Author Topic: AOG's version of the Stuart St Oscillator  (Read 4942 times)

Offline AOG

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AOG's version of the Stuart St Oscillator
« on: April 27, 2017, 03:45:39 PM »
After my last Elmer's engine I was looking for something simple while I work out what my next big project was going to be. I reached into the closet of castings and came up with the Stuart ST kit. This will be my first Stuart engine so we will see how that goes. The kit came nicely packaged with everything shrink wrapped onto the box.



If you'll notice, there is only one actual casting in the kit. The cylinder is a weird extrusion. The rest is made from bar and sheet. After a quick Jo approved fondling of the parts, I found that nothing is undersized and most of the bar stock is long enough to hold. Let's get started on the only casting. First I filed the sides of the base square. I then aligned the base of the standard vertically and milled it flat.



Then the mounting holes were drilled into the base.



I dusted off my small tooling plate and transferred the holes.



Unfortunately the casting must have slipped when I transfer punched the holes. When I mounted the standard onto the plate it wasn't square to the tooling plate. Next I milled the top flat.



Then I drilled the the main passages in the same setup.



I went to clean up and drill the intake and exhaust ports. One side went well.



This next photo is what happens when you get distracted and forget to tighten the vise.



Now that I have successfully ruined the only casting in the kit, I decided to start on the cylinder while I wait for a replacement. First I cleaned up both sides of the extrusion and took it to length.



Then the bore was drilled and reamed to size.



Next it was over to the mill to flatten the valve face.



The pivot hole was drilled and tapped and then the ports were spot drilled.



Then I made my second mistake. The plans call out a 30 degree angle between the ports. I misinterpreted that to be the angle between the port and the face. I ended up drilling through the side instead of into the bore. I plugged the hole and drilled at the correct 15 degree angle to finish the ports.



I have elected to clad the cylinder in wood instead of the supplied sheetmetal so I skipped drilling those mounting holes into the cylinder. That's all for this round.

Till next time.

Tony




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Offline DTR

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Re: AOG's version of the Stuart St Oscillator
« Reply #1 on: April 27, 2017, 03:51:15 PM »

This next photo is what happens when you get distracted and forget to tighten the vise.

I feel your pain, glad I'm not the only one who has done that....

Watching with interest :)
Dave

Offline b.lindsey

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Re: AOG's version of the Stuart St Oscillator
« Reply #2 on: April 27, 2017, 06:29:11 PM »
Bummer about the casting Tony, but at lease a replacement is available. It happens to all of us!!

Bill

Offline zeeprogrammer

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Re: AOG's version of the Stuart St Oscillator
« Reply #3 on: April 27, 2017, 10:40:00 PM »
Impressed that you just kept going without a hiccup.
I might have slept for a few days.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline AOG

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Re: AOG's version of the Stuart St Oscillator
« Reply #4 on: May 01, 2017, 05:54:23 PM »
Thanks everyone, for some reason I missed all of the replies. Zee, I'm used to screwing up. It doesn't even bother me anymore. The biggest pain is waiting for the replacement casting. In any event I did get some work done this weekend so let's get that documented. The first thing I did is to change my mind about the lagging. I am going to use the supplied lagging after all. I drilled and tapped the cylinder for the mounting screws.



Then I drilled the ends of the lagging strip.



Next up were they cylinder heads. I cut the supplied bronze bar to diameter and shaped the lower cylinder head. Then it was drilled and parted off to size.



That bronze was terrible to part off. It work hardens if you look at it funny. Then the part was moved to the mill and the mounting holes were drilled.



With that done, I cut the boss into the top cover and parted it off. Then the mounting holes were drilled and the decorative top was turned.



The covers were done so I started on the crank shaft. The plans call for you to turn it from solid. I usually fabricate mine but I didn't have the right size drill rod for the shaft so I said what the heck and turned it in one piece.



I must be getting better at this because I got right on the first try. The crankshaft was parted off and the backside trued up with the shaft.



Over to the mill where the crank pin hole was drilled.



Next the pin was pressed in. It got slightly bent in the press but I got it straightened out.



Here is a family shot to end this update

Only a few more parts to make and I will be holding on my replacement casting.

Till next time

Tony




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Offline AOG

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AOG's version of the Stuart St Oscillator
« Reply #5 on: May 06, 2017, 01:01:05 AM »
Ok let's close out the machining on this one. The next part to be made was the piston. It was turned to diameter and grooved for the supplied O ring.



Then it was drilled, threaded and parted off



Next the piston rod was turned down and threaded at both ends.



The big end was chucked in the self centering four jaw. The end was drilled, tapped and turned round.



Then over to the mill where the big end was drilled.



Next up was the spring tensioner knob. First a knurled some brass stock.



Then the knob was turned to form, drilled, tapped and parted off.



Next up is the flywheel. The material in the kit was brass but I decided to change it out for steel. Nicely blued, i think it will look good. First I brightened up the outside and drilled the center hole.



Next I cut a decorative groove in the end of the flywheel and parted it off. The other side was cleaned up and grooved as well.



Then I moved to the mill where the flywheel was drilled and tapped for a setscrew.



Just about that time my replacement casting came in. I redid everything I had done on the original so I will pick up from there. I machined the valve face and crankshaft boss flat



Then the hole for the crankshaft was drilled.



The part was flipped and I centered up on the crankshaft hole. From there I moved up and drilled the pivot hole.



The part was flipped again and centered on the pivot hole. Then I used the DRO to coordinate drill the valve holes.



I plugged the top holes on the standard completing the part and the machining. It's now fit and finishing time. I'll leave you with this final family shot.



Till next time

Tony


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Offline b.lindsey

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Re: AOG's version of the Stuart St Oscillator
« Reply #6 on: May 06, 2017, 01:28:35 AM »
You are making short work of this one Tony. The family shot looks great!

Bill

Offline AOG

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Re: AOG's version of the Stuart St Oscillator
« Reply #7 on: May 06, 2017, 01:39:51 AM »
Thanks Bill, this is one of those tide you over projects while I plan my next big one. I've been handed something of a challenge for the next project and I think you guys are going to like it. If everything goes well I'll get started on it next week.

Tony

Offline b.lindsey

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Re: AOG's version of the Stuart St Oscillator
« Reply #8 on: May 06, 2017, 02:00:01 AM »
Oh nice!! Will look forward to that then.

Bill

Offline Flyboy Jim

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Re: AOG's version of the Stuart St Oscillator
« Reply #9 on: May 06, 2017, 03:19:26 AM »
Thanks Bill, this is one of those tide you over projects while I plan my next big one. I've been handed something of a challenge for the next project and I think you guys are going to like it. If everything goes well I'll get started on it next week.

Tony

Well don't leave us hanging Tony................at least give us a little hint!  :shrug:

Jim
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Sherline 5400 Mill
"You can do small things on big machines, but you can do small things on small machines".

Offline AOG

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Re: AOG's version of the Stuart St Oscillator
« Reply #10 on: May 06, 2017, 03:30:00 AM »
Ok Jim, here's your hint. It will involve a steam engine build and a boiler build and a ...........   

Tony

Offline crueby

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Re: AOG's version of the Stuart St Oscillator
« Reply #11 on: May 06, 2017, 03:51:53 AM »
Ok Jim, here's your hint. It will involve a steam engine build and a boiler build and a ...........   

Tony
Excellent! I was hoping you would build that one! 


 :shrug:

Offline b.lindsey

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Re: AOG's version of the Stuart St Oscillator
« Reply #12 on: May 06, 2017, 01:30:53 PM »
Hmmmmmm.....maybe the PMR coke bottle engine and the vertical boiler  :headscratch:

Bill

Offline AOG

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Re: AOG's version of the Stuart St Oscillator
« Reply #13 on: May 13, 2017, 07:04:02 PM »
It's  done and in the showcase. Getting it running took significantly longer then I expected. I ended up with two of the ports blocked inside the casting by what looks like paint. Once  I got it cleaned up, it ran very well. Because of the size of the flywheel it doesn't like to run slowly but it does pretty well for its size. Pics can be found at the link:

http://www.modelenginemaker.com/index.php/topic,7120.msg148921/topicseen.html#new

Tony

Offline bwal

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Re: AOG's version of the Stuart St Oscillator
« Reply #14 on: August 24, 2018, 08:24:29 AM »
Hi,

I just started my one today.  This build log is a great help (that's why I've re-started the thread - I don't have to keep digging it up on page 5 or 6).

Cheerio Ben.

 

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