Weston Bye Magnetic Gear Clock

[kvom]

I see a couple of clock threads in here, so I thought I'd start one of my own.

Last year at Cabin Fever I saw a working model of this clock, the plans of which were published in Digital Machinist Magazine in 2012.  I know George Race and dreeves  built this clock.  I bought the 5 issues containing the plans at the show with the intention of building it over the winter.  The only thing I got done was to draw a few of the parts in CAD.  This week I decided to resurrect the project by finished some of the drawings, and today i obtained some aluminum plate at Metal Supermarkets.

I have a decent amount of brass sheet and am going to make any parts that fit the dimensions of the stock I have from brass, with the rest being aluminum as in the original design.  There are a few steel parts other than the fasteners.  Most of the fabrication is either milling on my CNC mill or manual turning.  I plan to buy the electronics from Weston.

[zeeprogrammer]

I saw Dave's clock over pancakes.

Are you planning at being at CF this year?

Some people may not know what clock you're talking about. Got a pic?

[kvom]

[Dave Otto]

I have admired this clock and have the Digital Machinist issues; but I have to keep telling my self.......Don't start another project, I will be happy to follow along with you though.

Dave

[kvom]

I spent the day making the first two parts, the main and secondary frames to which other parts are attached.  I had bought a good-sized sheet of 3/8" 6061 aluminum, so cut out two pieces for the two parts.



The stock for the main frame is 7.5" square and too big for the vise, so I planned to mount it on a well-used fixture plate.  Most of the parts will be either milled CNC or turned manually.  Here's a brief summary of how I'm doing the frame.

First find the center of the stock.  Since this is a 1-off part, setting XY zero at the center is pretty easy.



Next use the same CNC program to drill 1/4" holes in both the stock and the fixture plate.



The stock securely mounted to the fixture plate ready for milling and drilling.



Using a gauge block as a height setter:



The subframe is milled from a 5x3" piece and needs no fixture.  The CAM program provides 3 small "tabs" to keep the part from falling through at the end.  These will be broken and the stubs filed off.



And the two frames at the end of the day's work:



I still need to tap quite a few holes.  I also modified the design very slightly.  The holes where the shafts and bearings are mounted are drawn as .469" diameter.  I plan to use hex-head 2-56 screws which have 1/8" heads.  These would interfere slightly with the assembly (Weston used socket heads), so I reduced the bore diameter to .460".

[kvom]

Started on the magnet wheels today. planning to machine both the A and B wheels from the same stock with the same program.  However, had some DOC errors on the A wheel, and screwed up the fix, so only got the B wheel done:



To save time and material, I'll do as many of the brass wheels as I can on the same stock, which I'm cutting from a strip 4" wide that I bought 5-6 years ago.  For variety, the ABCD wheels will have 3, 4, 5, and 6 spokes respectively.

[Dreeves]

KVOM. Here is a little insperation for ya. 

Dave

[kvom]

Nice collection of magnet wheels:

[kvom]

Next part on the list was the frame spreader that connects the primary and secondary frames.  I turned it from some 1" brass rod; however, since a lot of the turned parts are .75" diameter or smaller I'm not going to waste material by using the 1".  Ordered some .75" rod online.

The mounting holes on each flange need to be aligned, or else the secondary frame will be cockeyed.  Drilling through both in one shot might have worked, but with no way to spot drill the inside of the flange I was concerned about the .096"drill walking.  So I came up with this setup:



After drllling one end, I just flipped the v-block and used the (mirrored) coordinates for the other side.



Screwed it in for a test fit:

[zeeprogrammer]

Good progress.
Nice tip using the v-block.

[philjoe5]

I'm following along.  I know nothing about "magnetic" clocks.  Do they have gears as well?

Cheers,
Phil

[kvom]

No gears.  The small magnets in each wheel act as gear teeth interacting with an adjacent wheel.  When 1 wheel turns, the adjacent wheel is pulled along.   The gear ratio is given by the number of magnets in each wheel.  You want the magnets to have the same separation (think tooth pitch), so the radius of each wheel is proportional to the number of magnets.

The motive force for the entire gear train is provided by a steel spoked wheel that is activated by 3 electromagnets.

[Dreeves]

Nice touch I like the brass add in. Going to be following along as I may change a few things on my clock.

Dave

[kvom]

Machined the "bobbins" on which wire will be coiled to make the 3 electromagnets that drive the gear train.  Used some .75" white acetal rod that I have on hand.  These are just shy of 1" long.

[kvom]

I got my 3/4" brass rod yesterday, and had a little shop time today.  Started the 3 bearing carriers.  After parting and facing to length on the lathe, I needed to drill the same three 2-56 clearance holes in each.  Here's my setup on the Bridgeport:



Then back to the lathe to do the first turning:



I'll be busy elsewhere through the weekend, so nothing more until next week.