GearHeads Corner

General Category => ClockMakers => Topic started by: Mand on September 09, 2018, 02:57:58 PM

Title: Topping/Rounding Up Tool?
Post by: Mand on September 09, 2018, 02:57:58 PM
Well, I wasn't sure where to put this, but I figured someone here might know and this category seemed broadly appropria te...

...does anyone know where I might find a set of plans/diagrammatic drawings for an old (1800s) topping tool (also a "rounding up tool")? I've been digging for patents etc., but haven't had much luck yet, and the tools themselve s haven't been in wide use for quite a long time.

I'm referring to this sort of thing:

I'm sorta consideri ng building one purely for the hell of it, but cannot afford to just buy one and copy it.

Title: Re: Topping/Rounding Up Tool?
Post by: ArtF on September 10, 2018, 06:45:28 AM

  Interesti ng tool, I hadnt seen one before. A kind of desktop hobbing
machine of sorts. I suppose they call it a topping tool as they use it
to get the cycloidic leaf tops from a gear made of squared teeth?

   Interesti ng machine. Please let me know how it looks if you start
building one. Looks like quite a neat project if you have the shop
for it.


Title: Re: Topping/Rounding Up Tool?
Post by: Mand on September 10, 2018, 07:40:03 PM
Yep, they seem to have been used for situation s (watchmaki ng, not clock making) where it was easier to run a slitting saw around a circle, and then load the result into the topping/rounding tool to get the final tooth form. They mainly seem to use what are often called Carpano cutters (although there may have been more than one manufactu rer of said cutters); these were fairly interesti ng little widgets -- basically disks, with one little section being cut nearly loose, bent up out of the plane of the disk, hardened, and then fitted with a little screw.

The screw, when tightened, tries to force the "sprung" section back down into the plane of the disk. Thus, by adjusting the screw, you can finely control the width of your cut while still using just one basic cutter for each "module" (they used their own numbering scheme described here: ).

I still only barely understan d these things, but they're kinda nifty.

Title: Re: Topping/Rounding Up Tool?
Post by: BobL on September 11, 2018, 08:38:31 AM
Thanks for the info Mand,  however I'm unable to connect to link.. 
 Anyhow, Until a few days ago, I was oblivious to how this tool really worked, so thanks for sharing.


Title: Re: Topping/Rounding Up Tool?
Post by: Mand on September 11, 2018, 11:04:02 AM
Weird, are you using Chrome? The link goes to a machinery reseller on the East Coast, and they don't use HTTPS, so some installat ions of Chrome may stop you from going there (I mean, if it's been set to avoid non-HTTPS sites as being a security risk).

Alternati vely, then, there are several listed on eBay at the moment (some for staggerin g sums); if you search for "rounding up tool" you'll find most of them (folks seem to list these using varying phrases, some wrong, so they can occasiona lly be found hiding under other search terms. I've seen at least one described as being a lathe, for example.)