Geared horizontal twin engine

[ajoeiam]

I was one of those graduate engineers... but started my "apprenticeship" at 13 - part-time cleaning, then using, machine in a machine shop, re-furbishing engines and compressors of all sizes. By 19 I was told I'd had at least as much train as the full-time apprentice. But 50 years on I am still learning. The best combine academic and expertise, like Brian, and that's my goal...
Nice work Brian.

IMO that kind of training is how you get a capable mechanical engineer. For the last who knows how many years people go to university for 4 years and then they're experts. A few use a co-op program and they get to learn a little bit of on the job stuff. Its easy to see paper engineering expertise - - - - you know when you just can't get at stuff to fix it or to remove it - - - or you need to take off the radiator and loosen engine mounts to change a water pump. The last 15 to 20 years - - - - to compensate for inadequacies all the engine intricacies for setup are hidden in software - - - - supposedly stuff that makes the engine work better - - - - yet these engines and the machines they're in - - - - well they are irreparable - - - - but that's the idea - - - - it makes more money for the company. I wish I could create a total boycott of all the useless stuff that is being foisted on us - - - - starting with automobiles that have no idea what economical travel is (second being appliances that don't even last 10 years).
> rant off

 

[Steamchick]

40-odd years in industry - the private sector that makes profit, pays tax and doesn't rely on government support - I learned a long time ago that happy customers buy your products again. So most of the design of modern products is designed to the desires of the committee of the public that buy the products... combined with what the government permit through regulations.
Not necessarily what everyone wants.
K2

 

[Brian Rupnow]

I learned early on that you don't antagonize or lord it over the guys in the shop. You are young and green. Some of the guys in the shop have been there 50 years, and seen it all. If a shop guy gets you aside and privately tells you something you designed isn't going to work and explains why, you damned well better listen. If you play the "I'm an engineer so do exactly as I specified" the shop guy will build exactly what you asked for. And it won't work. And then there will be a meeting between management, engineering and the shop steward. WHY did our shop do something so patently stupid and waste the companies money? And then the shop steward will say "My machinist told Brian that wasn't going to work, but he Brian blew him off and said he was an engineer and to do it his way. Then for the next week you walk around feeling about 2" tall, and wondering if maybe you should have taken up farming or sky diving instead of engineering.

 

[Steamchick]

I was taught that as a kid -from stern words, or a clip around the ear. "DON'T tell your betters what to do". Served me well. But also "Don't stop asking, just listen and consider the advice".
K2

 

[Brian Rupnow]

I believe this is the last part to be machined for this engine. Since the main air valve is a single feed and is then split to run out to each cylinder, there is no way to test and set up the engines individually. This single air feed adapter lets me take the main valve and air manifold off the engine, and then it attaches to one steam chest to set up only that engine. Then it is removed and attached to the other engine for setting it up individually. After both engines have been set up to run individually, then this part is removed and the normal valve and air manifold are reattached to the engine.

 

[Tim Wescott]

I liked working at FLIR Systems, because when you got a part back from the model shop, you got your drawing, too -- with all sorts of annotations and corrections. In red. It was great. After the second time I gave them a nicely detailed, incorrect drawing, I just started giving them rough sketches like the real ME's did. Things went smoother after that.

(And sometimes there is a point to getting a part assembled exactly according to your directions -- "I want to know where my design is wrong, so I can fix it". We had a guy on the shop floor who'd do that all day, or build it up and mark up the instructions where they were cockeyed. He could barely speak English, but his writing was fluent. We had another guy, from the same region of the world, fluent English, would use it to complain all day long about engineers -- but if you tried to hand him a red pencil he'd treat it like you were throwing a venomous snake at him.)

 

[Brian Rupnow]

All of the teachers in my engineering apprenticeship were Dutchmen who had immigrated to Canada. They were very patient and kind and all belonged to the Dutch Reform church, so if you gave them any kind of a chance they would do their best to look after your immortal soul as well. They could be quite severe and strict, but that was quite uncommon. They were great teachers and great people. I live forever in their debt. They are probably gone now and I hope they all went directly to their version of Dutch heaven.----Brian

 

[Brian Rupnow]

Santa came to our house last night, same as he always does. I must have been a good boy this year because I ended up with new socks, t-shirts, sweaters, and a new pair of shoes. I generally buy "odorless" varsol to wash down oily, greasy parts with. After considerable time "running in" my newest engine, and constantly supplying it with squirt can oil, it was filthy with a mixture of oil and powdered aluminum and brass. I was out of odorless varsol this morning, so tried to sneak some lawnmower gas into my workshop and wash down the engine. I immediately got yelled at by good wife for "Stinking up the house", so had to abandon that idea. Much later in the day, I finished cleaning up the engine and machined a new cam-shaft with keyways for the flywheels and a flat for the set-screws in the central gear. Tomorrow, if things don't come amiss, I am going to ty and run this engine. After I get it running to my satisfaction, I will remove the flywheels and the steam-chest covers and paint them.

 

[lathe nut]

don't want to get her mad you might be sleeping in the yard and stuck to the ground by daylight.

 

[ajoeiam]

Santa came to our house last night, same as he always does. I must have been a good boy this year because I ended up with new socks, t-shirts, sweaters, and a new pair of shoes. I generally buy "odorless" varsol to wash down oily, greasy parts with. After considerable time "running in" my newest engine, and constantly supplying it with squirt can oil, it was filthy with a mixture of oil and powdered aluminum and brass. I was out of odorless varsol this morning, so tried to sneak some lawnmower gas into my workshop and wash down the engine. I immediately got yelled at by good wife for "Stinking up the house", so had to abandon that idea. snip

Its not always easy to find but I bought a 5 us gal pail of a citrus based cleaner.
Not sure if this is the product but it could be something like this: Eco Orange Citrus Cleaner| World's Best Citrus Cleaner| The only cleaner you will ever need - - - - I am not endorsing this particular product - - - - just providing a possible example. This kind of product is MUCH easier on the hands - - - - it doesn't stink and yet it cleans parts well and leaves a thin coating so rust isn't an issue pdq. Would recommend looking for this kind of cleaner! (another option: Orange Peel-Citrus Cleaner - SpecChem )

 

[Brian Rupnow]

Thought I would have a runner today, but it didn't happen. The current valve control rod set-up is not strong enough, and due to the stresses involved the 1/8" diameter steel rod bent and then broke just beside the blue nut in the top picture. Tomorrow I will canibalize all of the existing parts and fabricate a new brass piece as seen at the bottom of the picture, which will have much more resistance to bending or breaking. Also, I am going to have to add a piston ring to the pistons. I can re-use the existing pistons and simply turn a ring groove in them.

 

[Brian Rupnow]

Today I revisited the valve control rods. These rods have a high bending moment applied to them if there is any binding between the eccentric strap area and the eccentric itself. As the eccentric revolves, this sets up a reversing moment in the rod, and if the rod is smaller than 1/8" in the threaded area, it soon fails in a stress type failure. I'm not concerned about weight, so have spent part of today making newer heavier links.

 

[Brian Rupnow]

This time around, I fitted the eccentric straps to the eccentrics off the engine. The broken 1/8" connection rod was totally my bad. Sometimes I try to cut corners, and end up in the $hit. The holes in the current and the earlier version of the eccentric straps was reamed to 0.750". The eccentrics were a couple of thou oversize. I thought I could work that down while running the engine in and gradually tightening the connecting bolts as things loosened up. This resulted in failure of the 1/8" rod. I have a vertical spindle sander here that takes different diameters of rolls. I used it to open the 0.750" bores on these new "eccentric straps" to 0.752+/- and then worked the final bit down with 600 grit lapping paste. Like the saying goes, "The hurrier I go, the behinder I get".----Brian

 

[lathe nut]

Hey Brain don't be so hard on your self, think we all get in that situation, make it with what we have and hope it will be stout enough to work, considering that you are building it from what is is in your mind's eye not something that someone one else has built and worked out the bugs, you did great, love the connecting rods that really looks with the flywheels, I know that you won't give up and won't give in.

 

[Anatol]

Hello Brian
I enjoy your thorough and thoughtful posts. In this case, i'm slightly shocked by the unusual and massive valve 'webs' you've made, fine as they are. I think every valve connecting rod and eccentric I've ever seen has been of the form you originally made. Was the breakage a result of simply too tight a fit? If so, why didn't you simply ream or lap the straps? I see that the relevant stress riser is at the joint, which is in this case a thread. Isn't there another mechanical solution for rod-meets-strap? clamp, transverse key, set screw, clevis, ... or simply a larger dia rod?

 

[Anatol]

Also, I am going to have to add a piston ring to the pistons..

why?
Iron or O ring?
looking forward to hearing about this.

 

[Brian Rupnow]

After much finessing today, I think I'm about half way home. I didn't o-ring the pistons because all my stores are closed due to Covid and I didn't have the size o-ring I need in stock. I do have one engine working. Don't have it all hooked up yet, but when I manually operate the slide valve, the piston and cross-head take off like a wild thing in either direction. The other engine isn't doing it's thing quite yet, but is very close. It needs some more attention to the slide valve and steam chest I think. I've had enough fun for one day .

 

[Tim Wescott]

I only re-read the story of the broken valve rods today - while 1/8" may be a bit light, it certainly seems that the main problem is the eccentric fit. Did you consider just fixing the problem in the assembly as designed, then arranging for a better rod-eccentric fit before attaching that delicate little bit of ferrous lacework to a 1/2 horsepower motor to run it in?

 

[Brian Rupnow]

Let me put it like this Tim---I THOUGHT it was fitted "close enough" to run it in and get rid of any tight spots. I was wrong. Today, I reworked the new eccentric straps so they were a definite clearance fit before reassembling to the engine. The new eccentric straps look rather monstrous, but I may like that.---If I don't, I still have the lightweight eccentric straps---all they need is new 1/8" rods. I think I will include drawings of both the lightweight and the heavy duty eccentric straps in the drawing package and let anyone who buys the plans to make their own choice.

 

[Brian Rupnow]

Anatol--If I do add rings to the pistons, they will only be buna-n rubber material. I will know better after tomorrow if I'm going to use rings or not.