cnc projects

First cut

I've not really aligned the machine yet so nothing too fancy! I decided that a good first part would be to make an X, Y, Z "window" for the front panel of the control unit. So I designed them with a raised letter (using pocketing) and a circular cut out (using contouring). The parts are cut from 3mm Perspex. 

Above you can see the cut in progress. This was the second attempt the first was ruined because my software cut G02 and GO3 circles in the wrong direction!

Above is a close up of the "Z" part, you can see how it has been cut out. The actual letter is raised 1mm by pocketing the surrounding area. I deliberately chose not to use a finishing pass because I like the texture of the rough cut on the part.

Above you can see the three parts temporarily mounted as part of the front panel and with the LEDs turned on.   

New Dremel mount

The mount I've been using so far came from the plans I got from John Klienbauer. The basic design is great but for my machine it had too big an offset. This has two downsides:
1) It means that the home point is very near the edge of the table
2) The larger offset means greater leverage on the Z Axis.

So for my first real attempt at cutting mdf I decided to build a new one. I created the design in TurboCad and used these to generate GCode (I quickly found out I'm not very good with TurboCad!). After a lot of design time I started cutting the parts.

Above you can see the machine cutting the back of the mount. I managed to cut at 15" per minute. I'm not sure I have the best end mill for cutting mdf, every now and again it seems to snatch (changing the speed of the Dremel helps but does not get rid of the problem).

Above you can see all of the parts. Since I'm doing this on a cnc machine I decided to make the parts push fit and to rely just on glue to hold it all together. I've cut a series of grooves and tabs in the mdf to lock the parts into place.

Here is the mount after being cleaned up (I had to square off the corners of some of the slots, and get rid of some fuzz on the cuts).

Another shot of the mount (just pushed together at this point not glued). You can see the slots for the mounting bolts. I need to round of the front edge of the upper horizontal part. Originally I was going to do this using a 3D milling operation, however my machine said it would take 8 hours to complete the milling of the part! So I decided that the 12 minutes for pocketing and contouring was a better bet! I'll round of the front edge using my belt sander.

The DXF and GCode files for this design are available for download here.

Table and Clamps

I changed the table top of my machine to use Slot Board (the stuff used for displays in shops), at the same time I made a couple of clamps to hold things in place on the table. The clamps are simple strips of aluminium angle held in place with bolts and wingnuts. The bolts run in the channels in the Slot Board and are held in place with some shaped PVC. The spacing of the holes in the clamps is such that I can use them either along or across the table.

I also used the machine to cut a grid and a rule into the table top. This makes lining things up much easier and makes it easy to ensure that the item to be cut is inside the work area of the machine.