Poppin 150 Build

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vederstein

Must do dumb things....
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Some of you folks know that my next project is the Poppin flame licker. I have a high distaste for tiny parts/fasteners. Therefore I redesigned the engine making it 50% larger.

Then I looked at the main frame the original designer called the Standard. I looked at my stock of materials and unfortunately I didn't have a piece of material large enough from which to create the Standard. So I convinced myself what the hell, I'll just cast it.

Other than in my profession to which I believe I'm a quite good designer of industrial machinery, I'm very much a jack of all trades/master of none type of hobbiest. Unlike some people here, I'm not that picky as long as it works, and my castings "work". They're never great looking, but then I'm still very much a novice at the whole aluminum casting biz.

Anyways, I designed and 3D printed a pattern I believed could be cast "open" mold.

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It took a few tries getting the sand to hold, but I do have what looks like a serviceable part. (At the time of this picture, it was still hot to the touch and I was unable to clean it).

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We'll see when I start cutting on this beast.

...Ved.
 

vederstein

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Overall, the casting was not bad.

The issue with castings is that nothing, and I mean nothing, is square. Castings have draft so they're crooked by design. Therefore the first step is to guesstimate squareness then qualify as many sides as feasible on that one set up. For my purposes, I clamped it reversed in the mill and qualified the bottom and outer perimeter (5 sides).

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From there, I flipped the part and indicated to the centerline of the casting. I eyeballed to the other center of the piston bore and I drilled/bored the cylinder mounting face.

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It's very important to record the DRO position from the bottom of the casting to the center of the bore because the design intent is for other features to be located from the centerline of the cylinder bore.

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Continued on the next post....
 

vederstein

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From there I can reposition the part and drill/ream the features for the crankshaft and valve pivot arm. Note that on drilled surface I spot face the feature to ensure a flat, qualified surface for whatever goes into that position.

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From the casting process, there's some (for lack of the vocabulary) bird **** between the Standard crank pivots. It's a combination of loose sand and aluminum. It's got to go. So another set up and from here I milled out the crap and qualified the inside surface to the correct width along the centerline of the part.

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Perhaps I should have put in the mounting threads on the first set up, but hindsight's 20/20. So considering I cannot accurately locate the part inverted again, I'll just wait to transfer punch the hole locations at a later time.

Other than that, I think this endeavor was successful.

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vederstein

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I won a cast iron auction on Ebay, so I forged ahead and created the piston and cylinder.

I machined the cylinder first; everything except for the center hole. The photos should be self explanatory:

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Continued on next post...
 

vederstein

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The cylinder was a bit more complicated.

I machined the outside diameter then used a parting tool to cut the cooling fins.

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Upon which I cut the cylinder from the barstock.

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Chucking the part back into the lathe, I drilled then bored the cylinder bore. I left a couple of thousandths for lapping.

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I have a lap left over from the 1/2 scale Essex stirling engine to which I could never get to run. The lap was close to the 1.5 times the bore of the original engine design, so I used it. After about 3/4 hour of lapping and testing with the piston, I got the fit where the piston would drop almost freely, but stop when I put my hand on the bottom.

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I know this fit is very slightly still too tight. I'm hoping to finish the lapping operation with the piston itself after the engine is assembled. I can work the engine with a drill and I expect the two parts to fit to each other.

After some drilling and tapping to which I didn't take any pictures, I mounted the cylinder to the frame.

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And that's enough for today...

...Ved.
 

Mark Duquette

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It is really looking good

I see you won the piece of cast iron I was watching on Ebay. I bought a bar from McMaster Carr to make a 20mm ring lap.
 

Brian Rupnow

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Vederstein--re lapping the cylinder with the piston after assembly.--not really a good idea. If you lap a piston into the cylinder while either the piston or the cylinder is turning in the lathe, you give it two different motions. One is truly linear, but the other is a twist as you are moving the piston or cylinder in the linear motion. If you lap the piston into the cylinder after assembly, the micro lines resulting from lapping will also be linear, because turning the engine in assembly only gives the linear movement. This gives compression a straight thru passage between the piston and cylinder walls.
 

vederstein

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Brian,

I'll keep that in mind. The current state of the lap is very, very close. I just think it needs a tiny bit more. It's at the state of the piston nearly free falling through (and sometimes it will). If the cylinder end is capped with my palm, the piston doesn't fall and I feel compression. If this wasn't an engine with extremely low power density, I'd call the current lap near perfect.

Based on your comments, if the engine doesn't run after a reasonable try or it seems to dies due to friction, I'll disassemble it and run the lap with a drill motor a bit more.

Thanks,

Ved.
 

vederstein

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Onto the crankshaft.

I've had various levels of failure when it comes to cranks. As usual, I made mine built up from components.

The plans specify 3/8" x 5/16" barstock. I didn't have any of that, but I did have some 3/8" x 5/8" CRS barstock. So I milled it to size.

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To ensure the holes for the parts are exactly in the same position, I drilled/tapped/reamed the holes in the material at the same time.

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From there I inserted the 1/4" roundstock into the holes and used a piece of the 3/8" x 5/8" to get the gap correct. Upon which I could drill and press in some spring pins.

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I used the same set up to mill out the 1/4" rod.

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Resetting the part I milled the "counterbalance" end to the length specified on the print. After a bit of filing, the part is complete.

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That's all for today.

...Ved.
 

vederstein

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Today I worked primarily on the flywheels. I have about a 30" of 3" diameter roundstock of cold rolled steel in my material inventory. Seemed close enough to a flywheel for me.

So I cut off a (far too big) chuck. Then I faced one side and drilled/tapped through.

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From there I would use a boring tool to create the flywheel web.

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I flipped the stock and realized I cut my chunk way too big. The amount of swarf was a bit obnoxious. Considering how blue it is, I was really working the lathe hard. After flipping I bored out the web as on the first side (above picture).

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The design has two flywheels, so I mounted both on a mandral and clamped them with the tailstock to make a single light cut to clean up the OD and make them exactly the same diameters.

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Off the the mill to drill out the flywheel web...

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I also made the Piston Yoke today, but it really wasn't a difficult component...

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That's it for this week.

...Ved.
 

vederstein

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It took three tries, but I finally got the connecting rod made.

The main issue was the big end which is two pieces put together, then the assembly has considerable machining. Both times I was close to finishing the part and a stupid mistake ruined the part.

So onto the documentation:

The big end's two parts are a turned piece of 3/8" brass and a 1/2" block. The brass was turned down, drill, and reamed. The block was drilled / reamed 3/8".

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The two parts were assembled then drilled / tapped #4-40 to hold the two parts together.

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The rod and big end was drilled 1/16" and a pin pressed in. This was the death of try #2.

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The big end was drilled / reamed 1/4". Then the big end assembly was narrowed .125". This was the death of try #1.

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The last operation was to support the rod, indicate, then drill/ream the small end.

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I went forth and assembled the engine thus far. Except for one wobbly flywheel, I'm thus far pleased...

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Bye,

...Ved.
 

vederstein

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I purchased a 12" x 12" piece of 14 gauge cold rolled steel for various arms. In this posting, the rocker arm...

I cut it out on a bandsaw then squared up two sides. From there I drilled out the pivot points.

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The ends are rounded with one end smaller than the other end. I believe it to be more for aesthetics than anything else, so my method to do this will probably cause some of you seizures, but it works for me.

I scribed the two radii (one at each end), then I eyeballed a tangent between the two radii and scribed that line.

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I clamped the part back into the milling vise with and lined up the scribed line with a parallel. I could then mill to the line. I created filing buttons (not shown) and rounded the ends.

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I created the round parts (sorry, no photos) then pressed the assembly together. The method seemed to work fairly well.

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That's all for now....

Ved.
 

vederstein

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Ok,

I've been screwing around with this engine for quite some time now and I cannot get it to run. The best I've done is get a few rotations off a MAPP gas torch.

Attached are a few photos (of the engine, not the burner) and a quick video. Any insights would be useful.

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coulsea

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Flame lickers can be difficult to get running because they don't have much power, once you have one running you get the feel for what it is doing.
everything needs to be running freely and the flame is very important. as a rule of thumb the wick should be the same diameter as the hole in the head and it should be a fiberglass wick because a cloth wick will produce soot which will mix with the oil and gum it up.
I use singer sewing machine oil which is quite thin but still thicker than things like wd40 which are not really lubricants.
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I notice that your valve works on the top of the cam, mine run on the bottom, the cam closes the valve and a light spring opens it. even the pressure of the valve on the head can stop it from running, a drop of oil on the valve helps it to seal without needing much pressure.
If you adjust the valve away from the head you should be able to spin the motor 6 revolutions by a flick of the flywheel, if you cant it is too tight and probably will not run
To start mine I put 3 drops of oil into the bore, with the bore standing vertical and turn it over a couple of times and then 1 drop of oil on the valve. the oiler on the back of the cylinder will only work while it is running as it need vacuum to suck the oil along the length of the piston.
if you are using bearings on the crank clean them with petrol, grease will slow it down too much to run.
good luck.
 

Brian Hutchings

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I have built 2 of these at the small size but use cigarette lighter gas lead up through a small pipe to get close to the hole in the cylinder. I did this to try to avoid too much soot forming.
 

coulsea

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Any luck with getting it to run yet.
I would like to build one of these, I have built 6 at the normal size for family and friends, one of those friends does casting so would you make your 3D printer files available. you could post them in the download section to be available to all.
 

vederstein

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In attempts to get a running engine:

I disassembled the engine with only the flywheels/crankshaft attached. The thing would spin seemingly forever, so that wasn't the cause of the friction. The small and big ends of the connecting rod were quite free, so I doubt that was the issue. There was just a small amount of drag between the piston and the cylinder wall, so I lapped the bore just a hair bigger.

After reassembling, the engine spun as per Coulsea's recommendation.

I adjusted the valve and noticed the piston/cylinder clearance was letting a bit of air out, so it was still sealing, but not as well as the tighter fit piston.

The net result is that I still couldn't get the engine to run, and I think I ruined the piston/cylinder fit in the process.

So, this project goes up on the Shelf of Shame.

(This is disappointing and that shelf is getting too crowded.) :(

...Ved.
 
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