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Triple tinkering : three times the fun?

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Michael S.:
Hi Dave,

I enjoy watching you make the parts.

I have the same set of cast parts waiting to be machined under my workbench. It's from the early 1980s, and it includes the same crankshaft. This will be a challenging job.

Michael

Chipswitheverything:
Thanks Michael.  With the weather improving now and other activities predominating, I will probably not get much more done during the summer, but I have been pleased to see something happening with this set of castings which, like yours, have spent 40 + years in their packaging!  As I mentioned, this is not meant to be a build log as such, but from time to time I'll add a few pictures and comments when something else is contended with.

As shown in the "so far" first photo, I have also machined the gunmetal bar device that holds the lower end of the slide bars. The DRO on the mill was a big help in the drilling and spacing of this. I mounted the drilled casting on an aluminium "waster" support for the shaping operations. I'd have used a more generous size bit of ally, but couldn't find any in my odds and ends bin ...
That little rotary table was very handy again for twirling in the assorted curves on this component.

Charles Lamont:
That little George Thomas rotary table is such a useful tool. I probably use mine more often than the bigger worm-drive job. Yours would be even more useful if you graduated it!

Chipswitheverything:
Thanks Charles : I have got a worm geared, 8" Tom Senior table with graduations, which I have used now and then for bigger stuff, and when I need the graduation for whatever reason.
 But actually, I don't think that I have ever been bothered by not having the small rotary table left plain, I almost always use it by setting the stops, having offered a cutter up to the marked out, or however indicated, workpiece, using a lens to adjust the cutter edge to the line, and then rotate to the stop. Or I might initially put the stops a little clear of the finished requirement and move them marginally to nibble up to the final position. For setting out holes on a PCD I'd usually favour the GHT dividing head, or these days I'd probably use the facility on the DRO to achieve that.

Chipswitheverything:
Have made a bit more progress with the triple engine . Got the flywheel machined and fitted. I don't use or keep much selection of carbide tools, could perhaps do with a few more, but I needed to attack the chambering out of the wheel with carbide. After getting through the considerable amount of sandy surface, the iron underneath did machine well enough with my usual HSS toolbits.

Then took a look at the two cylinder castings. Decided that the datum references for these lumps needed to be the side lugs that are drilled for the eight supporting columns, so that the holes fell decently spaced in these cast lugs.
The smaller casting for the HP was done in the lathe four-jaw, having marked a reference line across the two lugs, and then the distance to the port face.

The bigger casting has been work on the mill table. I cleaned up the top cast faces of both castings by filing, then did a preliminary facing cut on the other side, just to establish a couple of surfaces to help with the alignment needed to drill the four awkward holes for the equally awkward screws that hold the two castings together for further machining.
I was going to do some marking out, but in the end put my trust in my school arithmetic and the DRO for getting the two sets of hole in the right places.
Did a bit of clearing of the casting where the cap screw heads need to tuck in, using a little carbide burr in a mini-drill.  All went together OK, the DRO accuracy had been helpful ...

Then got the main facing to final thickness of the top and bottom done.  Met with a few nuisance chill spots here and there, so did use carbide to work the surfaces over.

The clamping up of the castings on parallels, and the alignment ready for the cylinder boring seemed to take a surprisingly long time, even by my standards!
So far, just got the largest bore done, the Geo. H. Thomas design boring head has managed OK, with an HSS toolbit given a fresh sharpening and honing for the final cut.

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