Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jeff on July 16, 2012, 03:07:15 pm
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I was wondering if anyone had some tips on cutting round holes with a flat side in a chassis, like for a fuse holder or cord stress relief?
I don't want to just drill a hole because the components may spin and pull the wires out.
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I use a tool called a nibbler.
http://en.wikipedia.org/wiki/Nibbler (http://en.wikipedia.org/wiki/Nibbler)
It works by nibbling away little pieces of the chassis until you're happy. Perfect for small jobs such as IEC outlets and D style holes.
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I use a tool called a nibbler.
http://en.wikipedia.org/wiki/Nibbler (http://en.wikipedia.org/wiki/Nibbler)
Brilliant! What kind do you prefer (they list several in the article you posted)?
Jeff, I've been struggling with the same problem, and my results have been less than stellar.
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I just use the inexpensive hand nibbler. I picked it up at the radio shack.
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Thanks I'll try it out.
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I checked out the Radio Shack web site. The describtion sounds like this is more for thinner material, meant for computer cases and such, does it work on thicker chassis gauge metal(aluminum)? I'm going down to Radio Shack today to check them out and see it it'll accept thicker gauge.
I do have a Dremel. Can anyone recommend the best Dremel bit for aluminum. I found the sandpaper drums do work pretty good but wear out pretty quick. I've also tried the grindstone bits but the aluminum kinda "gunks" up on them. Maybe a file?
Thanks
Jeff
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I drill a hole just shy of allowing the stress relief grommet to fit the hole, then use a combination of a small triangle file and round file to shape the hole the rest of the way. It's less than perfect, but functional.
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You can get a vintage D shape punch on ebay for a few bucks.
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Nibblers work great. You can also collar drill bits if you do not have a drill press. Keeps them from going in too far. The cheap way to collar is to use masking tape and spin the drill till you get about 1/4 inch. I have a complete set of punches from 3/16 to 2.5 inches. It is the best way, but I still use step bits from time to time. Punches are expensive, but garage/estate sales is where I get stuff like this. People give away tools at garage sales.
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+1 with Ed and others. Step bits on most things then it's the nibbler for square or other odd shapes, then it gets down to files from there. I have some great heavy duty coarse aluminum oxide dremel bits I got a long time ago from a hobby place when I used to build and fly radio controlled gliders and power planes. Something similar to these but even coarser...these should work to though. Great for deburring, etc...
http://www.bing.com/images/search?q=dremel+grinding+bits&view=detail&id=AEEBE3FCFEB932B1F9C9C91C7A8014630450F99A&first=141 (http://www.bing.com/images/search?q=dremel+grinding+bits&view=detail&id=AEEBE3FCFEB932B1F9C9C91C7A8014630450F99A&first=141)
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Nibblers are a nightmare on thick metal; you'd better have very strong hands. They are fine on thin metal, though.
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You can get a vintage D shape punch on ebay for a few bucks.
A link would be nice. :smiley:
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http://www.ebay.com/itm/GREENLEE-733-1-2-INCH-D-shape-Radio-Chassis-Punch-with-box-/360472810201?pt=LH_DefaultDomain_0&hash=item53edda92d9 (http://www.ebay.com/itm/GREENLEE-733-1-2-INCH-D-shape-Radio-Chassis-Punch-with-box-/360472810201?pt=LH_DefaultDomain_0&hash=item53edda92d9)
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Thanks!