A New Toy

I have got my hands on a new toy. A dividing head.


But it lacks a tool for tightening objects in to the chuck. So we need to make one.

I took a 22mm diameter shaft and measured that square hole has a 10mm side. So I need to take 6mm off from each four side of  the shaft. Chuck has a wheel of 36 teeth and one can lock those teeth in position, one at the time. A quick calculation gives that when the first side is milled down 6mm, 18th teeth must be locked in and then milling can continue. After that 9th teeth locked and milled. And the last 18th teeth and milled. (Of course this can be done by 9 teeth at a time.)

Her we are in the middle of the process.


When all sides was milled, I bored a 13mm hole to the shaft. At first I used a center drill bit and a lubricant and then I gradually moved from 6mm to the big one.


All I have to do is to cut those 22mm and 13mm shafts in convenient length and make some adjustments that 13mm shaft don’t slide through the hole in 22mm shaft. And of course to do some grinding. Shafts are just some ordinary steel (st52 or something like that) so I am not expecting them to last too long, but time will tell that. On the other hand, I don’t believe that this dividing head (and its new tool) is going to get too much attention in its current location. Conveniently other chucks around the shop uses a different size of a square tool.


Here is the Machine behind all of this..


And no, I don’t own it, I just can borrow it and facilities around it.

Remember to use at least safety goggles (and Colin’s safety tie 😉 ) when using metal working machines!




Arduino, LCD and DS1820

As I mentioned in previous post, I might use those DS1820-sensors. And I did. Platform is the same, but enhanced by one little but mighty sensor. (Actually that sensor can be seen in previous post also.) Those little things are packed full of technology. They look like an ordinary transistor but that fools you a lot. They measure temperature quite a wide range (–55°C to +125°C) and convert analog readings to digital in no time. Multiple sensor can work in the same line because every one of them have it’s own unique serial number. They have also some other tricks in their sleeve, your favorite search engine will tell to you a lot about them.

When measured temperature is already converted to digital values, it is easy to get those values to Arduino, for example. Code is in Git. Code is released under gnu gpl 3 and is patched together from others contribution with a little bit of my own code.

This apparatus measure temperature values and shows them in Celsius degrees in LCD. Video below.


Arduino, LCD, Rotary Encoder and Ikea USB-LED

Update 21.5.2014: Here is the source code: https://github.com/renerento

Yes, Arduino, a piece of electronics that divides people. Some of us like it and some of us hate it. I like it.
Some time ago I bought 2 Arduinos at once and started to play with them. At first my goal was connect an Arduino to LCD and display some data on it. Then I realized that I have a rotary encoder and it would be fun to use that component as well. I digged code snippets from internet and found many ways to connect a rotary encoder to Arduino. Some of them used external capasitors for debouncing and I did not like that. Then I found Ben Buxton’s home page and used part of his code to make things click.

I also had some DS1820 temperature probes lying around and I decided to connect also them to Arduino. Maybe later more about that topic.

I found a simple aluminum enclosure. I modified it a bit for my components to fit in and started coding. As I am not a real coder, I simply searched code from the internet and modified it to suit for my applications.

This code does following:

When powered on string on LCD is displayed “LED dimming test”. After that display goes blank. When one rotates encoder LCD shows either string “Minimum value reached!” or up going numbers. Simultaneously with up going numbers the USB LED from Ikea starts to shine. The more the numbers grow the more LED shine, until it reaches the max value. When that happens LCD says “Maximum value reached!” User can decrease or increase the level of the numbers and brightness simple rotating encoder. Numbers change 5 unit per one encoder click, min is of course 0, max is 255.


Here are some pics and video.





Changing Head Gasket for 2001 Clio

After I changed the cabin heater radiator to my ’01 Clio it was obvious that it was not enough. Overpressure in the cooling system was still a problem.  After driving, even if the car was not started in 12 hours, there was still so much pressure in the coolant system that if one opened it, a loud psssshhhh was heard. Next thing to do was to change a head gasket. Here are some pics of the process.

This was the starting point.

And some progress.


Cleaning cylinder head with sandpaper.


Engine bay, top of the cylinders cleaned.


Old gasket was a bit worn..


Closer look.




Fitting a new one..


Tightening order.


After this point I kind of forgot to take pics.  But repairing succeeded and there was no more overpressure problems.

Sail on!

Toy Repair

I received a caterpillar toy for a repairing.

The metal slots holding up the front shaft keep getting stuck with the shaft’s cranking mechanism, and obviously stopped rotation. The other slot is clearly visible in this picture(red arrow), and also is the way I finally got it right. (Those short white plastic tubes.) At first I tried to make a sheet metal support inside of the metal support frame, but there was no room for that, shaft’s corners came in the way.


Here are the tubes, marked with red arrows. Plastic tubes don’t let the shaft move too much sideways and that way cranking mechanism can’t get in touch with the slots. It is not perfect, it still get stuck sometimes, but it is a way much better than before. I saw the owner’s test-drive and it went okay.


Wooden wheels came off by just pulling hard enough and that way I could just slide in the tubes.

I found those plastic tubes from my part collection of a torn apart devices. Oh, and I had to use a file on the corners of the shaft to make things smoother.

Black bar’s other end is connected to caterpillar’s rear end.  The cranking mechanism makes the toy move like a real caterpillar. It is a quite clever invention, but execution is poor, tolerances are too big.

Toy was made by a good quality company, which make me kinda sad, they used to make good toys in the old days.. But on the other hand, one have to remember, this is the only one example of company’s many many products and maybe this was made on Monday.. 😉

Sail on!

2009 Mini Fuel Leakage

A friend of mine was on a holiday trip with his friends. They were going through the city I live at the moment. Their -09 Mini decided to burst some fuel on to the road only a couple of kilometers away from the place where I stay. 

First inspection showed nothing. But when we started the engine, the problem was clear: Pressurised rubber fuel hose had worn itself out towards the other hose and fuel was literally bursting out. It was Sunday and there was no place to go to get a spare part. And if shops were open, of course they had to order the spare part, I guess. We got an idea: What if we put some copper tubing into the broken area and secure joints with hose clamp? A quick Google search revealed that Mini’s fuel pressure is 4-6 bar. A reference call to a friend of mine confirmed that our idea was worth trying: The same trick has worked with a Mercedes, which has fuel pressure of 9 bar. My friend suggested that we should put two clamps per joint, total of four clamps. By doing that there should not be any problems. We managed to find some copper tube and hose clamps, and voila!


Fixing parts, or what is left after the repair.


Fixed! A friend of mine showing the results of our work.

The replacement part could be quite expensive, those proprietary connectors smells like a good amount of money..


It was a kind of difficult to reach but we managed to get it right.

Testing revealed no leakage. Success! Friends could proceed their trip. I suggested to the owner of the car that he should order correct spare hose as soon as possible.

Later on I got a message from my friend that no leakages has found. Good!

1999 BMW E36 Compact Blower Resistor

I was at a longish trip with my E36. Weather was a bit rainy. During way home my blower decided to quit. At first I did not recognize it but eventually next day I got it: Blower was not working. (Or almost not working, highest speed was okay.) This is very common symptom when blower resistor has broken up. Blower resistor changes the speed of blower. Location of this resistor varies for every manufacturer and even in different models and year, so at first I had to locate it. I looked inside under the both sides of dashboard – no luck. Then I got a hint from one of the forums: Pop up the hood and tear off some parts below windscreen at the engine bay. Couple screws and panels later I was back in business: long missing resistor was at sight. At first I had to remove pollen filter, resistor was under it, very near of the blower itself.

And then I realized why resistor was given up: Pollen filters was so dirty that practically no air could go through and thus resistor was not given any cooling airflow. Raining mentioned at first part of this post was the final key, it had blocked filters with water and dust..

Shiny new ones and old ones for comparison..


Location of pollen filters, new ones fitted for clarity. Blower resistor lies down below the another (right in this picture) pollen filter. Connector was a bit tricky to get back, wire was quite short. But I managed to get it 🙂


Broken resistor looks like this. I decided to try repair it, only problem seemed to be that small metal spring which has lost contact. (Two solder points between dark and light green areas.)




.. And progress. 35€ saved! Soldering was bit challenging so there is so much solder that next time in hot situations it may not work as planned. (It is a thermal fuse). (If you do this kind of soldering you need a good and capable soldering iron, there is quite some copper to be heated up.. )

But in our country very hot weather is rare occasion and I plan to change pollen filters more often than previous owners.. And there is always the another end of spring, which is untouched.


General view. At this point I drove a couple of days like this and tested how blower resistor worked. Everything seemed to be fine, so I proceeded. And I forgot to do another maintenance:  put some oil to blower bearings, at winter they tend to make some noise at higher speeds. Bummer!

But, on the other hand, now I know how to do it, so it is not a big deal. I just have to remember to dot it before winter..


Panels waiting to be fitted back.


Same panels upside down.


Almost ready.


And finally finished!