Cut myself the required 350mm of 4" x 1-1/2" 6082, lashed it down in the vise, touched off and went for it.
I've got enough for 2 attempts at this and 2 attempts at the X axis bracket:
Get the thing set up so it's sticking out far enough to clear the vise:
I touched off crudely using my T01 reference tool to get my WCS G54 X0 Y0 Z0 at the top back left of the stock, as defined in the CAM setup. Jogged it by eye, as I have reused T13 in the tool table that had the offset for the Martest (Haimer clone) indicator. Must set that up again but for this situation the reference tool is fine.
A bit of air cutting while I convince myself everything is looking good:
Then hit the green button:
That went well! Always difficult to take a photograph that shows the surface finish but this isn't too bad.
Then change to the 10mm 3-flute long series carbide end mill. This will spiral into the stock and then open out a cylindrical bore in 2 step downs. Then move across and repeat the same operation for the larger cylindrical bore.
Started out well but it's producing so much swarf that I ended up stopping to clear out the cavity. Needn't have bothered, as the remaining part of this move didn't quite come off:
After the tool broke(!!), I wanted to see if this was because the work had moved, so I used MDI to move to G54 X0 Y0 Z0 again. This is my first machining with the machine vise mounted on some 5" parallels I got from a guy on the ME forum for £45, so was half wondering if it would be rigid / secure enough. Obviously that wasn't the problem. It's right back where it should be:
Then, after I'd found the remains of the tool in the mountain of swarf, the real issue became obvious. Recutting mounds of swarf without a copious flood of coolant results in swarf welding itself to the cutter. It's hardly a surprise - you might say it was actually surprising that it had tolerated all that swarf for so long already. I think what tipped the balance was the tool breaking through (as planned) and releasing the puddle of coolant. It's not just wrapped around the cutter but actually welded in place:
The coolant pump is actually capable of supplying a torrent of coolant but the original flexible hose has a tiny hole (about 3mm or so) in its bell end, so it's rather useless at cooling and (ideally) shifting swarf from the work area. I used the belt sander to grind it back a bit and thus open out the hole a bit but it's clear that the internal bore of the nozzle body and the actual feed pipe isn't much bigger.
Ah well. I removed the hose from the feed tap / bracket and it's a fairly conventional 3/4" NPT male thread.
So I've ordered some 1/2" Jeton (Loc-line compatible) coolant hose and fittings from Cutwel. I got a vaguely decent discount of somewhere around 25% which is better than a kick in the teeth. If you don't ask you don't get etc. I should get these tomorrow, free delivery. I'm hoping that I will be able to shift enough coolant to keep the tool from welding or even better, to stop it piling up next to the tool in the first place.
I've also ordered three 10mm long series HSS end mills for the interim, until I've stopped breaking cutters. They are a fair bit cheaper than carbide, even though I think I got these carbide tools from ebay at a good price. Tool wearout as such isn't actually the issue right now.
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