A Margraf clock

[BRIAN]

Hi Dickr
All the plastic I am using is from old boat windows and hatches, so all I can say is that the gears that are taking the drive are from a unbreakable plastic, Gears that will only drive the hands are made from a plastic that will break if you score it deeply first,
Sorry to be so vague but it's all just a big fun project at the moment, If it all works I may do plans for it, but that's a long way off.
Good luck with your clock ,longing to se some pics.

Brian

 

[hman]

All the plastic I am using is from old boat windows and hatches, so all I can say is that the gears that are taking the drive are from a unbreakable plastic, Gears that will only drive the hands are made from a plastic that will break if you score it deeply first

Just to assist you, here's a quick "rule of thumb" I learned several years ago for identifying and distinguishing between acrylic (brand names like Plexiglass, Perspex, etc.) and polycarbonate (brand names like Lexan, Hyzod, etc.). Look at the edge of the sheet. If it looks bright (white), then it's acrylic. If it looks dark gray or deep purple, it's polycarbonate. That's assuming it's not otherwise colored. As a general rule, the only colored sheet plastics I've run into so far are acrylic. But there may well be colored polycarbonates as well.

Acrylic plastic is the one you noted that will break along a scored line. It's relatively resistant to many solvents, but will dissolve quickly in chlorinated solvents and somewhat more slowly acetone. These solvents can be used to "weld" pieces of acrylic together.

Polycarbonate is the "unbreakable" one. As a trade-off, it's not as dimensionally stable as acrylic. And be very careful with solvents. Alcohol is OK, but its surface finish will be instantly ruined if it comes in contact with acetone.

Just looking at the "colors" of the gears in your photos, I'd say that all of them except the "first" 200-tooth one you show (the one with the small holes) are polycarbonate. The "first" 200-tooth looks like it's acrylic. How close am I?

Hope this is of some interest/assistance.

Beautiful work!

 

[BRIAN]

Spot on John, thank's for the info.

It may be worth mentioning that. the parts made so far have nothing to do with the "Timekeeping" The gears just return the ball to the top of the inclined plane, and count the number of cycles (once every 30 seconds)that it takes for the ball to roll to the bottom.

I am also thinking of fitting Roman chimes to the clock. Roman chimes use 2 bells, a low chime for number five, and a high chime for number one, so 6 will be one low and one high.

We will see. Brian.