Poppin 150 Build

Discussion in 'A Work In Progress' started by vederstein, Aug 18, 2019.

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  1. Aug 18, 2019 #1

    vederstein

    vederstein

    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.
     
  2. Aug 18, 2019 #2

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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....
     
  3. Aug 18, 2019 #3

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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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  4. Aug 18, 2019 #4

    deeferdog

    deeferdog

    deeferdog

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    So do I. Looks good to me.
     
  5. Aug 18, 2019 #5

    johnmcc69

    johnmcc69

    johnmcc69

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    Cool stuff Ved!

    John
     
  6. Aug 25, 2019 #6

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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...
     
  7. Aug 25, 2019 #7

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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.
     
  8. Aug 26, 2019 #8

    Mark Duquette

    Mark Duquette

    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.
     
  9. Aug 26, 2019 #9

    Brian Rupnow

    Brian Rupnow

    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.
     
  10. Aug 27, 2019 #10

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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.
     
  11. Sep 2, 2019 #11

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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.
     
  12. Sep 22, 2019 #12

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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.
     
  13. Sep 24, 2019 #13

    johnmcc69

    johnmcc69

    johnmcc69

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    Looking good!

    John
     
  14. Oct 13, 2019 at 6:23 PM #14

    vederstein

    vederstein

    vederstein

    Must do dumb things....

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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.
     

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