First steam engine----Building a Wobbler

[Brian Rupnow]

Work is progressing on my "wobbler"---(somehow that sounds vaguely dirty!!) I am following a set of free plans that I downloaded off the internet. So far, so good. I did go up to Busy Bee this afternoon and spend a whole $15.00 for a 3/8" reamer to do the cylinder bore with. I just didn't trust my ability to bore it to a good enough finish to have it work right. I am glad that someone on the home machinists website told me about these free plans that could be built from bar stock. I saved $100 thru not having to purchase a "kit", but have now spent over $100.00 for tooling to build the darn thing!!!

 

[Brian Rupnow]

I am a design engineer, specializing in prototype machinery and factory automation. I bought a lathe 3 months ago, and am enjoying building this model steam engine. I haven't ran a lathe since my apprenticeship, 43 years ago. After I downloaded the plans, I converted them to 3D cad files to get a feel for the construction of the machine, then I added a virtual motor to the CAD model to see it run and understand the "wobble" of the cylinder. I am attaching both the 3D model, and a short vidio clip of the machine running.---

View attachment FULL ASSEMBLY.avi

 

[Tin Falcon]

Welcome to the world of model engine building.
tin

 

[Divided He ad]

Hello Brian,

Firstly, welcome to the fun

As I'm sure your aware, the good point about buying the tools instead of the kit is now you can make a lot more than just the kit! ;D By far the best choice.

Thank you for the running cad image, since I'm about to find and make my first steamer it will help to have that visual image of the cylinder/port layouts


Ralph.

 

[Brian Rupnow]

Divided Head---If you want I can hunt down the internet link that I downloaded the plans from and send you the link, or post it here.

 

[SignalFailure]

Divided Head---If you want I can hunt down the internet link that I downloaded the plans from and send you the link, or post it here.

Brian, I'm pretty sure almost everyone here knows the link for your Elmer's 'Wobbler'

For a first engine that's looking great so far! Reamers are expensive aren't they? I bought a job lot of odd sizes off e-Bay a year or so back (about 15 of them for around $50) but I've bought some retail at £15 ($30) each. Ouch!

Looking forward to seeing your progress.

Paul

 

[Divided He ad]

Thank you for the offer Brian, I've got about 50 sets of plans to choose from.... Been collecting them for a while and have a few new links as well!!

I have just now got to the point where I decided I am at a level to start to try to machine from plans.
It is not as easy to some of us as it is to others out there, I have trouble adhering to a set plan and always want to change stuff!
I'll try but will probably end up re-styling something... But it should be a runner if I keep the heart of the plan intact ;D


Ralph.

 

[Brian Rupnow]

This weekend, just as I was preparing to make the "throw" on my model steam engine crankshaft, the on/off switch buggered up on my lathe!!! If I hold the green button on with my finger, the lathe runs, but as soon as I let my finger off the button, the motor quits. I thought it might be the centrigugal switch in the motor, but my neighbour who is an electrician said that the relay in the start button that is supposed to "latch in" to keep the lathe running is not "latching in". I phoned Busy Bee in Toronto on Monday morning, and they sent me out a new switch (free) the same day by mail. I hope to be up and running again later this week.

 

[Brian Rupnow]

Well, my lathe is up and running again. I made the throw for my crankshaft tonight and pressed it onto the shaft. ---Haven't tried my hand at silver soldering yet. I can not get over how small this engine is. I have never built anything this small before. I have a devil of a time machining to size on my lathe. I try to sneak up on the measurements with my lathe, but there is a mighty fine line between "just a little more" and "Oh Damn---too much"!!!! I have the connecting rod finished, so I guess the next thing will be to machine the cylinder. I did buy a 3/8" reamer, so I will hopefully finish the cylinder first, then machine the piston to fit it.---Brian

 

[CrewCab]

but there is a mighty fine line between "just a little more" and "Oh Damn---too much"!!!!

Don't worry ............. your not alone ;D ............ but hopefully with the help of "this lot" ........... we'll get there 8)

Dave

 

[Brian Rupnow]

Well, I'm 95 percent finished. The finish isn't quite as horrible as it appears in these digital photos, but it certainly has room for major improvement. Today was my first experience with silver solder---it worked okay, but damn, its messy stuff!!! I got silver solder everywhere that I wanted to, and a whole lot of places I didn't want to. Fortunately most of it was in places that were easy to clean up with some carefull file work. The piston really dragged in the cylinder, so I sawed a slot into an end of 3/16" mild steel rod, wrapped some 400 grit sandpaper around it, and "honed" the inside of the brass cylinder with the rod chucked in my variable speed drill. When everything was first assembled, there was a lot of friction. I put a little wheel bearing grease on the piston and the bearing surfaces and kept working it by hand untill it freed up quite a bit. I may rig up a wide rubber band for a drive belt and use my electric drill to drive it for half an hour to "wear the bearing surfaces in". I'm certain that these things must have to spin really freely to work on 5 or 6 PSI of air. I still have to make an air inlet adapter to screw into the #6-32 steam port, and I have to track down a proper compression spring to hold the brass cylinder block tight against the side of the aluminum frame. I have been building custom cars, drag racing cars, and hotrods all of my life as a hobby, and I don't ever remember building anything this small before. I quickly found out with this project how limited my machining options are with a lathe, so this week I went in and ordered a milling machine from Busy Bee, where I purchased the lathe.---This has been an exceptionally good year for my business, so I thought that I could probably afford some "write-offable" machinery.

 

[mklotz]

Good job, Brian.

Elmer Verburg's version of this engine was the very first engine I finished (though not the first one I started.) I still remember my elation the first time it ran (using a tire inflator powered from the cigarette lighter on my car).

Obviously you've really been sucked in. If completing your first engine has already induced you to buy a milling machine, all I can say is...

Ok, guys, our work here is done.

Seriously though, I'm glad you're enjoying your new-found skills and your entry into a hobby that can provide you a lifetime of rewarding pleasure and save you from the need for psychiatric treatment.

Oh, and BTW, the parts on these tiny engines get bigger the more you build. it's a psychological thing.

 

[Brian Rupnow]

I just went to drill a 1/16" dia.hole through the center of the peice of round aluminum rod that I am using for an inlet steam port,and my tailstock mounted chuck won't close up enough to grip a 1/16" diameter drill. I assume that there must be collets or something that I can use to overcome this problem. Any suggestions?

 

[Bogstandard]

For a quick and dirty fix, you should be able to wrap some adhesive tape evenly around the shank so it holds, three or four wraps should do it. Don't drill too heavy handed, and only use this on bits that are non critical. As long as you have wacked a centre in it first, all should be ok.

John

 

[shred]

You could chuck the rod in the tailstock chuck and the drill bit in the lathe chuck if those jaws will hold the drill.

Otherwise, look up the threads and video on drilling really tiny holes with a hand-held pin chuck. That might work as well.

Long-term, you'll probably want a drill chuck that grips tiny sizes.

 

[Brian Rupnow]

Sometimes its being aware that a certain type of tooling exists. I did a web search for "pin chuck" and found out what a "pinchuck" was. then I went up to Busy Bee Tools where I bought the lathe, and sure enough---they have pin chucks with 3 different collets which will hold drills from 1/64" up to .100". The shank of the pin chuck is 1/4" diameter and fits my tailstock chuck just fine. Problem solved!!!

 

[Divided He ad]

Good to know you are back in business Brain ;D

I'm just starting to make my second offering... It is very similar to your engine but has a little twist... I'll post my progress on that soon

Yours should be running by the time I get round to that though??


Good luck with the drilling,


Ralph.

 

[Brian Rupnow]

I actually had mine running the other night. I just held the air gun from my compressor up to the steam port (couldn't wait to see if it would go). It almost went a number of times, but wouldn't quite kick over. Then I had the thought of putting the air gun to the exhaust port. When I did that it did take off and run quite well---IN REVERSE!!! I was very thrilled---Now to finish it off the right way!!!

 

[Brian Rupnow]

IT RUNS!!! IT RUNS!!! My God---its setting beside me right now, running like a ---well---like a steam engine!!!! I got the steam port machined and drilled this afternoon, and took apart an old mechanical pencil for the spring that holds the brass cylinder block tight against the side of the main frame. I ran up to the hardware store and got a peice of 1/8" i.d. polyurethane tubing and machined a small coupler and silver soldered it into an air chuck fitting. I tried it at a real low air pressure, and it wanted to run, but there was just a bit too much friction. I kept turning up the air pressure, and flicking the flywheel, and finally it started to run all on its own. I immediately had to call my wife down to the workshop to have a look, and then my next door neighbour!!! After it ran for about 10 minutes, it must have worn down some of the friction points, because I was able to turn down the air pressure significantly. I am totally stoked!!!

 

[ksouers]

Congratulations!!!

Now. Stop smiling and build another