CNC Tips: Engraving Glass Block

One of the neat things we can do on a CNC machine is engrave and lots of different stuff, glass, marble, granite metal, and the cutter that we'll use for that is actually a drag it's kind of a drag. It really is a drag. It's called a diamond drag. And in this device, there's a piece of diamond right there in the tip. And we don't run the spindle or router. When we use this, you wanna have zero RPM when you set this up, we've got this source for you and the company that makes it does a great job with their instructions of saying, here are the parameters to put into your software to make this work. So I'm not gonna talk about that cause they provide all that information for you. But the gist of it is diamond in the tip compression spring. So in a little bit, when we do depth of cut, we're not really controlling how deeply we're cutting, we're controlling how much pressure is being exerted on the tip, which controls how deeply it will engrave onto your surface. Surface in this case, I'm gonna do a glass block. I've been finding these things at home centers. They're very inexpensive, eight inches by eight inches. It's a neat looking surface, and this is not actually a glass block you would do in a glass block window. It's a craft oriented glass block and what's cool about that is there's a plug in it. And if you want to you could take that out and then fill this with sand or a liquid or marbles or something to increase the contrast between the surface and what you're doing. So we need just to have a little bit of look, a little bit of a look at the curve to understand what the diamond drag is about to do. So within my software, I have got an emblem that I brought in a logo that I brought in. The big square you can see here. That's my eight inch by eight inch glass block I've got this logo centered on it, and I'm gonna use for this what's called the engraving toolpath. So I'll open my toolpath up and you can see the toolpath is quick engrave. I've selected the diamond drag for this. And again the parameters for this tool and setting it up in your library are all provided by the manufacturer. This cutting depth is where we need to think about what we're working with here. And I'm gonna say that in order for us to get a good engraving on this glass, we wanna set this to an eighth of an inch of cutting pressure. Step over what this means is when we engrave this it's gonna make a line move, make a line move, make a line move, make a line it's literally engraving a line in this case, every 5,007 inch, that's really close together. And there's nothing wrong with that really close together would give you a very opaque engraving, but it also slows down the process and it's wear and tear on the diamond tip. So I'm gonna change that .003, 3007 inch. Hatch angle this is the angle at which we're gonna do the cutting. So at 45 degrees that means the cutter the engraver is gonna go bloop up, bloop up 45 degrees, or it can be dead horizontal, or it could be perfectly straight. I generally run it at 45 degrees and that works out just fine. So then quick engrave that by default is the name of the toolpath calculate and close out of this one. And then I've already done the same thing this inner portion we're creating an O here. That inner portion is this quick engrave toolpath. So I'm gonna get that set. One eighth inch pressure step over 3007 inch and here to look at this as long as we're here, we can outline which means we would only cut the outside of the shape or fill, which means we're gonna completely fill the shape. And that's what we wanna do here is completely fill. We're still at 45 degrees calculate. And with these other settings, it'd be a good thing you know at some point in your CNC messing around, throw a piece of glass on the CNC, change some of those parameters, see what different things look like and then save that so that you can go back and reference it later and see how you did what you did. Next thing is easy peasy. I'm just gonna output those two toolpaths into one file so I can bring them over to the CNC machine and we can start doing some engraving over there once we have the blocks set up. I got the glass block mounted into the CNC and a couple of things here. The surface of the glass block is not dead flat, and that's gonna figure in, in just a second when we z zero. So as a result of that convex shape, I've got shims under the outside edges and that takes the rock and roll out of it. Then I've got it secured using clamps and fences into the machine itself. The other thing I've done is I put a piece of masking tape on here that cross or X is the overall center of the block. That's my X Y zero zero. Now that can, I've already zeroed that. So that can go away. When we zero the Z it's high in the middle, lower out here. So you're gonna get your best result if you come here to a low spot and zero Z, and we can't use a touch plate for this, cause there's a diamond in here and we don't have conductivity. So I'm gonna just manually bring that down, looking for the spot where it kisses and the other thing that we can do is use a really fancy feeler gauge. Maybe you have one with you, I'm getting one piece of paper or a dollar bill slips under Z down right there it doesn't slip under up one click it moves a little. I'm gonna come down one click right there and then remember on your pod or whatever your device is. Now that we've manually done that we need to zero the Z. Then one more check what can't be running when we do this, the spindler, the router, I've got my RPM set to zero. Find my file there. Of she goes. Now you can see that 45 degree hatch is what's happening here. It's pretty neat and imagine so a couple of things you fill that with something creates a contrast against the engraving, or you put that on a window sill and the light's gonna shine through it. That's gonna really highlight the engraving. I think you could probably even mess around with led lights and put them inside there to highlight that so simple to do the glass block is very inexpensive and I think it is a really nice touch, has a lot of potential as something that you could make and sell off your CNC. So that is how one would actually design onto a chunka glass block.