Best way to make a 20mm hole in case with good finish?

Soldato
Joined
27 Mar 2009
Posts
3,290
Think with a hole saw or a step drill bit you are going to need a sacrificial bit of material underneath to help support the flimsy case material. I have no experience using either on sheet metal though.

What case is it? Think higher quality would be better in this situation compared to a £20 thin gauge steel case. Aluminium would be even better.

I have used one of these sheet metal hole punches once and it gave reasonable results but did warp a cheap steel case slightly but i was putting edging round the hole afterwards so it looked ok.

https://www.toolstoday.co.uk/q-max-...MI19Oyl8Pq2gIVWF4ZCh1bKgVrEAkYBSABEgLFg_D_BwE

Just for the record that was just the first one that popped up on google. I've never used that brand or shop before but its just an example
 
Associate
Joined
7 Feb 2017
Posts
1,016
Are you going to be removing all your components first, or will they have to deal with the vibration/being showered in metal shards?
 
Soldato
Joined
26 Sep 2010
Posts
7,146
Location
Stoke-on-Trent
Step drill bit is better than a 20mm hole saw in my experience. Or you could go all-in with a 20mm blacksmith's bit.

You'll need to tightly clamp something underneath where you're drilling to support the panel you're drilling and to stop the hole from burring up and getting messy underneath. Then masking tape your top surface, center punch and do a pilot hole 1.5mm to 2mm. That should give you a nice start point to keep the bigger drill bit on point.

I doubt you'd need any lube just to punch through a case; steel cases are only 0.6mm thick and aluminium cases cut like butter.
 
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