Glass Rod Pendulum

[Scottie-TX]

Still fascinated with the idea of a glass rod pendulum - this time for my clock - not for accuracy, altho well it may be; My plans for this one would be only TWO rods. Unique about only two rods would be that there is no wear plate. I plan to have the two rods accurately spaced such that the space between them would be the intersection of the crutch post! Bad idea? First question: Those three retainers - top middle, and bottom: Split with machine screws as pictured. Reckon how you'd secure the glass rods to them? Second: Attaching the hook and rod on top, and the regulating rod below, and wanting to keep all on center: How would YOU attach the top hook and bottom assembly?
http://farm1.static.flickr.com/59/184957440_4172a2ecaf_o.jpg

[John Nagle]

epoxy or super glue would give a strong bond

[Jeremy Woodoff]

Scotty,

Not sure I understand your question--but I'd prefer a mechanical bond. What if you lined the retaining clips with a rubber strip? This would increase the friction and also provide some padding to help avoid breaking the glass when tightening the screws.

Jeremy

[Scottie-TX]

I'm liking that idea JEREMY. There was this product - a sort of liquid butyl for dressing drive wheels on record changers. It is brushed on and dries with a rubberoid consistency.
Any thoughts about using shellac as a bond?
Actually, there are several questions. I may need to add rough drawings I have in mind.
Example - "How would you fasten top and bottom rods to split brass retaining blocks. I was considering threaded rods to be turned into the center of the split retainers to a hole drilled and tapped directly centered over the split. Are threads in two split, mated pieces viable?

[analogtime]

It may be possible to attach the assemblies to the inside of the tubes. a small peice of brass with two brass screws taped on center of the tubes and epoxy to set them in the tube. There will be a rod taped in the center bottom of this block for the regulator. The seperators for the tubes could be made from solid brass split in half and two holes drilled in the block at center for each tube,these will hide the ends of the tube that contain the epoxy and anchor screws.

[Chris]

Scottie, if you want liquid rubber, what about Liquid Electrical Tape? I use it to coat splices on electronics, etc. It's rubbery when dry and is sometimes used by people to coat the ends of household tools too.

Scottie, I do have to ask, do you have a mad scientist lab setup in your apartment? I picture you with the goggles, yelling "It's alive!! It's ALIVE!" :biggrin:

Also, how do you handle the rating nut for the pendulum bob, and why not have a glass bob too?? One word, Waterford!

[Scottie-TX]

I was considering rather, Lalique. Signed, of course.

[Chris]

Pardon me! Do you have any Grey Poupon? :razz:

[John Nagle]

Okay, since you want to try a different method, why don't you drill holes through the brass rod. You could then use spaces between the rods and have a very secure setup. A simple drill can be made from a piece of brass tubing.
Build a dam of clay around the area you want to drill fill dam with abrasive grit and oil and drill. It is not difficult other than taking some patience.

[Ralph]

Montaigne,

The diamond coated drills are very effective for drilling glass. Harbor Freight, as much as I hate to promote them, carries a cheap set, under $10.

Oooops, just tried what I had in mind. They are carbide, not diamond. The diameter of glass rod I have on hand too small for an 1/8" drill. The glass rod I have is only 1/4". Maybe with patience and a jig set up.....

They drill through plate glass fine.

Ralph

[Scottie-TX]

My glass rod - tubing actually - is even smaller; 3/16 dia. Too small to Poupon.

[John Nagle]

I have those drills too. I have used regular drills with oil and grit to drill holes too. Someone smarter than me can probably tell us if this is actually true, I never bothered to look further. from what I understand if you can keep the glass from vibrating it is easy to drill without fractures. I especially like the import pliers, cheap so you can grind and drill the faces for all types of special work without ruining a good pair of pliers.

[RJSoftware]

I wonder if anyone has ever made a completley glass clock, gears and all. Wonder how the pivots would act. Would they need to be oiled?

A glass escapement. Probably has to be recoil. Or maybe like a woodworks clock the ew and palette/verge would be made of metal.

I dont think it would be spring driven :smile:

Cliccckkk, creeek, Pachiiinnnngggg. Glass flies everywhere!

RJ

[Sooth]

If it were me, I'd stay with the three rod version, and use rods that are hefty enough not to be too fragile (3/8 min). I would either drill holes in the rods for mechanical support, OR, do something like the original, where they look like they are held with pressure.

Is it possible that on the original they made some sort of groove, or notch, to keep the pieces from A: being too fragile, and B: keep them in place?

For the top and bottom, I'd try a setup like the original also, a piece that holds all the rods, with the mechanical parts attached to it.

If you were to consider another easier option, you could try to find plexiglass rod, which can EASILY be glued, drilled, and won't break easily. If you're careful not to scratch them, they'd look just like glass, too.

[Ian D Pomfret]

Hi Scottie,

There was a whole issue of the NAWCC's Chapter 161, Horological Science Newsletter dedicated to this:- "Fasteners for quartz pendulum rods", 1996, issue 5.

They boil down to compressive fasteners, mechanical fasteners (using a pin through the rod) or bonded fasteners, with one very early method by "Satori" using a brass fitting and a groove in the rod, the brass fitting was then filled with solder. The solder filled groove providing a solid mechanical attachment. Be aware that the quartz rods had almost a zero co-efft of expansion so didn't object (break!) to being heated as much as ordinary glass would.

If you have difficulty getting hold of that newsletter, email me offlist at idp1@verizon.net.

Ian
Rosendale, NY.

[doc_fields]

RJ--I have not seen one yet, but I understand that the French did make some clock movements with glass plates. Wheels and such were the standard brass and steel, I guess. You certainly would never want to 'bush' those plates! I would think that being able to see the metal wheels and shafts turning within the glass would be interesting to the consumer, and a little more practical to make. Anyway, FWIW.........doc

[Ralph]

You can buy an interpretation of a French glass plate clock, made in China, from one of the dealers of the imports.

For instance...
Glass Frame Clock (http://www.emtime.com/eshop/item.php?item=355&cat=132)

Wilding published a book describing the building of a crystal wheel clock. I think it was an interpretation of a 19th century English skeleton clock.

Wilding Page (http://craftsmanshipmuseum.com/Wilding.htm)

Ralph

[Chris]

Not to stray too far, but an entire glass clock would be interesting. After having become addicted to Food Network, I really wanted to try building a gingerbread movement, based on a wood works type of movement.

Regarding the brass spacers, I would think a light coat of liquid electrical tape would do the trick.

[Chris]

Speaking of glass clocks, did you ever see the large acrylic one that was on that cruise ship they were redoing as a special series on TLC? Gigantic clock that never worked a day in its life!! They finally got it running just before it was scheduled to be dumpstered.

[Scottie-TX]

This one, RALPH?
http://links.pictures.aol.com/pic?id=bd60PBQIR*7UJfbRkeA-UHlpv*8O3kalopdLv4xQp5Fd3Ig=&size=l

[leeinv66]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Scottie-TX:
I plan to have the two rods accurately spaced such that the space between them would be the intersection of the crutch post! </div></BLOCKQUOTE>

Scottie, after some thought (yea I know, not something I do enough of), I like the two rod idea. The only thing I would do is space the rods far enough apart to let me insert a wear plate between them. It would only need to be quite thin and could be glued in place.

Just a thought
Peter

[Scottie-TX]

Interesting point, Pee-Tah; In fact, may not be a good idea, just pushing against the glass rods. LAB taught me the value of a THICK wear plate and since make all of them thick. A thicker wear plate can more accurately guide the crutch, reducing isochronal error and wobble. With only two glass rods, I'd have only two very microscopic points of contact. That may not be good.

[Ralph]

Actually traditional clock design has the edges of the fork radiused and use pendulum rods, or drive pins to minimize contact. If your wear plate is keeping your pendulum stable, you are wasting energy.

Ralph

[Scottie-TX]

Interesting:
Then YOU'd be in favor of a "point" intersection.

[leeinv66]

Scottie, I understand what you are saying about wear plates and their thickness. But with your glass rod being 3/16, I would have thought that would be thick enough to avoid pendulum wobble. How thick would you want the wear plate to be?

Cheers
Peter

[Ralph]

Yes, I'd be in favor of only point contact.

A quick look at Gazeley's and De Carle, both instruct to radius or round the edges. Whether it be the fork or the wear plate.

If the pendulum is wobbling, there is some issue with the suspension or the the crutch to pendulum connection.

Ralph



Ralph

[Bill Ward]

Scotty, I'm weighing in on this with Ralph. It's impossible to get the suspension spring aligned at exactly a right angle to the wear plate, so there would always be friction if the wear plate is designed to correct the suspension angle. Thus, the radius.
Also, I'd avoid any organic materials in the suspension (epoxy, glue, lexan, rubber, shellac, electrical tape). They creep, deteriorate, and have strange expansion properties. For example, two years ago, I replaced the glass panes in my triple track storm windows over a stained glass window with polycarbonate (to protect them from missiles; this was after a kid threw a brick though my kitchen window). In the following winter, the plastic shrunk so much in the cold that it fell out of the frames. I put it back in in the spring, but on the first hot day in the sun, it expanded so much that both pieces broke in half, and the frame was bent! Back to glass for me.
Bob Matthys's book "Accurate Clock Pendulums has a chapter on the subject; borrow it from the NAWCC Library. You'll find lots more in it of interest.
Also, I might have a source for you of quartz tubing or rod; PM me if you're interested. Rod looks better than tubing, and a quartz pendulum rod instantly turns the clock into a REAL regulator.
".)" gives pirate emoticon