Algemeen's Electronics and Bicycle Tinker Blog

The Shimano 7 gear hub with a roller brake is a very common hub for city bikes in the Netherlands. Sooner or later one needs to be able to remove the rear wheel with this hub, e.g. to fix or replace a flat tire. Releasing brake cable for the Shimano roller brake is easy, just press the brake lever forward as, a like the good old Sachs drum brakes. A small trick to release the gear change cable for the Shimano 7 gear hub. See the small hole pointing backwards in the plastic ring closest to the gear/chain? Insert a 2mm Allen key there and use that to lever the ring forward, and use needle-nose pliers to release the cable end. Easy :)

For many years I've liked these Retro-Futuristic lamps that are floating around in the family house. They were collecting dust because each used a 40 Watt E14 incandescent light bulb, plus the cables didn't seem to make correct contact. However, the bulbs could not be replaced easily with LED bulbs because they have a mirror surface, really adding to the looks and design. But luckily I found these nice looking LED bulbs (tad pricey) in a Saturn electronics warehouse in Vienna some time ago. Only the cords with a switch were in a really poor state. It seemed a certain tinkerer (very well known to me) had a habit to put some solder on the wire ends. However, with age this tin will start to oxidise heavily on the surface, make contacts really bad! (always use press/crimp ferrules instead!) Also the plug style wasn't up to current standards so replaced it with a new transparent style Klopp Euro style cord. https://www.conrad.nl/p/kopp-140310090-snoerschakelaar-tr-140...

Just learned again that finding correct parts for an older bicycle can be challenge. Even parts for the here ubiquitous Dutch city bike can get hard so source when the bike is over 10 years old. Sadly the manufacturers either go for planned obsolescence, make it hard to repair or simply just not sell parts to consumers directly. Next time I will not buy this brand again. Note that the Batavus, Gazelle and Sparta brands are all in the same holding company I think, the Accell Group and suffer from very similar problems. In this case I needed to replace a worn chain, the rear chainwheel and the drive chain wheel. The right cranks are fused to one piece with the front chainwheel, and are usually sold in a set. Finding a replacement crankset was a bit of a headache. The square taper of the bottom bracket axle can be in two sizes, ISO and JIS. It has a minimal difference of maybe a tenth of a millimeter, but the 2 degree taper could result in a few millimeter difference when it is mounted...

Brazing is a soldering technique at high temperatures and using a silver alloy to join two  pieces of metal together. The temperatures can be 480 up to over 800 degrees Celsius. Normal or ‘soft’ soldering with Tin-Lead or Tin-Silver-Copper alloys uses temperatures well below 480 degrees. Unlike welding, brazing will not melt the parts, and the joint is very smooth. And unlike welding there is no need to flatten or smooth the joint after brazing. Most classic city or road bicycle steel frames are brazed instead of welded. Cheap modern steel or aluminum frames are mostly welded, and one can recognise this easily by the ugly joints and the absence of the lugs in where the tubes are seated. The most common technique for brazing is using a gas flame. Somehow I dislike the idea of storing and playing around with big, heavy and slightly dangerous gas bottles. Mostly this reason prevents me to experiment with this technique. Recently I found another technique: induction brazing! Equipment ...

Made the SIFAM collet knob tool today! And it turned out quite nice, see the pictures below. I don’t own a Proxxon or Dremel. Instead I used a normal 550Watt Metabo power drill at 2800 RPM. The maximum setting.  Such tiny diamond coated grinder bits are usually run at about 20000 RPM, so this made progress a bit slow. For a one-off it’s okay.  Proxxon Micromot 28 240 diamond coated grind bit (1.8mm) It’s a bit awkward to steer such slightly heavy machine for those small movements. To ease the grinding process, I’ve put the extra front handle in a horizontal position. Also used a bit of drill/cutting paste to improve cutting performance. Tried to apply as little force as possible since such miniature bits aren’t made to be used under high loads, such as with normal HSS/Carbide milling or drill bits. Because it’s more a cylindrical steel shaft instead of a disk type tool, it probably is a bit sturdier. The Metabo power drill with grind bit. WARNING: Never try the o...

Last time mentioned ordering cheap 8mm slot screw bits, 1.2mm thick. This to make my own SIFAM collet tool. Received the bits with a bit of delay, just before I left last weekend. It is a small pack of 3 bits for €2.75 so one bit is about only 90 cents. When unpacking, I was slightly alarmed by the claims ‘Extra Hard’ and ‘Made in Czech Republic’. So this actually might be very good quality, instead of the cheap and soft steel I had hoped for at this price... Bosch 2 607 001 468 Extra Hard S8 bits Tried a small needle file file on it, and can confirm it is really good steel. Instead of using a lot of patience and elbow grease ordered a Proxxon Micromot 28 240  diamond coated grind bit (1.8mm) for about €3.49 Bit clampled in a small vice with red marker     Will try it in a drill at a high RPM setting and gradually mill a small indent, as marked inside the red region in this picture. If it fails, still can have two other tries.

A quick update, since next weekend I’ll be in Vienna again so I won’t be tinkering for a while. Today ordered the electrolytic capacitors and checked how to remove the knobs from the pot shafts. It was a bit of an unpleasant surprise to me, since I was expecting just a hex nut under the plastic cover cap as most of these style knobs have them. But instead there is some slotted rounded nut, some bespoke SAFIM brand brass nut it seems. SAFIM Collet knob Found out by some googling, the SAFIM Collet knobs are also used in designs by SSL and the likes. SAFIM sells a special tool for this, but I’ll just make my own tool. It clearly doesn’t follow DIN546 spec for slotted nuts so I guess there is no alternative “standard screwdriver” anyway. Added some cheap-ish 8mm slotted 1/4inch hex drive screw bits for the purpose to the order, and I’ll just grind or file my own “snake” style bit with an approximate shaft gap of about 5mm. Meanwhile thinking about the enclosure design. Cheers fro...