# A "Poppin" for Christmas



## JLeatherman (Nov 12, 2012)

Seems to be a popular theme, judging by some old threads, but I'm thinking of diving into my first engine project.  I never finish anything if I don't set a deadline, so here's the deal.  I want to make my Dad a model engine for Christmas.

This is my first post, so for a bit of background I am familiar with old engines having restored several hit-n-miss, and I am a hobby machinist.  My uncle gave me a half-finished Little Brother kit that my grandfather started and then passed away, but I don't feel up to that challenge just yet and I don't want to mess up any irreplaceable castings.  So I want to make something bar-stock based.  Christmas is coming and I figure I owe my Dad something for all the free lessons I got as a kid on building things.

Also, I recently sold my South Bend 10L (Heavy 10) lathe and made room for a 14"x40" CNC.  I need a project to cut my teeth on conversational CNC with (MachIII) without too much pressure, so this seems like a good idea (for now anyway).  I've got about 6 weeks, although the last few will be pretty cold in my unheated shop, so I'd better get started.

The "Poppin" plans look pretty nice, although they're old and a bit tricky to read/grasp at first glance.  I was also considering the 4-in-1 from J.E. Howell or the plans from Jans Ridders.  Can anyone comment on these, and which one I might be better off tackling on a somewhat abbreviated timeframe?  I really liked the simplicity of the engine from Jan Ridders, particularly the valve arrangement with no spring or cam.  How thorough and understandable are the plans, and are they tricky to convert to SAE units (perhaps they are dual-dimensioned)?

I am also planning on making two at once, so I can keep one for myself or so I'll have an extra of all the parts in case I mess something up late in the build.


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## lensman57 (Nov 12, 2012)

Hi,

I would say that Jan Ridder's plans are very well drawn and thought out and quite easy to follow. The screws are metric but you shold have no problem using the equivalent or close unc stuff, the rest are easily converted to imperial.

Regards,

A.G


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## Herbiev (Nov 12, 2012)

Hi Jleatherman. Welcome to the forum and good luck with whichever engine you decide on


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## JLeatherman (Nov 12, 2012)

I contacted Jan for a copy of his plans to review, and unfortunately his computer has been hacked and he says it will be 1-2 weeks before he'll be able to send me plans.  That would put me thoroughly behind schedule and I would have to pick one of the other engines.  Would another member be able to send me a copy of the plans?  Please PM me and I can provide you my eMail.

Also, just kicking around ideas, I really like Jan's valve arrangement, but I prefer the more traditional appearance of the "poppin" engine.  2 flywheels and a one-piece crankcase.  Has anyone ever considered modifying the poppin plans to run Jan's valve arrangement?  It would save most of the headaches of the popping that I can see, namely the extremely small pieces in the valve train?  Just a thought, Jan's valve might not work at the smaller scale of the poppin.


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## IronHorse (Nov 12, 2012)

The Poppin is such a good design. I built mine a few years ago and I run it weekly. It is so nice to just light the wick, and off it goes. Originally I built mine with an aluminum piston in an aluminum cylinder. It ran OK, but needed a pre-warm on the cylinder. Recently I remade the piston in graphite and the improment is amazing. It will start cold and reves at 1000 to 1200 RPM if I let it. Usually I pull the flame back to run it aroung 500 RPM.


IronHorse


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## lensman57 (Nov 13, 2012)

IronHorse said:


> The Poppin is such a good design. I built mine a few years ago and I run it weekly. It is so nice to just light the wick, and off it goes. Originally I built mine with an aluminum piston in an aluminum cylinder. It ran OK, but needed a pre-warm on the cylinder. Recently I remade the piston in graphite and the improment is amazing. It will start cold and reves at 1000 to 1200 RPM if I let it. Usually I pull the flame back to run it aroung 500 RPM.
> 
> 
> Hi IronHorse,
> ...


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## rleete (Nov 13, 2012)

Leatherman, PM sent.


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## JLeatherman (Nov 13, 2012)

OK, so based on my materials/tools on hand and my timeframe I'm going with the Poppin build.  Many thanks to rleete for a copy of Jans' flame-licker plans, I do still intend to build one of those.  I got a small start today.  I had to make atleast a few chips for this to qualify as "under way".  I started by tramming my mill and squaring the vise.







Then I hunted around the scrap pile til I found some suitable material.  I needed some 1" x 2" aluminum bar, but all I found was some 2" x 2" so I milled it down.  Gave me a good chance to prove that I had set the mill up close to square.

















And that's about as far as I got.  I only had an hour and a half to spend in the shop, so I'm glad I can at least say I have officially started.  As a side note, 2 1/8" brass (for the flywheels) is prohibitively expensive for this project.  I do however have some 2 1/2" steel round stock.  I would think that it is a suitable replacement for flywheel material?  I just wonder if it would start rusting too soon.  If I can believe my notes it is "1144".






And just for some amusement, this is why I'm doing this:






My grandfather made this engine, along with quite a few others.  I received this one when he passed away (I didn't let it get this dirty, it's how I received it and how I've left it).  Unfortunately by the time I was old enough to visit his shop he was too old to do much anymore, but it's still a family tradition of a sort.  A little crude compared to many of the engines built on this site, but I've seen the tools he had to work with and I know he had no real training as a machinist.


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## AussieJimG (Nov 15, 2012)

Here's to one lucky Dad. If this doesn't make him mist up I will be very surprised. Gifts like this are literally priceless.

Jim

PS Just make sure it comes back to you in the fullness of time.


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## IronHorse (Nov 15, 2012)

AG.......I was lucky and scored some hi-grade graphite rod (1.125") from a friend of mine who has a EDM shop. He said it cost $100 a foot! but I think you can use a lower grade. I remember looking a few years ago on the net and I could buy standard grade for about $15 a foot


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## lensman57 (Nov 16, 2012)

Hi IronHorse,

Thanks for the info, the only stuff that I can get at moment are some graphite rods that are used for stirring liquid metal in jewllery making or some graphite impregnared PTFE, 15% I believe. I dont know if these are at all suitable.

Regards,


A.G


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## JLeatherman (Nov 16, 2012)

I assume you're talking about the graphite rods available on Amazon?  I hope they are suitable, because I ordered a .625" diameter rod from them for this project.  It should be delivered any day now, and I'll see if it is machinable and smooth/strong enough to hold up as a piston.


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## starnovice (Nov 16, 2012)

Hey leatherman,

One thing I have learned in this hobby is there are some people whose only interest is in getting the engine to run and that tickles them pink.  Others like to spend a lot of time doing bling and making it pretty (in addition to making it run).  I suspect your grandfather was the first type and found "making them pretty" to be boring when he had so many more engines to build.  There is nothing wrong with that.  There is a museum not far from here with many many engines built by one man and he never spent time doing bling or making them pretty.  Instead he gave us maybe a hundred examples of different types of engines to enjoy.

Good luck with your build.

Pat


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## Cogsy (Nov 16, 2012)

I've used the stirring rod graphite in my flamelicker and it machined well, is very smooth and holds threads even when quite a bit more than operating force is put on them. I haven't used any other grades so I don't know how they compare, but these ones worked for me.


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## JLeatherman (Nov 22, 2012)

Gotta love holiday weekends.  I made a ton of progress today on the Poppin.  Last weekend I started work on the "standards".  Unfortunately part way through I discovered I don't have all the reamers I need.  I got the outline of both roughed out (one at each end of the same bar of aluminum).






I didn't want to disturb the mill setup so I started in on the lathe parts.  First up is the cylinders.  My initial thought was to make them at the same time, but when I tried parting them off I didn't support the end and they caught and bent :wall:.  Enter Plan B.  I picked up a dozen or more 7075 aluminum drops around a shop I used to work at (among many other scraps of useful material).  I chucked them up and turned a smooth spud to grasp them by on one end.






Then I flipped them around and turned the other end to 1" for the cylinders.






I had to grind a tool for the .050" wide grooves, and then I machined the grooves in both cylinders.











Then they were bored to 9/16" while still attached to the spud, parted off, and finish bored to .630".











They're bored to .630" because the "5/8" graphite rod I bought turned out to be 16mm (.629") and since the surface is quite smooth already I decided to bore the cylinders to fit the graphite and not machine the OD of the graphite at all.  I made a little test piston and it works quite well.  With my thumb over one end of the cylinder it takes it nearly a full minute to descend.


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## JLeatherman (Nov 22, 2012)

I planned to make the flywheels out of a piece of 1144 steel I had, because brass is prohibitively expensive.  Unfortunately the 1144 proved to be way too difficult to work with.  I couldn't even get it cut into sections with my portaband.

Fortunately I came across a piece of 2.5" x 1/2" brass bar in my scrap pile.  I cut it into 2.5" x 2.5" squares and chucked them up in the 4-jaw to bore a 1/4" hole in the middle.






Then I made a little arbor to bolt the squares to and turn them round.
















Once I had blanks I turned the offset into each side and reamed them to 5/16".  Not a bad day's work.


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## AussieJimG (Nov 23, 2012)

Right on track for Xmas by the looks of it. Great job.

Jim


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## JLeatherman (Nov 25, 2012)

All I managed to get done the rest of the weekend was the flywheel hubs.  I cut some slugs of random 1/2" brass rod I had laying around.  It was too hard to be 360 but it didn't machine too badly.






Then I turned the profile of each and bored/reamed it.  Note that I turned a .005" relief for the area that will be threaded as well.






And here they are threaded, de-burred, and chamfered.






I'll tap them for the setscrew once my mill is open again.


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## gabby (Nov 26, 2012)

Yup I think I will follow this build through 'coz I have started on the barrels for the poppin then I decided to pull my mill to bits and add a spacer to the column so I can mill bigger bits and do the usual maintainence things, so I should be back on track in about 2 weeks, God willing
cheers
Gabby


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## JLeatherman (Nov 26, 2012)

Gabby, it's funny but to tackle this (and presumably future builds) I've had to buy things to make smaller parts.  Smaller end-mills, smaller reamers, collets to grip material under 1/4", etc.  All I've done til now is full size parts for my motorcycles and gas engines and such.


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## JLeatherman (Nov 29, 2012)

Since I'm trying to work out a surface-finish issue with my lathe, and my reamers and other bits came in, I got back to work on the "standard".  I was making two, but after forgetting to add half the diameter of my edge-finder to the location of the crank-bearing-bore I ruined one :wall:.

Christmas is getting close, and I don't need mine to run by then, so I just forged ahead with the other standard good thing I was working on two).  Here it is, complete except for the radius around the cylinder mount and the counterbore for the valve rod.

The only issue, which you can't see, is a .046" drill bit is currently broken off in one of the crank bearing clamp holes .  It's a Ti-coated HSS bit, so I'm going to take a shot at the "Alum" trick this evening.  Wish me luck


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## AussieJimG (Nov 29, 2012)

You have to make one more standard, would it be quicker to make two more than to remove the drill?

Jim


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## JLeatherman (Nov 29, 2012)

If I have to re-make it I'll make 2, but I'm hoping that I can dissolve the bit with the Alum trick which doesn't really require any great time or effort on my part.  Of course I'd like to make another one, I'm not entirely happy with this one, but I don't have any more 1x2 aluminum and it would take me a lot of time to start totally from scratch.


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## AussieJimG (Nov 30, 2012)

Sounds like a couple of good reasons to me. And Dad is not going to be too picky when he unwraps it on xmas day.

Jim


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## JLeatherman (Dec 9, 2012)

Oh man, Christmas is coming up fast and I still have so much to do (in addition to a few woodworking projects for my wife and others).  Fortunately it turns out I won't see my Dad until the 29th, so that gives me a few extra days breathing room.  Anyway, I spent all last week in Texas, so I didn't get to work on it until this weekend.  The alum trick failed (guess Harbor Freight bits aren't made of steel  ) so the first order of business was a new standard.  Actually it took 6 more to get it right.  I screwed them up for a variety of reasons; math errors, an accidental climb milling incident, etc.  I was rushing, so I took a breath and tried really hard on the last 2 and got them.  I also got a little smart and finally machined up some brackets for the DRO that had been sitting on a shelf for at least a year, which really helped get everything right.






I had to make it out of 2" x 2" aluminum this time, having run out of the 2" x 1.5" I was using before.  Made quite a mess.





















Thoroughly sick of working on a second standard I took a break after the hardest parts were done and turned to the crankshafts.  I also spent some time making a collet-closer for my lathe so I could turn the tiny shafts for the cranks.

Here they are glued up with Loctite 680 and drying inside the house (where it's warm):






I assume for a little engine like this I shouldnt need to pin the crank, right?  After my previous luck with tiny drill bits in aluminum I'm leery to try drilling this stainless.  Both the shafts and the throws are 303, which is pretty soft as far as stainless goes, but still.  Maybe I'll get brave sometime in the next couple days and try it anyway.


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## Todd... (Dec 10, 2012)

with the small diameter drill bits did you try running them at a high rpm? the smaller the bit the faster they need to turn in order to work correctly and not break on you


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## JLeatherman (Dec 10, 2012)

Yeah, I was running them pretty fast.  1800 rpms I think, but I'd have to double check what speed my bridgeport is capable of in 3rd high.  I didn't have any trouble with the first hole.  I think I may have gotten a piece of aluminum stuck to the end of the bit.  I cleaned the chips off, but the second hole just didn't seem to drill as easy as the first, and then I heard the crunch


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## AussieJimG (Dec 10, 2012)

Making 6 to get 2 strikes a resonant chord. I am trying to make 3 heads for a Tiny IC engine and have an impressive (well, I am not impressed) collection of sinkers for when I give up and go fishing. But I am pleased to know that you are making progress. Dad will be pleased.

Jim


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## ninefinger (Dec 10, 2012)

Yeah - making practice parts is very familiar territory for me too.. lots of those frames in the scrap aluminum drawer too.   Also - drilling small holes in stainless is really hard due to the stainless work hardening if you pause just a moment.  Lots of broken drills so I gave up pinning the joints.  I ended up remaking my crankshaft without pins (needed to start over due to craters left behind from drilling attempts) and its holding up quite well to abuse. 

Mike


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## JLeatherman (Dec 17, 2012)

The time is flying by! Between Christmas parties, decorating/cleaning the house, and working on my wife's present it seems like I never get to the shop. Last night after the kids' pageant at church I snuck out for a couple hours of work.

I machined a blank for the connecting rod big-ends. I turned two ends of a piece of 1/2" brass rod to .160" and bored the hole for the rod. Then I flycut two sides until the whole thing was 3/16" thick. now I can cut off the little pieces of the connecting rods and make the big pieces from what's left and they'll match up (I hope).

I also went ahead and pinned the cranks. I'm a worrier, and I knew if I didn't I'd always be waiting for the loctite joint to fail. If it was just for me that'd be fine, but this is a present and it's gotta stay together. Went quite smoothly actually. I bought some small (.059") stainless brad nails at the hardware store, and I drilled all 4 joints for a slip fit and used 680 loctite to glue the pins in.  Once it's dry I'll nip off the ends of the pins and then take a few thou flycut off both sides of the cranks to make the pins disappear.

So much to do still, though


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## AussieJimG (Dec 17, 2012)

C'mon Leatherman, you can do it!! Just be VERY careful making interrupted cuts on those crankshafts (how do I know?).

Jim


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## JLeatherman (Dec 17, 2012)

Woohoo, two nights in a row I manage to get in a little shop time.  I flycut the sides of the cranks to smooth out the pins, and then finally cut out the middle of the crank with a small endmill.  I also made some good progress on my pair of connecting rod ends, shown below the cranks.


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## JLeatherman (Dec 27, 2012)

Well, I'm still plugging away on this.  As I mentioned, I won't see my Dad until Saturday so there's still a chance.  Things haven't gone quite according to plan, and I've left a lot of the 'fiddly' stuff until now, so progress is slow.  I have gotten a lot of good work in the past few days.  I finished the flywheels with the holes/chamfers, tapped the hubs for setscrews, made the connecting rod (a bit different since I'm using a graphite piston), tapped both ends of the cylinder, made the head, and cleaned/polished some of the finished parts.  I've still got most of the valve-train to make, and tomorrow is basically my last real day to work on this, so we'll see what happens.


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## gabby (Dec 29, 2012)

Hi ya J L,
              I have just got back from a short break and have discovered you have really got on with the build, did you make your presenting time? now i have the "poppin" bug and have started to build a couple just because they look and sound great, i have managed to make the barrels and pistons so far, mine are all brass as that is what i had on hand so now i just have to keep the focus on getting the rest of the parts up also my standard will be steel as once again that is what i have on hand.
So i hope you got yours done on time,
as for me, I hate time constrictions like your build ha ha.
cheers
Gabby


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## JLeatherman (Dec 30, 2012)

I did present it to my Dad, but unfortunately it wasn't yet a runner.  I got the whole engine finished, but I didn't have time to make a burner or get it mounted to a base yet.  I tried running it with a BIC lighter but it wasn't happening.  Here's the engine as it sits now:











It makes a decent 'pop' when you spin it over but it wasn't really even trying with the lighter.  I suspect that even once I finish a burner it will need some fiddling.  The current valve is .003" steel, the .002" I used for the first one warped with I tried running it.  There were a lot of surprising little headaches at the end.  Threading the 1/16" rod to #0-80 was tough, and so was the cam (surprisingly).  I ended up making the cam out of aluminum because it was easier to shape the profile on, and I made a ball-bearing follower instead of the steel roller in the plans.

The whole engine turns very very easily.  Easily enough that the crank will always fall back to the rod end when it stops.  I got it "running" with a straw jammed into the head and blowing into it in time, so I think I can make it run the "right" way eventually.

The saga continues!


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## AussieJimG (Dec 30, 2012)

See, I knew you could do it! The Poppin looks superb. What was Dad's reaction?

Happy New Year (tomorrow)

Jim


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## gabby (Dec 30, 2012)

Wow I hope your dad can see past the "not running yet" thing 'coz that looks cool and I guess by now it is a runner.
Cheers
Gabby
(dunno about the counter sunk screws on the head though)


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## JLeatherman (Dec 31, 2012)

Haha, I knew someone would notice the screws.  The hardware store ran out of #2-56 x 1/4" panhead screws so I put those on just to get it together.  I'm replacing them before it goes back to him.

Nope, not a runner yet.  I'm working on a nice wooden base and a burner before I try tweaking it enough to run.


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## gabby (Jan 1, 2013)

Hi ya J L, Sorry for pointing out the obvious, good idea to make the burner for the engine then it would have the right volume of heat (more than a bic lighter) and with luck you may not have to tweak much at all.
Happy new year
Gabby & family


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## JLeatherman (Jan 28, 2013)

Well, sadly I have to report that at this time the Poppin still does not run.  It does spin longer with a flame than when simply spun by hand, so I can assume that it is sort of trying to run, but alas no sustained running.  I have two things I need to try.  I'm going to make a small riser for the engine so I can get the flame closer without hitting the valve rod.  This is actually called out in the plans, but I didn't have the time or see the necessity before this.  I am also going to re-make the valve again and polish the cylinder head more finely and make sure I'm getting a good seal there.  I know I'm getting a fairly good seal because if I spin the engine backwards, such that the valve shuts when the pistons is approximately half way down the cylinder, the engine stops turning in less than 1 revolution due to the suction.  I thought this was enough to make it run, but apparently not.

On the issue of timing, I have tried many possibilities but am always open to suggestions.  I notice that if I advance the timing too far the engine will stop itself much faster even when turned by hand, from the suction against the closed valve before piston reached BDC.  The engine does not even attempt to run at this setting.  If the timing is retarded too far, such that the valve doesn't close until nearly the bottom of the stroke and then remains closed for 75% of the return of the piston, the engine spins very freely by hand but makes a strange wheezing noise from the piston pushing air past the valve.  I assumed this was too far retarded, and adjusted the timing to a sort of sweet spot that offered the most revolutions when spun by hand before the wheezing occurred.

At the moment I'm running my burner on white gas (Coleman fuel) which is blackening the cylinder had a bit but has not caused any residue inside the engine.  I'll dump it out and change to pure alcohol as soon as I find some.


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## gabby (Jan 29, 2013)

still here JL still here


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## AussieJimG (Jan 29, 2013)

Don't give up JLeatherman, I can't offer technical advice but I am sure that if you persist, it will run. Others have got their engines to run and so will you. 

If all else fails, ask for advice on Model Engine Maker and hope that Bogstandard will reply.

Jim


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## ninefinger (Jan 31, 2013)

JLeatherman said:


> At the moment I'm running my burner on white gas (Coleman fuel) which is blackening the cylinder had a bit but has not caused any residue inside the engine.  I'll dump it out and change to pure alcohol as soon as I find some.



The fuel and flame can make the difference.  Ask me how I know!  I originally tried some 70% isopropyl alcohol that I had and my poppin wouldn't quite run - almost but not quite. I put a BIG (comparatively speaking) flame on it from a propane torch (turned all the way to almost off) and it started running very happily so I sourced some 99% technical grade alcohol and now it runs very nicely.

Keep it up - it will run someday soon.

Mike


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## JLeatherman (Feb 1, 2013)

Mike, I tried a propane flame once from my mini soldering torch.  It immediately warped the .002" valve.  I'll try a different fuel once I get the head cleaned back up and the engine on a riser.  Hopefully I'll have some time this weekend to play around with it.


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## gabby (Feb 8, 2013)

just a small observation, is the bearing that runs on the cam much bigger in diameter than the roller on the drawing ? that may have some "bearing" on the no run problem as the cam should be altered to compensate for the extra wide opening and closing, what I am trying to say is, with the cam as per the drawing and you time it from the opening point, then the closing point would be delayed and if it was timed from the closing point then the opening point would be advanced.
have you tried a bearing of the same size as the drawing roller ?.
just a thought.
Cheers


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## bob shutt (Feb 10, 2013)

Hi J
First off nice looking engine. What I ran into on mine was the seal from the shim stock. I made a steel disc .325 dia by .040 thick with a .060 stem. I drilled the shim stock and peened over the stem. the suction will hold it over the opening better. Another deisign is to make another plate and space it out over the head the thickness on the shim stock. Try the disc and if that does not work I can give you more information on the plate. I also use Gas line Antifreeze (Methyl alcohol) for fuel with a PM research burner.
Bob


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## JLeatherman (Feb 11, 2013)

Bob, that's a great idea.  I'm working on a spacer for the engine so I can get the burner closer, and I've picked up some 99.8% pure isopropanol.  Next step, failing that, is a new valve arrangement.

Up next "A poppin for valentines day"


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## GT53 (Feb 11, 2013)

Hi, looks like a very well made engine and I'm sure you will get it running with a little
experimentation. I also had problems getting mine going but finally ended up where it
will run until the fuel runs out. 

Here are a few additional ideas which may help you.

I found the cam timing needed to be quite precise, 5 degrees either side of the sweet
spot and the engine would not run. Start at the recommneded timing and then move
5 deg at a time until you find the best spot. 

My engine takes a couple of minutes to warm up before it will run. Until then, the hot
air drawn in on the down stroke is cooled too much by the cylinder and head before
the valve closes. I used cast iron for the piston and cylinder and steel for the head,
wonder if your aluminium construction is conducting even more heat away.

The cooling of the hot air in the cylinder once the valve closes will result in the
cylinder pressure being less than atmospheric. This will remain lower for most of the
piston travel towards TDC and consequently the valve will remain tight against the
cylinder head. Close to TDC the pressure will equalize and the final travel of the 
piston will cause the pressure to be above atmospheric and the valve to 'pop' away
from the head. The lower the initial temperature of the trapped air in the cylinder the
earlier the valve will pop away from the head on the up stroke. You noted that air
wheezed from the valve on the upstroke when you retarded the timing. It may well
be that the timing was OK but the air trapped in the cylinder was not initially hot
enough to keep the valve closed during the up stroke.  

I eventually settled on a 0.004" valve blade cut from a feeler gauge. I found a 0.002"
valve warped very quickly. An 0.003" valve warped in use but returned to flat when
cooled. Although a 0.006" valve worked fine for a while it eventually fractured. Even
now the valve is not perfectly flat but the low pressure in the cylinder is enough for
the blade to flex and seal tight. 

I use ethanol for the fuel with a Zippo wick. The wick is teased open into a large
head to produce a large, wide flame. The top of the flame reaches just past the top
of the valve so that on the downstroke, the tip of the flame is drawn in over the top 
of the valve and into the cylinder.


I'm sure you are very close. Keep at it and you will get there. I will keep watching 
this post for the good news. 

Gordon.


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## JLeatherman (Feb 18, 2013)

Just a quick update.  Here's a shot of the engine, burner, and base (unfinished):






Still not running.  The burner is filled with 99.8% Isopropanol now, still nothing.  I'll spend a few more nights playing with the timing before I tear it apart for cleaning and make a new valve.


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## JLeatherman (Mar 17, 2013)

It runs!!!!  Sorry, no video (stupid dog chewed the "record" button off the camera) but I assure you it runs beautifully.  I promise to get a fideo up once I've finished the base and made the cap for the burner and loctited all the screws in place.

What was wrong, you ask?  Piston-to-cylinder fitment.  I made the mistake of assuming the round/smooth graphite rod I purchased was actually round.  I made the cylinder until it was a good fit to the rod as-shipped and called it a day.  Turns out the rod was .0010"-.0015" out of round.  I pulled apart my engine and found three or four contact points on the piston, and I noticed you could see daylight around it at places.  Unfortunately I needed to make a new cylinder too, once I turned the material round.  I made the cylinder from steel this time, just to increase my chances that I was going to have a runner.  I think an aluminum cylinder would still work fine with the graphite piston if the fitment was done properly.  My new graphite piston/steel cylinder has a little drag when cold, but fire off after just a few seconds of warmup.  This is still the same head, valve, and timing I had before.

I'm just glad I can now move onto a Farm Boy engine with a clear conscience


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## rleete (Mar 18, 2013)

Congratulations!


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## chucketn (Mar 18, 2013)

Congrats JLeatherman! I'm rebuilding my Poppin that I couldn't get running now. I hope I'm as sucessfull!

Chuck


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## JLeatherman (Mar 18, 2013)

Ok, I coaxed my phone to take a video.  The sound is a bit off and stops partway through, but I have proof that it runs.  This was a room-temp startup.  One flick was all it took.  Initially the piston was snug, but I've run it for probably 5 or 10 minutes total now and it's limbered up and even cold it turns smoothly now.  A much better video will be posted in the finished section, once I've lacquered the base and made the plug for the burner and such.

But, it runs!

http://www.youtube.com/watch?feature=player_detailpage&v=taq6-_tfe1M

PS I couldn't embed this video using either Photobucket or YouTube.  Hence the link.  Could someone tell me how to embed this?


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