Projects:Brass Engraving on the CNC Router
Project by: AlexN
I've done a bit of work with soft metals on our Fireball V90 CNC router, and I wanted to shared my latest experience with doing texturing on an old brass handle. I was given a piece of brass from Ned over at Chase's Garage to see if I could do something with it. Not having any clear ideas on how to turn it into anything other than a door handle, I decided to just make it look cooler.
I opened up everyone's favorite CNC design program, VCarve Pro, and started drawing the outline of the handle. It was a pretty simple rounded rectangle, so I just drew a box the size of the piece, drew to circles, and joined things together to make the shape. This would serve as my reference for laying things out.
I then started playing around with the Create Vector Texture to make wavy lines. I thought some diagonal pattern would look the most interesting, so I put it at around a 45 degree angle. The line spacing I thought would look best if it was close together. I was planning on using a ball endmill to do the carving and wanted the grooves it cut to meet up and make sharp peaks. The following were my settings for the carving.
2D Profile Toolpath:
- Cut Depth: .06 inches
- Tool Type: Ball Nose
- Diameter: 0.125 in
- Pass Depth: .06 in
- Feed Rate: 30
- Plunge Rate: 6
The plunge rate is slow, but with metals very necessary, otherwise the bit will not only complain as it goes in but could get chipped and dulled right at the start of your cut. The hardest thing for these machines to do is make plunge cuts into hard materials. Generally sideways movements are the easiest. To make it easier on the machine you can use a Ramp in your toolpath, which will go diagonally a specified horizontal distance until it gets to the pass depth, and then proceed to do the cut as normal.
After a few back and forths of previewing and tweaking it, I had it looking the way I wanted. I then decided to carve the other side as well, ideally using the same pattern. I did some rough measuring to find out where the holes were (previously used to mount the handle). Then I cut out an oval shape on that end so I could cut around the holes, thinking it would be better if the wavy lines didn't have holes interrupting them.
Securing the Brass to the Table
One of my favorite techniques for mounting pieces like this is to mill a pocket in a piece of scrap wood almost exactly the size of the piece. If you do it right, the workpiece can be force-fit and held in place without much external clamping. For this one I used superglue to hold it in the pocket, coating the bottom of the pocket and the bottom of the part to get a lot of surface area. I came to regret using that much glue when removing it turned into a huge pain. A lesson I learned for the second cut was to just use a few dabs of glue in 3 or 4 spots on the sides where the part meets the pocket. It holds plenty well, and comes off much easier.
The carving went pretty well, though whenever doing metals it usually sounds pretty bad. The thing to listen for is excessive chatter, or vibration in the cutting bit. Sometimes it's unavoidable given the small diameter of the bit and the hardness of the material, but if you let severe chatter go without doing anything sometimes the cutting bit can come loose and drive itself into your material. Luckily that didn't happen!
Carving the Back
When it came time to flip the part, I had assumed I could heat up the brass piece to loosen up the superglue. That... did not work well. I then moved to brute force, trying to hammer the part loose. It eventually came off, but not because the glue gave out. The MDF had peeled away and stuck to the brass. It was a bit of an ordeal trying to clean it up, but I eventually got most of the wood and glue off.
Since I hammered on the piece to get it out, I wound up shifting the piece (losing my perfectly machine-made position for the pocket) and couldn't use that pocket again. So I carved another pocket. Not a big deal, takes all of 3 minutes. The second time I put the part in, as described earlier, I just used a little superglue on the sides, rather than slather the whole thing in glue.
The machine carved this side just fine with the lesser amount of glue! It did carve a pattern I wasn't fully expecting, but it still looked neat. I must have picked multiple patterns when I made the toolpath for the back and the overlapped or something.
A pretty door handle.
Not sure what to do with it yet, but Ned suggested turning it into a necklace. I'm warming up to the idea.