Greene Automatic Cutoff Steam Engine

I just checked the website to see that they're not open every day.  Sent a message asking to visit the day I'm in MA.  If not I'll probably just head to Newport for the afternoon.  I have an airline credit that is use it or lose it, si I'll be doing the trip regardless. 

June 6 is volunteer workday at the museum, so I extended my trip by one day to participate.

Yesterday I decided to start the build by attacking the flywheel casting.  It's a big bugger: almost 12" diameter and probably over 20 pounds.  There's no real way to mount it on my lathe to start, so I started by reducing the lump of iron on the wheel's axis.  (These were needed in the mold to keep the wheel portion from cooling too rapidly).  Here's the setup using 123 blocks to raise it enough to clear the other lump.  Removed enough so that the remainder is inside the rim.



Back at it today.

Turned it over to mill the other "lump".  Now the rim can rest on the table, and the clamping is somewhat more secure.



Next the inside of the rim is machined to remove the draft.  This surface will be used to secure the wheel on the lathe via the 4-jaw chuck.  I was nervous about clamping too hard on the spokes, so this operation was done with many passes of 5 thou stepover.



Final operation on the mill was to face the side of the rim.  This gives a straight edge needed to ensure that the wheel is straight when mounted on the lathe.



Now for mounting on the lathe using my large 8" 4-jaw chuck, with the jaws on the inner rim.  Turning the lathe on a low speed allow verification that the inside face of the rim is close as possible to running true.  Then I centered the wheel using the inner rim as a guide.  Note that all of the machining done on the chuck side will be modified later.  Once centered, I used my 1/2" boring bar to turn the inner rim, and then faced the side of the rim and the hub.  The length of the hub was faced to close to the final size.



Next I turned the hub using a cutoff tool, then drilled the center 1/2" and bored to 0.855".



Final op for the day was to ream the center hole with the .875" reamer, which I had as this was the size of the axles on the Kozo loco.

The face of the rim is now the reference surface for further ops, as is the center bore.

Off to a great start, thats quite a big wheel.

Kirk , You didn't waste any time getting this project started , good job .

Not as long in the shop today, but some progress.  I moved the wheel from the lathe and mounted on the CNC mill table with the reference rim face down.  Centered on the bore, and then milled half of the outer rim.  Second op was to face the side of the rim to make it parallel to the reference  face.



Next session I will carefully move the clamps one at a time so as not to disturb zero position, then then mill the hub.  Once that is done, flip and mill the other half of the outer rim.  Surface finish looks decent, but I'll try to polish it once back on the lathe.

Turning the rim on the lathe using an upside down boring bar would have been easier, but my lathe has always refused to run in reverse.

Very nice!

One suggestion I would make is before removing a clamp, add another one out on the rim on the same side as the one you are moving - I have had things shift slightly when moving them one at a time like you mention.

Off to a great start Kirk. It's a big un but at least the other castings should be easier to hold.  Will be following along.

Bill

Finished the milling.



Slight mismatch on the rim that should be fixable later on.  Once I can get a 7/8" axle secure in the hole I could use the mill as a lathe to true it up.

Next up are the castings for the main journals.  As the bottom surface seems the most level, I sawed off the excess of the pour and face milled.



Then the top surface was milled to be parallel to the bottom.



Then  one face was milled to provide a flat for a parallel.



Then the entire side could be milled flat.



Then it was reversed to mill the opposite side.  Dodging hot chips is not fun.

Next time in the shop I'll do the other one the same way.  My intention is to eventually machine the holes for the bearings on both pieces together.  I'll see if that's possible in the end.

It seems that the sides of the bearing castings would look better if they had been left as cast; Is there a reason that they need to be milled flat?

Dave

I'm too dumb to do anything but follow the drawings and 3D model.  The other three builds of which I'm aware also made the sides flat and parallel.  There was a lot of extra metal in the casting vs. the drawings, with more to come off on all 4 machined surfaces.

Makes since, I was just wondering.

Thanks,
Dave

Machining the tops of the bosses for the mounting screws.  Took about .160" off using precision Mark I eyeball.



Piece measures 3.818" tall vs. 3.54" in model.  I will remove metal from the tops of both at the same time.

After machining the 2nd journal to the same state as the first, I clamped them together to perform the next ops on each simultaneously.



These ops were as follows:

1) Machine top surface to bring part height to 3.55".

2) Machine the sides to give a strip .15" high.  This removes the case surface and provides references for determining the center line of the parts.

3) Mill the center slot .75" deep to widen it to 1.374".  The bearing cap will subsequently sit on the resulting ledges, which in turn will be on the horizontal centerline of the bearing.

For the next shop session I need to further machine the side strips so that the two top surfaces are .463" across.