jamesjung21 said:
Grainger is a great company, but very expensive -- it's "kindof" your "just in time" high end hardware store for manufacturers... if you break a belt or fry a motor on a packaging system or die caster you can usually get the replacement from them in an hour or so -- they charge premium prices because they stock everything, and they situate their locations where manufacturers o.e.m.'s are going to need them.
Yes, I suppose you'd call it a spade bit. Like I said, it's messy and noisy. In my 1/8" aluminium chassis, I drilled ten octal-sized holes, 4 miniature-7-pin-sized holes and three fuse-holder-sized holes using spade bits. I then telephoned my wife, apologized for the noise and begged her to come back home.
DIAR said:
I also use a Unibit in my drill press for all sorts of holes in metal, valve sockets, fuse holders, you name it. Works great. I do use emery cloth to remove any burrs and "round" the edge a tad so it isn't so razor like!
I have used that second bit to cut holes in MDF and birch ply for speakers. Take your time, wear a dust mask as well as safety goggles and they work like a charm. Of course speaker holes don't have to be as exact as valve socket holes since the flange usually hides any imperfection. (These days though my plunge router and circle template have mostly replaced that bit so I can do bigger holes and work farther from the edge than allowed by my drill press.)
Use Greenlee punches - there are two punches in their standard set of 8 that exactly fit 7 and 9 pin tube sockets and one that is perfect for octal tube sockets. I've punched hundreds of tube socket holes in aluminum and heavy steel chassis with my Greenlee set since 1965.. I bet you can buy this set of 8 Greenlee punches on eBay for about $25, altho I have not checked that out.
If you are punching a heavy steel chasis, use 30 wt oil on the punch cutting edges and also on the punch threads. Makes the cutting a lot easier, and also will keep your Greenlees going forever!
Another hint is to put the cutter section on the chassis top, to avoid marring it. And use a socket wrench to turn the punch - sure makes it easier..
Happy punching -
Mort Caldwell in West Virginia, USA
Tube circuit building since 1953.. A one tube radio first project
If you are punching a heavy steel chasis, use 30 wt oil on the punch cutting edges and also on the punch threads. Makes the cutting a lot easier, and also will keep your Greenlees going forever!
Another hint is to put the cutter section on the chassis top, to avoid marring it. And use a socket wrench to turn the punch - sure makes it easier..
Happy punching -
Mort Caldwell in West Virginia, USA
Tube circuit building since 1953.. A one tube radio first project
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