Scroll Chuck

[VicParticipant @vic]

The Scroll Chuck was invented in 1840. How did they make the Scroll wheel. Any ideas?

[Tony Pratt 1Participant @tonypratt1]

Maybe some sort of special purpose lathe set to face at the required pitch, with the scroll set up on a faceplate?

Tony

[Peter Cook 6Participant @petercook6]

I would agree with Tony. Some sort of specialised “lathe”. Fusee engines which cut a 3 dimensional spiral were around in the mid 18th century, so a machine to do the same thing in 2 dimensions would be relatively easy to do.

Interestingly in the 1840 patent Fairman explicitly does not claim to have invented the scroll mechanism. His patent ends with “I do not claim to be the inventor of the above, described mode of working the holders by means of the convolute grooves,” So the idea of a scroll being used to move holders was probably already in use  – although in what sort of device I don’t know.

[Martin KyteParticipant @martinkyte99762]

Although Brown and Sharp had built the first universal mill in 1861 and there were dividing heads available the end mill doesn’t appear until the 1940’s so the scroll would have had to be turned in my opinion. It is effectively only a screw thread after all.

 

[SillyOldDufferModerator @sillyoldduffer]

Natural for us, who are used to general purpose screw-cutting lathes, to assume they came first and scroll cutting was developed later.  Maybe not.  Whilst Maudsley came up with what became ‘our’ type of lathe in about 1800, facing machines existed before 1800.

Facing machines worked exactly the same way we face in our lathes.  A cutter is power traversed across the end of a disc.   As the cutter removes metal in a spiral all that’s needed to cut a chuck scroll is to alter the gearing.

Maybe we think scrolling is hard because our lathes, if they have power traverse at all, can’t alter the feed rate enough and the gearing is fixed inside the saddle.

However, anyone who has faced off by hand will have noticed spirals, and it’s a short step from that to a deliberate gear cut scroll.  I suspect circa 1800 scrolling was conceptually easier than screw-cutting.

Dave

 

 

 

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