Lathe Boring Job Mounting Plate

I'm making a 6 inch plate that will hold my Aprilia SR50 scooter's engine cyilnder for lathe boring.
The first step is to interface with the lathe spindle using an
existing lathe chuck mounting plate. I set the Super Shop's compound rest parallel to its lathe chuck's outer face by eye and feel. I gripped a 1 inch long cut of 6 inch malleable iron stock in the chuck. I took a few cuts to see how it felt.
Sooner than I could imagine, I found I was burnishing and hardening the malleable iron, but I dug under the hard area with one of those tricky two-handed cuts (long and cross), and had only slight burnishing after that. Doh! It would have been smarter to just bang my head on the door until I was sure what I was doing. :)
I set up rough left and right turning tools in the four way tool post for facing in and facnig out, and eventually got it to where the pocket I faced was deep enough and the diameter close enough to risk lapping the parts together. That worked OK.
I faced the outer face of the work and put a groove into it about 5.512 inches diameter, checking with calipers. I intend to use 3 M10x1.5 cone point set screws to adjust that groove's actual diameter to "feel right" with the chuck mounting plate against it; a kinematically correct 3-point contact. Hats off to Scott Koppel at Maryland Metrics for finding 3 set screws I can use for this. Thanks, Scott.
I held a 16 inch level to the top of the headstock with duct tape and marked a line to match the lines I'd previously indexed around the chuck mounting plate (the one holding the chuck, not the spare lapped to the work) I indexed 12 hole positions around the face of the work with a v-grooving tool on its side, using the cross slide. Later, I make a "real" pointer.
To Do: Drill and c-bore 12 holes Bore through <41 mm Face other side Face a lip to catch the engine cylinder's 41 mm damaged bore Drill 4 places for cylinder studs Take a deep breath, and ... Bore the cylinder, hone it, and send it to Texas for porting.
In no time, I'll be back on the road. Say, the first day of Spring? :)
Cheers,
Douglas (Dana) Goncz Replikon Research PO Box 4394 Seven Corners, VA 22044-0394
(The above is a perfectly good mailing address; give it a try. Send Money! LOL)
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It was me) wrote:

Woops! That's the diameter for Set-Tru chucks. It's 5.592 or so (about 5-19/32 I reckon) for mine. I "erased" the groove, restored the recess, lapped the parts together, and cut the new groove.

I haven't done this, but I did get a 9/16 drilled hole through the center, to start the 41 mm bore later. Then I got the rusty shank of the drill stuck in my keyless chuck! And the 33JT keys may not fit, since it's on a mandrel. Whatever, on with it...

No, drill 12 holes and tap at least 3, maybe 7, or all 12

It's coming along!
Doug
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