A Mini Tower Clock

[crueby]

Got the frame pieces sanded down with some 600 wet/dry paper, looking much better. Here they are assembled again:

Bit hard to tell the difference in the pictures, its now much brighter and an even color now, before sanding the brass had a lot of spots and tarnish on the un-machined surfaces. I'm picking up some of that clear that Marv posted, and will try that out!

Today started shaping the gear holder posts. These will bolt to the horizontal frame bars as shown in the CAD drawing earlier on. The lower ends of them get a decorative shape to complement the column finials. Would be possible to do the shape on the mill, but to do eight of them and get them consistant would be tricky. So, fired up the new CNC mill and have started running the blanks through to shape the one end of them. I'll do all the remaining milling/drilling on the normal manual mill. So far two have been shaped, and I can get started on them this afternoon, shaping the top ends, and adding a bead detail around the edge before drilling the holes and milling in the slots to mount them...

All eight will get the same bottom end detail. The length of each pair varies with the gears that they hold.

[cnr6400]

  Two points already! 

[crueby]

Two points already! 

Now six!  (one of them is over on the mill in the next post/picture - as Monty Python would have said, "Sir Not Appearing In This Film")

[crueby]

While the CNC is cranking out the other decorative ends on the gear holders, I started the next step in shaping them. The upper ends of each will be a simple semi-circle, and there will be a bead detail on the edges of each. I started out by taking an old offcut that got turned into a workpiece holder for some other project, and put it in the 3-jaw mounted to the center of the rotary table. Then milled a shallow recess the same width as the holder bar stock. To ensure the recess was centered, I finished up the recess by turning the rotab 180 degrees between cuts, and moving the mill table in till the recess was 1" wide (the width of the bars), making each cut on each side of the stock. That left the center of the recess in the center of the rotary table. Finished by drilling/tapping a pair of holes for a crossbar I fuond in the box of hold down clamps.

The blue line you see across the center of the round fixture is the centerline, and I marked the center of the desired arc on the part so I could line them up in the fixture before tightening down the clamp screws. Then started making passes on the bar, 50 thou at a time, and with the mill table moved out slightly so the initial cut was back from the finished edge.

Once I was through the bar, and the excess length removed, I moved the table back in so the final light cut was to the edges of the bar, leaving a nice semicircle.

And the finished (well, to this stage) first bar:

I'll repeat these steps on the other seven, then move on to the beaded edge...

[Dave Otto]

Hi Chris, how will these be attached to the frame?

Dave

[crueby]

Hi Chris, how will these be attached to the frame?

Dave

Where the recess is across the horizontal crossbar, there is a threaded hole for each post. The post will get recesses to match the flanges/rails on the top/bottom of the recess, and a slot will be milled at the height of that threaded hole. That way these gear holders can be screwed to the crossbar, but still will allow slight adjustment horizontally to fine tune the gear mesh. The recesses top and bottom will keep the holders from rocking side to side.

[Dave Otto]

Cool, thanks!

[Kim]

Pretty clever, Chris! 

Kim

[crueby]

Thanks guys!
With all the modern CNC done on the decorative lower ends of the plates, and all the ends rounded off on the top ends, time to give it a little more decoration with traditional CNC, namely Count Number Cranks, or Chris Now Cranks...      Switched the square ended mill with a ball end mill, and went back around the rounded ends to put in a little cove

Then over to the vise to continue the milling down the sides:

In that last shot you can see the kind of tarnish/spotting that the raw bar stock has, that is what I was wet sanding off the other day. So far I've got half of them milled down the sides, after the rest are done I'll start in on the slots to fit over the frame rails...

[cnr6400]

  Hard to beat a nice bead!  Looking great! 

[crueby]

Hard to beat a nice bead!  Looking great! 

Lotsa beads, must be a hippy clock!

[crueby]

After a couple more play sessions in the shop to get the rest of the beads done, here is the collection of gear holders:

Next will be to cut the slots in the backs of them to let them fit closely over the horizontal rails on the frame:

Also, I picked up some of that clear spray that Marv mentioned, and have given some scrap pieces a couple coats. Letting that cure up before deciding for sure, but it does go on nice an thin and even, very clear. May give the frames a clear coat after all...   

[Sanjay F]

Looking spectacular as usual Chris ....... 

[crueby]

Thanks  Sanjay!

[crueby]

This morning got the slots cut in the back of the gear holder plates to fit on the frame rails:

Once the first one was cut, the same handwheel moves were used for the rest. The work stop was very useful in replicating the cuts on each piece, offsetting positions as needed to do the different length plates.

Here are all of the slots cut:

Then went back and cut the through slots for the mouting screws in the center. The slots will allow for adjustments to the mesh of the gears.

Closeup shows how the slots allow the plates to fit over the crossbars, and lock in the plates from rocking side to side:

All the plates test fit:

After letting the test pieces that I sprayed with the clear coat had set up overnight, I liked the results for appearance and also scratch resistance, so I have gone ahead and sprayed the main frame unit. The gear holders still need more drilling for the gear shaft bearings, pendulum mounts, dial mount, and bevel gear mount, so they will be sanded and clear coated after all that is done.
Quite happy with how its looking so far. Next up will be to drill for the shaft bearings...