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12-04-2018, 06:56 PM
Hi Vostre
There is no need for the tubes to go through the chassis unless you put the parts on the same side of the board as the sockets.The usual mounting has the components and tubes on opposite sides, allowing just the tube socket to protrude slightly or be flush with the chassis outside surface. The other issue could be of using stand-offs that are unnecessarily long.
For the 9-pin tubes, it is about 0.75" if you are really precise, but 1" if you need some slack - this is also good clearance for the tube itself. The stand-off might be 1/4" here.
For the octals, 1-1/8 to 1-1/4" hole depending which part of the socket you have to clear. The stand-offs would be 1/4" to 3/8".
Step bits work well in thicker material than Hammond's chassis. The steel is actually not that thick but if you are used to aluminium then it will seem pretty tough - stainless could seem impossible! With most consumer-grade drill bits and cutters, the number of flutes and hence the number of cutting edges is usually minimal. For example, counter-sinking bits are most often three-flutes and sometimes only two for the smaller sizes. Good counter-sinks are five-flute. I had to order them from China recently because no one had them locally.
With the low-flute-count drill bits and a slightly wobbly drill chuck, it is difficult to get a smooth cut unless the drill speed is a bit higher. That can lead to an out-of-control situation pretty quickly, though, but one defence against it is to loosen the belt in the drill press. This will keep the bit from grabbing the piece out of your hand, or out of any jig or holder.
Another way to fix the holes is to use a nibbler. This is a single-tooth cutter that you use to nibble away material - great for making the IEC mins plug hole.
There is no need for the tubes to go through the chassis unless you put the parts on the same side of the board as the sockets.The usual mounting has the components and tubes on opposite sides, allowing just the tube socket to protrude slightly or be flush with the chassis outside surface. The other issue could be of using stand-offs that are unnecessarily long.
For the 9-pin tubes, it is about 0.75" if you are really precise, but 1" if you need some slack - this is also good clearance for the tube itself. The stand-off might be 1/4" here.
For the octals, 1-1/8 to 1-1/4" hole depending which part of the socket you have to clear. The stand-offs would be 1/4" to 3/8".
Step bits work well in thicker material than Hammond's chassis. The steel is actually not that thick but if you are used to aluminium then it will seem pretty tough - stainless could seem impossible! With most consumer-grade drill bits and cutters, the number of flutes and hence the number of cutting edges is usually minimal. For example, counter-sinking bits are most often three-flutes and sometimes only two for the smaller sizes. Good counter-sinks are five-flute. I had to order them from China recently because no one had them locally.
With the low-flute-count drill bits and a slightly wobbly drill chuck, it is difficult to get a smooth cut unless the drill speed is a bit higher. That can lead to an out-of-control situation pretty quickly, though, but one defence against it is to loosen the belt in the drill press. This will keep the bit from grabbing the piece out of your hand, or out of any jig or holder.
Another way to fix the holes is to use a nibbler. This is a single-tooth cutter that you use to nibble away material - great for making the IEC mins plug hole.
