cutting holes

[MACHINE MEDIA]

> In all the catalogues I've looked at, the punches will not handle 1/8"
> aluminum. Even on the 5000lb presses they sell, 1/16" is all it will do.
> Have I missed something?

Greenlee (the dudes who make those big cable cutters) make punches that 
do 1/8" aluminum.  An eight of an inch is awfully thick though -- 
somewhere between 10 and 11 gauge (U.S. Standard for Sheet Metal). Do you 
need such thick aluminum??  Is this for a panel or some sort of custom 
heat sink??

If you want a strong panel perhaps you should choose thinner mild steel over 
thicker aluminum.  Steel will give you better sheilding and will be more 
resistant to scratches. Otoh, aluminum won't rust, but it isn't like you are 
going to leave your modular outside in the rain.  Of course, there is always 
acid rain, so you might want to only if you are building a lopsided diode 
ladder filter :)

> The one question I had was about the 'ovals' that are drilled for rack
> screws on each side. I thought perhaps a nibbler might help, but probably
> not. I was thinking perhaps having the metal shop drill two holes for each,
> that overlap. I'd file down the surface to make it more ovally. I don't
> know if they can drill overlapping holes though, I've not yet been down
> there with a design.

Maybe you can get away with just using oversized circles (oversized just 
in case you have to float the chassis from the rack -- personally I 
engineer my grounds given that all the chassis in the same rack will be 
tied to the same ground as floating a chassis from the rack is a royal 
pain). If you know the exact dimensions of your rack, you probably don't 
need ovals.  However, if you still think you do, just drill two adjacent 
holes and then remove the metal between them with a rat tail file -- this 
should be really easy with thick aluminum.

PEACE OUT :)
MARK