Monday, 1 September 2014

Other wierd and wonderful clocks

Whilst building the Topsy Turvy Clock, I've been on the lookout for other interesting clocks or other interesting clock modifications.

There are quite a few examples of the Weasley Wizard Family Clock which has multiple hands to show the locations of the different wizards in the family. The best example I've seen is Brad Collette's "The Magic Clock" and inspired the mechanism for my own clock.

Over on Tindie Akafugu Corporation have also been looking into fiction for ideas. They have a Vetinari Clock based on a standard clock module with a modified tick.

The Twitwee clock has a LCD display which normally shows the time in the form of an old fashioned cuckoo clock, when it recieves a message from the internet it swaps to display the message.

I can definately recommend googling for "Microcontroller Cuckoo" as there's lots of other interesting modifications in this category such as Joe Meiser's Robotic Vulture.

An example of non linear numbers is this "F-Stop" Watch, however the mechanism runs in a conventional manner.

Over in France back in the late 1700s they altered time completely with the concept of decimal time and a 10 hour day. I believe this is really just the renumbering of the dial and the mechanism and hand movement has not changed. If you know if the inards were changed too, please let me know.

My final find is from Brett Oliver and is more radical in it's thinking and has three analogue volt meters to show the time. Although Brett did not come up with the idea of using volt meters to display the time his clock is very stylish and has a very detailed write up.

Thursday, 21 August 2014

Car wheel removal

I have a small car which means that the spare wheel is hidden away in a hole under the floor of the boot. Down at the botton of this hole is a nut and threaded into this nut is a handle that screws down and holds the tyre in place, just incase it tries to escape when you are driving over a speed bump.

For some reason when it rains the water manages to make it's way into the hole contain holding the spare wheel.

The other day we discovered a slow puncture so I set about swapping out the spare so I could drive around to the tyre shop. As always my first challenge was removing the wheel trim. I'd taken a screw driver for that job so managed it with relative ease i.e. no blood.

When I tried to remove the spare from the boot, the handle would not budge. Because of the location it was difficult to get anything into the hole to help unscrew it. In the end I resorted to gripping it with a pair of pliers and managed to loosen it up. Not surprisingly the nut in the bottom of this hole had rusted to the handle. I cleaned up the thread on the handle with a die and soaked it in WD40.

I then made a simple tool to help unscrew the handle next time we need to remove it.

Finally I plan to get some old tea towels so that any water in the hole is soaked up and does not slosh all over the nut or if appropriate water proof it with some Sugru.

Sunday, 17 August 2014

Clock Numerals

To make the new numbers for the clock I considered a few options.

Firstly I thought about simply chopping up the existing numbers and resoldering them in the new positions. The problem with this is that the numbers have been specially shaped to fit their current locations. In some cases this would mean that I would need to add small pieces to them.

I also thought about etching, unfortunately to have that done commercially has some expensive setup costs so for a one off it would be a few hundred pounds. However it is worth considering if I wanted to make a lot of clocks. I don't really have the experience to try DIY etching, something I'd like to try but on a simpler project.

3D printing was also suggested but I thought it might not be a good match as it is a large flat shape.

Finally I thought that laser cutting might work, I made some enquiries and to have the part cut in metal again would have some high setup costs so would likely be £50 to £100. However I did find a company who could laser cut in cardboard. Given that my numbers will be behind a glass face and would be white to match the originals then this material could work well. The costs for this are a lot lower so I set about drawing it up.

I downloaded some numbers via the MSOffice clip art and arranged them around some concentric rings. This was then swapped to Libre Office which has some good spline editing tools. It took me some time by I'm happy with the results. The dual rings was one of the features I liked about the donor clock and I think it will give the numbers a strong connection with the clock, "as if they were original"

Wednesday, 13 August 2014

Spindles finished

The final piece of mechanical engineering on the clock was the spindles. As previously mentioned I had a couple of different ideas on how these might work. I went with something roughtly like my second spindle design and that's worked out nicely.

I knew that cutting the diameter for the hands to push fit onto would be critical so I turned this first before machining the spindles to length. The inner spindle then only required cutting to length and polishing. The hour hand spindle had to be turned so that it would fit through the "top hat" component, I've since discovered these are called "split nuts" and are often found on hand saws. Once the hour spindle was turned to fit the "top hat" I then turned a section to mount the gear. Finally I sawed this to length and turned it around to faceoff the other end.

It was a bit tricky to film these as I needed an extra hand hence the use of the pliers to hold the top hat whilst I turned the two gears beneath.

The next step is to fit these into the clock and ensure it's all running smoothly before testing with the motors.

Sunday, 10 August 2014

Clock PCB mounting

My plan to mount the printed circuit board onto the back of the clock was to use some screwed PCB mounts which were screwed onto double threaded woodscrews fixed into the back of the clock.

I chopped the end of some brass screws and using a thread gauge confirmed that the thread was 3mm x 0.6. I tapped the screw shank and used a hacksaw to cut a screwdriver slot in the top.

I created a pilot hole using a bradawl. Unfortunately when I tried to screw the modified screws into the clock they broke. One I managed to removed but the other need drilling out.

To hide the resultant mess I drilled holes large enough for the standoffs to slot into. I then used a packet of Sugru to hold them in place.

Monday, 4 August 2014

Flea Finalist

My flea made it to the final of the Metal Masterpiece competition

Sunday, 3 August 2014

Sheetmetal shears failure

Sheetmetal working is something that I've recently taken an interest in. A gift from work gained me a few pieces of equipment to allow me to expand my skills in this area.

One of these is a small set of disk shears designed for steel sheet up to 1mm thick. These work by having a driving wheel with lots of small teeth to grip the metal and a lower sheer wheel. The upper wheel is driven by a handle and ratchet mechanism. This pulls the sheet between the two wheels shearing it. The tool comes with a limited manual containing safety instructions and exploded diagram of the shears.

I had a practice with these with some thin zinc sheet and they worked really well. When I swapped over to steel things started going wrong.

When trimming one of my practice welds, 2 small 1mm steel sheets butt welded together the driving wheel climbed on top of the lower shearing wheel. This jammed the mechanism. I managed to free this up. I discovered that there was a cam mechanism that raised and lowered the lower wheel and that the lower wheel had dropped down. The lower wheel was raised back up and the allen key screw that held the cam in place was tightened.

I then tried with an old piece of stainless steel. This was not entirely flat and that caused the driving wheel to slip. When flattened out it worked again but quickly jammed. This time I could not free it and something internal broke meaning the ratchet mechanism stopped turning the driving wheel.

At this point I was not happy that I'd just broken my new tool. I stripped it down and quickly realised that there was a clever design feature in the shears. A small 4mm x 20mm pin connected the ratchet and driving wheel. This sacrificial component had sheared to stop the tool getting damaged.

I cut a new pin and reassembled the shears. I also noticed that the cam pin had a circlip holding it in place and this was not in its correct position. This was reclipped. I tested on thin sheet and the shears worked correctly, the thicker sheet caused the same problem as before, although I realised before causing damage.

There seemed to be two issues with this tool. Firstly that the cam moves out of place causing the wheels to separate. Secondly that the wheels move out of alignment with the driving wheel climbing over the shearing wheel. For the time being I will only use this with thinner sheets but hopefully at some point I'll have a chance to revisit and make improvements. I also hope to make a mounting plate so that it can be held in the vice more effectively.

Workshop Practice Series