Large hole in thin plate?

[r_jik45]

Hi,

RCA/cinch connectors are widely used in DIY audio builds.
Wondering what is the best way to drill large round holes in a thin back plate for RCA connectors: 10mm holes in 1mm plate.
Normal drills bits or end mill ones, or ...?
Thanks.

 

[ferret]

Stepped bit

Hi r_jik45, I have always use a stepped bit for that. Use at least a 20 mm piece of scrap wood underneath to provide support while drilling the plate. Just be careful of the rpm you use. Normal drill bits do not work well. Of course if you can get a knockout punch of the correct size, that is an option, but requires a pilot hole first.

 

[r_jik45]

Hi ferret,

Yes, normal drill bits are likely not the best option for that diameter, that's why I asked some advices.
Stepped bit, did not think about that. Thanks for your reply.

 

[2bz]

Hollow Punch Metric 3MM-30MM 16 Pc Set

 

[r_jik45]

Thanks 2bz, will check the punch tools too. At least for 10mm diameter.
If I got it right 1" is 25.4mm.

 

[rayma]

If the material is very thin, I'd back it up with scrap material on the bottom.
It will then punch much more cleanly.

 

[r_jik45]

As far as I got it: the chassis is made of steel (1mm thick); RCA connectors require 10mm diameter holes.
Already made such 10mm holes in an aluminium chassis (maybe 2mm thick): not so clean; don't want to mess the new chassis 😱

 

[Decker]

I have sandwiched thin metal between 2 pieces of particle board before drilling with a step drill. Put a big hole in the top piece, a little bigger than the hole you want in the metal. Clamp or screw the sandwich together and then drill. Don't forget to use lubricant for the bit.

 

[rayma]

Already made such 10mm holes in an aluminium chassis (maybe 2mm thick): not so clean;
don't want to mess the new chassis 😱

Just buy a chassis punch, anyone serious about DIY should have some. They will last for many uses,
and are good for up to 1/16" steel. Punch from the outside as that will be the cleanest edge.
Drills do not work well for this purpose.

If you keep watch on ebay, there are great deals on Greenlee punches from time to time,
mostly English not metric though. I got over a dozen Greenlee punches for $1 each.

This is a great deal for a new punch, usually $60. each.
Q.Max Sheet Metal Punch Hole punch - 10mm | eBay

 

[r_jik45]

Thanks for you advice rayma. Checked for a 'chassis punch' for the few holes to make. Also was supposed to drill something like 7mm for 10mm holes.
Went the 'stepped bit' way as proposed by ferret. Worked fine. Will anyway follow deals on the bay, in case.