BMW V8 dry sump from billet

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AdeV:
Cheers chaps, keep up the encouragement.... it's needed just now...

Spigots of Death - Part 1

I need 3 spigots, one per pipe, so that the flexi hose to the oil pump can be fixed on. This means lathe work... In my defence, the lathe is much newer to me than the milling machine, and I've had a lot less practice on it. Which probably explains why I now have 2 scrap spigots & no good ones... and I'm rapidly wearing my 1" ali stock down...

Here's the two attempts:

Attempt #1, incongruously, is the one on the right that looks just fine. OK, the shoulder end of the thread is a bit messy, but that side is basically OK. The thread was cut with a mixture of single pointing & then a die. As it transpires, I had my metric threading tool in the toolpost, so it didn't cut a particularly good BSF thread... Switched to the imperial cutter tonight and that did better.... except I cut the threads too deep. So, when I drilled out the centre, the last drill just ate the threaded end. Doh!

Looking from this side, you can see the problem with the "good" spigot - I've badly over-cut the spigot wall, so there's nearly no meat left. Certainly not enough to clamp a hose to. It makes for a really light part, though! Wall thickness on the other one is better. All it needed was a chamfered end, and it'd have been bob on.

I cut the spigot end (on both parts) using a parting tool: I'm sure that's a Really Bad Idea, but I can't think of a better way to cut between the shoulder and the 4-jaw chuck. Won't be a problem after tomorrow, I've got a tasty new ER32 collect chuck + some collets arriving :clap: so I'll finally be able to turn stuff around without having to spend 1/2 hour dialling it back in. I just hope it sticks out past the 4-jaw, so I don't have to take that off... 'cos that would be a right arse ache.

So..... a disappointing evening on the lathe. But fear not.... I will not be beaten.... Part 2 tomorrow (hopefully).

Darren:
Hey, chin-up .... it's not a failure, just call it practice to get you closer to your goal .... :headbang:

I'm sure we have no doubts of your capabilities :clap:

AdeV:
It's funny, but as I look at the semi-failed part (the first one, with the holes I just noticed in the threads - clearly visible in the 3rd photo...), it still amazes me that I made it myself.

I. Made. It.

I mean, how cool is that? :med:

Even though it's useless, I think I'll finish it off - the final operation was to mill a hex on the central section, so it can be spanner tightened onto the sump.

It also raises the question... can I run a 5/8" bore through a 3/4" BSF threaded section without it failing due to being too thin? Evidence to date would suggest not; but, then, I can try cutting the threads a little shallow, safe in the knowledge the tap seems to be cutting a trifle deep

No1_sonuk:
Could you not cast up some of your wax into a cylinder and test the idea?

AdeV:

--- Quote from: No1_sonuk on March 29, 2010, 08:10:35 PM ---Could you not cast up some of your wax into a cylinder and test the idea?

--- End quote ---

I'm pretty sure the wax is too delicate at that sort of thinness, it would just break up as the drill went through. Having said that, it's got to be worth a go...

I've found a BSF chart which suggests that, theoretically at least, a 5/8" bore WILL go through a 3/4" BSF thread, with a "generous" 0.018" wall thickness between the minor diameter & the inner bore... I'll have to get out the measuring tongs tomorrow & see if the hole I'm cutting is oversized; but, as I mused above, I reckon I can cut the thread a bit shallow to give me a bit more elbow room with the bore size. Of course, 5/8" is the ideal bore, I could get away with 19/32" if it's going to be a problem.... except I probably haven't got a drill or reamer that size...

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