Pocket Watch Winding Stem

The first stem attempt for the pocket watch was handmade and it wasn't easy to do. It also didn't work very well. So I decided to use the CNC machine to make the next stem. Starting with 2.5mm silver steel rod (2.5mm is the largest dimension of the spindle) the machine gradually turns the profile of the spindle using a 0.2mm D bit.

The setup is able to machine to less than 0.1mm, but the initial attempt failed to give a good profile due to flex of the rod when the tool lowered in for a cut. After adding a wooden block under the rod and running the machine again, a good profile was machined.

The broken stem is on the left, the new one on the right.

The dimensions aren't absolutely correct, but it did work, after the sloping edge was added by hand. The square profile was also added by hand but was filed too small and eventually the corners were rounded off and the stem stopped being able to wind the spring.

I'm going to do a third attempt, with better dimensions and the second slope machined rather than done by hand.

The G code for the machining was done using a custom Tcl script that reads a DXF profile and outputs X-A axis G code to machine the same profile around a cylinder. This can't do the square end, but I'm going to create a new program for square pegs. That will be run as a second stage of machining after the main profile. Creating these scripts as separate tools should hopefully make them more reusable in the future.

CNC 4th Axis

The 3040 CNC machine came with a 4th axis for making round things. I finally got round to setting it up as I think I can make the pocket watch spindle on it.

I had a go at some manual carving and all seems well.

I now need to find some software that will let me make round things. I think I'll have to make my own.

More PCB Milling

I'm experimenting with milling more detailed and double sided PCBs. So far I have tried a smaller cutter (D bit) that was 0.1mm, but I suspect turned out to be a bit larger than that. The fine tracks have disappeared in a few places so it's not usable, but overall it's encouraging.

The four large holes are my attempt at registration pin holes, which failed as the PCB software auto centres the artwork so when I milled the traces they weren't registered with the pin holes properly. I need to experiment with methods of creating these holes.

The second attempt at the double sided OLED watch PCB was more successful. I mistakenly drilled the via holes from the wrong side, I hadn't remembered that the holes are drilled from the bottom of the board, so I milled the top side tracks then drilled holes. Of course they were wrong and this PCB has an extra set of via holes. It is probably just about usable, but I am going to make a new board more suited to milling and also add some of the circuit changes as well.

This second PCB looks a lot better. I cleaned the copper up using some fine wet and dry paper as there's a lot of rough burrs as it comes off the milling machine.
The blue PCB is the one I had made in China, for comparison.

The registration using pins worked well, the program I wrote to generate the pin holes now uses the board outline, which has to be the correct size.

Collet Holder

This is the sort of thing that the CNC router is great for. I wanted a simple way to hold the collets that came with the CNC spindle, there's 13 of them and it's easier to use them if they are stored in order. So I made this holder:

Each collet is in a hole that is made up from four holes of different radii and depths so the collet is held snugly.

Making this without a CNC machine would be a trial indeed and simply not worth it. With a CNC it's trivial, well almost.

3040 CNC Demo

The Chilipeppr software that you can use to drive the TinyG controller comes with a demo file. Once I'd calibrated the CNC so it moved 1mm for every 1mm it was told to (instead of 4mm for every 1mm it was told to), I had a go at carving the demo. Before the recalibration I had terrible problems getting the machine to do my bidding. I don't know why I didn't realise that I needed to calibrate it, it seems silly now that I didn't. Why I thought the two bits of kit (TinyG and the router) would have worked together out of the box(es) I don't know. Anyway, here's a video of the machine carving part of the demo logo:

I've just used some masking tape to hold the workpiece down, it's fine for a quick test.

CNC

I've done some more wiring and have run the small spindle up to speed using the controller. I've also got chillipeppr working using the web version, so all should be well once I have the connectors for the stepper motors.
They haven't turned up yet, hopefully they will be here tomorrow.

CNC Router

I have just bought the parts for a CNC router, which I hope to use for PCB milling and maybe some other routing type stuff. It's a 3040 type and I have an air cooled 2.2kW spindle (which is admittedly a bit large) and a 400W smaller spindle on order. I'm going to have to make a spindle mount for the larger spindle as the one on the 3040 is a 52mm diameter and I need 80mm.

I have a TinyG controller so I should be able to use USB as a connection to a host PC (which I also have to cobble together), which will be better than a parallel port.

The TinyG controller PCB:

I'm currently mounting the bits and bobs onto a shelf above the cnc. There's quite a few boxes, PSUs, controllers etc.