Tips for Drilling Post Powder Coat

[aziltz]

Hey Friends,

So I have access to a pretty decent Milling Machine in the grad. student shop.  I've been hesitant to do any of my own drilling simply because the people I might buy a powder coated box from can usually do it better.

In the interest of cost though, I think I could figure this out.  There's a few different sources out there that I'd like to try and use that would paint, and I would do my own drilling (pedalenclosures.com, our own JLyons, etc).

I know how to use the machine, but I'm wondering if anyone's has tips or pointers for how to successfully drill into a pre-powder coated box without messing up the finish, either from the drill or the clamping.  Thanks in advance.

[pazuzu]

center punch your holes so your bit doesn't walk. start with a 3/32"~1/8"~etc. pilot hole, then drill to size. put some un corrugated card board or a shop rag in between your part and the clamps if you are worried about marring, although if the machine is good it shouldn't be a problem. you can clean up aluminum with a scotch bright if it scratches.

edit>

oh...PAINTED box. duh. cover it in a couple of layers of blue painters tape before machining.

[MoltenVoltage]

use a step drill bit

[aziltz]

thanks for those suggestions.  Cardboard in the clamp?  That should do the trick!

I'm going to be using a milling machine, so the box will be clamped in tight and I'll center the drill bit using all the gauges and such, so I shouldn't need to worry about the drill wandering anywhere.  I probably won't bother with a stepped bit either.  I have access to everything I need for free, starter bits, various drill sizes

[pazuzu]

is it cnc? you could make up a program on cad, otherwise just home your tooling to a zero point and then watch your gauges.

machining is incredibly easy.

[aziltz]

is it cnc? you could make up a program on cad, otherwise just home your tooling to a zero point and then watch your gauges.

machining is incredibly easy.

nope, no CNC, but I feel confident enough with the gauges to pull it off.

[Processaurus]

The only allowance I make for powdercoat vs a bare metal box is to stick bits of a 1/4" rubber sheet that's been kicking around in between the vice I hold the box in.  It's tough paint!

[Tantalum7]

Even a couple of even layers of masking tape put on the vise jaws will do the job (if they're the standard smooth milling machine vise jaws).  You shouldn't need to squeeze the life out of these enclosures to hold them well for drilling. 

[aziltz]

thanks for the tips!  I'm itching to get done in the shop now.