Greene Automatic Cutoff Steam Engine

Kirk,

The starting point with the flywheel a few posts back where you started to machine the flywheel on the mill before it went on the lathe - was that using a rotary table to turn the flywheel or CNC?

The Lane and Bodley has a very similar sized flywheel (might even be the same casting) which I have hanging over me - it's way to big to fit on my lathe so was wondering about at least rough machining the rim on the mill.

Simon.

CNC mill initially to machine the inner rim.  This allowed mounting with the 4-jaw.  A rotary table would work as well or better as long as there is a means to clamp it centered. 

Before any of that I manually milled off most of the outside area where the iron was poured so that it would clear the ways.

I am considering a fixture to mount the wheel on the mill spindle in order to get a good finish on the outer rim.  That will need to wait until the center keyway is broached.  The fixture will start with a 1" round rod turned to 7/8" leaving a collar on one end;  diameter reduced to .75" on the other.  Keyway milled on the 7/8 diameter portion.  Then the wheel is put on with keystock and resting on the collar, while the 3/4 portion is clamped into a R8 collet on the mill spindle.  Then with a lathe tool clamped in the mill vise, very fine cuts taken until the rim is smooth.  I doubt more than 10 thou needs to be removed.

Do the drawings show such a thick rim? Seems this engine along with many similar US engines tended to have a much thinner section to the rim which would be nice to reproduce, you could even add dummy bolt flanges and a joint line to get the look of a two part flywheel.

The drawing shows a very thin rim, and the 3D model shows it as .16".  However, all three model builds I've seen pics for leave the cast rim quite thick.  While accuracy is nice, I suspect that having more weight on the rim helps in allowing the model to run slowly.  I don't intend to take off more than is needed for a good finish.

I'd guess that the original builders opted for thinner rims to make casting them easier (and probably less expensive).

Kirk,
I didn't even see that you got this casting at the show. I must have been to busy or... I did finally meet Jeff & his wife while I was packing up on Sunday. He gave me a few of his business cards & I will post them at shows. You are making good progress and coming up with good workarounds for machines to small for the job.
Art

The L&B and the Green automatic share the same flywheel ,and can be machined to a thin rim but I agree with Kirk I would leave it a little thicker .
I have in the works a pattern for a two piece flywheel for both of these engines , most people who bought or inquired about the castings asked why the flywheel wasn't a two piece one , trying to make every builder happy here .

Milled the outside edge to bring the top surface width to spec.  Then roughed the bearing cap castings to square the sides and bottom.  Also took a slight edge off the rounded ends in order to be able to obtain a center line with an edge finder.



Further machining of the caps will require accuracy as they fit closely to the journals as shown here:



Here the bottom of the cap is to meet the internal ledge while the slots in the cap meets the top of the journal. 

Worked on the first bearing cap for a couple of hours this morning to get a fit to the journal:



Comparison with start point:

Quote from: jeff lThe L&B and the Green automatic share the same flywheel ,and can be machined to a thin rime but I agree with Kirk I would leave it a little thicker .
I have in the works a pattern for a two piece flywheel for both of these engines , most people who bought or inquired about the castings asked why the flywheel wasn't a two piece one , trying to make every builder happy here .

Thanks for confirming that Jeff.  Personally I was going to go for a thin rim as per the engine in the museum;

That bearing cap is a great fit, watching along!

I worked on the second one this afternoon, and the fit at the end is not as good.  A bit more fettling needed. 

My MSC order came in the the bushing and broach needed for the flywheel and crank disk.  Also a bunch of drill rod for future use.

I gave the 7/8x3/16" broach a trial run on a piece of 3/8" thick CI through which I bored a 7/8" hole.  My #3 arbor press was able to handle that, but not the 1.25" thick hub of the flywheel.  One issue is that handle hits the wheel on the down stroke, and as it doesn't ratchet, I can only apply maximum pressure on a relatively short range of motion.

So I'll have to use the hydraulic shop press, which is currently employed as a rack for round stock and is blocked with a bunch of other stuff.  That will wait for next week, as I have an out of state trip for offroading to get ready for tomorrow.

Finally got back in the shop after the long weekend.  I needed to use a press to broach the flywheel hub for a key.  3/16" B broach.





Then milled the semi-circle in the journals for the main bearings.



Afterwards, since the journal was in the vise, I decided to swap the inserts in my face mill and take .01" off the sides.  Much better finish.

A bit more progress on the journal assembly. 

Machined the bearing space into the caps.





Next job is to drill the mounting holes for #6 screws into the journals.  Normal chucks are obstructed by the sides,  but luckily I had this tiny one.  However its maximum size is 1/8".  So I first drilled through using a drill bit of that size.  The hole locations were found using the Mark I precision eyeball to center in the boss.



Then I reversed the piece to enlarge the holes from the bottom.

Continuing along, I face milled both the journals and caps to within .02" of the specified 1.3" width.  I'm not sure if I want to mill them together when attached.  At present this looks good enough as the width is not a critical dimension.  Then drilled and tapped the tops of the journals for 8-32 screws.  For the caps, I drilled from the bottom after using surface plate and 123 blocks to set the caps vertical.



Then reversed to spot face the holes in the tops.



Since a #8 washer diameter is 3/8", I used a 7/16" endmill for this operation.