One way to cut slots is to drill a series of overlapping holes, and file
the scalloped edge straight. You may need to experiment to find the
amount of overlap that is best, too much and the drill will tend to veer
off to the adjacent hole. (If you are making a longer slot consider
drilling holes 1, 3, 5, etc., and then go back to drill holes 2 and 4,
so that holes 2 and 4 have a hole on both sides, a more balanced
arrangement.) If you have too little overlap, it will be hard to remove
the excess metal.

For a 1/2 inch hole in steel, the maximum RPM should be around 400 RPM.
If you use faster RPM, it will tend to burn up the bit. If you burned
up the bit, it needs to be replaced or perhaps resharpened.

Richard


Rod wrote:
I'm working with 2" angle iron from home depot making a frame that will
support a dc winch motor for rolling a pool cover onto a spool. I'm having a
hard time with drilling and cutting slots.

I'm trying to drill several 1/2" holes using a bench drill press. Using
pilot holes I'm able to work my way up to 3/8" holes with no problem but as
soon as I go for the 1/2" bit it just spins and spins and doesn't want to
cut anymore. I end up forcing it down pretty hard to get through and it
takes for ever, what's the trick?


The next question that I had was, I need to cut some slots into the angle
also, so that the dc motor that I'm mounting can be adjusted a little, I've
been using a cutting torch to cut some slots but with my skills they come
out extremely messy, any good advice or ways to cut these with standard
tools? (drill, jig saw, sawzall)?

Thanks for any help.


Mark