Hey everyone, I have a work holding question. How would I machine a roughly 70x70x2.1 mm copper plate, where the thickness and flatness need to be down to 0.05mm on both flat faces? My main concern is that I can’t find stock of the right thickness, so I don’t know how I would machine something down to this very specific thickness; also I wouldn’t trust stock to be the exact thickness that I need it to be.
I only have a modest mill. We have a CNC mill in our hacker space but the vice simply isn’t large enough so I’ll have to use an older manual mill; the shape is not that complicated, so I can manage without CNC, although I would use it if I could (but I haven’t learned their software yet either). I don’t know how to machine this without bending up the copper.
For the outline, I thought about maybe putting the copper between two thick alu plates, and screwing them tightly together. The shape is basically a 70x70 square with a 50x50 square removed from inside it; the outside edge has some features (it’s not just a plain square) so it needs to be machined as does the inside edge. I’m not sure how best to do things without bending up this delicate copper plate. But my main concern is with making the thing the exact right thickness. It’s a copper shim that goes between a GPU cooler and the RAM chips, and the chips are very fragile so the item needs to be just the right thickness.
Too little thickness will mean the cooling will be bad and the thing will overheat and possibly damage itself. Too much thickness will mean I will crush the chips (plastic and silicon bonded to the fiber glass resin PCB using lead-free solder). Insufficient flatness will mean that the thing will not fit and again crush the chips. A bad outline will mean interference with other components.
Here’s a picture of the thing I’m trying to make (the paper cutout):
There are more images of the cooler I’m modifying / making at this gallery here. Please bear in mind that the cooler at that link is my first project both in CNC and manual machining, so it’s not pretty, but it does the job. I’m still learning and I hope to learn a lot here at the Titan Academy 