Rectangular opening in aluminum chassis

[Frank O]

I have a 12" x 8" x 3" aluminum chassis, basically a panel 12" x 8" in the X and Y directions, plus sides that extend 3" in the Z direction. I need to cut an opening in the panel about 5" x 3.25". Squared-off corners would be ideal, but rounded corners ok.

Thinking I'd be doing this on my LMS 5550 mill, unless there's a better idea.

Any suggestions on the easiest way to get this done? Tooling, etc?

Also, any recommendations on the best workholding scheme to keep it secure on the table without marring the finish?

 

[RJSakowski]

It should be an easy task. Using a wood or similar sacrificial backing and clamp the chassis to the table. Square the chassis to the table and locate two edges for reference datums, Calculate your tool path. leaving material for a cleanup pass and plunge an appropriate end mill and cut the first pass. Then move for a cleanup pass and make your final cut. If you wish square corners, you can cleanup them with a file. The size of the end mill will determine your cleanup . A small end mill for less but too small and there is a possibility of breaking. I would probably use a 1.4" end mill.

 

[matthewsx]

I just did similar holes in a stainless cabinet I'll be using for network equipment.

My trusty HF angle grinder with a cutoff wheel did the trick.

John

 

[Weldingrod1]

Adel nibbling tool rocks for funny chassis holes where the thickness is ok.

Sent from my SM-S911U using Tapatalk

 

[markba633csi]

RJ basically outlined the method- fasten a piece of plywood to your mill table and fasten your chassis to the wood. You can put a few wood
screws in the window you will be cutting out. Cut nearly all the way around but leave two small bits still attached. Then wiggle the piece
out and clean up the edges with a file.

 

[whitmore]

Adel nibbling tool rocks for funny chassis holes where the thickness is ok.

Yeah, this is the quickest; you can start with marking dye and scribe, make one drill-press hole (with a brad-point drill)
and nibble out from that to the lines. A quick application of your Noga deburring tool and it's done.

 

[ChazzC]

Yeah, this is the quickest; you can start with marking dye and scribe, make one drill-press hole (with a brad-point drill)
and nibble out from that to the lines. A quick application of your Noga deburring tool and it's done.

Can also use any of the various power nibbling tools that are available (oppurtunity to get a new tool!):

https://a.co/d/0daZxzkv

https://a.co/d/06fn4IGl

https://a.co/d/0bPkLOsL

Plus any number of similar, name-brand tools.

Whichever method you decide to use, be sure to tape off each side of the chassis using either painters tape or Polyester Tape to protect the surfaces from scratching.