Some useful notes on Machinability, here: **LINK**

https://www.pentaprecision.co.uk/services/bronze-machining/aluminium-bronze-machining

MichaelG.

The Link confirms what I have experienced in the distant past, I was given some aluminium/bronze to make some 2stroke cylinder head buttons that were threaded and finished in a tapered end to seal the gasses in.
In aluminium this tapered face would be pushed down into the combustion chamber with constant plug changes, the al/bronze held up to the job for a much longer period.

Emgee

Edited By Emgee on 26/02/2021 18:20:05

The most appropriate material for such an engine's flywheel is cast-iron, but if a solid disc-type rather than finely-spoked, mild-steel would work well, be easy to machine and probably cheaper.

I made a manifold for the tank plumbing on a locomotive, using what someone later identified as probably aluminium-bronze. The external turning was not too bad, but it was a nightmare to drill and almost impossible to silver-solder.

Should be ok in ali bronze. Heavy enough for a model flywheel and will allow those nice cast spokes. Just machine it at a bit slower speed than for other bronzes and to minimise drill grabbing, grind or stone a small flat on each cutting edge of the bit to give zero rake as you do for brass. To make tapping easier if needed, drill the tapping hole a bit oversize, a la Tubal Cain's suggestions in his Model Engineer's Handbook. If reaming, drill first to about 5 thou under final reaming size. It won't be as easy peasy as machining brass or even leaded bronze but completely do-able with suitable care.

Another alternative if you are getting the other bit cast in ali is get the flywheel cast in ali and turn up a steel rim that can be shrink fitted onto the machined down ali centre section. This will put a bit of weight at the outside diameter where it will do the most good.

Edited By Hopper on 27/02/2021 09:03:13

After my adventures tapping 6BA holes, there were only six, I thought about what I would do next time. The only thing I could come up with was to heat the item, lets say to about 180C, before releasing the tap. Time consuming to say the least. That is why I never want to see the material again.

By the way, I managed not to break any taps.

JA

I was tapping 1/4" x 26 tpi for grease nipples. Ended up grinding up the tap flutes to make the tap really sharp. This stopped the tap binding on withdrawal. A 5/8" reamer that had previously cut a bit oversize left a tight hole and bound up on withdrawal enough to release the Morse taper.

Depends on what else they have available. Cast iron or brass would be fine too and both easier to machine. You are lucky these days to find a foundry that will give you the time of day on small jobs. Lucky to find a foundry at all most places today. Let us know how it works out for you.

Edited By Hopper on 28/02/2021 12:24:05

Edited By Hopper on 28/02/2021 12:24:34