Some of you saw my previous efforts at making my own reflector entitled "DIY Reflector". It worked out just sort of ok after many hours of work. DBStm tested a reflector that I made and it was...meh.
Anyway, I still have the DIY reflector bug since there are not any great reflectors for the MT-G2. I made a spreadsheet and made a mandrel so I could do this
Here is the mandrel
I started out with some scrap aluminum sheet metal and it kept breaking using a metal rod that I shaped to emulate some that I had seen on the web. That didn't work. I then bought some known alloy aluminum (5052) in various thickness. Still no good.
So I made this thing.
Still no good.
I have many hours into this project and refuse to give up. Below, you can see the fruit of my labor to date. Some of them actually gave me hope for a little while before they broke off.
This one was over an inch deep before it broke...
I have one or two more ideas to try out. I'll let you know how things work out.
Well you might have failed (temporarily) at making awesome custom reflectors…but you HAVE succeeded in creating the newest Madonna or Lady Gaga bustier caps
Have you tried raising the temperature of the metal while working it? (softening it up?) Kind of like hot rolling instead of cold rolling. Means you can work it a lot more.
Even stopping every quarter inch or so, reheating it to around 800degC and then working it more.
It'll reset the grain structure within the metal relieving the internal stresses.
Maybe it is also the metal chosen. Have you tried something purposed for ductility? A grey nodule high graphite steel?
Just from looking at the way they rupture it seems the bottom is continually stretched while the further you get from the center it is less so until the rim where it is more bent than stretched. If it were done in stages with truncated forms that worked the shape of the rim first but leaving the middle flat and undisturbed, then a second form that pushed deeper, and finally use this one to finish it might not rupture the bottom this way. The first forms needn’t be precise, just merely truncated cones a hair smaller in OD than the succeding one so that the last one can true the shape.
I am not currently planning on coating these. I have thought about it and might try it out some day if I don't have to buy a ton of crap to do it.
Update:
I ran the lathe flat out and increased the radius on the spinning wheel. Both seem to help. My best product so far is 1.75" in height. I'm going to make another wheel with an even larger radius and see if that helps.
You probably already know this. Aluminum can be annealed. Rub some normal household soap (No skin softener agents though) on the area you need to anneal. Then heat the piece until the soap turns black. Careful, you will taking the metal close to its melting point. Once the soap is blackened, dunk the piece in water. It should be much more pliable.
I can only add my untrained layman opinion. Can you look into how metal-formers select the correct anvil size to shape their smaller tighter radii? When I saw the anvil you were using it just looked too aggressive for the sort of radius you were trying to achieve. I think you could find something more suitable with English wheel anvils.
