Bergeon Platax Punches

Bergeon Platax Punches

I've been gathering watchmaking tools for a while as they are useful for making small things, and especially useful for fiddling with watches. I have a project watch that I want to work on and having the right tools is always a good idea. One tool I recently bought is a Bergeon Platax tool which is used for dismantling balances.

Unfortunately one of the punches that it came with was broken, so I decided to make some more. These are not easy things to make, as they have various holes in the end of 0.1mm, 0.15mm and 0.20mm.

I used 3mm silver steel for the punch body, and some EN1A rod to make the stop rings. I'm using the CNC engraver/mill to drill the holes in the end of the punches using carbide drills. I created a tcl script that writes gcode with appropriate feed speeds and pecking cycles. It took a few attempts to find something that works, but I seem to have that now. And a pot of broken drills... The results are pretty good:

That's mine on the right and the original on the left. This is the broken 0.20mm punch on the left. The hole is about 1mm deep, I've no real idea if that's the correct depth, but it seemed to work on the balance I had a go at dismantling. The silver steel isn't particularly hard, but then, if it wears out I can make another punch...

One problem is the accurate positioning of the hole in the end of the punch. I think I may have to build some sort of something that I can use for positioning the CNC spindle when making small things. Trying to do it manually by poking me head round the spindle just doesn't work very well.

You can see the hole here, and the fact it's a bit off centre:

I've also ground a used D bit down and used it to create the rounded edge to the hole that the original Platax has on its punches. I may have to do something more accurate for that too. Somehow.

Second DRO Gauge

The second gauge has been fitted to the lathe. This one was a cut down 'hardened stainless' gauge I got off ebay:

I'm not sure what was hardened or stainless, this machined like butter on the mill. I'm not complaining, it made my job easier.

The mounts are 3d printed, the gauge display unit fits neatly into the metalwork, I added a copper shim to remove the last 0.1mm of movement, now there's no measurable movement.

This metal gauge works better than the plastic 0.1mm resolution one I put on the compound. Even though you can get 0.01mm resolution on the data output, it doesn't stay very stable.  I think I may use one on the compound as well, if I can buy one. I'm going to experiment with other calipers, I need another 4 for the mill and the gauge on the lathe ways.

Box

A pen and box seemed appropriate for an upcoming birthday, as I always think it does. I turned a blue ballpoint pen and made a box from some pine.

The person the box was for is musical, so I added some engraving on the top of the box.

The notes are the first few from 'Happy Birthday'. I engraved it from a bitmap. I converted the bitmap to gcode with a utility that was slightly tailored for this engraving job. It looks like I finally have a set of tools that will allow arbitrary image engraving. The depth is set by the greyscale value in the bitmap. These notes were engraved at a single level.

DRO Displays

The displays for the axes of the DRO are going to be LED digits. I have some modules that use the MAX7219 chip and have 8 seven segment digits plus decimal points. One Arduino UNO and some code and we have a trial display:

So now I have a display and a gauge attached to the lathe. I thought it would be a good  idea to check the DRO gauge and see if it would be useful. It's not worth going through the hassle of building all the gauge channels if it doesn't work very well.

The first attempt was OK, but the gauge didn't slide very freely. Some adjustment of the gauge mounts might be a good idea. After some gentle filing the gauge freed up and all worked quite well.

I set the lathe dials to zero and the gauge to zero as well to check the calibration between the two measurement systems.



After moving a distance from the zero, I noticed that the gauge didn't match the scale. I finally found that when the gauge read a round number of millimetres:

The scale on the handwheel isn't at zero. I was about to give up on the DRO until I noticed that the ball on the handwheel was in the zero position.



So the dial had slipped when moving the handwheel. It looks like the DRO was more reliable than the dials in this case. Looks like it is worth continuing.

A Pretty Small Hole

I want to drill some small holes in some steel for another project, so I have had a go at some small hole drilling. Actuall a better phrase is small drill bit destruction.

The holes I want are 0.1mm, 0.15mm and 0.2mm. Of these I only had 0.2mm bits so I had a go with them. Several attempts in steel ended up with broken bits after about 2mm.

An attempt in aluminium was successful though, after I had used up all nmy 0.2mm bits and started into my 0.25mm bits.

I used a gcode program that was generated by a Tcl script, this program slowly drills into the material, with the occasional removal for chip clearance.  I think the program is still a bit wrong, as I have broken a lot of bits with it.

Anyway, here's a 0.25mm hole in 2.3mm aluminium:

This is the hole being drilled:

Mini Lathe DRO

I'm looking at building a DRO for the mini lathe and mini mill. The electronics isn't much of a problem, but the mechanical aspect of fixing gauges to the lathe and mill is another matter. I've decided to have a go with the cheap plastic digital calipers that you can get from China for a very cheap price. They have a data output that can be attached to a processor of some kind, which is very useful. The plan at the moment is to have a processor per gauge to handle the data stream and then have a larger master processor that handles the LED displays and does the keypad and clever stuff.

After hacksawing a caliper apart and 3D printing some parts I have the first version of a mounted caliper:

There's a couple of problems with the 3D printed parts, but it all seems to fit and work. It also doesn't seem to interfere with the operation of the compound. I need to put the PCB back on the gauge and wire up to the electronics, but it's looking hopeful. I'm not going to replace the LCD or buttons one the caliper PCB, I'll just use the data output.

From the data output it looks like there may be better resolution than the 0.1mm resolution that the caliper itself displays.

Sony 7035 Volume Control Replacement

I have been asked to look at a crackly volume control on a Sony 7035 tuner amplifier. This is a nice unit from the 80s or so. The volume control is a ganged potentiometer along with balancecontrols. There's no way to get a replacement after all these years, so the only option is to attempt a repair or replace some parts with something else.

Looking at the circuit diagram, the volume pots are centre tap versions as well, which is used for the LOUDNESS function. Not having managed to find any four gang pots, one option was to use a processor and digital pots. Unfortunately the voltage on the pots is +/- 27V which is too much for the digital pots I coukld find. So, using a dual gabg pot for volume I decided to fix the banalnce to mid position and remove the LOUDNESS function.

I made a PCB on the CNC router

then removed the unwanted copper due to the voltages

Once fitted into the Sony, the volume control works with no crackling.

The original pots had an extended stem which the volume knob attaches to, so I need to machine an extender for the shorter pot I fitted. I hope the extender is solid enough once the knob is attached and that it won't wobble about too much.

The balance is mid position, the LOUDNESS and MUTE don't work, and I fitted a linear pot as the log pot I fitted didn't feel very good. I'll see how this solution works, but a second version may be in order.

I'm wondering if I can put a processor on the PCB and use FETs to effectively create a high voltage set of digital pots. One problem with this is that the processor may cause noise due to switching which the radio may pick up, as it is quite sensitive and will be in the same box.