Astro Skeleton clock.

Here is a link to another months work on the clock. This is what happened in October. http://www.my-time-machines.net/astro_10-17.htm

It is mostly about how I produced cams to give a annual cycle of positions on the shutters that display the length of day and night. It would, no doubt, be possible to calculate the correct profile for the cams, but, then one must machine them to those dimensions, I do not have a CNC cam grinder ( there are some beauties on this site!) so I have to do it manually. It took about a week to make these two cams. I think if I went the calculation route, I would have taken longer, as, I would need to learn how to do it first and then make a cam machining fixture to fit on my mill. If there were any errors after that I would have to correct them with a file anyway!

Sorry ,No new photos as I have not done much since the last post.

Thanks for the compliments, they are really appreciated.
Buchanan

I watched your video. What a magnificent instrument. I am in awe of your skills. Simply beautiful.

Rick
Sth. Australia

I have started the final assembly of the moon dial .Most parts are finished to 1000 grit sandpaper and then given a quick rub with Brasso to brighten them up. The two plaques are just paper at the moment. They will be fired enamel with a brass frame finally.

I needed some small stars for the day/night shutters.

I had some ‘scrap’ Stirling silver from a previous clock dial so decided to use it. A simple five sided star toolpath was manually written in g code and a Dimond point milling cutter made and the machining trials started. By varying the angle of the cutter and the slope of the tool path an acceptable star was machined. Taking a leaf out of Terrys(Merlin) book, I machined away the back of the star until it was complete. The stars are attached to the glass with shellac.

The sun/moon dial is almost complete. I am working on how to get fine black lettering on thin glass that is real permanent and not having much luck. The best results so far are laser etching through a ceramic spray that should give a dense black print but not the best results so far. If any body knows how to print fine 2mm high numbers in black on glass I would love to hear about it. The complete mechanism is mounted on the clock now and just waiting for the glass dial. The machining operation is when I needed a circular round groove in the back of the dial to provide clearance for the moon. Buchanan

Here is the next update on the clock, http://www.my-time-machines.net/astro-01-18.htm I have ben tidying up a few details, Made new balance springs out of NiSpan C steel which has a zero coefficient of elasticity.
Then started on the cosmetic design of the Planisphere as well as the gear ratios and positions of gears to fill all available space. The bezel and plinth are at present Corian bench top material spray painted gold. Finally they will be Brass. I have made the bayonet clamp mechanism to hold this assembly in place. I have made most subsections easily detachable so that if there is a problem on a subsection , it can easily be removed and sent to me with out disturbing the whole clock. You might also like my skinny gear. The first photo shows it while the spokes were getting cut. This gear has 516 teeth. In total the Planisphere tooth count is 2699 teeth in a set of 16 gears. I have a digital dividing head and auto cut and feed on the milling machine so gear cutting is almost automatic, so, high tooth count gears are just fun.

Just stunning! I've spent 'more than a few' hours on your web site

I know this is just scratching the surface. But generally, when you make your ornate frame components from sheet brass stock, I've seen a few pictures with cad templates attached to the stock outlining the shape, what looks like a Hegner scroll saw?, I think a binocular looking magnifier. After that, once cut 'to the line', is it essentially all hand file work thereafter to get the surfaces all blended in & looking so good? (I'm talking about the more ornate pieces, not precision fit stuff like gear teeth & motion transfer surfaces). Or is there a 'power tool' like an upright rotating abrasive cylinder or maybe a filing machine?

Also, I was lurking on some of the jewelry & clock sites to see what they use for temporarily holding stock to do machining & then releasing it without distortion. It seems like there are some old school favorites, what they call setter cement or dop wax? Seems like a shellac/wax type base usually burgundy or sometimes green color? Others seem to be going for epoxy or CA & then releasing with heat (likely more heat?) or sometimes solvent for CA. I've seen some of that on ClickSpring videos for example. Do have a favorite method for this operation? For reference, say .050-.100" thick stock, mounted either on a plate in the lathe for turning work or sacrificial plate for milling work.

Pertha.

Yes it is like you say. For the ornate work , I Photo copy the piece of brass plart, the drew the art design around pivot and mounting holes on the photo copy,(you can make a many mistakes and changes you like until you are satisfied). Any circular bosses are scribed around existing holes on the plate. I then spray both the paper and brass sheet with aerosol contact adhesive, While the glue is still wet, I apply the paper design to the brass and slide it around on the wet adhesive until the design is aligned withe the predrilled holes in the brass plate. when the glue is dry i cut along all the Design lines with a scalpel blade. This transfers the design onto the brass as a scribe line as well. Then I remove the paper. Yes the saw is a Hegner, and I have a low power binocular microscope. The microscope make it possible to cut along a scribed line with great accuracy very easily. When the design is cut out, the round bosses are filed to shape around filing buttons.( I used to make the harden the buttons, but ruined far to many good files, so, now I make the buttons long and leave them soft. A soft filing button will remain accurate for at least ten bosses.) The rest of the design is finished with files by hand. I have made a belt type sanding machine which has some unique features, but it has a few short comings as well, so, will be redesigned before I use it regular.

I use car body filler , super glue, epoxy and shellac for part holding, No special favorites. The job dictates! It depends on the requirements of each particular job. , Myhugh tells you how to do it in the Merlin and Radial engine threads.

Are the curves all hand drawn, or done with CAD?

Kvom.
Most curves are drawn by hand on an enlarged photo copy if the uncut brass plate. Often we will explore 2 or more designs before completing a part. The final refining is done by file, as , but that stage we are working with the final part and it my look too heavy or a curve just not flowing properly. i have used splines on cad a few times but it is more cumbersome. Any CNC'd part has every radius left by a cutter removed so that it is the same as if it had been hand made.

Here is the latest update. http://www.my-time-machines.net/astro_05-18.htm
Next is the orrery.

Wow, Wow, WOW.
I've been looking on your site & elsewhere (purely for interest) for the machine & process that makes these intricately curved, cut patterns. Can you provide any info/reference links?

It is a home made CNC mill, Mach 3 Draftsite 2 D cad and Cam Bam. Nohing extrodanary. look at the drawing in the last installment.

If I understood the writeup the planisphere cover in Corian was a mockup prior to making the final part in brass. With spray paint it looks pretty good.

I was surprised to see the drafting table when you also use Draftsight. Brings back memories.

Simple, do not you?

I should have said that the pink in the last drawing shows the path of the drive to the outer moon on Saturn.
For the engine turning . I draw the outline of the dial and then made an array of overlapping circles around the center of the dial, then deleted all the lines outside the area that I want machined in the pattern. On CAN BAM, I selected all the lines and engraved along them with a v shape cutter. Corian counter top scraps make a lovely material for test machining. The only disadvantage is that it is a little dusty. It does not melt when milled like plastics and cutters stay sharp for a long time. It also takes paint well. I pull it out of the scrap bin at a Kitchen cabinet manufacturer. For me, the drafting table is better when designing something complex and a lot of changes need to be made. For CNC machining CAD is a requirement. From this point on I will use hand drawn sketches. As I do all the work myself I know what is happening so only the important dimensions are calculated. The rest is done by eye.

Back in post #65 you were asking about printing 2mm characters in black on glass.(Just catching up.)

You've probably already thought about it, but what about the techniques/materials they use for hand painted stained glass? Printing the 2mm characters should be no problem and after it's fired the printing would become part of the glass. You'd probably have to experiment a little bit, and it might cost the better part of an arm and a leg to get the parts printed and fired, but with the work that's already gone into this beast that cost would probably be a drop in the bucket.

Don

ddmckee54 said:

Back in post #65 you were asking about printing 2mm characters in black on glass.(Just catching up.)

You've probably already thought about it, but what about the techniques/materials they use for hand painted stained glass? Printing the 2mm characters should be no problem and after it's fired the printing would become part of the glass. You'd probably have to experiment a little bit, and it might cost the better part of an arm and a leg to get the parts printed and fired, but with the work that's already gone into this beast that cost would probably be a drop in the bucket.

Don

Click to expand...

Don. That is exactly what I am working on right now. I had a test part that worked really well. When I received the real part , while I was machining the glass the print just floated off. I possibly did not clean the glass properly before I sent it to the printers. I am going to have another try before I discard that route. Thanks for the input.

@Buchanan That's incredible!