Metals used in LF cameras

[lxdude]

Magnesium in my shop would cause the biggest fire the city has ever seen. Is it possible to do die cast aluminum at home with any precision? In college I worked at the Pacific Car and Foundry and know how the process works for steel, molds and mold makers, huge metal pours and machining, lots of machining. Now a smaller part for a camera wouldn't be as massive in weight and size but the precision is the same, very tight tolerances. It's intriguing though, do I feel the heat of the foundry again?

Impractical. To die cast you first must make a die. Remember, some of the most highly skilled machinists are tool and die makers. I was for a time a moldmaker making aluminum molds for plastic injection. That's easy compared to making a steel mold for die casting. Precision castings are not precise compared to machined parts. They are cast oversize to allow for cooling shrinkage and have draft angles to allow the die to release the part.

There's nothing to be gained by casting your own aluminum parts. You'd have to get them heat treated to strengthen and stress relieve them which often distorts their dimensions, so finish machining has to be done after.

Make them out of readily available stock of the proper alloy and temper. The different shapes and sizes allow selection of materials which will minimize machining.

[lxdude]

Hi, did you read my full post ?

I have a habit of typing out of sequence but I was referring to how best to work metal into profiles. I don't think wood would work at all for what I was talking about, pesky grain, dimensional conflict issues etc... and it doesn't take kindly to welding either

But yes, out of all the things I could and should have learned by now with metal work is that without proper set up your work will be next to useless (and likely dangerous) ...

This thread is part of a larger scheme of mine to gain that expertise you mention. I'm at the point where the only thing left is to start really working with it

Yes I did read your entire post and saw the part about metal inlayed into wood. That's what I recommended you start with.

It's important to not take on too much at once. Otherwise a project stops being fun. Build on experience. Generally, fabricating from metal is harder than it looks. It depends, though. With easy to work material usually much can be done with simple tools. I've made complex brackets with multi angle bends out of mild steel by using a vise, a brass hammer, an electric drill and a file. And paint.

Softer, easy to work materials like brass and aluminum are the place to start. If you're working with aluminum it's soft enough that careful hand work can often bring a high level of precision. A file used carefully can, with careful technique, make perfect outside radii. By using a technique called draw filing it can produce very flat surfaces. Silicon carbide paper on a really flat piece of plate can also be used to make very flat and true surfaces. Wrapped around a piece of stock it can smooth and bring to size complex shapes.

It takes patience and a certain knack. But it allows you to compensate for machine limitations like not enough precision or a lack of rigidity, and sometimes for not having a machine. If you do much hand work you will be astonished at how precise you can become. A lot of guys hate it because they want to go fast, but I enjoyed it. One place I worked, because of my ability to do precise hand work (often to rework a bad part) I got the nickname "Deadeye". It was nice to have a non-insulting nickname for once.

Precision layout, where dimensions are scribed onto the workpiece, will help big time. Work to the line and you will be close. Holes to be drilled can be center punched on the layout and a good drill press will give the needed precision. If you're careful enough and good enough, even a hand electric drill can be used for through holes.

Weld if you want, but you should be able to avoid it if you'd rather not. Choose your alloy carefully, as many don't weld while others are pretty easy with tig or mig. There's a reason 6061 is used so extensively. It's good all around. The heat of welding does anneal it though, so it will lose strength near welds. It will recover some of its former strength and hardness with time. 7200 is nice to weld, because it recovers its strength after welding.

About obtaining material: many metal distributors will sell to the public. They often have odds and ends, short pieces etc. from fab jobs. They usually sell it by the pound, not units like length or area.

[eclarke]

Indeed it does. And it used to annoy my workshop manager when I used to set fire to it!


Steve.

Used to grind the parting lines off mag castings and once in a while there was a fire in the dust collector. The first time, we put some water on it, don't try that!!..EC

[alanrockwood]

...Are the mini lathes any good? ...
Curt

Here is a good site on setting up and using a mini lathe.

http://www.mini-lathe.com/

Here is the mini mill section of the same web site.

http://www.mini-lathe.com/mini_mill/main/mini-mill.htm

Here is a site that has a very extensive stock or parts and accessories for these machines.

http://littlemachineshop.com/info/minimill.php

These web sites are all concerned with the Chinese lathes and mills.

It is possible to do very good work with these machines, but what they say is that when you buy one you should think of it more as a kit than a finished product. The idea is that you tune it and adjust it according to the instructions in these web sites and then it is capable of good work.

Other well known makers of small machine shop equipment include Sherline and Taig. These might be better for out of the box use, but they are more expensive, and I don't think they are necessarily better than the Chinese machines once the Chinese machines have been tuned up.

[Curt]

Yes, I won't be setting up a foundry, it's just not practical or needed by me anyway. I've been to the web sites there Alan, there is a lot of good information. The one thing I learned about these products and the Chinese specifically is they need to be set up carefully and adjusted correctly, then they can do some outstanding work.