Author Topic: Chris's Marion 91 Steam Shovel  (Read 272632 times)

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #945 on: March 28, 2018, 07:57:57 PM »
More on the spoke-ification process this afternoon. Milled the depth of the spokes in at the ends where the slots are, and out to the rim.

then switched to a 1/8" diameter ball end mill, and took that depth 1/16" into the rim:

Did the same on both sides of each of the two gears. Now its time to start chopping out the pie shaped bits between the spokes. As before, I made the first cut just inside the actual dimension so I could clean up the cut with some lighter passes. The spokes are tapered, so the rotary table was set to 5.4 degrees off centerline of the spoke.

You can see in that last photo that one of the screws is still in place to ensure the gear does not turn - that will be cleaned out last.
With the table swung over 5.4 degrees the other side of center, rough cut the second side of each spoke, releasing the chunk in the middle - was careful to go slow on the last bit of each, and was pushing down with a metal rod to force the chunk away from the cutter as it let go, did not want it catching in the cutter.

Then back around each spoke, taking light cuts till they ended at the bottom of the stop holes in the corners.

Last step was to take the rest of each spoke down to depth, then mill the square hub outline in the center. Normally I would not square the hub, but thats how the original is. For the final cuts, the side screw was put into different holes as needed. Same pattern on both sides of the gear, with the squares aligned to each other.

And here is the first gear all milled out and set on the axle - still some trim bits to add, and need to make the final axle, for now been using an offcut which is a little short.

One down, one to finish up...
 :cartwheel:
« Last Edit: June 16, 2018, 09:15:16 PM by crueby »

Offline Farmboy

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Re: Chris's Marion 91 Steam Shovel
« Reply #946 on: March 28, 2018, 08:42:42 PM »
Beautifully done. That gear is a work of art, shame it's going to be painted  :cheers:

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #947 on: March 28, 2018, 11:02:50 PM »
Beautifully done. That gear is a work of art, shame it's going to be painted  :cheers:
Just think of paint as really heavy tarnish!   :Lol:

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #948 on: March 28, 2018, 11:12:45 PM »
Got the second gear up to the same point as the first:

Here they are on the boom:

Realized I did not show the arbor on the rotary table - you can see how the mill left the pattern of the spokes in the top. There are three sets of holes: middle one for the axle hole, three outside ones used during initial drilling for the spokes, and 6 middle ones that are at the point where the spokes meet near the hub. Two of those were drilled/tapped in for screws used after the pie sections between the spokes were cut out, to keep the gear from turning.


Next is to figure out how to make the little angled plates at the ends of the spokes, like in this photo:

The red arrows are pointing at the little angle braces cast into the gear (also, you can see how incredibly worn the gear is after 50 years of use! ). They would be really small to fabricate and solder in, wonder if putting down a blob of JB Weld and carving that with a dental bit would work better. Don't really need them, but it would be one of those neat little details...
« Last Edit: June 16, 2018, 09:15:25 PM by crueby »

Offline Brian Rupnow

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Re: Chris's Marion 91 Steam Shovel
« Reply #949 on: March 28, 2018, 11:25:50 PM »
Thanks for your answer Chris. I've always been to concerned about breaking an endmill to try cutting a slot all in one bite.---Brian

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #950 on: March 29, 2018, 03:26:54 AM »
Thanks for your answer Chris. I've always been to concerned about breaking an endmill to try cutting a slot all in one bite.---Brian
If it was steel, I wouldn't have tried it, but the brass cut fine with a slow feed.

Offline J.L.

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Re: Chris's Marion 91 Steam Shovel
« Reply #951 on: March 29, 2018, 10:17:47 AM »
Hi Chris,

Superb sequential photography on the making of these two gear wheeels. Do you think you will put in those little reinforcing gussets?
Knowing your attention to detail, I bet you will.

 :popcorn:

John

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #952 on: March 29, 2018, 01:40:40 PM »
Hi Chris,

Superb sequential photography on the making of these two gear wheeels. Do you think you will put in those little reinforcing gussets?
Knowing your attention to detail, I bet you will.

 :popcorn:

John
Thanks John. 


Had an idea how to add the little gusset plates last night (my usual late night idea delivery from back of the brain). Going to try cutting thin slots with a dental bit and high speed air tool to hold triangles cut from brass shim stock, could hold in with loctite or jb weld. Will try on some scrap and see, but it should work. Its one of those little details that draws the eye in a model.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #953 on: March 29, 2018, 05:28:26 PM »
Gave the gusset paltes a try this morning, so far so good. Used the air-powered TurboCarver tool with a fine dental bit (about 0.020 slot from it) and made slots at the rim and hub edges for the plates.

Here is a bit of shim stock sitting in the slot:

I used some JB QuikWeld to glue plates in all the slots (48 of them), let them set up a couple hours, and trimmed them off:

They are a subtle detail, but once painted I think it will add a nice touch.
« Last Edit: June 16, 2018, 09:15:39 PM by crueby »

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #954 on: March 29, 2018, 06:53:24 PM »
I got the gears loctited on to the shipper shaft and things re-assembled again, here is a couple photos, then a video of it in action:




Video showing how the motions work on the dipper:
« Last Edit: June 16, 2018, 09:15:46 PM by crueby »

Offline Dan Rowe

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Re: Chris's Marion 91 Steam Shovel
« Reply #955 on: March 29, 2018, 08:37:56 PM »
Hi Chris, nice work as usual. How many were in the crew for one of these machines? It seems like at least a fireman and an operator would have been needed.

Cheers Dan
ShaylocoDan

Online sco

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Re: Chris's Marion 91 Steam Shovel
« Reply #956 on: March 29, 2018, 08:38:31 PM »
Great result as usual Chris!

Any ideas why it's called crowd engine though?

Simon.
Ars longa, vita brevis.

Offline Kim

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Re: Chris's Marion 91 Steam Shovel
« Reply #957 on: March 29, 2018, 08:56:38 PM »
Beautiful, Chris!  That is just down right cool!

Any ideas why it's called crowd engine though?

I've been wondering the same thing!  Why "crowd engine"?

Kim

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #958 on: March 29, 2018, 09:08:30 PM »
Hi Chris, nice work as usual. How many were in the crew for one of these machines? It seems like at least a fireman and an operator would have been needed.

Cheers Dan
They had a bare minimum of 3 - operator in the front of the cab, second operator on the turntable for crowd and bucket release, and engineer on the boiler. Normally had 8 men in the crew - added stoker, and a crew of misc laborers for clearing fallen rock at base, moving jackscrews, getting water/coal, things like that.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #959 on: March 29, 2018, 09:17:52 PM »
Great result as usual Chris!

Any ideas why it's called crowd engine though?

Simon.
That is a good question - and why do they call the shaft the big gears are on the shipper shaft? I have not found out where those terms come from, the earliest catalogs mention terminology as being semi-agreed upon between the manufacturers, terms seem to date from the very early machines. I wonder if it is one of those terms simplified from some other language terminology? I have seen wording where the act of pushing the bucket down into the ground is 'crowding'.