Author Topic: Greene Automatic Cutoff Steam Engine  (Read 44594 times)

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #465 on: May 29, 2021, 10:13:41 PM »
I finished powder coating ending with the cylinder block, so now I could do a partial temporary assembly of the largest pieces to determine bolt hole positions in the base plate.  The engine is attached to the plate with twelve bolts, 4 each for the bearing standards, and 4 for the cylinder feet.  As cab be seen in the photo, the two holes under the frame aren't accessible to a marking punch, so after the others are drilled the two standard will be attached with the 6 holes so that these remaining two can be marked.  Note that bottoms of the flywheel side standard and cylinder feet must be marked for the correct orientation.

« Last Edit: May 31, 2021, 12:36:10 AM by kvom »

Offline crueby

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Re: Greene Automatic Cutoff Steam Engine
« Reply #466 on: May 29, 2021, 11:15:01 PM »
Like the colors.  How big is that base, looks like a very large engine overall?




 :popcorn: :popcorn:

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #467 on: May 31, 2021, 12:35:35 AM »
Aluminum baseplate is 18x23".  Wooden base is petty heavy, so total will likely approach 100 lbs. 

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #468 on: June 17, 2021, 01:53:49 AM »
Having gotten the Bridgeport back in operation along with the shop AC, I drilled and tapped 6-32 the mounting holes for the engine.  I then inserted a 1" screw from the bottom in each hole.  I was pleased to see that all the components slid onto the "studs".  For the bearing standards, the screw is too short to clear the casting, but they do so with the engine feet.  Plan is to use 6-32 threaded rod as studs with jam nuts under the plate.



I was also quite happy to see no visible wobble when turning the flywheel.

I still need more holes in the base.  The two holes in the crank side bearing standard are blocked by the frame, so I'll need to detach the frame and cylinder in order to use a transfer punch there.  In addition I need to drill holes for the dash pot canisters.  I'll need to do this with the cylinder attached to the plate as their locations are based on the surface of the block and its vertical centerline and are a close fit to the cylinder feet.


Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #469 on: June 19, 2021, 04:43:40 PM »
I'm now starting re-assembly that hopefully will result in a running engine.  I'm trying to avoid skipping any steps that will require major disassembly after it runs. 

Installation of the fixed exhaust valve requires removal of the cylinder foot.



The final holes in the base plate are for the dash pot canisters.  Locations for the center and mounting holes are relative to the vertical centerline and face of the block.  Here I used a 236 block in the vise and a 123 block to align the cylinder, then determined the zero points with a wobbler.  A long center drill was then used to mark the center of the canister and the our mounting hole.  The drill is too short to reach the inner hole, and I located it afterwards with a transfer punch.



With the canisters over the punch marks, I have enough clearance from the feet.



The next job is to install the gears into the governor gearbox.  The assembled governor is show here with temporary screws used for assembly.  Gear install hopefully done the next post.


Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #470 on: June 19, 2021, 08:33:17 PM »
First order of business today was to machine a lucite version of the gearbox cover, to allow some visibility into getting the gears to mesh properly.  This was made from some 1/8" clear sheet.



As can be seen, the teeth of the pinion need to be quite high in the box.  To attach the pinion, a length of 1/8" drill rod is inserted into the end of the shaft.  Its length is determined once the pinion position is known, and then it will be secured with loctite.



At this point I hit the wall, as there is no way currently to position the pinion high enough.  After thinking about this for a bit and considering that other builders have made it work, I went back to the drawings.  Sure enough I had neglected to open the top of the box as can be see in this cutaway section of the model part.



This opening gives room for the pinion shaft, and will be the next thing to do next time in the shop.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #471 on: June 21, 2021, 06:42:15 PM »
After machining the .375" pocket in the top of the gear chamber to match the plans, I discovered some additional issues that need some more complex solution.  The first issue is that when in the mesh position with the bevel gear, the shaft of the pinion is completely within the pocket, and thus the grub screws for securing it to the main shaft are inaccessible.  And if the pinion were to be attached by adhesive neither it or the shaft would be able to removed.  Furthermore, the pinion shaft is .281" in diameter, and able to flex somewhat within the cavity.

So after some thought, I have come up with the following "fix".

a)  Replace the .125" diameter portion of the main rod where the pinion attaches with 5-40 threaded rod.

b)  Make a bushing .375" diameter with a .282" bore that will be placed inside the top cavity of the gearbox

c)  Drill the pinion to open the center hole to .188 or a bit large.  Into this hole loctite a length of rod that has been drilled and tapped 5-40.

Now the pinion can be inserted into the bushing and the main rod screwed into it until it bottoms onto the end of the .188" portion of the main rod.  The length of the rod or the pinion shaft will be set so that the pinion meshes with the bevel gear.  Rotation of the pinion when the engine is running will be same as when screwed into, so the pinion won't unscrew itself.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #472 on: June 26, 2021, 11:00:49 PM »
With a bit of fettling I was able to get the main parts of the governor body assembled with the center shaft and gears such that turning the pulley causes the center shaft to rotate.  Here are the center shaft and pinion gear:



The small end of the shaft is a length of 5-40 threaded rod.To assemble the shaft is passed through the upper body and lower body so that the threaded rod extends into the gearbox.  Then by holding the pinion with tweezers and turning the shaft, the pinion is screwed fully onto the shaft.  The pinon itself has a center section of through-tapped steel secured with loctite.  I needed to adjust the amount that the center extended from the shaft to position the pinion at the proper level in the gearbox.



Once assembled, the governor is attached to the engine frame by two 3-48 cap screws.



I think there would be enough space for hex  head screws if the holes were move inboard slightly.  In any case, my 1/4" long screws are too short, so I've ordered some longer ones from McMaster for delivery on Tuesday.


Offline Kim

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Re: Greene Automatic Cutoff Steam Engine
« Reply #473 on: June 27, 2021, 05:20:38 AM »
Very nice, Kvom!

It seems like it will be hard to set the level of the bevel/pinion gear since it will be hidden when it meshes with its mating gear.  How will you do that?

Kim

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #474 on: June 27, 2021, 01:44:01 PM »
Did it by trial and error, filing a bit off the pinion bushing at a time.  But it was close the first time by mark II eyeball measurement.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #475 on: July 01, 2021, 10:40:40 PM »
After several hours of trying things, I finally was able to get a good mate between the bevel gear and pinion gear with smooth rotation of the governor pulley.  The inside mount of the bevel gear looks like this:



The gear is secured to the shaft with a couple of grub screws, and positioned so that the end of the gear's shaft is against the gearbox cover while the teeth are engaged with the pinion.  It's possible to get this quite close by trimming the gear shaft, or adding spacing washers, whichever is needed.  However, getting the last bit of play while retaining good mesh was elusive.  My solution was to put two coils of a spring around the shaft between the end of the gear shaft and the cover.  This provides enough gentle pressure to keep the gears meshed.

I clipped off the end of one of the same springs specified for the dash pots;  It was an excellent fit.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #476 on: July 02, 2021, 11:07:01 PM »
With shaft turning as desired, it remained to assembled the rest of the governor parts and to make a drive belt.  I had purchased both square and round rubber a good while back, and decided after a test fit that the round is a better choice.  I might try to find a smaller diameter at some point.  In any case, cut to a length that put a little tension and joined the cut ends with superglue.


Note that I cut the "studs" from 6-32 threaded rod, but the weight of the engine holds it all down without any nuts, so I'll leave those for later in case I need to dismount it from the base plate.

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #477 on: July 10, 2021, 07:54:58 PM »
I completed and installed the control rod that connects the governor to the cutoff bell crank.  This rod (5.4" long threaded 3-48 on both ends) and its rod ends are, as far as I know, the last new parts needed to be made for this engine.



Now to reassemble all the rest of parts and try to get a runner.

Offline Dennis

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Re: Greene Automatic Cutoff Steam Engine
« Reply #478 on: July 12, 2021, 10:03:01 PM »
Your engine is looking good Kirk.  Thank you for all the drawing improvement notes you sent.  I am looking forward to seeing the engine run.

Dennis

Offline kvom

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Re: Greene Automatic Cutoff Steam Engine
« Reply #479 on: July 16, 2021, 01:51:33 AM »
I reassembled all of the parts except for the exhaust valve assemblies.  I have decided that both of the brackets need to be remade because of various errors I made on both, and fudged up to now.  So back to reply #106.  However, I have a slightly different order of machine ops in mind so as to avoid getting powder coat where it shouldn't go.