Silver Sawdust

After conducting a successful test yesterday, I thought today’s effort would be a little more rewarding, but events proved otherwise.

After spending a good hour or so (felt like longer) getting set up with the cameras, lights, mics etc for the video, I starting recording, then starting the nesting operation on the CNC.

I was routing into 6mm thick aluminium, using a 1/8″ single flute upcut bit specifically for the job.  I was running at 10mm/sec, with a 1.2mm depth of cut.  Compressed air to clear the chips, and WD40 used generously for lubrication

The first piece cut cleanly, but only a few inches into the second piece and without warning the bit snapped.  By no warning, I mean that it didn’t sound like it was struggling, or vibrating, but snap it did.  It didn’t break near the cutter either, but about 1/2 way up the shaft.

So I thought I’d change to a 1/4″ cutter, cut all the pieces, then go back over with a 1/8″ cutter to refine each piece, and cut the required slots and mortices to join it all up/

This did not go well.  I needed to have completely changed the layout for this to work, and the tabs.  What happened was the sheet’s structural integrity became compromised more and more as the pieces were cut, to the point that they would break free from the sheet.

By the end, the cutter was blunt, the sheet had suffered from so much lateral load that it had begun ripping the screws out that I used to hold the sheet down, and pieces were coming loose left and right.  And there was no chance to refine the pieces to their final dimensions.  The pieces look good, but at this stage they are unusable without a lot more work.  Back to the drawing board.

Al-1Hope these pieces don’t go to waste – took about 4 hours of machining to get to this point.

One Response

  1. from the forums on cnc and such it could be your feed rate being still too fast and thus blunting the bit… Or you’re taking too much in one go… or combination of both… doing aluminium on CNC is a completely different beast… Feed rate and depth are critical while in timber you can easily get away with slight errors on feed rate

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