12G206 Head Chop

[bwaminispeed]

Well, finally got my Milling machine back together, been apart for ten years since I moved out to the country from Oakville.......
What better first job than to beat some sense into one of my Mini Cylinder heads

That cutter is a bit over the capacity of the Clausing (my slowest spindle speed is not quite slow enough), but, it does work, and, gives an acceptable finish

The head is a 12G206 for 998cc/1098cc engines.....Took about two hours to take off 20 thousands of an inch.......Like I said, right on the capacity of the poor old mill, but, hey, I do have the time.......

The only reason I'm doing a 206, is, because it was the closest one to the mill ......This is more a test of my Mill than any specific reason to be doing a 206 head (which, despite the coating of rust, is an NOS bare head)

12G206-Cylinder-Head-Machining-02.jpg

12G206-Cylinder-Head-Machining-01.jpg

[ricardo]

Is that an alloy face mill? What type of inserts are you using? Do you have a close up picture of the finish?

[bwaminispeed]

Yes, 4" face mill, no idea what the inserts are, only, that, they are the "better" ones, whatever that means........

Here's some pics after a couple of passes......

12G206-Cylinder-Head-Machining-03.jpg

12G206-Cylinder-Head-Machining-04.jpg

12G206-Cylinder-Head-Machining-05.jpg

[Spider]

Very nicely clocked in

[bwaminispeed]

Yeah, thanks, I'm actually using this head to dial my Clausing mill in a bit closer.......

I've had the mill a little over 50 years now, and, done a lot of Mini cylinder heads on it, probably approaching a hundred or so......

Mill isn't big enough to run a full width cutter in one pass, so, I always do it in two.......It always left a little step between the two passes, close as I can measure, about .0012". It has never caused a problem with the head gasket sealing, and, I have never had a head gasket failure due to this......so, pretty well left it alone.....

This indicates that the head assembly is slightly angled downward toward the front, there is no adjustment for this, it is pre-set in the design and manufacture of the mill, what to do, what to do, thinkin, thinkin, thinkin..........

Ended up undoing the two bolts that hold whole assembly onto the vertical column, lifting it up a wee bit, and, inserting a piece of .0015 brass shim stock between the main assembly and the column, and, bolting it down again, very Hoot Gibson, and, very un-engineering like, but, it works......

Hooray, after 50 years of being not quite correct, it now leaves just a shadow between the two passes, that I can just barely measure between .0001" and .0002".............more than close enough......

Onwards....