Author Topic: Chris's Build of Steering Engine  (Read 52188 times)

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #585 on: December 01, 2022, 05:25:14 PM »
After playing around on the plans pages at the MIT museum, got back into the shop to get the eccentrics lapped with the arms. I made a little rod with a screw head for a key, and used the lathe to spin the eccentric. The arm block rested against the back of a turning tool in the QCTP - with the eccentric action it looked like a REALLY REALLY dull hacksaw machine!  Let them spin for a while at different speeds, adding more compound and tightening the screws as it went along.

Then cleaned up the parts, and got started shaping the big end of the arms. Started out rounding over the cap end, using the same setup on the faceplate as was used previously to bore the holes.

After several rounds of milling, here are the parts so far. The big ends are mostly done, they need some rounding on the sides of the portion between the end plates still. After that I'll start shaping the small end yoke, before moving on to the shaft of the arm. For scale, the wide part of the blocks are about 1" across.




Offline Jo

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Re: Chris's Build of Steering Engine
« Reply #586 on: December 01, 2022, 06:21:27 PM »
I am pleased you are only lapping those straps onto their eccentrics. When I first saw the picture I had visions of the lathe jumping around if they were clamped onto a bar and you turned it on.   :paranoia:

How are you planning to make sure you remove all of the lapping compound?

Jo
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Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #587 on: December 01, 2022, 06:54:33 PM »
I am pleased you are only lapping those straps onto their eccentrics. When I first saw the picture I had visions of the lathe jumping around if they were clamped onto a bar and you turned it on.   :paranoia:

How are you planning to make sure you remove all of the lapping compound?

Jo
Yeah, I just had the side bar on the tool post there to keep it from spinning, the part was not clamped to it. The arm did oscillate back and forth like it would on the engine, with the side of the arm rubbing on the side bar. I made sure that the eccentric was not clamped too hard by the cap and could rotate in the hole before turning on the lathe!

One of the things I like about the Timesavers lapping compund is that it breaks down into finer and finer grit as it is used and can easily be flushed away, so in commercial settings often they just add more oil to dilute it away. Very different from diamond paste, which can get stuck into the metal and doesn't break down or clean off easily, continuing to abrade the metal. The Timesavers comes as a powder (4 different grits available) that you mix with a few drops of oil to make the slurry. Years ago I got their trial pack which has small tins of all four grits, these tins are tiny for a machine shop but for hobbyists like us its a lifetime supply. They make yellow and a green versions, for use on different types of metal. I usually just use the yellow one, works great on bronze and brass.

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #588 on: December 01, 2022, 06:58:52 PM »
Here we see again how Chris makes it look like in the end. Nice to see what is created from the two bronze lumps. Very good.

🍻   :cheers:

Michael

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #589 on: December 01, 2022, 07:04:02 PM »
Thanks Michael!


One thing I might do slightly different on the model is to make the pivot pin in the eccentric upper end be keyed rather than cross pinned like the original, the sides of the yoke are pretty narrow at model scale. I'll decide that when I get the rest of the arm shaped. I used a keyed pin on the Sabino model (the original had it that way too) and it worked out well, allowed me to put a thin nut on the side so the pin was easily removeable, which is important to allow disconnecting the yoke to screw the valve rod up and down for timing the engine.

Offline Michael S.

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Re: Chris's Build of Steering Engine
« Reply #590 on: December 01, 2022, 08:23:58 PM »
I think you can do that too. It makes adjusting the piston valves much easier.

Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #591 on: December 01, 2022, 08:27:30 PM »
Some more playing around online, this time back at the National Archives site - found a complete set of plans for the steering engines in the Kearsarge class pre-dreadnought battleships (just before the Ohio engine I've been modelling).
 :whoohoo:
Here is one of the sheets, scaled way down for the forum, was able to download high res versions for study.


Offline cnr6400

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Re: Chris's Build of Steering Engine
« Reply #592 on: December 01, 2022, 10:35:37 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline derekwarner

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Re: Chris's Build of Steering Engine
« Reply #593 on: December 02, 2022, 10:44:09 AM »
Nice to see some ISO Metric tapered pins, carefully hammered in :hammerbash: , to the yoke arms & pin :ThumbsUp:...... Derek
« Last Edit: December 02, 2022, 10:47:36 AM by derekwarner »
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Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #594 on: December 02, 2022, 03:44:23 PM »
Got the rest of the shaping done on the eccentric arms, lots of setups in the mill vise, worked my way back from the top ends to the big ends. The final rounding was done on the belt sander, to round the top ends of the yoke and a couple places on the sides where the recesses come back up to the thicker sections.


Then back to the engine for a test fit. It turns out that when I milled the engine bed I didn't take the side walls of the trays under the eccentrics quite thin enough, thinking by looking that 'oh, thats plenty of clearance'. Wrong!   :hammerbash:   So, a little bit of thinning on the insides of the walls at the ends and a little touch up paint, and it all clears.


EdIT: NaTURally ChRis tried To tAke (Elfric, stop jummping on the shift key!)  all the credit, but of course it was us shop elves who did all the work...




Offline RReid

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Re: Chris's Build of Steering Engine
« Reply #595 on: December 02, 2022, 03:54:54 PM »
Well, someone is doing some very nice work! :ThumbsUp: :popcorn:
Regards,
Ron

Offline steam guy willy

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Re: Chris's Build of Steering Engine
« Reply #596 on: December 02, 2022, 05:43:18 PM »
hi , oops ..sorry got that last comment all wrong and I can now see how it all goes together !!! and lovely work as usual  :praise2:

Willy

Offline Kim

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Re: Chris's Build of Steering Engine
« Reply #597 on: December 02, 2022, 05:49:55 PM »
Always the problem with painting as you go... but a little touchup and all's good!   :ThumbsUp:  :popcorn:

Continuing to enjoy your build, Chris!

Kim

Online steamer

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Re: Chris's Build of Steering Engine
« Reply #598 on: December 02, 2022, 06:29:08 PM »
It's coming along magnificently!    Love the project and the guts to do it!

Can't wait to see it running!!!

Dave
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Offline crueby

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Re: Chris's Build of Steering Engine
« Reply #599 on: December 02, 2022, 07:45:58 PM »
Thanks guys!  I'm very pleased with how its coming along, and at a guess I'd say it could be running around the end of the year. The cylinders are a pretty complex shape, been thinking about how to do them and making notes/crumpling some of the notes and throwing them away, keeping others... The usual process!

 

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