General Category > Oddball

Strutt Epicyclic Train Clock (maybe?)

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kvom:
Since model shows are far away and I no longer like to make long drives, I've thought about trying to make a clock.  In browsing various websites I came across this one, originally designed about 1829 by William Strutt.  The plan book by W. R. Smith details the build process.

To actually attempt this build I'm going to need a CNC mill, because chain drilling and filing are not something I'd enjoy.  The mill I'm considering is the DMC2 Mini from a company in Toronto.  It can be had in kit form or assembled, but both are back-ordered.  This mill has a 20K RPM spindle, and I have endmills small enough to cut the gears in profile. 

The front and back plates have overall dimensions 9/13".  Rather than investing in engraving brass to the tune of $400+ to begin with, I plan to cut them from 3/16" clear acrylic sheet using the CO2 laser my daughter and I just purchased.   The dial will also be engraved on acrylic sheet.  For the rest I have a decent stock of 260 brass.

Before getting in too deep, I thought I'd try to make the fusee.  This part requires manual machining on the lathe in an unorthodox manner.  I showed the blank on Kim's clock build as he was also trying to make the fusee for his clock.  But rather than barging in on his build I'll continue here.

The blank (pic below) was turned from a piece of hex brass rod that is 1-7/8" across the flats.  Since this is the desired diameter of the blank it just needed to be turned down.  Before that I faced to length, drilled a through hole 9/32" and reamed it for a press fit.  Then cut a pocket in one end where a ratchet will live.  The shaft is a piece of 5/16" diameter drill rod that was center drilled on both ends and then pressed through the blank.  I used the vise on the Bridgeport as a press.

The profile of the fusee is circular with a diameter of 2-7/16" and centered at the left side.  The cross slide on my lathe (Monarch 10ee)  rotates easily.  I moved the toolpost to the right so as to center of the tool holder over the axis of rotation and then adjusted the cutter in the holder to achieve the needed radius.  This all required some finagling and was as close as I could make it.  Then set the cross slide perpendicular to the blank with the tool tip at the left end of the blank and lock the carriage.

I took a shallow .02" passes.  The tool I used might not have been the best choice as the surface wasn't smooth and my head was continually hit with tiny brass bullets like being in a sandstorm.  Eventually I got the end and smoothed the surface somewhat with sandpaper and some small files.  Since the surface will be cut with spiral grooves its current surface isn't a real concern.

crueby:
Very interesting  way to turn in that arc.   :ThumbsUp:   Did you have a long handle on the tool holder to control the rotation across the arc?  Looking forward to seeing the rest!   :popcorn: :popcorn:

Kim:
That's a great start to your fusee!  :ThumbsUp: :popcorn: :popcorn:

I don't know that the finish on this initial shape needs to be that good since you'll lose nearly the whole surface by the time you have the spiral groove cut :)  (that's what I told myself, at least!)

I'm looking forward to seeing how you cut the spiral groove.  I'm still playing around with mine, and I'm not sure the fancy rotating tool is going to do it.  I may end up trying the other method of disconnecting the cross slide and moving it, and see if that works any better.  But I'm stuck now till I get my lathe back together.

Kim

kvom:
Since my lathe has a taper attachment the cross slide can be detached from the screw by loosening a bolt.  So I will try pushing a threading bit manually against the work. 

When cutting the arc I held onto the top slide, which is quite long.

This will have to wait while I do the assembly and setup of the laser.  The cart to hold it should arrive today, and it needs to be assembled.  Then the riser base for the laser needs to be assembled, and finally the laser needs to be unpacked and adjusted before the first test.

Jasonb:
Can you not replace the straight taper attachment guide with a template of the curve. Then you just use that to have the tool follow the curve as the leadscrew moves the carriage along at the required pitch. Repeat as needed putting on a deeper cut each pass.

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