but we wont get into that in this article. If you have a variable speed spindle motor or router then you will be able to control the speed to save your bits from burning up. In Artcam you can set the spindle speed for each bit. Artcam can get a bit tricky and confusing. I'm sorry but I can't get into every little detail in this article. Artcam is just to complex to go over everything, so lets keep it simple.
So now we have three or four tool paths. Depending on your CNC router, you might be able to create one big G-Code with all three or four bits in it. But lets keep it simple and create three or four G-Codes with the name of the bits. So you will select the tool path and select your G-Code CNC requirement file format and for example save as "half-inch ball nose.cnc" in a directory with the name of the piece you will be making, because there will be several tool paths inside of this directory.
Once you have all the tool paths saved into your directory you will copy this dir into your CNC router controller PC. and load the first G-Code file into your CNC router program. One by one until you have finished the Dremel bit. Now your ready to do some showing off.
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