Misc

Wedding seal

As part of sending out our wedding invites, I wanted to do something a little special. Somewhere along the line we got the idea of making up our own seal for the envelopes. I fancied the idea of using my CNC machine to make up a stamp, and it didn't seem like it would be too hard to do.

First step was to make up a drawing. This was more work than I imagined, as there were a number of requirements:

Must contain no details smaller than the size of the end mill. That means fancy fonts with thin ascenders are a no-no. Thick block sans-serif only please.Can't be too big. The bigger it is the more wax that will be used and the harder it will be to machine.Must look good!

In the end I came up with a design that incorporated a bit of both of us:

M and R are our initials obviously. Below my initial we have a lump of railway track... again distorted and "chunked up" due to the above requirements. Then below Rachel's initial we have a daisy, the ...

MrCNC - part 4

Continued from part three...

At the end of the previous update I was busy waiting for a 5-8mm shaft coupling to arrive. However I realised that with a big of creativity, I could always steal one from elsewhere on the machine.

Using some heatshrink tubing, cable ties, superglue, and flexible tubing from an old inkjet printer, I bodged together this flexible coupling:

That left me with a spare aluminum shaft coupling, just what I needed to finish my new spindle.

The spindle I made out of MDF and consists of:

ER11 collet nut2 608zz ball bearings2 more 608zz ball bearingsA 8mm to 5mm shaft couplingA big DC motor with 5mm shaft, from an old cordless drill

It went together reasonably easily with a good helping of 5 minute epoxy glue.

The hardest bit was aligning the motor and the shaft. If it's not perfect, it rubs and the power transfer suffers.

Meanwhile, a pair of 2 flute, 4mm HSS end mills had arrived i...

MrCNC - part 3

Continued from part two ...

Now that the machine works, it is time to do something with it! My first carving was the LinuxCNC text which took a few attempts to get right, but once working seemed good. Second cut was something called "chips", which it turns out is a lovely wee penguin:

Detail is a bit rough around his foot, and the other flipper snapped off, however for a first go I was pretty impressed. The foam isn't amazing to machine, the beads tend to remain, but it's about all my machine can manage at the moment with it's poor-man's-spindle.

I spent quite a bit of time getting the homing configurations correct, as there are many different variables and they don't all make a whole lot of sense. When I finally got my head around HOME, HOME_OFFSET, MIN, MAX, etc it started making sense and I was able to get the results I was after.

For my second piece, Rachel had said "I...

MrCNC - part 2

Continued from part one...

With the Z axis mostly done, it was time to turn my attention to the Y axis. The Y axis moves across the work, and supports the Z axis.

I started by cutting the two end pieces out and match-drilling them. I now had a problem though; my linear rails were each 1m long, and not especially cheap, so in order to gain some vertical work-height, I had reduced the Y length and now had a gap to span between the outside faces of the machine and the ends of the Y axis rails. In other words, I had to make some spacers. I made these out of 18mm MDF which gave me some extra space for the shaft coupler and 8mm ball bearing at the other end.

As per the Z axis I added the linear bearings with my patent-pending mounting blocks, and another cast "bolt". Some careful measurements and adjustments with my square ensured that both sides of the Y axis were true and then it was ...

MrCNC - part 1

Today I present the latest project to come out of my workshop: a CNC machine! CNC stands for Computer Numeric Control, which is a fancy way of saying computer-controlled. A CNC machine has a rotating spindle that is movable in 3 dimensions and is able to carve, cut, and machine objects according to the input file on the computer.

Building it has taken most of the past month. An initial plan was roughed out on the computer and I started ordering bits online.

The first bit to be built was the bed of the machine. I made this out of Open Beam, which is aluminium extrusion, 15x15mm with built in slots to accept M3 nuts. This makes it easy to bolt the bits together, like some kind of giant Meccano set. The corners are chopped up T connectors and help square things up.

Ends for the bed were made out of 6mm MDF, which is g...