Osvaldd":37zcmxc9 said:
What a great little brass thumb screw. Thank you Andy. I don't know how you made it but it's perfect!!
Glad you like it - it was a nice excuse to mess about on the lathe. And just in case anyone was going to ask how it was made, I took a few snaps along the way.
My lathe is an old, bread and cheese powered one - the whole story is in this old thread
i-blame-roy-underhill-t72124.html
I reckon it's just right for this sort of project.
This photo shows a lump of hex section brass in the early stages. It's held in a three jaw chuck at one end and on a half centre at the other, where I have already drilled a central hole. I've turned the head end round, leaving it as big as I could, from the stock I had. I've also started turning down what will be the threaded part.
I slowly crept up on the thin part until it was 8mm in diameter, with the tip chamfered. Then I swapped the cutting tool for a two wheel knurling tool and attacked the head. This needs a lot more torque, so the lathe is running with the back gears engaged.
I then used a die in a holder to thread the stem. This is much like hand threading in a vice, but the lathe is better for gripping and the die holder handle can bear on the slide rest while I pull the flywheel round slowly by hand, reversing from time to time to clear the chips.
I swapped back to a cutting tool to clean up the inner face of the head and neaten the rim.
I've not had much success with thin parting tools, so I locked the head up and hacksawed through the brass from each side of the hexagon in turn.
That produced this untidy mess.
I then needed to re-chuck the screw. Unfortunately, my old three jaw chuck doesn't centre very well, so re-chucking something doesn't work nicely. The solution is to swap to the four-jaw.
If you look very closely you can see that I have wound thick copper wire around the thread to protect it from damage. Here I have a dial indicator set up so that I can get the work central enough.
With that done I could come in from the end with a curved cutting tool and do some decorative rings. I like doing this sort of thing - it's almost freehand, like wood turning, not aiming at an accurate dimension from a drawing.
And here's the finished item. It may be a bit too long, so do feel free to adjust it to suit.
