Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: hesamadman on April 23, 2014, 10:21:44 pm
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Hey guys. Last chassis I did was aluminum. I used a jigsaw. Not pretty. This chassis is a little more sturdy. People suggest a roto zip for the square knock outs for rocker switches. What do u suggest?
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Drill (many, many) small-diameter holes just inside the perimeter of the desired cutout. Cut shape out with a needle file or hacksaw blade. Finish outline to desired shape with files.
Or buy the correct size/shape Greenlee punch for the opening. For square/odd shapes, that is $$$$$. Best for things you will cut out many, many times like tube sockets.
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If it has to look good & professionally finished that's a real problem. Anything but a quality knockout punch will leave a burr that has to be dealt with. Other possibilities for clean holes are a router, maybe using a milling bit, and a template for the hole; or a milling machine. But you'll still have a burr; and need to square the corners of the slot you machined into the chassis. A "nibbler' is another possibility; but straight, pretty lines may be tricky.
Other options. Don't use square switches. :icon_biggrin: A lip on the square SW may cover imperfections in the hole; but this is more suited to pure DIY, than for resale to others. Fine metal work is yet another world of skill sets.
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It all has to do with the amount of metal work you plan to do in your life. If it is a lot, start buying punches, breaks, shears and welders. If you are only going to do one chassis once in a while, draw it in Autocad or illustrator and take it a metal fab shop. You would be very surprised to find out how much the second one with the exact specs cost.
It is the first one where all the cost is. I was a metal worker as a career in my younger days and have acquired lots of tools and still have access to metal fab equipent, but still will pay for one chassis if that is all I need.
HBP's suggestions were great for cutting holes. A good place to start is buying punches in the most common sizes, but you would be surprised to find out what you can make in most available prepunched chassis and mort are less than 1 punch.
If I did not already have the metal working equipment I have, I would never buy anything other than step bits, nibbler, nice saws and files and of course a nice corded 1/2 drill and corded 3/8 to go along with my cordless. Oh yea, great drill bits in a complete box with triplicate of all the ones 1/8the and smaller.
For instance, I have a TIG welder I use once every year maybe. Doesn't make sense to even have it or the argon bottle.