My build of Scotty (Elmer's #8)

[Metal Butcher]

I wasn't sure about my choice for the next build, so rather than dwell on it I decided on a quick build. Last year when I glanced over all of Elmer's plans the #8 looked like a wobbler due to the poor quality pictures available. Upon closer examination I discovered that its actually a strait line sliding piston and rod operated by a "scotch yoke." Since I don't have a model that is representative of this interesting set up it was an easy choice to make.

The original drawings indicated a smaller engine than most in my collection. I simply up sized my build by 50% along with numerous other minor changes. I believe the piston rod diameter is all that remains of the original drawing. The addition of a mock cylinder head can be seen in the picture below.

The size and shape of the yoke was changed. The yoke, frame, and foot were made of steel with a Parkerized finish applied.

Up scaling the model by 50% seemed about right. The iced tea can gives an indication of the finished size.

To maintain the "simplicity theme" inherent of this design, a simple wooden base was added for cosmetic reasons. The self stick rubber feet also add stability during demonstration runs, and protect furniture when displayed.

This is a very nice model that demonstrates how the "scotch yoke" system works coupled with a combination crankshaft and rotary valve.
This is a nice project for builders with all levels of skill, whether your a novice or commercial model maker.

[youtube=425,350]9TXYnyMCMMM[/youtube]

Hope you enjoyed the video.
-MB

 

[Twmaster]

That's terrific! As I've said in other threads. It somehow always makes me smile when I see these engines run!

One question. How are you getting the rounded edge on the cylinder? An edging mill bit?

 

[rake60]

NICE MB! Thm:

Rick

 

[Metal Butcher]

That's terrific! As I've said in other threads. It somehow always makes me smile when I see these engines run!

One question. How are you getting the rounded edge on the cylinder? An edging mill bit?

I bought an inexpensive 8 piece import set of corner rounding end mills. The seller is a regular on E-Bay. I'm real pleased with the way they cut and the quality of the finish.

They were on my wish list for quite a while. I'm sorry I procrastinated as long as I did with the purchase.

If you can afford a set there well worth every penny.

-MB

 

[zeeprogrammer]

Very nice build MB. Thanks also for telling us the 'finish' and the tip on corner rounding end mills. I don't spend too much time on eBay...every time I do...I can't seem to get out.

 

[Metal Butcher]

Very nice build MB. Thanks also for telling us the 'finish' and the tip on corner rounding end mills. I don't spend too much time on eBay...every time I do...I can't seem to get out.

Thanks for the compliment Zee. Leaving a project "in the white" is also very attractive, but not an option for me. Any thing I touch tarnishes or rusts. Its either very salty or acidic sweat that comes out of my pores. When I uncovered my mill a few weeks ago there was a perfect rusty hand print on the top of my vise that would have put a smile on any CSI trainee's face!

E-Bay can take you on a long journey of wasted time. But I do like to check all the usual sources to get an idea of price. So happens the deal I got last spring towards the end of my shop season is not there at the moment, or else I would have posted the link. I looked for the paper work in case any one was interested but that's long gone too.

-MB

 

[Twmaster]

Thanks MB. I'm going to have to wait to get a set of those milling bits. Come Monday I will be unemployed so I need to go into super cheap so-n-so mode.

 

[Metal Butcher]

Thanks MB. I'm going to have to wait to get a set of those milling bits. Come Monday I will be unemployed so I need to go into super cheap so-n-so mode.

Sorry to hear that. There's a lot of that going around in my area. Seems that about half the people I meet and talk with are temporarily laid off. Lets hope that the "temporary" part proves true.

On the brighter side of things: You can work on hobby project(s), or whatever else needs to be done, and just plain relax!

"99 percent of the things you worry about already happened, or never will"

-MB

 

[Twmaster]

Thanks. I'll be fine. I'm shutting down a trucking company I've owned for nearly 7 years. Just no money in it any more. Time to do something else rather than keep sinking.

Of course this will allow me some time to hack on some projects. Although I do need to set about replacing the lost income. Fortunately I have a small amount of cash set aside that will cover my basic expenses until the end of January.

I'm awaiting parts to repair a borrowed Taig lathe so I can make some parts for all sorts of goodies. I want to try to build one of these #8 motors sometime soon.

Sorry for the slightly off topic chatter... Now back to our regularly scheduled mayhem!

 

[Metal Butcher]

Your not off topic, your just answering my reply.

Things have a way of turning around. Things have a way of turning around if you make them turn around! If your a rugged enough individual to be involved with the trucking industry, then you'll be just fine in what ever you endeavor to undertake. A very close friend of mine who has a trucking business up in Canada almost threw in the towel year before last. I can't say for sure that it was my advice that helped him, but he pulled through last year and is doing just fine. He got lucky, and I was right!

Best of luck.

-MB

 

[ttrikalin]

The iced tea can gives an indication of the finished size.

Still, where did you find such a big can?

Jokes aside, this is a very nice build.
tom

 

[Metal Butcher]

Still, where did you find such a big can?

Jokes aside, this is a very nice build.
tom

Thanks for the compliment!

Last year I tried to pull a fast one! Here's the link.

http://www.homemodelenginemachinist.com/index.php?topic=4515.0

-MB

 

[nemoc]

Hey MB, Beautiful engine, runs good too. How do you get the spokes in the flywheel? What is a Parkerized finish?
This is the first time I have heard of it. It looks great.

Craig

 

[Deanofid]

Looks nice, MB. Very nice! Has a nice little "pop" when it's running, too.
This type of yoke takes a little power to run, usually. How much air pressure does it take to start?

Good job.

Dean

 

[ChooChooMike]

VERY VERY NICE

 

[Metal Butcher]

Hey MB, Beautiful engine, runs good too. How do you get the spokes in the flywheel? What is a Parkerized finish?
This is the first time I have heard of it. It looks great.

Craig

Thanks for the compliment! The spokes are really simple. Say you want a 1/2" wide by 2'' diameter fly wheel. Start out by cutting off a 1/2" + 1/16" disc. Chuck it in the lathe and machine out a recess 1/2" deep. Face the blank and drill/ream the crank hole. Transfer over to a horizontal indexing head or spin-dex. A collet block could be used, but the spokes will be limited to 3,4,6. Drill through the outer diameter and part way into the hub for 3,4,5,6,or however many spokes can fit in or whatever creative spacing you would like. If your using brass, then flux the appropriate areas and solder thing together. Aluminum can be assembled e with loc-tite and peening on the ends of the outer diameter. And of course brazing is the strongest option. A little "pillow" cut from solder can be dropped into the hub holes before inserting the spokes, and the solder applied from the outside of the outer diameter of the fly wheel to help keep the soldering neat. Afterward return the work to the lathe by reversing it in the chuck to face off the excess on the opposite side.
http://www.homemodelenginemachinist.com/index.php?topic=4363.0
Parkerizing is a concentrate that you can buy at gun shows and online. You add it to the specified amount of water, heat it up a bit, and stick the parts in till the desired color is reached relatively simple and safe. It forms a rust resistant crystalline structure by converting the metals surface. Glare free, holds oil well to prevent rusting, used on military firearms to name just one use.
http://www.parkerizingkits.com/

-MB

 

[ChooChooMike]

VERY VERY NICE ENGINE !! :bow: :bow:

Love the contrast between the black and brass. Love the sound of the engine too

KUDOS !!

Mike

 

[Metal Butcher]

Looks nice, MB. Very nice! Has a nice little "pop" when it's running, too.
This type of yoke takes a little power to run, usually. How much air pressure does it take to start?

Good job.

Dean

Thanks for the compliment.

In the video the start and slow run parts are at 1 PSI, during the higher speed parts it was at about 4-5 PSI. At the very end the pressure was droped below one PSI when the engine stalled.

This is about the normal pressure for most of the previos models I built.

-MB

 

[Metal Butcher]

VERY VERY NICE ENGINE !! :bow: :bow:

Love the contrast between the black and brass. Love the sound of the engine too

KUDOS !!

Mike

Thanks Mike, much appreciated!

-MB

 

[nemoc]

Thanks for the info MB. The rim of the Flywheel is so nice I couldn't tell the spokes went through it. I will be trying the parkerized finish on a future project for sure.

Craig