Posted by Hopper on 05/03/2015 06:06:48:
Nice work yet once again John. I've a BMW fanatic mate who does so many of these he made a jig to mount the head on his large lathe faceplate and cut the new thread after getting the ally welded up. I like the idea of a bronze thread though. Much more durable.
Keep on bodgin' — always a good read.
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I did a couple like this early on but was not impressed by the job quality at the end of the day, even with decent TiG rods the finished thread was gummy and the alloy to alloy fit of head and nut didn't appeal to the 7% engineer in me hence the move to bronze.
That angle plate on the mill, first pic is a jig. It's an old plate I picked up from somewhere and the vertical face was made blank. Some one had drilled tapped a few holes in it so I drilled and tapped a few more. 
In fact in the first picture you can see a hole top left and what looks to be another at the side of it? That is actually white marker paint saying "XXXXXX Pump Jig" so I can bolt a weird shaped pump on and bore the seal housing out for a bronze sleeve when they corrode, as they do.
Underneath that are two more sets of holes for the BMW heads, one RH, one LH, both paint marked.
Before I did this I probably took 20 minutes setting the heads up on normal angle plates and trying to get bolt positions to fit slots. Today I can have one on the machine in minutes.
I actually have a book here, one of those with the clear covers inside, fixed not loose and I'm now in the habit of taking pictures of set-ups with my phone then at night print them out, make any notes on the back as regards setup, sizes tooling etc and file it away in this folder. This is because at times I have come across a repeat job only to spend ages scratching my head how I did it in the first place.
Anyway thank you all for taking part in this thread. I was not sure how this basically, an industrial thread would be taken on this site but then realised that many methods can be scaled and transposed to smaller jobs and machines.
[edit] some spelling
Edited By John Stevenson on 05/03/2015 12:30:42