BMW V8 dry sump from billet

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Stilldrillin:
Looking good Ade! :clap:

May good luck stay with you...... :thumbup:

David D

kvom:
FWIW, roughing out the pockets by drilling may save some time vs. milling. And it will save the endmills.

AdeV:
Funny you should say that Kvom - I did wonder about making lots of drill holes, but in the end I settled for spotting & drilling the corners of each of the remaining 3 pockets. I drilled them to the biggest drill the little Albrecht will take, 10mm.

Here we are after the spotting work is done (including some idiot lines), but before I drilled out the holes:

After that, it was just a case of mill, mill & mill some more. Each pocket is 3cm deep, 75mm wide, and either 81 or 102mm long. Using the 12mm roughing cutter, going 0.5mm undersized all round, and taking 5mm deep stripes, eventually I had all 3 holes dug. To finish, I went around each hole twice with a regular end mill, opening out to the full size, then cutting back & forth across with 0.025" depth of cut to get to the final 3cm (sorry about the mixed units, the knee is in inches, as is my depth mike. In the end, I missed my depth by 0.002", but frankly life's too short, and it's not a critical dimension.

Here's one of the finishing cuts going on. I did all the finishing under oil:

Some wax offcuts do service as crude spray shields. Each pocket is milled in the classic English Lawn Style (i.e. stripes), which reduced the number of full-width power-fed cuts to just one per pocket per 5mm. So, after many hours (including an extended break for taxi duties):

It may not look much, but the surface at the bottom of each pocket is some of the best surfacing I've ever achieved with a regular end mill - it's absolutely perfectly smooth to the touch. I'm not sure how many tenths of imperfection you can get away with before you can feel it, but I know it's less than a thou. So, it's a shame it's going to be hidden away under the oily bits of the engine (actually, most of it won't even survive to see that.... it gets milled away when I make the slope down to the drain holes). Ho hum. ::)

PS: No cutters were harmed during tonight's production :thumbup:

Divided he ad:
Now that's looking nice :beer:

You must have been there for hours?

Good to see it all going to plan :thumbup:

Ralph.

Brass_Machine:
I agree with Ralph... looking nice!

Can't wait to see it finished.

Eric

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