About Me

I've been taking things to bits, and making things ever since I can remember, starting with dismantling knackered alarm clocks and watches and helping my dad fix the car. Now I have a well-equipped workshop and have aquired lots of new skills, so I can make better stuff. When they first appeared, I became involved with personal computers, and these and developments in electronics have increased the scope of the things that I can do. Just recently retired, so O yes, now I can make all sorts of stuff.....

Tuesday, 1 October 2013

October update

Doing stuff is still getting in the way of writing bloggery, and this is how it should be, so this is the current state of the game at the end of September.  The main events this past month have been the Magic Clock and the airbrush, and in response to a couple of constructive comments I am trying to include more pictures and a bit less wordage - however, I've never been a man to use ten words when a hundred will do, so its unlikely I'm going to change now :-)

First the Magic Clock.  I've been banging on about this for a couple of months now, ever since I discovered that I could make gears on my little milling machine. Well, here it is, pretty much finished.
Magic clock - finished
"What makes it magic?" I hear you cry, so this is why. Although the clock is powered by electricity, it continuously stores a record of how many steps the motor has done since midnight on a small SD memory card and uses this to remember the time when the power is removed and when the juice comes back on it 'fast winds' to the correct time and then resumes normal timekeeping.  As it runs normally, it constantly checks that its not running too fast or too slow, and if it is it automatically adjusts itself.  Its seems silly, but unplugging it for half an hour so that you can watch it catch up is one of those things that you never tire of. Here is a short video of it just finishing its starting up routine:-

video


Goncalo alvez block with black streaks
The observant ones will notice that it fast winds, then hesitates before doing another quick squirt:  it does this because the startup winding can take a couple of minutes and it makes a secondary adjustment to compensate for this.   There are two LEDs on the front, one to show that its powered up and the other flashes when its making an internal adjustment.

This month I've made a big push to finish it off, starting with the purchase of a couple of hefty slabs of goncalo alvez timber and a less hefty chunk of black walnut, both from my local woodyard.  The goncalo alvez is a reddish timber with random dramatic black streaks, so I cut the chunk to make the most of these. Finished with danish oil and beeswax, all of the wood will gradually darken to a richer colour over time.


Fixings and cable grommet
The visible part is the brass mechanism - basically a pair of drilled plates with brass gears which make up the correct ratio between the minute and hour hands, and with a secondary gear train to the stepper motor which drives the whole thing.  No big deal in this part, other than the need to cut the gears and drill the plates with a fair degree of accuracy to ensure the train runs smoothly and without too much backlash.  It even has its own hand made miniature custom spanners to lock the hands on to the spindles

The mechanism is intended to appear to be hanging in mid-air and is contained in a glass fronted space to keep the dust and inquisitive fingers out. 
Stepper motor and drive module

The stepper motor and controller module came from China at a ludicrous price of around three quid including postage.

The part that drives the stepper motor is an Arduino microcontroller with a few add ons - a module to hold a SD memory card; a real time clock module, and the controller module for the stepper motor. All of the modules and the Arduino came from my friends in China with a total cost of around fifteen quid.

The software is in two parts - one to set the whole thing up, and the other to run the clock.The setup routines set the real time clock module to the current time, and creates the SD card file with a zero entry.  Once the setup routine has been run, the mechanism has to be physically set up with the hands pointing directly at 12:00 before loading the 'run' software.  The clock reads the data from the card (zero the first time out), compares it to the 'real' time and calculates the number of steps that the motor needs to run in order to catch up.  Once the fast wind is completed, the clock also calculates how long this process took and kicks the motor the right number of steps to compensate, then settles into a routine where it pumps the motor by n steps, compares the result with the 'real' time and makes any required adjustments by either pumping in a few more steps or stopping the clock for a few steps-worth.  In practice these adjustments are only around 10  - 15 steps worth (there are 36864 steps in an hour) and occur every couple of minutes - at the moment the software is full of information messages which affect the running speed of the software and I expect to be able to fine tune it better once the software is cleaned up a bit more. All along the way the number of steps completed by the motor is saved to the SD card, and the next time the clock is powered up after a power failure it reads this number and resets the clock.  Simples.

The software has taken me a fair time to write, C++ not being my first language, but with a lot of trial and error and help from Jon with the SD card it now works. There is loads of online help for these little computers, but although there are countless examples to play with, none of them ever seem do what I want to do.  Unfortunately - like there is in the linux community - there is also a fair number of self-styled 'experts' out there who when you ask a simple question make it their mission to make you look as stupid as possible instead of giving a plain answer, or giving a solution that is so complex that its impossible to understand. I have to assume that these people a) are twelve years old, and/or b) have a very small willy. If anyone wants to have a laugh at my code, or even have a go at building their own version of the Magic Clock, let me know


Rear access plate
The electronics are crammed inside the wooden slab, mounted on a metal plate to allow them to be slid out in case of internal derangement.  I'm expecting that the SD card will probably be the part that is most likely to fail, so I've made it accessible from outside with a retainer to prevent it being popped out of its slot by accident.

It was a real pig to hack away the wood to make the space for this, and in retrospect I realise that I could have split the slab in half and routed out the hole in both halves then glued it back together again.  Didn't think of that at the time, so it was out with my Japanese chisels and my little hammer.


Japanese oire nomi chisels

Not clock related, but every time I use them I realise again how spectacularly good these chisels are.  They are made from the same type of laminated steel that made the Japanese swords so good at taking and holding a keen edge even after hacking up a few assorted bad guys.  The steel is  heated up and hammered flat, then reheated and folded over on itself before hammering flat again:  repeat a few hundred times or more and the steel develops the ability to be hardened to a higher level than most other steels while retaining its strength and chip resistance.  The chisels don't do much in the way of bad guy hacking, but they take a fantastic edge and hold it through a lot of hard timber.  By contrast, the english plane blade that I have had for many years takes a fairly decent edge but loses it very quickly, requiring frequent re-sharpening throughout even fairly light wood butchery, and this is the case with pretty much all of the newer tools that I have - the steel is mostly selected for its cheapness and not its quality and it is increasingly difficult to get any kind of a tool that works properly. I especially hate the tools which claim to be 'titanium coated' but which actually seem to be  made entirely of cheese with a lick of brown paint.  Having recently seen a bloke making axe heads with a tray of hot coal, a big 'ammer and an anvil I'm tempted to have a go at making my own Japanese steel edge tools.  Watch this space.

All of this has taken up most of September, and because I wanted to get the clock finished before starting anything else, it has diverted me away from my other exciting new foo-foo which is my new Chinese Airbrush.  

If you search the 'web, the general view seems to be that some of the best airbrushes around are made by a company called Iwata.  They may be good kit, but with prices starting around £100 they are outside my budget, so I'm off to China via Ebay.  Well, blow me down, here's a Veda WD180 airbrush which is pretty much the identical jobbie to the Iwata HP-SB (priced at around £180) at a bargain price of twenty-five quid including postage.  Found some online reviews which rated it pretty highly, so worth a punt.

Veda WD180 airbrush
Well the little beastie arrived a couple of weeks ago after the usual 3 -4 weeks shipping, and its an absolute ripper.  Beautifully made and finished, and comes in a padded box just like the real thing.  In fact, its so much like the real thing that I suspect that it is made in the same factory as the Iwata.

I have a limited number of paints that I can use with it, and have only played with it a bit so far, but the first impressions are a) its a great bit of kit, works a treat, and b) its fiendishly hard to use.  The trigger presses down to release air, and pulls back to open the needle to let the paint into the airstream, but getting the co-ordination right is a bit of a challenge.  Like all these things, practice makes it better, but I need a fair bit of time before I am going to be able to do a Banksy on the side of the village hall.  So far, this Iron Man  is the best I can come up with - 


I have already found out that the water based paints which I have are really easy to use and clean up, but they only work on fairly absorbent surfaces like paper - on a hard surface you need to spray a bit, wait for it to dry off, then spray some more, and while waiting for it to dry you need to clean the airbrush to stop the paint drying inside (which is easy to do but tedious and wastes the paint).  I'm going to experiment with thinner-based paint and see how easy that is before re-painting my computer case with the Donald Duck picture. 

I've also discovered that the freehand work that you see people doing on Youtube is about as easy as knitting with fog underwater, and my best option is to use multiple sticky stencils - another new skill I have to learn.  I'm planning some flames on the kart side pods for next season, so now that the clock is done that will be my next focus.

And last, a quick medical update.  At long last I started the radio therapy yesterday, seven and a half weeks of going to the hospital every day, spending an hour drinking a gallon of water and three minutes in/on the radio machine.  First observations:  plain water is only interesting to fish, dogs and horses; the staff at the centre are really great, couldn't wish for any better; and while in the machine, they play music from the 1960s.  I thought this was a carefully thought out caring idea because most of their patients are aged 60 plus, but apparently they only have three CDs and this is the best of them.  Although the treatment itself only takes a few minutes, by the time I've hiked there and back its about a two and a half hour for the round trip.

I also had the last of the hormone injections today, can't say I'm sorry to see the back of them as they give me a constant dull headache, stop me sleeping properly, have added a couple of kilos to my waistline and generally make me less enthusiastic than usual. This last one should have mostly worn off by the end of October and I should gradually get back to normal after that.  With the radio therapy finishing mid-November I aim to get stuck into some fitness work after that and return to some form of martial arts training after Xmas.  Can't wait.

Next month?  Well, the airbrush will get a bit of a pasting as soon as I can get the paints organised, and I need to rebuild my desktop PC with some new go-faster guts provided by Jon - just received the memory today, but this will entail re-loading all the software so it will be probably the best part of a week loading discs and staring at the screen.  There's also the design work for the new 'Star Chess' game that OB and I have been talking about, some outside work to do in the garden before the weather closes in, and of course trekking back and forth to the hospital every day is going to limit my time a bit.


As the Honda advertisment used to say: "more forwards, please"

No comments:

Post a Comment