BIG PLANS

[1hand]

Well guys I think its time to nail down some plans and actually pick a design that will work for me. As some of you know I pretty much got my machines and shop area ready to go. It only took a year, but that's the life of a traveling road construction worker. Now is the time of the year when I get some down time.

With that said, I'm going to be building my first engine. Looking at the Elmer's 33 Mill Engine or one of the Beams out there. Here is the kicker, I want to go BIG. Big as I can. I have a 9" lathe and a SX3 mill. How big can you scale up these plans before you run into trouble with things not working.

As some of you also know about my disability, tiny tiny parts I don't enjoy handling. I'm looking for plans that I would only have to use fasteners the smallest of 6-32.

I know this is a tall order for you guys, but was wondering if you guys could get me set up with a design and plans of whats going to work at this mega size.

Thanks, I know you guys will get me going down the right road

Matt

 

[tel]

While my 'comfort zone' is the 3/4" to 1" bore size, I see no reason, with the equipment you have, not to be able to go out to 2" bore at least.

 

[1hand]

Tel

Ok but if you have a 1/2" bore with a 5" fly wheel. Now you scale it up to a 1" bore, do you have to have a 10" fly wheel in order for it to function. Or can you get by with a 8"? And differences between different kinds of metal.

 

[Cedge]

I doubt you'll encounter any problems with using an 8 inch flywheel. The proportions might look a smidgen off but it should do its duty and keep the engine turning.

Steve

 

[cobra428]

Here's an engine with the proportions close to yours

http://www.stuartmodels.com/inprod_det.cfm/section/casting/mod_id/46

Tony

 

[tel]

My flywheels generally turn out to be the size of whatever stock I have on hand (within reason) so it's not critical, as Steve says, an 8" would be quite acceptable and, if you were worried about the inertia factor you could always make the rim a little thicker to compensate.

 

[pete]

1hand,
I'm suprised no one hase mentioned this, If your buying your materials new, Then as metal is usually sold by weight, If you double up your plans this will require 8 times the ammount of metal that the smaller one did. Obviously your finished engine will also weigh 8 times as much. Just one more thing to consider.

Pete

 

[Kermit]

And don't forget the same 8 times on the quantity of steam (or air) you will need to make it go.



Is that right? ??? one inch stroke one inch bore. dia(sq)xht. = 1 2 inch bore would be 2 squared times the one inch stroke(height) for 4.

Four times the increase in volume for doubling bore and leaving stroke the same?
Eight times for doubling both dia and height. OKay.

I think I got it. unless someone says I don't ???

 

[1hand]

Just to refresh my memory..............How is it that when you double something it turns into 8 times more?

 

[1hand]

opps didn't see the rest of the last post. jumped the gun a bit there.......lol

 

[ozzie46]

Imagine a 1 in. cube. When you double it to 2in. it grows in 4 directions.


Therefore 2X4= 8

Ron

 

[hammers-n-nails]

twice the length, hieght, depth. 1x1x1"cube=1cubic inch 2x2x2" cube=8 cu.in.

the plans for this engine you see here for my avatar are posted on this site, this one is 2x scale using mostly 8-32 bolts 1"bore and about an 8" flywheel, ariz made a POM winning version of this engine in 1.5scale with simplified side frames.

 

[Kermit]

I knew something smelled fishy. I was wrong. It's a circle so (pie) has to be involved here.

Wiki corrected me (pie) x radius squared(not dia.) x height(stroke).

so 1in by 1 inch stroke becomes 1/2inch (sq) x (pie) is .25(pie) x 1 which comes out close to .8 cu in.

2in by 2 inch stroke is 1squared x pie x 2 or 2 pie 6.3 cu. in. approx.

Check it out for fit.

8 times .8 is 6.4 It fits.

;D Volume increases eight times if bore and stroke are doubled

 

[pete]

1"X1"X1" = 1 cubic inch, 2"x2"x2" = 8 cubic inches, Have won a few drinks in various bars with that one.

Pete

 

[hammers-n-nails]

if you double the size of a circle the area will increase 4x

 

[1hand]

pete

I'd be owing you guys some drinks.

 

[1hand]

Hammers is there a build thread on that engine you got there?

 

[hammers-n-nails]

no i didnt do one, i think i satrted it before joining this forum. what do you want to know.

 

[1hand]

That's Gerry's Beam right? I printed off a set of plans last winter as a possible first engine. I but at that time I didn't see that anyone had built it yet. I wanted to make sure my first was a working design. And now you have done it in 2x scale has really got my attention. Wonder what you think of this for a first build? How did it run? You said you used a 8" flywheel when 2x would be 6"? What materials did you use and for? Is everything else just double size? How many psi does it take to run? I have a ton of aluminium and can I substitute this for the brass parts? And anything else that would be helpful. I sorry to bombbard you with this but I like to give myself the best chance for success.

Thanks a Million for your help!!!!!!!!

Matt

 

[hammers-n-nails]

yeah its gerrys beam. do you by chance have autocad and a dro do you? none of the parts on this engine are rocket science, the frames are the most complex part and you can easily simplify them, its the second one ive build with no prior experiance. you can get it to run with a 6" flywheel scince the way the valve is made provides 100% cutoff you are always under power, ariz had his runing with no flywheel, but i think i would do as tell says and beef up the rim plenty, mine could even stand more rim weight. everything on mine is steel exept for the bronze bushings and the cylinder wrapper. it takes between 5 and 10 psi to keep itself turning but the gauge doesnt really read that low so i dont know exactally. the only thing about this is that the drawings are incomplete so you have to figure it out but thats just a matter of adding and subtracting the known dimensions.


http://www.homemodelenginemachinist.com/index.php?topic=6503.0