Author Topic: Chris's Marion 91 Steam Shovel  (Read 309077 times)

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #495 on: January 08, 2018, 04:36:42 PM »
I think you have it now Chris. That small link does make some sense. Even back in the day those designers were pretty sharp. It actually amazes me how much of that we have lost over the years.

Bill
Would have been wonderful to talk with some of those designers!

I recall on the photos of the original beam engine that Willy did the model of, that they did make the occasional goof and had to cut away a bit of casting for clearance, but I'm sure the next one they made had that correction in the molds.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #496 on: January 08, 2018, 04:47:17 PM »
As for the mechanical advantage - the measurement on the links works out to 2:1 on the first link, 3:1 on the next, and another 3:1 on the chain-to-rope link, so 18:1 overall?

Oh, and there was the question from Jim of the rope lead from that final link. It did go through a small pulley on the main boom to keep it from sagging down to the ground and keeping the angles good. That was just a guide pulley though, no change in leverage from it, but as you say it would keep the angles better.

Offline Kim

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Re: Chris's Marion 91 Steam Shovel
« Reply #497 on: January 08, 2018, 05:18:56 PM »
Well, not only are my estimating skills off, but my eyesight isn't so good either apparently.  I completely missed the lever E in my calcs.  Those levers still look like 4:1 to me, not 3:1.  But you've got the actual measurements Chris, so I'll go with your numbers! :)

Kim

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #498 on: January 08, 2018, 09:56:02 PM »
On to working on the latch mechanism - going to start with the two guide for the latch bar. I started with some rough sawn chunks of 3/8" stainless, held them over the edge of the tooling plate to shape the top/sides.

Then, figuring that I am better off going with as-built offsets rather than designed measurements for this, I traced the opening from the bucket latchplate:

I'll drill the corners and the bulk of the center of the hole, then finish them up with a file, then start on milling the recesses in to the side fins.
« Last Edit: June 16, 2018, 08:47:42 PM by crueby »

Offline Farmboy

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Re: Chris's Marion 91 Steam Shovel
« Reply #499 on: January 08, 2018, 10:37:45 PM »
Chris,

I am so much in awe of your attention to detail and amazing work rate on the Lombard that I hardly dared comment here but having seen similar types of linkage, on somewhat smaller machines I just felt something was not quite right.

At the risk of trying your patience even further I suggest the link would serve no purpose if it were directly in line with the main lever, being effectively an extension of it. My impression from the photo was more like the attached very simplified drawing. This would avoid sideways deflection of the latch. Of course I'm working in the dark since much is hidden behind the guide bar, so I may be way off the mark, but I thought the mount post appeared to be centred a bit further up in the photo  :shrug:

Mike.

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #500 on: January 08, 2018, 10:47:06 PM »
Hi Mike!  Never be wary of pointing something out to me, its very much appreciated! You make a good point, that it needs to be offset to work right. I'll take another look at the photos and see if I can work out the angle they had it at (too cold and snowy to get out in person if I can get it from the photos).


Thanks for pointing out this one, saved me rework when it would have jammed up!!


 :cheers:

Offline Farmboy

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Re: Chris's Marion 91 Steam Shovel
« Reply #501 on: January 08, 2018, 11:02:43 PM »
Too busy on other jobs to spend any time in my own workshop at the moment so checking in to see your progress every morning is my little daily treat  :cheers:

Just make sure you don't send that snow over here to the UK, our transport system can't seem to cope with an inch of the stuff  :rant:

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #502 on: January 08, 2018, 11:10:57 PM »
Too busy on other jobs to spend any time in my own workshop at the moment so checking in to see your progress every morning is my little daily treat  :cheers:

Just make sure you don't send that snow over here to the UK, our transport system can't seem to cope with an inch of the stuff  :rant:
Uh oh. They already picked up the box of snow... A really BIG box!   :lolb:

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #503 on: January 09, 2018, 12:32:58 AM »
Last bit of shop time for the day - more on the guides. Started by drilling the corners of the holes, and then milled out the bulk of the center, ready for some filing time to square up the holes for the latch bar.

Then turned the guides upright, and took .150 off each side to form the ribs:



And a test fit, sighting down the holes they line up well with the striker plate, so on to some filing time.


Earlier today I got the head cast in epoxy for the RC sea turtle submarine that I mentioned a few times in earlier posts. The head is cast as a solid piece, the neck behind it will be cast as a hollow tube of platinum-cure silicone rubber, and will surround the flexible mechanism to articulate the head (more on that in another week or so). The top and bottom halves of the shell have also been cast, using fiberglass matte and resin. Next steps on it will be to make the wire-controlled flex mechanisms for the flippers, neck, and tail. The break for Cabin Fever will give the resins a chance to cure up fully - the silicones wont cure properly if the resin is too new. The castings so far have come out pretty well, just a couple of small air bubble flaws to fill in.

« Last Edit: June 16, 2018, 08:48:00 PM by crueby »

Offline crueby

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Re: Chris's Marion 91 Steam Shovel
« Reply #504 on: January 09, 2018, 03:10:12 AM »
Mike, think I have finally cracked it! I had been assuming that the pin at the end of the retaining bar "F"  from my earlier picture was also the pivot for the short link you describe. In going through more of the photos in detail, I found an angle that shows that there is another pivot pin for the short link, up at a 45 degree angle from the other, but mounted on the same base as the original pin. Here is a blowup of that spot with labels:

This new pin makes much more sense for the linkage as you describe it, now I get how it would allow for the latch bar to stay centered in its holes. All that white/gray stuff over everything is the remains of the tar that the quarry sprayed on everything when they abandoned it decades ago, now cracking, falling off, and trapping water. That is the stuff that will be stripped and repainted starting this spring, hopefully, as the stabilization project gets started.

Thanks again for spotting the need for that link!  I'll get the 3D model updated to match this.
 :cheers:
« Last Edit: June 16, 2018, 08:48:07 PM by crueby »

Offline 10KPete

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Re: Chris's Marion 91 Steam Shovel
« Reply #505 on: January 09, 2018, 05:32:42 AM »
Yep, two links between the bar and the bolt! Free floating...

Geez you took some great pics!

Pete
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Offline derekwarner

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Re: Chris's Marion 91 Steam Shovel
« Reply #506 on: January 09, 2018, 07:32:28 AM »
Yes Chris......sidewise deflection or seizing of the vertical latch bolt 'A' had me concerned :facepalm:....as it would have by the designers all those years ago

This latest revision  would appear to eliminate this

Derek
« Last Edit: January 09, 2018, 10:15:22 AM by derekwarner_decoy »
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Online Steamer5

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Re: Chris's Marion 91 Steam Shovel
« Reply #507 on: January 09, 2018, 07:54:07 AM »
By Jove, Looks like Mike cracked it!!

Had both the PC & my phone open last night, so I could zoom in on phone to the earlier pics, pretty hard to see but your latest pic shows it well...well better! The tar spray makes it hard to pick the detail. One more thought....would that little short bar be free to pivot just enuff to allow Bar B to maintain its position as it as the latch would keep it from moving anywhere? Looks also like the Bar F "support is "L" shaped, the low side the pivot point for the short bar & the long leg the anchor point for bar F.

Keep up the good work...the turtle head is looking good!

Cheers Kerrin
Get excited and make something!

Offline Farmboy

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Re: Chris's Marion 91 Steam Shovel
« Reply #508 on: January 09, 2018, 08:39:25 AM »
Phew! Glad it wasn't all a figment of my imagination  :)

The bucket alone would be a 'project' for many of us. Really looking forward to watching this machine develop  :popcorn:

Mike.

Offline Admiral_dk

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Re: Chris's Marion 91 Steam Shovel
« Reply #509 on: January 09, 2018, 11:30:14 AM »
I believe that the "F Bolt" is a pivot too, and that explain why they needed the "F Bar" to support it.
One link will not give a parallel movement, but two can - or in this case a short link conneted to a "link" that has an offset and it can turn on a pivot.

Sorry but no way of making a drawing to post here at work ....