milo's project blog

Before and after: ISO F63 to ISO KF40 high vacuum reducer.

This part was a bit big for my lathe. The stock was 166mm in diameter and my lathe has a 180mm swing, leaving a 7mm gap. I had to bolt it to a faceplate to machine it.

I just finished mounting this cute 80mm 3 jaw chuck on a W20 arbor for my lathe. The chuck is concentric to the arbor within 0.02mm which is not amazing but is better than the concentricity of the chuck itself so it’s fine.

Having it on an arbor is more convenient than a backplate and allows me to use it in my indexing head.

I recently repaired this english verge watch c1800. Like most watches of its age it had a laundry list of problems:

The click in the fusee was worn to the extent that it slipped, causing the cain to come of and quite possibly fly around the watch.

The screw securing the balance cock was missing, the balance was loose in the case. Presumably someone had been in the watch before me and lost it.

The balance staff was bent, see above.

The hairspring was very badly bent, see above.

One of the case hinges had a broken pin, a corresponding dent in the back of the case suggests it was dropped.

A lot of the steel parts had significant rust, including the fusee chain.

The repair is detailed below:

One of my friends coppied her entire personality appearance from Chloe Price from the videogame Life is Strange. As a birthday present, I made her a replica of Chloe's necklace from the game:

High stakes sewing of my lathe belt.

The stitches are distributed across three rows to distribute the load and each of the groups of six holes is laced independently.

My lathe was designed when leather belts were standard, they are typically laced or stapled to length so can be made an arbitrary length. Thus they can be made slightly short then stretched over the pulleys, requiring no tensioner.

It’s back!

I re-installed my lathe after too long not being able to turn valuable raw stock into scrap parts and swarf. I am so happy.

I made a belt with eyelets along its entire length - convenient for attaching things - and a shorter strap with spikes along its length which can be worn as a collar or doubled up and used as a bracelet.

The other day I started volunteering at a local repair café. The idea is, people can bring their broken things and volunteers repair them.

First someone came in with a LED torch but the battery terminals had rusted beyond repair. Next was a lamp stand that was barely broken at all. Then came one of those early-200s CD-player radio alarm clocks, it was a pain to take apart but it turned out it just needed a new electrolytic capacitor. It went on like this for a few hours. It was very rewarding and the people who used the repair café were all quite interesting to talk to.

Then a client came in with her blender and explained that it had stopped working during heavy use. I started taking it apart. There were two screws at the bottom and clips about half way up but I couldn’t find what was holding it together at the top.

Since it was already broken we decided to just pry harder. I pried it open all the way around the clam-shell but it stayed together so there must have been something holding it together in the centre. I removed all the stickers but they weren’t hiding anything. I tried to pry off the buttons but they wouldn’t budge. Maybe it was glued? I tried unreasonable force, slipped and it closed on my finger spraying a little blood about. A few more people tried with increasingly excessive prying tools but ultimately failed.

By this point the owner of the blender and I wanted to know what was making it so impervious so we decided that I would take it home, saw it in half and report my findings.

It was a screw under one of the buttons. The buttons are barbed and can only be removed from the inside. Once the button had been installed at the factory, disassembly was nearly impossible.

I know designs like this are fairly common but they still really annoy me.

It gets worse:

I tested the circuit board and the motor and everything was fine except a fuse which was soldered to the PCB and inaccessible without disassembly. The fuse was the only thing limiting current to the motor so it had likely been blown when the blender was overloaded. This is bound to happen occasionally eg. when encountering a particularly thick soup.

The overload protection should have been re-usable!

Normally when a zip pull breaks it can be replaced easily by threading a new pull through the hole in the zipper. Some (older) zippers don’t have a through hole but rather two parallel trenches, frustrating repair. I have a vintage leather jacket with one such zip pull missing. I could have replaced the entire zip but because stitching makes permanent holes in leather I would have had to sew it in by hand which would have been a pain.

I found this loose zipper for 10p at my local haberdasher:

Liberated the pull from the zipper with a hacksaw:

Bent the pull open with toolmakers clamps:

At this point I realised the prongs which mate with the slots in the zipper were too long and too thick so I fixed this with a #2 file (not shown).

I then slotted the pull into the broken zip:

And bent it flat; fixing it in place:

I just got a Nikon Labophot with a broken lamp holder so made these 3d-printed Ls which can be glued on to it.

Like so:

The mirrors in moving coil meters corrode over time making them hard to use but they are easily repaired. They are just a thin aluminium sheet glued to the back of the scale and can be removed with a blade. (be careful not to scratch or bend the mirror)

You can then polish the mirror and glue it back on. It looks good as new.

I got this Spectra Physics 155 HeNe laser on ebay for £10 not working. It ended up being an easy repair since the only problem was that it had carbon composition resistors that had drifted off tolerance (by more than 2x in some cases). This always happens with carbon composition resistors.

I want a nanopositioning stage that’s less expensive than a commercial one but less rubbish than those piezo buzzer ones. I found these 1x1x5mm PZT multilayer stacks on ebay for <£10 each which work great and designed this very simple flexure for them.

The stage is driven by ±100V and has ~4µm of travel (20nm per volt). It probably doesn’t have the best repeatability because of hysteresis but I can’t measure displacements smaller than 0.2µm so I can’t characterise it.

I’m planning on adding a third piezo on the end of the beam and trying to use it in an atmospheric STM (since piezo buzzers can be used for STM I think it could work)