Another Poppin project.

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Oct 13, 2014
Reaction score
Hi Folks,

It's been a while since I've been at it with machines and building things.

I recently made the decision to shift my hobbies to one main one and that has become engine building, along with other small stuff that I can do in the house with the mini lathe, mill and some other shop machinery and tools, some of which I've had for years, and others I've just gotten or rebuilt.

I always wanted to build an engine like Poppin, as I saw my first one at a steam show in around the early or mid eighties.
Life can be busy and fly by in a hurry, and the next thing you know is that you've become older and never did some of the things you always wanted to do.

So..., Here we go.

I started by getting my "shop" ready and sacrificed a small bedroom for now until I can build a room that's more suited to this kind of work.

I started with the cylinder as I read the original author's build log and figured if he thought that was a good place to start, who am I to argue? So did the same thing.

Pictures will show up, but I am not convinced that I know all about "how to do that here".

The first cylinder (picture) is now a memento and example of my eager but lacking skills, so another was carved out and also was not quite right but will work (I think).

Personal touches are allowed and so I plugged on and made it seem like I know what I'm doing :wall:


The fins on the cylinder showing are not as in the plans because I do not have a thin enough parting tool, and the tool I bought to replace the fat one ended up being the same thickness as the old one.
Fine.., use what you have and make it work.

Cooling is not an issue from what I can tell so I will experiment.

Next comes the standard for the engine and after laying it out I then drilled the necessary holes and removed a broken drill end and the bulk of the material to be machined out.
I thought it was going to be a quick build but for some reason the brain can't seem to access the knowledge I once had! Procedures can be a pain when you know little.

After some time, and breaking that one drill off in the hole for the crank bearing cap, I managed to extract (I machined around it) the broken end of it from the standard and merrily carried on like the proverbial bull in the china shop, but am happy as a lark! (And more careful.)

A few of the holes are not quite as they should be, but then the government isn't what they say they are either, and if they can get away with it, most likely I can too :eek:


After a few weeks I progressed enough with both the standard and the cylinder to carry on with courage and made the cylinder head, and it fits!

The piston is next while at the same time I will either turn up two flywheels or work on the crank shaft and its related parts.

I needed to see the few parts (roughed out and not finished) together, so I fitted things so it looks more like what it is supposed to when finished, and I must say I am happy to report that it actually doesn't look as bad as I thought it would be, and have hope that I will not be thrown to the dogs by some of you, who comparatively speaking, are the Kings of machining excellence.
No magazine will ever do an article on my exquisite layman's masterpieces!

This is what I have done so far, and with a bit of luck and less snow up here, I could probably finish this by spring, as I am seldom home long enough to lay hands on my machines for too long.:(


Anyway, the last thing I got to do was mock up the pieces to see what I have wrought, and I am unashamedly letting you see itwoohoo1


Thanks for watching, J.
What fin spacing and fin width did you end up with? I prefer the look of yours to the original drawings.
Cheers Garry

The fins are spaced at approximately the width of the parting tool, from 0.90"- 0.94", and the width of the fins are approximately 0.32"- 0.35".

Reason for that is of course that the parting tool does not allow for the sizes as planned, so I eyeballed the whole fin thing, not without some trouble, to make it fit.

If you want to mount the oiler on the base ring, you'll need to steal some thickness from the head ring and shift that to the base ring in order to have enough meat to drill and tap the hole for that.
Another way would be to make the cylinder a tad longer (I'd say between 0.30" - 0.40" and adjust the conrod length accordingly.
Or you can plan a spot on the cylinder wall itself between the fins at the base, that will increase the amount of work and tedious placing between the fins, but could possibly look better.

There should be enough thickness in the wall wall to drill and tap for that.
To use that method, you might want to sit and consider placement for a minute (closer to the bottom I suppose) to mitigate possible heavy oiling due to suction, Don't know that one yet either.

I will try to install mine on the mounting flange on the standard proper if that can be done, but I think that the piston may not travel sufficiently far enough to be useful.
Haven't calculated that yet.

If I can't, I will machine and harden a steel piston which should allow running with out oil, an Aluminum or Aluminium (for you Southern Roo hunters with all the good weather ;D) piston would gum up the cylinder IMHO.

If all else fails, I will machine up a proper (but nicer looking) cylinder according to plan sizes after I buy a new parting blade.

Hope that does it for you Thx, J.
Thanks J.

I think you intended to type 0.032 - 0.035" and 0.090 - 0.094" - anyway I've redlined my drawing set. I'll probably eliminate a few fins at the case end for cosmetic reasons so placing an oiler shouldn't be to problematic.

A cylinder head looking like whatever you supported the cylinder with in the last photo would suit me!

Thanks for taking the time to answer. Good luck with the engine.

Cheers Garry
Thin fins with wide gaps gives better cooling than big fat fins with equal size spaceing. Look at any air-cooled motorcycle engine.
It's looking good.
Thanks J.

I think you intended to type 0.032 - 0.035" and 0.090 - 0.094" - anyway I've redlined my drawing set. I'll probably eliminate a few fins at the case end for cosmetic reasons so placing an oiler shouldn't be to problematic.

A cylinder head looking like whatever you supported the cylinder with in the last photo would suit me!

Thanks for taking the time to answer. Good luck with the engine.

Cheers Garry
I thought I'd already written a small "Duh!" note once, on account of the spacing sizes, but do not see it.

Well..., Duh! and thank you for pointing out the error Garry, you are right of course and I apologize if I may have sounded foolish with the original answer to your correction below here, thx, J.
Spaced at 0.90-0.94 and thickness at 0.32-0.35 is what I meant.

The other cylinder head was for an attempt to turn a diesel RC engine into an IC engine of my own design, after which some of the engine parts were lost in the shuffle of moving and I lost interest.
Now that I'm at it again, I'm making new ones for a twin IC idea that's floating around in my head.

Have fun, J.
Thin fins with wide gaps gives better cooling than big fat fins with equal size spaceing. Look at any air-cooled motorcycle engine.
It's looking good.

Howdy Hopper,

Funny you should mention "motorcycle", that's all that seems to go around in my head when I deal with making this little cylinder for Poppin.

I agree with the cooling being better with more airflow and wider spaces.
The fins should have been "thinned at the end, or tapered if you will for looks.
I had to force myself to stick with as close to design part making as I'm capable of as I often go off on a tangent and double my work re-doing stuff.

Poppin should be as close to the plans as I can manage without changing things too much.

Cheers, J.

Haven't done much as I was on another trip to NC and DC.

Got home last night and fell into bed.

Anyway, I did do some stuff today and turned up the start of what I think is a better looking set of crank flanges..
It'll be a counter weighted look, but there really isn't anything much to counter for lol.
I will play with that until I get it figured out and make it work.
I'll have to balance the web with weight forward so all I will have done is add some meat for the piston to push but the balance will be right and you'll see what I mean when it gets finished.
Think of it as a bit bigger flywheel by weight but not much.

So much for keeping with the plans!

I always liked the looks of open flywheels, but the one on Poppin looks dull and dreary (no offence meant) so I'm dressing it up and hope that my thinking doesn't backfire on me.
I can always make a new set the right way if it all tumbles down.

Here's a few pics,


Well.., couldn't sleep,

So off to the races and did some more on the crank parts, this will give an idea as to what I meant by doing it slightly different from the plans.

I may run into mass problems where the engine may not pull the weight, but I am a Dutchman, so I'll die trying.

Cheers, J.

Its nice to be home,

Having a blast with the machines and chips are flying.
I wish I could be having this much fun all the time, but work interferes a lot.

I did some more work, and whittled out two flywheels basically to stock size but just a tad lighter, instead of the OD being 2-1/4" (didn't have 2-1/4" here anyhow) I used 2" round and that will take a tiny bit of weight off the whole as the crank webs are heavier than they should be.

I will also mill two or three radiused slots in the wheel webs instead of holes to help lighten the assembly, and it may even look better or at least different from the original.

I have a balancer for RC aircraft props that I will use to balance the whole assembly for static balance once all the pieces are made.

Here are some pics of the mockup with the parts I have so far.

Hmmm, looks like one picture didn't come out too well.

I also wonder how to insert the pics into the script as you write, it would be much better and more appropriate as a part gets discussed, but I haven't found out how to do that yet.
Does it maybe have to do with using attachments versus URL's?
I don't really care for the lot of them at the bottom.

Cheers, J.

flywheels finished.jpg

Hi folks,

I was able to get my RT mounted and a centering mandrill made to hold the two flywheels one on top of each other.
Once I had figured out what I wanted to do and could finally mount them, I laid out the two slots I wanted to cut and set up two starting points and cut slots 120 degrees long.

I really wanted to make the slots curve out from the center to the outer diameter, but the amount of time and work involved to figure out and make the jigs for that left me to cut them the way I did.

That went off with out a hitch and the wheels are now finished other than cosmetics.

I am really enjoying my new hobby as things seem so easy to get at, versus having to be outside freezing off the proverbial nuts to get anything done in Winter.
I am seriously thinking of selling all other projects off as I am losing more interest by the minute.

Anyway..., I may still go again and cut some bearings or other small stuff, but it is getting tired out there and bed sounds good about now, it just depends whether I can sleep or not.
I received Phillip Duclos' book today so I could probably read that for a bit also.

Here is a picture of the two wheels cut and ready for polishing, but the polishing will get done after all parts have been made, WHEN/IF the engine is actually running lol.:D

Thanks for watching. J.

slotted wheels.jpg
I also wonder how to insert the pics into the script as you write, it would be much better and more appropriate as a part gets discussed, but I haven't found out how to do that yet.
Does it maybe have to do with using attachments versus URL's?
I don't really care for the lot of them at the bottom.

Cheers, J.

See this post for an explanation on how to add pictures within the text. Good work so far on the Poppin.
Thank you Paul.., Weeze,

Compliments will only get you everywhere, I am a doubter and therefore a tinkerer (on top of being a Dutchman!) so eventually things will come to life, but probably after quite some hammering and bending!

I have never been a true "machinist" other than having run of the mill jobs in plants as a journeyman or maintenance machinist (which is just not the same as tool and die making and fine work,) so the "machinist" distinction truly gets a lot of respect from me.

I think that people who can put things into a plan, think three or more steps ahead and especially to make blueprints the RIGHT way, AND put it together according to those plans using their brain and skills, are special and gifted.
Not that I can't do these things, but I get a headache just thinking about doing all of that, when all I want to do is machine up what's in my head! :hDe:

Visualization is my forte, and I build accordingly.

Myself, I have many trials and errors to overcome all the time (makes it interesting though, it sure overworks the brain cell!) because I make so many mistakes that I have basically re-designed the project by the time it is done!:eek:

Since there is no pressure to do well other than ones own level of perfection, or to have it done yesterday, I can enjoy being what I always wanted to be.., a happy guy who loves working with machines to please himself and create things that may last a few generations to come.
If others should look at the end product and like it.., bonus!:D

I will go and check out the link Weeze, thank you for posting it,

Regards, J.
Ok, just off subject for a minute, I will now try picture placing within the conversation.

The first picture is a bottle engine I want to re-make to lay down like a factory driving engine.


I did it once before but forgot how to do that.

Pic number two is the same engine, different angle.


Thanks to Weeze, for directing me to the proper way of doing this.

I'm a happy camper, off to consume some beers!

Cheers, J.
Greetings my friends,

I wanted to deal with the out of balance issue on the crank shaft flanges but keep the look of the way I made them.

I went back and set up the RT again and mounted the flanges two high, just the same as I did before with the flywheels so I could machine the webs out in another curved pattern in keeping with the look of the flywheels.

It took a bit of thinking to find the right way to clamp, but I had no problem to bring the tool to the work otherwise.

Pic one is of the flanges in the (uncompleted) standard, pic 2 is the same deal, different angle


I thought that the way I machined the parts would bring a different look to the old design, and that is basically to satisfy my need to do things a little different so I can say "I personalized the work".

Also.., I do not care for the way the main shaft bearings are made, and in keeping with standard looks (and because of a misplaced bearing cap screw hole,) I want to use the proper separate bearing cap idea, which will allow me to hide my location mistake of the bearing cap screw hole, and should give a better overall look IMHO.:D

Not that the engine needs it at all, but I like to tinker.


What do you think?.., is this a pleasing look, or am I way out in left field?

Last pic, assembled in the standard, and I like the looks of it.


Please feel free to comment and don't hold back, If I can make it work I will keep the changes, as I personally like the looks of them.

I would like this little engine to look as mechanical and involved as I can come up with, and the "busier" it looks when it runs, or when it is stopped, the better it is IMHO.

So I hope my thoughts are acceptable and will give it the interesting look I mean to give it.

Cheers, J.

I had a few visitors today, and alcoholic beverages were consumed.

Not complaining and feeling great.
I keep some safety standards for myself so I did not do anything further with machining other than to tap some holes, and I messed around with socket head screws I had in a drawer left over from some previous project.

I didn't like the slot screws I bought so I tapped the head and base out to 3-48 and feel a lot better about that for strength and it is also easier to turn them into hex head screws by simply filling them with solder or even a dab of weld, if I want to blue them again I can do that with cold blue (only if filled with ferrous metal), and that will make them look as close as I can get to be like genuine hex head bolts.


All went well, and now that I am back to the world of sober reality, I have nothing further to do than to relax, read or chase women.

Reading it is, and the Philip Duclos book is a dandy one to read and learn from.

I did a second mock up, and that looks good as well.


I must say that I am delighted with the progress I have made, and look forward to work on the engine again in a week or so, as I have to scoot down to SW Colorado to drop a load there.

Just a last shot of the engine now, Thanks for watching,


Cheers, J.
Howdy folks,

I'm still here but haven't been able to do much on Poppin as I have been busy working and have had no time to do anything meaningful in a while.

When I got home this time I was beat and felt sick so I took a day to relax and regroup.

Today I got into playing with the lathes to see if I could true them up a little better as I didn't care for the Atlas's inaccuracy over the bed length, and the newer mini MIC lathe for the same reason but not half as bad as the Atlas.

The mini MIC came out surprisingly well after messing with it for a bit and the saddle is now within 0.0005 to 0.001 over the length it travels between centers (give or take.) but the travel on it is only 5 or six inches. The cross slide, and the compound are pretty close to 0.0005 but I am still not happy with the flex it gives and it flexes too easy.
I'll end up making a better mounting table for it (mobile, steel and on wheels.)
I like to be able to move it to where I like to do some of the small stuff, rather than have it all in a clutter in the same room. It is so small I can do that easily, I just need to build a better and more rigid base for it.

The Atlas is a different animal as it is from the early sixties and tired.
I bought some things to change the cross slide on that and also make (or buy) a decent qctp.
I priced one one like the mini MIC has, but the cost is typically outrageous, as the parts that make up the complete tool post are individually priced and just about add up to the price of a new Cadillac.
I'll probably make the same and a better copy of the one I have on the mini MIC or buy one if it's going to take too long.

The ways are fairly good (for the age of it) on the Atlas but the runout over the travel length is out more than 0.0015 over about 20 inches. and I am working (trying) to bring that back to a better tolerance as it is worn enough that when I move away from the spindle, it tightens up just enough to be irritating closer to the tail stock area. Basically I'm block sanding the good part of the bed down to try and match the worn section closer to the spindle, as I can adjust via the gib spacers. sofar so good.

If none of that works, my buddy who had a new and longer base cast and machined for him for his Atlas, will help me to get one done for mine as I definitely want to keep mine (22" travel), I had that forever and I don't like to lose it.

So.., with Christmas coming and probably getting a few days off, I may just get somewhere with Poppin and I'll be sure to post pics of any progress if there is any.

Cheers folks, Raising my glass to y'all, J.:D