Gallery, Projects and General > How do I??

Cutting sheet metal on the mill?

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AdeV:
I'm making some flat covers for a little project I'm working on (full write-up soon...). Whilst the perimeter tolerances are of the "hold thumb and forefinger just so and squint", i.e. eminently achievable with an angle grinder, I do have to drill 6 reasonably accurately positioned holes, so I can screw the top in place. So since I've got to put the metal on the mill anyway, I could also quickly run around it with an end mill to give me a nice rectangular cover of pretty much the exact right size....

The question is, what's the best way to hold it?

My first attempt was with double-sided sticky tape on a piece of wood. I'm sure you can all imagine how well that went.  :palm: I'll pause here, until you stop laughing.

Second version, I drilled a couple of holes in the middle, made a jig* with 2 bolts, the jig went in the vice & the sheet (rough cut to size) went on the jig. This works well - but it does leave a couple of unnecessary holes in the finished cover.

So - Is there another, better, less holey, way of holding a flat sheet (0.9mm thick) for both milling and drilling operations?

Cheers,
Ade.

*Calling it a "jig" is to massively exaggerate really: It's just a rectangular block drilled & tapped to take two M6 cap-head screws, and is deliberately smaller than the outline of the cover...

Brass_Machine:
Sacrificial piece of aluminum. Bolt it down to the table or hold it in a vise. Super glue the thin sheet on. make your cuts, then some applied heat to pop it off.

Eric

chipenter:
Drill your 6mm holes first and use those to clamp it down with a spreader bar on top , I have made sleeve  thread adaptors for my t-nuts 8,6 and 4mm for small stuff , that are very useful .

Spurry:
For any of those awkward jobs, my favourite is a backing board of 19mm mdf. If it won't fit on a spare bit of mill bed, then, horror-of-horrors I have to remove the vice as a last resort. A bed-size piece of mdf pre-drilled 12mm at its ends to suit the slots secures it to the mill bed. The metal sheet can either use proper clamps through the mdf to the mill bed or just screw washers round the edge of the sheet to the mdf. All depends on the relative size of sheet to be machined and mill bed.

Pete

John Rudd:

--- Quote from: Spurry on April 05, 2020, 04:38:33 AM ---For any of those awkward jobs, my favourite is a backing board of 19mm mdf. If it won't fit on a spare

Pete

--- End quote ---

And......make sure you set the depth stop so you dont drill right thru the mdf.....should you get carried away with your success..... :lol:

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