EDIT – I have decided this is not good enough and will need remaking!
Well, as with last time when I hadn`t posted for a while, it isn`t not because I`ve not been working on it, just struggling!
For the first time, I`ve gone ahead and made a part without actually understanding how it works and fits together. The daisy wheel is very clever. Gadget builder has posted on youtube a nice video showing as best he could how it runs but despite his best efforts, reading all the books I could, I still couldn`t quite understand it.
EDIT: A fellow machinest, BillTodd over on the madmodder forum kindly did this animation for us after I had made the part:
The basic idea is a daisy shaped wheel running on a cam like action to get your 12:1 reduction. It is an amazing concept since most geared motion works requires a number of gears (two gears would get your 12:1 reduction but would have the hour hand running backwards!) This concept does just use 2 parts, the daisy wheel and pin wheel and gets the 12:1 reduction!!!
The first part is the pin wheel, you can in theory use 12, 4 or even 2 pin, I went with 4. My filing is improving as is my use of a piercing saw but with this being such a central piece, I wanted a nice finish so marked out with off centre holes and mounted each hole on the arbour in my rotary table to cut the shape:
I then spent all my time on daisy wheels making 4 attempts in total. I ended up using my first but I am determined to make a better one before I call the clock complete. Just getting the concept to work made me happy but I think now I understand it better, I can make a nicer looking one.
Marked out the daisy wheel
and then no more close ups or details as it looks like a rat chewed it!! All I will say, is that the petals are not needed and are just an added possible problem so get rid of them. I first read that the petals can be removed by looking at a picture sent to gadgetbuilder by Anthony Adams who had “abbreviated” the petals. They are not needed. In action it does appear like the pin wheel is riding the petals but in theory, the pins are simply locating in the “V” of the petals and not riding on the petal top itself.
Here are all the parts to the daisy wheel including some clock hands that I dug out of my stash which luckly fit.
At this point, I could then place the daisy wheel in the pin wheel and locate the pins in some of the bottom daisy “V”s. I could then spin the wheel in the pin wheel and you could observe the 12:1 reduction. The issue was then making a cam with the correct throw. Too much and the pins bind, too little and the pins wouldn`t engage. When I got it somewhere near, the petals tops started causing an issue which is why I lobbed them off in a desperate attempt to get it to run, and I was lucky, and it did!
The daisy motion is a totally independant unit. At the very back of the pin wheel arbor I have put a piece of bent spring steel with a taper pin behind it. The entire daisy motion is then pushed up against the bent spring steel and a taper pin inserted at the front to hold everything in place. This then acts a clutch allowing you to alter the time as the daisy motion/minute hand is not stuck or screwed to the pin wheel arbor, it is just being held by friction against the spring steel.
And finally a video for you:
It has only been running for about 2 hours and is working OK with the hour hand turning nicely. However plenty of time to stop and bind yet!!
Although my daisy wheel works, it looks a mess and also the “V” between petals is too large, this means the hour hand hangs for a good few minutes without moving rather than a nice gradual progression with the minute hand. It isn`t really noticable but I`ll notice it….this part will be re-made!