Author Topic: Chris's Marion 91 Steam Shovel  (Read 574872 times)

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2955 on: January 19, 2019, 09:05:51 PM »
Okay, been doing some experimenting, looking, measuring, and think I have the issue narrowed down to the throw on the reverse link from the control lever up front. The throw will go too far in the reverse direction,  and not far enough in forward. The middle of that control rod, under the floor, has a coupler connecting the two halves of the rod through all of the cross beams it goes through the center of (worked out best to do that so it was easier to install the rods - Marion did the same thing). This can be re-centered by seperating the two halves of the rod slightly, but the coupler in there does not have enough slop in it. So, I will remake the coupler with a longer tube so I can adjust the throw position. The coupler is just a length of round bar, drilled down the center for the rods, with a pair of grub screws on the side.

Enough crawling around under the model for today, will rest on my laurels for the evening and tackle that tomorrow.

Thanks all for watching along!

Now, wheres that cookie.... Ahah! the elves are trying to drag the bag into the other room... Get back here!   :LickLips:

Offline Don1966

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Re: Chris's Marion 91 Steam Shovel
« Reply #2956 on: January 19, 2019, 11:35:09 PM »
Ma sha that there thing she runs like that mud boat yea!... :lolb: love it Dog just love it!

Don


Offline cnr6400

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Re: Chris's Marion 91 Steam Shovel
« Reply #2957 on: January 20, 2019, 12:04:59 AM »
Congrats Chris! the hoist engine runs great! Amazing work.  :popcorn: :popcorn: :popcorn: :ThumbsUp: :ThumbsUp: :ThumbsUp:
"I've cut that stock three times, and it's still too short!"

Online Kim

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Re: Chris's Marion 91 Steam Shovel
« Reply #2958 on: January 20, 2019, 12:17:43 AM »
Always fun to see it run for the first time!  Congratulations, Chris!
Kim

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2959 on: January 20, 2019, 12:21:48 AM »
Oh yeah, first run on any engine is a blast!


Test, tweak, test, tweak... repeat... Then it just takes off, big grin!

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2960 on: January 20, 2019, 03:04:54 AM »
As is my usual pattern with a logic problem, along about 10pm, while watching TV or reading, the back of my brain figures out the answer to a confusing puzzle from earlier in the day and smacks me in the forehead.




The real issue on the reverse gear was that the linkage from the control arm under the floor to the Stephenson linkage was coming up at an angle that got steeper as the eccentrics went through thier cycle. Doh! That is changing the hieght of the link during the motion, and is worse at the forward setting.


So, the real solution is not changing the coupling as I thought earlier, I need to modify where on the stephenson link that the control arm connects, so the arm goes back and forth evenly either side of vertical rather than off to one side and farther off the same side!


 :facepalm:


To paraphrase the old saying,  Oh sh*t, geometry works!




Offline 10KPete

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Re: Chris's Marion 91 Steam Shovel
« Reply #2961 on: January 20, 2019, 03:43:53 AM »
Aayyhhh yup!

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2962 on: January 20, 2019, 03:49:02 AM »
Aayyhhh yup!

Pete


Having spent a lot of time in Maine I would say  Ayuh.  Ayuh.


 :Lol:

Offline 10KPete

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Re: Chris's Marion 91 Steam Shovel
« Reply #2963 on: January 20, 2019, 06:24:11 AM »
 :lolb: :lolb:

 :naughty:

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Online sco

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Re: Chris's Marion 91 Steam Shovel
« Reply #2964 on: January 20, 2019, 02:25:46 PM »
Just brilliant to watch those videos Chris !

Still following you with interest,

Simon.
Ars longa, vita brevis.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2965 on: January 20, 2019, 03:46:19 PM »
I know that my description last night may not have been very clear of the issue on the control link, so here is a quick sketch, with the sizes exagerated a bit for clarity.

On the left is what it should have looked like, with the travel of the control arm from the bell crank under the floor up to the Stephenson linkage. The travel is centered, so the vertical movement at the valve rod is small. On the right is how mine came out - since there is a cross-beam under the floor, I could not move the bell crank pivot back under the linkage, so it started at an angle and got worse during the travel, meaning a large vertical movement. That vertical movement changes where the valve rod hits the Stephenson link, messing up the movements. It is more movement than on most engines, since the Stephenson link is very short. So, I am going to change where the control arm connects to the link to make it act like the one on the left. Pics to come later as I make the corrected part....

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2966 on: January 20, 2019, 09:13:51 PM »
After some more measurements, experimenting, research, and cogitation, I decided to redesign the Stephenson link and control arm to put the pivot in the center of the two straps to the eccentric, where it gets minimal movement from the rotation/rocking of the ends. This is the way it is on my Kozo New Shay build, and that works very well.
So, started on the re-make of the links, with the two blanks stacked and screwed to a bit of aluminum for drilling/milling:

Here it is with the outside taken down, and the corners rounded off on the belt sander:

I had to confiscate them from the shop elves, who thought they were brass knuckles....   :Lol:

The center hole of the three will get a post added to let the control arm clear the clevises - start on that tomorrow....

Offline Craig DeShong

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Re: Chris's Marion 91 Steam Shovel
« Reply #2967 on: January 21, 2019, 12:37:01 AM »
Just got back from the Cabin Fever Expo and am catching up.  All I can say is
 :ThumbsUp: :ThumbsUp:  :pinkelephant::ThumbsUp: :pinkelephant: :cartwheel:

And then....  :popcorn: :popcorn: :popcorn:

Craig
The destination motivates us toward excellence, the journey entertains us, and along the way we meet so many interesting people.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2968 on: January 21, 2019, 12:48:20 AM »
Just got back from the Cabin Fever Expo and am catching up.  All I can say is
 :ThumbsUp: :ThumbsUp: :pinkelephant: :ThumbsUp: :pinkelephant: :cartwheel:

And then....  :popcorn: :popcorn: :popcorn:


 :cheers:


Hope you enjoyed the show. The weather here would have made traveling down to PA pretty nasty, hope I can go next year.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #2969 on: January 21, 2019, 05:26:56 PM »
This morning I got the extension posts onto the middle hole in the reverse links - these will hold the control arm out beyond the clevises. The posts are threaded on the inside, and have a shoulder at one end to fit into the hole in the link to keep it aligned for silver soldering.


And they are installed, appear to be moving correctly, and the vertical motion during the cycle is gone.


Ran an air test, and looks like I need to retime it again, not surprising in that the motion before was a bit wacky. I think the valve sliders need to be recentered, which is a pain to do but thats part of the game. Time for lunch first!  Oh, anbd you may notice that the large slew gear is not in the photo, got tired of working through the spokes and took that axle out for now.

 

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