# Building a double acting wobbler



## Brian Rupnow (Jun 18, 2008)

I have decided that since I had such good luck building a basic wobbler steam engine (One of Elmers Engines), that I would try something similar but a bit larger. I am going to build a double acting wobbler based on plans posted by Eric-Jan Stroetinga of the Netherlands. This is a nice looking engine, the only thing that concerns me a bit is that the cylinder caps are glued in place with loctite 648. Has anyone built this engine or do you have experience with loctite 648??? I plan on building Chucks poppet valve horizontal engine, but want to improve my skills a bit more before tackling it.---Brian 

View attachment WobblerEJS.pdf


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## nemt (Jun 18, 2008)

Hallo Brian,
I think there is no problem in using the mentioned Locktite. In general the temperature of these engines running on steam is around 100 deg. Celsius.
No problem for the locktite.
On you site I saw that you use Solid Works or drawing! I teach students to use SW in our college and like to use it myself.
But sometimes I still use Acad for 2D drawings.
Nemt


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## lugnut (Jun 19, 2008)

That engine your showing is the first one that I made.. It runs great I used the locktite and it work very well.. I'm glad you posted the plans as I lost mine and couldn't remember where I got them. 
Mel


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## Brian Rupnow (Jun 19, 2008)

Progress is being made. I finished the crankshaft and the crank "throw", but I have to go to town today and buy some material. My new milling machine is supposed to be delivered on the 26-June, and some of the parts for this engine will be built on it. I have never used a milling machine before, so I am going to jump in with both feet and make chips.


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## bretk (Jun 19, 2008)

Brian,

 Nice progress 8) As for the mill, there is nothing quite like jumping in with both feet ;D

-Bret


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## Bogstandard (Jun 19, 2008)

Brian,

Jumping in with both feet with any machinery can be a very dangerous and expensive exercise, and the milling machine is no exception.

I would suggest you just dip your toes in first, and spend as much time as possible before the machine arrives, on reading up and inwardly digesting the various safety precautions about using a mill.

You will not be able to get anyone here to give you all the information required to operate a mill with reasonable safety and accuracy, because to do it correctly can take many years.

I would suggest as a minimum starting point look for articles on 

Climb milling - a very dangerous exercise if you don't know what you are doing. This is the cause of more milling accidents than anything else, and a certainty to be done by a beginner who has never milled before.

Milling cutter types - you need to know the basics of the operation of three basic cutters that are in general use by beginners, slot drill, end mill and fly cutter. All have their own specific uses, and all can be used to do the same sorts of jobs, within the limitations of the cutter.

Setting up and workholding in a vice - it is no use just holding the piece part in the vice and hoping for the best. The vice has to be set up correctly in relationship to the table and cutter, and the job has to be held correctly and safely in the vice jaws in the right position.

If you can read about and understand the three items above, you stand a chance of staying almost safe, if you can just remember to take very small cuts on your initial experiments. Always play safe.

There is a another set of rules, but I would expect you to be using them already, the usual things, safety glasses, no loose clothing etc. You can replace cutters and lumps of metal, but not body parts (well you can, but not very efficiently).

I am sorry about going on about this matter, and not being able to supply the relevent information, but you will soon be starting on another journey, and need to get the correct ticket to get to your destination.

Best of luck on your trip

John


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## Brian Rupnow (Jun 19, 2008)

John---I appreciate your concern. Believe me, I know the danger associated with powered machine tools. In my years as an apprentice during the 1960's I seen a senior engineer killed instantly in the shop. He had come across from the office to see how a large lathe job was progressing. He leaned in for a close look while the machine was running, and his neck tie got caught up in the revolving part and broke his neck!!!  I have been operating power machinery for over 40 years--I build custom racing cars and hotrods as a hobby. I have been reading books on mill operation, and downloading a number of articles from the internet and studying them as well (There are a number of very good articles on Little Machine Shop and places like that.)---When I said that I planned on "jumping into" my project, I plan on wearing my "safety parachute".


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## Bogstandard (Jun 19, 2008)

Brian,

Sorry about that, I thought you were new to the game, and as you know, it's always better to be safe than sorry.

At least if a newbie reads it, it will give them a pointer in the right direction. So it won't be wasted.

John


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## bretk (Jun 19, 2008)

John,

 If you get a chance, check out Brian's website. He has done some interesting stuff in his career  8) 

-Bret


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## Bogstandard (Jun 19, 2008)

Bret, 
I now remember going to Brian's site and giving it a dose of looking at. Many years ago, they were the sort of machines I specialised in repairing, one offs, for doing a specific job.

But as usual my brain cell let me down, and I had forgotten. I can remember things from years ago, but not something I did an hour ago. Senility creeping up on me.

John


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## Brian Rupnow (Jun 19, 2008)

John--No offence taken. I would far rather have someone warn me of a hazard I was aware of, than have someone assume I knew what I was doing and stand by while I damaged myself!!!


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## Brian Rupnow (Jun 19, 2008)

Its Arrived. It came in today, and I brought it home in my pickup truck. Its a heavy little devil, weighs in at about 300 pounds. The bed is 7" x 19.75". I just took inventory of all the scrap angle and square tubing I have left over from various projects, and determined that I have enough to weld up a good base on the weekend.


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## CrewCab (Jun 20, 2008)

That looks like a nice piece of Kit Brian 8) ............. enjoy getting to know it and above all, have fun 

CC


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## Brian Rupnow (Jun 24, 2008)

I had to take some time away from the steam engine project to install my new milling machine, but I have made a flywheel---and man, what a flywheel it is!!! I had a peice of mild steel shaft about 3" in diameter, and no brass or aluminum, so I made my flywheel from steel. I have to clean up the bore a little bit, and a bit of polishing to do, and Oh yes, drill and tap for a set screw, but other than that its done. but my, oh my, its a heavy little sucker.I may drill a series of lightening holes in it, but really, for the amount of material that lightening holes actually remove, it may not be worth the bother. I am not sure what the consequences are of running such a beefy flywheel, other than accelerated bearing wear, but methinks it will probably let the finished engine run a bit more slowly, because of the inertial effects.


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## bretk (Jun 24, 2008)

Brian,

I've found the heavier the better, More inertia = slower running

-Bret


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## Brian Rupnow (Jun 25, 2008)

We're getting there bit by bit!! My work day ends at about 3:30, and my wife doesn't get home from her job untill about 5:00, so I get about 1 1/2 hours a day to play machinist. This afternoon I finished the main bearing and the cylinder end cap. I will soon be finished all the lathe turned parts, and then I have to figure out where to start on my milling machine.


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## bretk (Jun 25, 2008)

Brian,

 I noticed your metric to english conversions on the drawings ;D Once you are done, would you mind passing those numbers on? I was thinking about doing the engine too, perhaps building two, one with my wife (that may be an ill conceived notion, but it might interest her a little in what I do "down there") So your proofing the engine in english measurements would save a few grey hairs :big: 

Thanks, Bret


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## Brian Rupnow (Jun 25, 2008)

bretk--I just keep 25.4 stored on my calculator. Any metric dimension (in millimeters) divided by 25.4 will give you the British Imperial equivalent to as many decimal places as your calculator will display.


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## bretk (Jun 25, 2008)

Brian,

I agree 25.4 is a handy number  but sometimes bolt hles and clearances just aren't quite the same when you are debugging a steam engine. (been there, dun that) so it's nice to have a pathfinder at times 8)

-Bret


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## Brian Rupnow (Jun 29, 2008)

I just completed milling the main "frame" from aluminum flatbar. This is my first ever milling project, and I am very pleased. I made the frame much thicker in the area where the main bearing fits, because my steel flywheel is so heavy that I wanted the full thickness to support the full length of the brass bearing.


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## Brian Rupnow (Jun 29, 2008)

Progress in a big way this weekend. New mill works great, everything goes together so far---


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## CrewCab (Jun 29, 2008)

Nice work Brian 8) ........... your learning curve seems almost vertical : ....... but it seems to be working well 

 CC


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## Brian Rupnow (Jun 29, 2008)

CrewCab ---I have been using tools and machinery all my life, to build drag racing cars, show cars, and hotrods. The only reason that I didn't have a mill and lathe was because I couldn't afford them. Professionally, I have been designing machinery for 43 years, so I know what a lathe and mill are capable of, from a theoretical/capability standpoint. I am plagued by fairly bad arthritis now, and just can't get up and down well enough to continue building hotrods, so I thought that in preperation for retirement in 3 years I would buy a lathe and mill and get into model machining as a hobby. So, in a way its new, but in another way its not something "brand new" to me. This is a picture of my current hotrod that I built 4 years ago. I do all my own chassis design and build, welding, bodywork, and paint. This car has taken many trophies, and what most people don't realize is that I started with a 2 door sedan, shortened it 5 foot, cut off the top, built the box from scratch, and designed and built the convertible top frame from scratch.--Working with tools is not something new to me. Thanks for your kind words.---Brian (and it wasn't me that hit the lamp post---it was my freakin snow plow guy)


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## CrewCab (Jun 29, 2008)

Brian, I'd picked up some of your background and experience through your posts and links  It's the mill (and lathe) that's new but you seem to be taking to it like a duck to water .............. engineering's clearly in your blood mate.

Sorry to hear about the arthritis, I have several friends and family members who suffer from it. A very close friend recently (well ..... in the last couple of years) had a change of medication to a fairly "new" treatment and it's worked wonders for him ..... I hope you find something similar; I know it's *not* a nice ailment, ........... best wishes.

I really do love the "Yellow Peril" 8) ............ and the paint job is to die for  ........ once you start painting your models everybody's gonn'a have to step up a gear or two. ...... Personally I ain't worried, I can cope with most things but, spray painting with a finish any better than orange peel has always eluded me to date ....... then again the most expensive spray gun I've ever owned cost about $15 ???


Anyway, it ain't just you who's been butchering aluminium all day   ......  ;D .... although my offering is a bit of a tiddler by comparison ......... drill bit in the photo is 1/8" dia.







CC (Dave)


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## Brian Rupnow (Jun 30, 2008)

We have a base!!! I milled that pocket with a 4 flute end mill, 5/8" dia., and brothers, you were right--Four flute end mills don't plunge cut worth a darn. I was taking it pretty easy, plunging 1 millimeter at a time, then going around the profile. I found that when squaring the ends up on the outside of 1" thick aluminum, I can take a 0.010" thou deep side cut on the full 1" depth before the mill sounds like it might be straining. This is the first pocket I have milled, and it went very well. I used my carriage stops for the first time while machining the pocket---my mill only has stops on the side to side table movement, not the front to back axis, and I really wish it had them there as well. I find that everything gets so quickly covered with swarf that you can not see your scribed layout marks, and so I spend as much time brushing away chips to clear the field of vision as I do actually milling.


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## CrewCab (Jun 30, 2008)

Brian Rupnow  said:
			
		

> I spend as much time brushing away chips to clear the field of vision as I do actually milling.



I find an airline nearby is very useful  ................... doesn't make cleaning up later any easier though 

CC


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## Brian Rupnow (Jul 1, 2008)

So---Today is Canada day, nothing big planned, so maybe I will make some good machining progress. Wouldn't you know it!!!! I drilled one hole on the mill and then the friggin 10 Amp fuse blew!!!--And no place is open where I can buy another. Oh well, the lathe still works, so I built my piston, con rod, and con rod end, and layed out all my hole positions in the main body that have to be drilled. The best laid plans of mice and men----


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## CrewCab (Jul 1, 2008)

Brian Rupnow  said:
			
		

> The best laid plans of mice and men----



Oh well ........... Happy *Canada Day* anyway  .............. make sure you buy a few fuses, which reminds me though .......... I must buy some spare lathe belts ....... and fuses for the mill 

CC


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## Bernd (Jul 1, 2008)

Brian Rupnow  said:
			
		

> I drilled one hole on the mill and then the friggin 10 Amp fuse blew!!!--And no place is open where I can buy another.



I've gotten around the blown fuse by using some very thin stranded wire. I unwind one strand and solder that across the fuse ends that is blown. If there is a dead short it will blow that wire also. Then you know it's time to look for the cause because it could be major.

Bernd


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## Dick L. (Jul 3, 2008)

Looks great Brian! Can't wait to see the video of it running! 
 Nice Hot Rod you have there.
                regards,
                Dick


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## Brian Rupnow (Jul 3, 2008)

Well, its really starting to look like an engine!!! I still have to wait for the #5-40 unc tap and die that I ordered to come in so that I can put the cylinder 'wobble shaft" in place, and I had to order some 648 Loctite--(I realy hope the Loctite works as good as its supposed to.) I have to machine some brass plugs to cap of the ports in the side of the vertical aluminum frame, and have to drill and tap the crankshaft throw for a set screw to hold it in place on the crankshaft. That flywheel that I machined from steel is so awsomely heavy that I think I will cross dowel it to the shaft. That way if I have to make a lighter flywheel out of aluminum, it will be a lot easier to take it apart.---Brian


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## chuck foster (Jul 3, 2008)

looking real good brian.........can't wait to see a video of it running ;D

chuck


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## Dick L. (Jul 4, 2008)

Brian , when I did mine I threaded the ports and some brazing rod. Screwed them in and filed flush. Worked pretty well for me.
         regards,
         Dick


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## Brian Rupnow (Jul 4, 2008)

Damn!!!--Talk about pickin' fly poop outa pepper---I made the port plugs tonight, and if they were much smaller these old eyes wouldn't have been able to see them. My #5-40 tap and die came in today and I was able to thread my wobbler shaft (I still think that sounds vaguely dirty) and tap my brass cylinder where the wobbler shaft fits. (Yeah, that too). All I'm waiting for now is my Loctite #648, and I have to make up an inlet port hose adapter and an exhaust header.


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## Powder keg (Jul 4, 2008)

There's dirt on your calculator 


Nice job on the parts)

Wes


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## Bogstandard (Jul 5, 2008)

Brian,

Nice work you are turning out there.

As you get further into this game, you will find the bits get smaller and smaller.

You will need to grow suction cups on your fingers and auto magnifiers on your eyes.

John


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## Brian Rupnow (Jul 6, 2008)

Today was the nicest day we've had so far this summer. And where did I spend it ???---Down in my shop---fittin and assemblin'. Should have been outside doing something, instead I was silver soldering, filing, threading, and getting everything to run freely with no bind. I silver soldered the brass end of the connecting rod to the steel shaft, and made a new aluminum piston, then tapped the piston and threaded the end of the con rod that attaches to it. The plans call for just loc-titeing it all together, but I never have trusted any kind of glue too much. Somehow I tapped the cylinder crooked where the wobbler shaft goes into it, and of course this didn't show up untill I assembled it to the main aluminum body and noticed that the cylinder was touching the aluminum body at one end and .045" away from it at the other end. I had too much work in the cylinder to scrap it, so I set it up in the mill, drilled the threaded hole out to 1/4" diameter, made up a brass plug that I tapped in the lathe, then press fitted it into the cylinder and brazed it. Second time around it fits properly, with full contact at both ends of the cylinder. I sacrificed another mechanical pencil today---the spring in them fits over a 1/8" wobbler shaft and has just the right amount of compression to hold the cylinder tightly against the aluminum body, but not so tight that it binds. Thats what I used on the first wobbler I built also. Trouble is, now I'm out of mechanical pencils.---Of course, where else am I going to find a spring on a Sunday?? If my 648 Loctite comes in this week, I may be just about ready to run this thing. I have to build an air inlet tube yet, and maybe a 90 degree bent exhaust pipe. Where can I get small (as in 3/16" O.D.) brass tubing in Canada?


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## CrewCab (Jul 6, 2008)

Brian Rupnow  said:
			
		

> Where can I get small (as in 3/16" O.D.) brass tubing in Canada?



Brian ............ over here in the UK it's readily available as car "Brake pipe" 

This stuff .......... surely you have some, I've got 3 coils somewhere in the garage, ..... not that that helps you much 

Nice work though 8) and it sounds like your having fun, at the end of the day that's what it's all about imho 

atb

Dave


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## Brian Rupnow (Jul 6, 2008)

Crewcab--We have that here also, but it is copper (same as the link you posted). I was thinking of brass, but that is not as easy to find. I just did a little calculation here, and with a 3/8" (10 MM) piston, and 20 PSI of air pressure, that is a force of 2.2 pounds (about 1 Kilogram) of force exerted on the piston.


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## CrewCab (Jul 6, 2008)

Must be an age thing Brian .......... read "Brass" and reply "Copper" :wall:

Sorry  ........... but then again .......... it could work if you have a problem sourcing brass.  

The "force" calculation, is that related to the head and the locktite joint ?? to be fair I spent many years doubting adhesives, but, in this present era their development has changed my views considerably; out there ......... there is something to stick anything to anything ........... even Delrin apparently ??? .......... unfortunately in some cases it comes at a cost.

I used a locktite oil tolerant adhesive to retain the pin in the crank of my little engine and I've got to be honest and say ............ It worked very well.

hth 


CC


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## Brian Rupnow (Jul 6, 2008)

Crewcab---It was more just a curiosity thing. You are probably aware that I am a design engineer www.rupnowdesign.com and many of the machines I design use pneumatic cylinders, and I always do force calculations based on an available supply of 60PSI. The majority of cylinders that I use range from 1" bore up to 4" bore, and for obvious reasons I have to calculate to know if they are going to exert enough "push" to do the job required of them. I was just wondering how much "push" could be developed by such a small diameter piston. If a person wanted to, you can then take the known "push" that is calculated, and using the length of the crankshaft throw as a lever arm, do torque and horsepower calculations. The reason I chose 20 PSI was simply that that is the pressure my first little single acting wobbler likes to run at. It had nothing to do with the Loctite. I REALLY hope that the loctite will do the job for holding the cylinder cap and the cap at the other end in place adequately. In a pinch, I can silver solder them, but I really don't want to.---And---Speaking of "age thing"---wish me a Happy Birthday"---I'll be 62 tomorrow. Ringo Star and I share a birthday, but I think Ringo is a couple of years older than I am.


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## CrewCab (Jul 6, 2008)

I follow your train of thought now Brian, to be fair 1kg from a 3/8" piston is pretty fair imho .......... though it' s unlikely to be punching holes in aluminium plate : ........ I've found with my little wobbler that torque is almost non existent, then again that isn't really surprising when you consider the overall dynamics  

Its a real learning curve to be fair ;D ............. but an enjoyable one.

CC


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## joe d (Jul 6, 2008)

Brian

here in Montreal, most of the hobby stores have a small supply of brass and aluminum tubing and structural shapes from K&N Metal in assorted sizes... perhaps a little pricey for what you get, but convenient!

Joe


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## Brian Rupnow (Jul 8, 2008)

Woweee!!! Lookit' the horns on that sucker!!! (My air inlet and exhaust) I'm still waiting for my Loctite 648, and I'm running out of things to make. I am going to have to step up to the polishing wheel in a big way, but I'm getting anxious to see this thing run.


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## chuck foster (Jul 8, 2008)

brian you sound like you are having way too much fun  

this little engine is looking good...........hope to see a video of it when it is running ;D 8)

chuck


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## Brian Rupnow (Jul 9, 2008)

I went down to Brafasco's annual barbeque at noon today (Brafasco is short for Brampton Fastener Company) --(they are the industrial nut and bolt place around here) and managed to scoop a bottle of Loctite #638 from the rep. This is the same as #648 but it is thicker, and is billed as being for "loose fitting parts". I rushed home and slued everything together, and tomorrow I'll see if this thing runs or not!!!


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## Brian Rupnow (Jul 9, 2008)

Well boys and girls--It runs like absolute magic!! It self starts too, as soon as I plug in the air hose. It is running on about 5 to 8 PSI in this horrible little video. if anyone cares to tell me how to get a better video with my 2 megapixel camera, or how to edit this one, I would be happy to listen. Far as the engine goes--I couldn't ask for a better runner. The fact that it is double acting, and the flywheel weighs a lot, seem to make a tremendous difference over the first little engine I made. 

View attachment NEW ENGINE RUNNING001.MPG


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## CrewCab (Jul 9, 2008)

Congratulations Brian ;D

 ............ that runs like "GUD UN"  ....and IMHO the fact it runs on such a low air pressure is a compliment to your engineering skills 

Nice one, unfortunately I can't get any volume........... which may well be my computer ...... nor can I offer any advice about Video on the ethernet, I leave that to the youngster's .............. Ralph, Twinsquirrel ............ shout up guys 

I've enjoyed following the progress of your build from the start, well done, I'm well chuffed for you, very sweet runner 8) 


Dave


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## Brian Rupnow (Jul 10, 2008)

Trying out a video 

View attachment Untitled.MSWMM


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## shred (Jul 10, 2008)

See my other post-- that's not the video file, but the project file for Movie Maker that tells it what clips to use and where to do the cuts for the final video-- you need to publish or save the movie file also and upload that (it's not clear in Movie Maker-- the usual 'File->Save' only saves the project file)


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## Brian Rupnow (Jul 10, 2008)

Okay--trying this video thing one more time.---Starting to feel like that saying about "Old dogs learning new tricks"---thanks Shred
http://s307.photobucket.com/albums/...ion=view&current=DOUBLEACTINGWOBBLERMOVIE.flv


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## Mcgyver (Jul 10, 2008)

congrats, good on you.


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## Dick L. (Jul 10, 2008)

Looks great Brian! Your on your way to having a collection now ;D Best of all you built it, there isn't any part you don't understand and can't explain or give advice on how to construct! A good feeling to be sure!
                   Dick


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## chuck foster (Jul 10, 2008)

well Brian you better start designing and building a BIG display cabinet cause at the rate you are going ............ by Christmas you will have 40 or 50 engines to proudly display ;D 

very nice engine and the video was well worth the wait 

chuck


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## bretk (Jul 10, 2008)

Brian,

Very nice engine and a good runner too! Ready to get going on Your Chuck's Horizontal Single Yet? I'm Sure You can get plenty of advice from us  ;D 

-Bret


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