On 2011-02-09, Ignoramus25972 wrote:
I have a little project which would be to put my 1,400 lbs generator
on a heavy duty Radio Flyer cart and make outboard legs, so that when
it is stationary and not being moved around, it stands on those legs
and is not supported the wheels of the cart.

To that end, I would need to drill an estimated number of 112 holes,
probably 9/16" or 5/8" diameter each, in 3/16" steel tubing.

I *hope* that you mean in 3/16" *wall* steel tubing (presumably
square tubing, but maybe round or rectangular. :-) If it was 3/16"
*diameter* tubing -- which is how I read it -- there would be nothing
left where you drilled the hole.

This does seem like a great CNC project. My question is how to drill
them with minimum fuss. I would prefer, if possible, to avoid any tool
changes and general putzing around.

So, what is the CNC guru's approach to this? Just get a short 5/8"
drill bit? Or to bore them with something smaller?

How clean do the holes need to be? If clean, I would go with a
trepaning cutter -- a hollow mill perhaps with a spring to eject the
blanks. Otherwise, you might try hole saws, which tend to leave an ugly
hole, not a smooth-walled one. With those, you would need a lot of
pecking to clear chips.

The 5/8" drill bit should work well, at the right speeds and
feeds -- just more metal turned into chips, so more energy consumed
over the whole job.

I do not care too much if, say, boring takes a bit longer, the machine
will be working and not me. But I would personally prefer to avoid
tool changes and hassles.

Since you don't have a tool changer on your machine. (Neither do
I, FWIW. :-)

Good Luck,
DoN.

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