A round hole in a square peg

[Matty F]

I needed to make some square brass nuts to go with the screws that I made earlier. Usually I would put some hex bar in the lathe to drill it accurately and chop off as many nuts as I wanted. I didn't have any hex bar and I wanted square nuts. I had some 5/8" square bar but I wanted 1/2" wide nuts. How was I to drill the hole accurately when I had only a three-jaw chuck? As it happened I was able to use the three jaw chuck like this:

DSC00133lathe.JPG

Then I milled the bar down to half an inch and the hole was in the middle!

DSC00134mill.JPG

I finished tapping the hole by hand as the tap kept slipping in the lathe chuck:

DSC00135tap.JPG

Here's a finished nut on the screw that I made earlier:

DSC00144nut.JPG

Here's the screw and nut in place on the bell unit:

DSC00137bell.JPG

Everything but the screw and nut was cast in a foundry from an original sample.

[robgraham]

In fact you solved the problem more neatly than if you had had a 4 jaw independent chuck which I would have reached for, as you only had one milling operation.

Thanks for the WIP photos - you never know quite when something like that might be useful.

What I am left with however is the puzzle over how the bell works and what it's for - and finally why the reproduction?

Rob

[The Natural Philosopher]

this:

DSC00133lathe.JPG

earlier:

DSC00144nut.JPG

unit:

DSC00137bell.JPG

My gfuess its similar to a friend of mine's work - reproducing old metalwork for museums and historic conservation work.

[Matty F]

Actually I milled 1/8" off one side of the bar and 1/16" off two sides, to get a 1/2" square. The job was too small to go out and buy exactly what I wanted, and I would not be able to buy such a small quantity. I tend to design jobs around what materials that are lying around.

There's a lever that is yet to be attached, that pushes the knocker down when a cord is pulled, on a tram. We got one bell from somewhere and needed to make three more. I can't remember the details but a bell is needed at each end of the tram because the driver swaps ends, and two more bells because it's a two story tram.