# Quick fix: New Paint for the Jakob Maul Bilateral Scale

I had this sitting on my shelf for a while the paint on the base stated to come off, I happen to have some black glossy spray paint at home so I figured let’s give it a new paint job. I removed the paint with a brass brush on my Proxxon tool (like a Dremel), then used 1000 sand paper to clean it up a little. After that I cleaned the surface with Isopropyl alcohol and covered the sections I didn’t want to paint.

# Repairing a FACIT TK Mechanical Calculator

I have this old FACIT TK mechanical calculator, the reset lever for the cycle counter became stuck so I figured I give it some maintenance. It is in a bad shape in general, I haven’t bothered to clean it either and the previous owner evidently had it in a dilapidated attic or barn. Stuck lever Turns out the lever was stuck because this gear could not freely slide on the axle.

# Microscopy Insights #3: Vostok Komandirskie

Some close-up stereomicroscope shots of my mechanical Vostok Kommandirskie wristwatch. I disassembled it quite far in order to repair it a while ago but didn’t take any pictures, I didn’t wanted to disassemble it now as it’s working so here is only what is visible if you open the back cover. Pictures taken with a Sony SLT-a37 on my MBS-10 (МБС-10) with the МФУ tube.

# Microinjection Dispenser Controller (Part 2, Construction done)

Continued from: part 1 This is more of a quick update, this weekend I finished the mechanical and electrical construction of my microinjection dispenser controller. Back Panel So I finished the back panel as mentioned in part 1. The BNC at the top gives a TTL marker signal and I also added a 4mm banana socket for grounding. Remote In order to trigger it I wanted the possibility of a small remote with a button instead of having to press the button on the front panel every time.

# Microinjection Dispenser Controller (Part 1)

Continued in: part 2 I saw some people building open-source microinjection dispensers like OpenSpritzer and PuffAdder a while back and thought “hey I can easily build this”. And so as an excercise I did. This is a pressure ejection microconjection dispension controller. It works by having a regulated pneumatic pressure being dosed by opening a fast acting solenoid valve for a specified amount of time. The relation of the pressure and the open time of the solenoid then dictate how much volume flow will be ejected.

# DIN912 Stainless Steel M4 Screw Weights

DIN912 M4 screw weights, sample size $$n=10$$, weighted on my Sauter L10 which has a declared error of $$e=0.1\rm{g}$$ and $$d=0.1\rm{g}$$. Conducted at room temperature $$T=21^{\circ}$$. I did this on my Sauter scale because it is a direct reading scale making it faster to handle, than my other (more precise) laboratory scales, especially considering the sample size of 10 I’m using here.

Values in between indicators were rounded up to the next higher 10s of milligrams.

# Making a LOMO Power Supply Safe(er)

As mentioned in the MBS-10 (МБС-10) post the standard LOMO power supply is not safe by modern standards. It uses a non-earthed metallic case and does not have fuses. I recently got this supply together with my new LOMO R15 (ЛОМО Р15) where the prior owner cut off the standard europlug and added a Schutzkontaktstecker using screw terminals. It is as safe as it looks: While disassembling it I also noticed that the shrinking tube was improperly sized, exposing live 230V terminals:

# LOMO R15 (ЛОМО Р15)

I recently got this LOMO R15 (ЛОМО Р15) as I wasn’t satisfied with the accessories my Hertel & Reuss microscopes have and the virtual non-availability of further accessories for those on eBay. So I decided to go with a microscope I can get more easily upgrades for. As visible from my earlier posts regarding this: LOMO ST-12 (ЛОМО СТ-12) Repair Cleaning a LOMO R15 (ЛОМО Р15) Frame LOMO OI-35 (ЛОМО ОИ-35) Repair There was some cleaning and mechanical maintenance required, to get it back into operation.

# LOMO OI-35 (ЛОМО ОИ-35) Repair

I got this together with my new LOMO R15 (ЛОМО Р15), the iris diaphragm inside was broken, so here a quick note on how I repaired it. I started with dissembling everything, in order to get the diaphragm out the two levers need to be unscrewed as well as a small set screw on the bottom needs to be removed. I also disassembled the mirror part for cleaning. The diaphragm was completely sticky due to dried up grease, so I carefully disassembled it and removed all grease remains using WD-40.

# Analog Threshold Relay

This is part of my readout electronics system. This is one of the oldest modules I built that I haven’t desoldered so far. It is an analog threshold relay with voltage reference and amplification. There is a 10V reference voltage feeding into the 10-turn potentiometer on the front panel, this selects the threshold voltage. A lever switch selects whether the input signal is amplified by x10 or just passed through to the comparator.