Cutting a clock fusee using the Turnado turning system

There are many ways to cut a clock fusee ranging from complete freehand turning with graver to machining a mathematically perfect curve on a CNC lathe. The commonest method recommended in books on the subject is a copy lathe arrangement where the cross slide follows a template. I've just cut a fusee using the Turnado free-hand turning system and I have not seen this described before. The Turnado system consists of a flat surface bolted to the cross slide on which a tool post is free to move under manual control. An option with the system is a copy attachment and I set this up with a template of the fusee curve as below

This is the fusee during cutting

and this is the final fusee before cutting the grooves

This was my first attempt at using the Turnado copy attachment and I was very impressed. The tool post followed the template very accurately and the whole set up is much more rigid than you might imagine. I was very pleased with the result. My preferred method for fusees from now on I think. Thought other constructors might be interested. Could be useful method for other curves on a manual machine.

P.S.. cant work out how to rotate the pictures.

Edited By JasonB on 01/03/2020 17:12:43

That's very cool!

The Turnado kit is very clever and by all means use it if you have it ....But, please don't think that you HAVE to have some complicated equipement to make and cut fusees. Fusee procuction is one of those things in life which look very difficult but which turn out to be fairly simple once you get into it. Any small lathe is all you need to cut the curve, or 'curves' if you decide on a more complex profile and the grooving is easily accomplished by turning the chuck by hand. It helps to fit the blank piece to it's arbor before starting but there are plenty of ways and means to arriving at a very acceptable fusee.

At Epping Forest Horology Club we often see members who are quite intimidated by their need to make a fusee but they invariably express surprise at how easy it is to get a nice fusee result. The only problems are with people who insist on making it more complicated than it needs to be.

EDIT;  Just remembered that I have  a few photos in my album here of fusee set up on my small lathe...no idea how to put the pix into this post 'tho!

Edited By Bob Stevenson on 01/03/2020 18:40:53

How to post photos!

Neil

Or the first page may be of more help

All I had available (in the 70’s*) when turning the fusee for John Wilding’s skeleton clock with lever escapement (and room for a pony), was the taper-turning attachment.

It was a relatively simple exercise to mount the curved template to the slide bolted to the back of the machine, seen here but set for taper turning.

The follower was a ball race secured to the cross slide (with its leadscrew removed).

At the same setup (without removing the workpiece), it was a simple matter to cut the groove. Light pressure applied to the ‘front’ end of the cross slide was all that was needed while the saddle was engaged to traverse. The top slide, set to 90°, provided the depth of cut.

On the down side, the curve was specified as a 2” (two inch) radius. There was no mention in the text about calibrating the curve from the main spring performance.

Sam

*Mr John Stevens’ clock design was first published in five issues of Model Engineer commencing in February 1972. Vol 138, issues 3434, 3435, 3437, 3438, & 3439.

I remember about 1980 picking up a copy of, I think, Physics Review Letters in the library of the place I then worked and finding an interesting article about the derivation, for the first time, of the correct form for the fusee curve. About a century late to be of any use of course!

Having checked the box for bookmarking this thread, I've just found it didn't work.

With nothing more to say other than good luck with the rest of your fusee Ifoggy, I'll sign off.

Sam

Nice use of the Turnado tool.

Please update us when you cut the groove. I'd be interested to see the finished fusee.

Martin.

Fusees with completed grooves. These were 'screw cut' in the usual way (2mm ptich) with the cross slide screw disengaged and manual pressure applied to the cross slide to keep the tool following the curve of the fusee. Finish in the gorooves is not bad but not perfect either. I will be using steel cable which tends to mark the grooves anyway so will leave as is. Now I just need to trim to length, tidy up and drill holes for the cables.