# Opposed 4 Compressed Air



## cfellows (Dec 25, 2008)

I finally got back into the shop today and made some chips. I've been doing chemotherapy treatments for the past 5 months months and haven't felt much like making anything (the mind was willing, but the body wasn't). I had my last treatment last week so it's time to get back to work. I'm also going to be moving to Austin sometime in 2009 and will have to work on getting the house in Arizona ready to sell. So, I figure this will be my last engine project until after I move.

This engine will look similar to the Liney RV2 (2 is the model number, not the number of cylinders).  Bore will be 1/2" and the stroke will be 5/8". It will use a rotary valve setup on top of the crankcase between the two cylinders. Brass tubing will send the high-pressure air to the cylinder heads where I'll use my slave ball bearing valve assembly for the exhaust. It will also be 4 stroke operation, so I'm hoping it will have a nice sound and run slow.

The crank will be silver soldered and set screw together so I can use one piece connecting rods (even though the drawing shows a two piece rod). Today I started on the Webs, making them out of 1" diameter cold rolled steel. I'm making them heavy to add some flywheel effect. Here's a couple of Visio drawings.












Chuck


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## stevehuckss396 (Dec 25, 2008)

I like it!!

I am a big fan of compressed air motors. Cant wait to see the progress pictures!


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## rleete (Dec 25, 2008)

I really like the lines of the RV-2. Is this one going to have the same external gear for the valve?


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## cfellows (Dec 25, 2008)

rleete  said:
			
		

> I really like the lines of the RV-2. Is this one going to have the same external gear for the valve?



Yup. The valve chest will be narrower and, of course, the engine will be about 25% larger.

Chuck


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## radfordc (Dec 25, 2008)

Looking forward to seeing your engine develop. I'm a fan of the RV2 since I built one last year. Neat to see it run.

Charlie


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## cfellows (Dec 26, 2008)

Nice build, Charlie. I bought the Liney RV-2 plans and kit several years ago. It's still sitting on a shelf in my closet. I could probably build the RV-2 and modify the head to use my own valve design, but I decided I wanted something a little bigger.

I'm using my own valve design because I hope to get a little more sound out of it than the stock RV-2 delivers. We'll see.

Chuck


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## cfellows (Dec 26, 2008)

Got a couple of pictures to post tonight. Nothing very exciting yet. I got the crank webs turned and bored from 1" cold rolled steel. They'll need a little polishing but that's later. I've got them mounted on a 1/4" rod for display only.






I needed an offset jig to bore the holes for the connecting rod journals. I didn't particularly want to use the 4 jaw chuck and I didn't want to build a special jig. So I pressed my boring head into service. I faced off the bottom rail so it would be square, the drilled and tapped a 1/4" x 20 hole in it. I used an allen head screw to mount the crank web for drilling. Got repeatable accuracy on all 4 webs and I can use it on future projects for different spacing on the offsets. Only problem was I couldn't bore the hole all the way through without hitting the boring head, so I stopped 1/16" short and finished off the hole in the drill press.






Chuck


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## Bernd (Dec 26, 2008)

Chuck,

That last pic gave me an idea for a fixture/jig that could be made to drill offset holes. :bow:

A tip here. You could add an aluminum plate or brass plate between the part and boring head. Then use an end mill to finish drilling the hole through completely. I say end mill because you wouldn't need to dill to far into the sacrificial plate underneath. 8)

Bernd

P.S. Had to give you a karma point for that idea with the boring head.


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## cfellows (Dec 26, 2008)

Watch out Brian! I'm on the fast track to learning 3D Cad!  :big:

Pretty humble start, but I managed to model the crancase in Alibre. Long ways to go...






The crancase will be made from a 2" length of 1.5" square steel tubing. The current plan is to silver solder the two, 1/8" thick end plates on, like I did with the John Deere engine.

Chuck


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## stevehuckss396 (Dec 26, 2008)

cfellows  said:
			
		

> Watch out Brian! I'm on the fast track to learning 3D Cad! :big:
> 
> Pretty humble start, but I managed to model the crancase in Alibre. Long ways to go...
> 
> ...




If you need any help with Alibre, i might be able to talk you thru some of the easier stuff. Stick with it and you will be happy you did. 


Here is a crankcase I drew. I did Not! design this thing.


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## cfellows (Feb 9, 2009)

I finally got back to making chips on my Opposed 4 cylinder engine. I also prettied up the drawing some:






The Crankcase is made from 1.5" square steel tubing, 2" long. The holes are 5/8" diameter.






I've been spending most of my time over the past 8 weeks trying to get the shop organized better to get ready for selling the house and relocating in Austin. I decided I'd get some model engine work in while the spouse isn't paying attention. Unfortunately, time sure goes fast when you're having fun. It's a little disturbing at my age!

Chuck


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## Brass_Machine (Feb 9, 2009)

Hey Chuck!

Looking good there! I am a big fan of the RV2. Probably will be a bigger fan of this one you are designing. Alibre is a great thing.

Eric


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## steamer (Feb 10, 2009)

Nice looking engine Chuck! 
I really like the boring head trick. That has me thinking now..... :

Dave


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## Maryak (Feb 10, 2009)

Go Chuck, 
	

	
	
		
		

		
		
	


	




Neat trick with the boring head :bow:

Best Regards
Bob


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## cfellows (Feb 11, 2009)

Nothing too exciting tonight. I drilled the holes in the crankcase that will accept the socket head cap screws which are used to attach the cylinders. I made a jig with the hole patterns to accurately position the bit when drilling the holes.

The jig has a 5/8" plug on one side to fit into the holes in the crankcase. With the jig clamped in place the holes are drilled into the crankcase.

The jig has a 1/2" plug on the other side to fit into the cylinder bore.

Using this jig for both the crankcase and the cylinders will ensure that the holes match and that the cylinders are interchangeable. Much easier than trying to use standard locating methods to drill the holes.






Jig in place:






Chuck


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## putputman (Feb 11, 2009)

I don't want to change the subject as I plan to follow your build to the end.

Are you guys using the free copy of Alibre to get those drawings or have you purchased the advanced copies. I have never tried 3D CAD but would like to try it. Can't afford to purchase a copy if that's what it takes to get a decent drawing. This is strictly for my hobby work.


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## cfellows (Feb 11, 2009)

I used the free version of Alibre to draw the crankcase:






For this drawing, I used Visio. I use Visio for most of my drawings made during construction.






I hated Visio when I first started using it. But now I like it a lot. It won't do 3D, other than 3d shading effects, but it's fast and easy once you get familiar with it.

Chuck


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## cfellows (Feb 11, 2009)

Got a little bit more done today. I milled the opening in the bottom of the crankcase and cut the end plates for the crankcase. The next step will be to silver solder the end plates on to the crankcase.






I'm taking my time on this part of the engine. Trying to get it right.

Chuck


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## ksouers (Feb 11, 2009)

This is going to be interesting, Chuck.

Following along.


Kevin


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## NickG (Feb 12, 2009)

Looking good Chuck, will the ends be welded or soldered?

Nick


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## cfellows (Feb 12, 2009)

Another day and a little more progress. Here is the crispy critter with the end plates silver soldered in place. Always kinda fascinates me when I'm successful with silver soldering. Seems more like black magic than science.












Chuck


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## Maryak (Feb 12, 2009)

Chuck,

Coming along. Don't know about black magic but it sure is a good feeling when it's done and all is OK. 

Best Regards
Bob


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## NickG (Feb 13, 2009)

Yeah, I know what you mean, it's the combination of cleanliness, flux and the right amount of heat! Sometimes the last one has a pretty fine line! Then of course there's securing it!

Good job!

Nick


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## tel (Feb 13, 2009)

It's coming along nicely. I always enjoy silver soldering, it's a process you have a great deal of control over once you get you head around it.


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## cfellows (Feb 13, 2009)

One last picture of the Crankcase to show how it cleaned up and with the end holes bored.






Chuck


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## stevehuckss396 (Feb 14, 2009)

Nice job so far!

Wow

Steve


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## cfellows (Feb 19, 2009)

After some lengthy negotiations (with myself) I finally settled on a new cylinder design. I was originally going to make the cylinder barrels from 3/4" square brass but decided that looked too "dainty". So I went with 3/4" x 1" brass for a little beefier look. I also like the look of the rectangular shaped cylinders. I need to make the cylinder base flange square and I may increase the radius on the edges some

The bore is 1/2" and the stroke will be 5/8" and the cylinder holes are blind since I decided to just incorporate the head into the cylinder. Fewer parts to make and fewer holes to drill and tap. ;D
















3 more to make... 

Chuck


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## Maryak (Feb 20, 2009)

Chuck,

Fascinating build coming along really well. :bow:

Many from North America seem to favour rectangular and/or square cylinders. Is there a reason for this ??? I can see savings in machining time, especially for multi-cylinder engines made from stock. Just curious.....Again :

Best Regards
Bob


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## cfellows (Feb 20, 2009)

I wanted to use a square cylinder to add more substance to the engine. Round cylinders just seemed to puny. Then I thought, rectangular would be even better. However, now that I look at it, I may go back to square since the rectangular cylinders seem to be a bit much...

Anybody have any thoughts?

Chuck


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## gilessim (Feb 20, 2009)

Chuck, I think that the rectangular cylinders look great and very original, I'd stick with them!

Giles


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## Kermit (Feb 20, 2009)

cfellows  said:
			
		

> I wanted to use a square cylinder to add more substance to the engine. Round cylinders just seemed to puny. Then I thought, rectangular would be even better. However, now that I look at it, I may go back to square since the rectangular cylinders seem to be a bit much...
> Chuck



how about using hex rod?


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## cfellows (Feb 20, 2009)

Kermit  said:
			
		

> how about using hex rod?



Kermit,

Trying to stick with materials I have on hand, which, unfortunately, doesn't include any hex stock.

Chuck


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## cfellows (Mar 8, 2009)

I haven't been in the shop much the past couple of weeks. I've been fighting a vicious bout of bronchitis.

I finally got around to finishing the other three barrels for the engine. I pondered for a long time on the overall shape and finally settled on the 1" high x 3/4" wide brass. The propeller is kind of nice touch. It's a chrome plated gun metal prop that's a replica of a Hamilton Standard steel prop like the ones used on the Spirit of St Louis. I picked up several of these on ebay sold as letter openers! Don't know yet if I'll use the prop or if I'll go with a flywheel.

Chuck


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## chuck foster (Mar 8, 2009)

nice work chuck but i have a question for you..............do you ever sleep ???  :shrug:

chuck


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## cfellows (Jan 6, 2010)

While I'm waiting on parts for my Plumbing Parts engine, I've decided to resurrect this project after nearly a year. I've got some new ideas for valving that I want to try out, and while I haven't finalized the inlet valve design, it will use a version of my slave exhaust valve setup. I'm sticking with that design because I want it to be a 4 stroke and I like for my engines to make some noise when they run! :big:


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## cfellows (Jan 6, 2010)

Kind of figured out where I was on this thing and got busy on the connecting rods today. Here's a few photos of my progress.

Random bits of aluminum destined to become the rods. I like using up the smalles pieces of scrap I have that will accommodate the piece I'm making. Unfortunately, it usually means extra cutting and milling to get the scraps to a decent shape. Managed to run my thumb into the bandsaw on one of the smaller pieces when it slipped off the blade. Kind of deep, but nothing serious!






Here I'm center drilling the rod blank for the big end. I'm using my little home made depth gauge to position the blanks in the vise.






Here you can see me milling the edges of the connecting rod. To do the other side, I just flip it over and repeat the operation. Again, I'm using my home made depth gauge to position the blank in the vice. I'm then reading the x-screw dial to repeat the start and end of the cut. Aahh, if I just had a DRO...






And, here's a pretty good start on the four rods. Just need to round off and pretty up the two ends.






Just to bring everyone up to date, here's where I am at the moment.











Next I finish up the rods, then get started on the pistons.

Chuck


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## ksouers (Jan 6, 2010)

Chuck,
Glad to see you back to work on this engine.
It's been so long I'd forgotten about it, maybe thinking you'd finished.

Anyway, lots of good work. I'll be dropping in on it, for sure.


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## zeeprogrammer (Jan 6, 2010)

Oh nice Chuck.
This was before my joining the forum so I read the thread.
I'm looking forward to seeing this build.


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## cobra428 (Jan 6, 2010)

cfellows,
Nice engine. Not to distract from that but where did you get or did you build the prop?

Tony


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## cfellows (Jan 6, 2010)

cobra428  said:
			
		

> cfellows,
> Nice engine. Not to distract from that but where did you get or did you build the prop?
> 
> Tony



It's a metal replica of a Hamilton Standard prop that was used, for one, on the Spirit of St Louis. I picked up 3 of them on Ebay several years ago. They were (and are) sold as letter openers. There's several for sale on Ebay right now.

http://cgi.ebay.com/Hamilton-Standard-Classic-Propeller-Letter-Opener_W0QQitemZ320470082585QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item4a9d816419


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## Deanofid (Jan 6, 2010)

Chuck, how'd you get the rods on the pins? Crank pins come out of the throws?

I vaguely remember this engine from when I first joined here. I went through the WIP's of older projects, picking out titles that sounded interesting. Still haven't seen them all. There are a lot!

Glad you're back on this one.

Dean


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## NickG (Jan 7, 2010)

Chuck,

Seeing that crankcase has just reminded me I saw this from the start!

Wow, don't you need a rest after the i.c. engine! Obviously not!

Good going.

Nick


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## cfellows (Jan 7, 2010)

NickG  said:
			
		

> Chuck,
> 
> Seeing that crankcase has just reminded me I saw this from the start!
> 
> Wow, don't you need a rest after the i.c. engine! Obviously not!



Nick, it's like Metal Butcher says, "If I don't keep busy, I'm afraid I'll roll to a complete stop!"



			
				Deanofid  said:
			
		

> Chuck, how'd you get the rods on the pins? Crank pins come out of the throws?
> ...



The crank pins are silver soldered into the outer crank webs. Setscrews hold the crankpins in the thick, center web. It did it this way to simplify the connecting rods.

Thanks for the words of encouragement.

Chuck


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## ariz (Jan 7, 2010)

very nice engine chuck!!!

but I can't understand how the crankshaft and connecting rods may enter in the crankcase... :-[
how do you do?


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## cfellows (Jan 7, 2010)

ariz  said:
			
		

> very nice engine chuck!!!
> 
> but I can't understand how the crankshaft and connecting rods may enter in the crankcase... :-[
> how do you do?



Good Question! I had planned to assemble the crankshaft inside the crankcase, but just discovered that it ain't going to work without some modification. I'm going to have to bore the hole at the back end of the cylinder larger so the crank can be inserted from both ends. I had originally planned to insert it piece by piece through one end but I can't get the back 2 rods over the crankpin that way. Nice catch!

Chuck


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## cfellows (Jan 7, 2010)

Well, ariz, took a little wind out of my sails, but I'll get it fixed. In the meantime, I spiffied up the connecting rods.







Chuck


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## NickG (Jan 8, 2010)

Really nice rods chuck, were they finished with a file or rotary table?

NIck


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## Powder keg (Jan 8, 2010)

Looking good there Chuck!!! I want to start my Con rods this weekend. We'll see how things go.


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## cfellows (Jan 8, 2010)

NickG  said:
			
		

> Really nice rods chuck, were they finished with a file or rotary table?
> 
> NIck



I have a small rotary table which fits in my milling vise that I used. It's not a geared rotary table, but rather swings with a handle that inserts in one of 12, evenly spaced holes around the periphery. I built it from plans in Model Engineer's Workshop a number of years ago. Actually, I'll try to post some pictures and maybe a video of it later today in the tools section. I use it a lot since it's quick to set up and pretty handy for lots of rotary operations.

Chuck


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## cfellows (Jan 8, 2010)

Had about 6 hours out in the shop today. The temperature outside hovered around freezing all day, which is cold for Austin, but my shiny new electric heater kept it comfortable.

I bored the smaller end of the crankcase so I could install the crank pieces from either end. I had to make a new bearing block for that end which also meant drilling more holes and threading them... not my favorite activity! But, all is well that ends well. Here you can see the crankcase with the crank and con rods installed. So, next, it'll be on to the pistons.






Chuck


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## Powder keg (Jan 8, 2010)

Looks like your making good progress Chuck.


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## putputman (Jan 8, 2010)

Looking good Chuck. 
Could you take a few minutes to tell how you assembled the crankshaft in the block and how you keep the shafts in line. Is it keyed and pinned.
I have a heck of a time keeping the shafts aligned on a single throw crank.


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## Deanofid (Jan 8, 2010)

I like the way it's going together, Chuck. Very Volkswagen-ish.

(That's a compliment!)

Dean


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## ariz (Jan 9, 2010)

great work Chuck, very well done :bow:

what are those little pin (?) that I see upward roughly inline with the shaft?


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## vlmarshall (Jan 9, 2010)

I like that crankcase idea, and the look of the assembled parts. 



			
				Deanofid  said:
			
		

> I like the way it's going together, Chuck. Very Volkswagen-ish.
> (That's a compliment!)
> Dean


Darn right it's a compliment! ;D :bow: Ok, the crankshaft halves are 180 out, but it's close.


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## zeeprogrammer (Jan 9, 2010)

Looking neat. I have the same questions about the pins and keys.
Oh...and don't forget about the pics for the rotary table!
[EDIT: Just saw you have another thread for it. Thanks!]


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## cfellows (Jan 9, 2010)

putputman  said:
			
		

> Looking good Chuck. Could you take a few minutes to tell how you assembled the crankshaft in the block and how you keep the shafts in line. Is it keyed and pinned. I have a heck of a time keeping the shafts aligned on a single throw crank.



I'll take it apart later today and include some pictures of how the crank is assembled. At the moment, I'm trying to figure out how to keep my outside faucets from freezing up again tonight!



			
				Deanofid  said:
			
		

> I like the way it's going together, Chuck. Very Volkswagen-ish.
> (That's a compliment!)
> Dean


Thanks, Dean, hadn't thought of the VW engine, was basing it more on the Liney RV2, only bigger (and different) ???



			
				ariz  said:
			
		

> great work Chuck, very well done :bow:
> 
> what are those little pin (?) that I see upward roughly inline with the shaft?



Those aren't pins, they are dimples, also called witness marks maded with a center punch, so I know how to put things back together the same way.



			
				Vernon  said:
			
		

> I like that crankcase idea, and the look of the assembled parts.
> Darn right it's a compliment! ;D :bow: Ok, the crankshaft halves are 180 out, but it's close.



Thx Vernon. The crankshaft is a little different than the VW to keep it simpler.

Chuck


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## cfellows (Jan 9, 2010)

Here is a how the crankshaft, rods, and crankcase go together:

These are the pieces unassembled about as far down as it will go. Note that the main crank shafts and crankpins are soldered into the two end crank webs:






The big ends of two of the connecting rods are inserted through the piston holes on one end:






One end of the crankshaft is inserted through the end of the crankcase and the crankpin is inserted through the big end of the two connecting rods:






The large, center crank web is inserted through the other end of the crankcase and the exposed end of the crankpin is inserted into a hole in the center web. A set screw tightens against the crankpin to hold it in place.






The process is then repeated with the other end of the crankshaft, rods, and crankcase.






There is another setscrew on the other side of the center crank web to lock in the other end of the crankshaft.






Aligning the center web with the two outer webs is a wooley booger and I haven't figured out an easy way to do it other than trial and error. Probably won't be an engine that I will be disassembling very often!  

Chuck


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## Deanofid (Jan 9, 2010)

Gotta keep those wooley boogers out of the shop, Chuck.

The VW engine thing was made out of my fondness for flat engines. All of them in general. VW's in particular. I just like them.

Thanks for the assembly pictures.

Dean


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## ariz (Jan 10, 2010)

yes, thank you for the assembly pics, I'll never find out how to do it without something 'to see' ;D


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## Maryak (Jan 10, 2010)

Yes, a big thanks for the assembly shots. :bow: :bow: Had me beat 6 ways to Sunday on how it went together, thought Houdini had given you some pointers.  ???

Best Regards
Bob


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## putputman (Jan 10, 2010)

Thank you Chuck, that cleared up a lot of questions. 
I really enjoy following all your builds. You seem to have a unique approach to a lot of these tasks.


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## kustomkb (Jan 12, 2010)

Very nice work chuck!

its coming along great.


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## Bill Mc (Jan 18, 2010)

Hi Chuck - Are you going To Convert This Engine Over To Gas Also ?      Hee-Hee Just Kidding -  Billmc


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## cfellows (Jan 30, 2010)

Waiting on a new bearing for my Tool & Cutter Grinder mods so I'm back working on my 4 cylinder boxer compressed air engine. I finally settled on and got some work done on the valve assembly. The engine will use a rotary valve located in the center on top of the engine. A 2:1 set of gears will rotate the valve 1/2 turn for each full turn of the crank, giving me a 4 stroke operation. The larger valve gear will go on the left side of the valve assembly. The Compressed Air tube from the compressor will fit on the tube on the right side of the valve assembly which will be the back of the engine. Air will enter the rotating valve tube through the hole in the center, then be directed out radial holes in the side of the tube as they align with the holes drilled in the valve body. 1/8" brass tubing will carry the high pressure air to the top of the cylinders.

Since I will be using my slave valve design in the heads, the air will exhaust out the bottom of the cylinder, opposite the air inlet holes. With this design, there will be no need to worry about a return path for the exhaust air back the way it came in which is typical of most rotary valve engines. 

The valve body is made from aluminum with a thin wall brass tube pressed into the hole drilled axially down the center, the rotating valve tube is made from drill rod, and the air inlet piece at the back of the engine is made from cold rolled steel.

















Chuck


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## stevehuckss396 (Jan 30, 2010)

Holy smokes that is nice Chuck.


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## Blogwitch (Jan 30, 2010)

Chuck,

I really love the way you can come up with these small engines 'simulating' the real thing.

I have just got out of deep storage one that I was working on a couple of years ago, and was the first one I designed and made with your help. I am just in the process of 'putting it right' after the better half lost one of the cams I used on it, during her monthly clean up of my shop, and of course, a little bit of bling.

You really do make extraordinary engines out of ordinary materials. A great credit to you.


Blogs


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## cfellows (Jan 31, 2010)

stevehuckss396  said:
			
		

> Holy smokes that is nice Chuck.



Thanks, Steve, nice compliment, especially coming from you.



			
				Blogwitch  said:
			
		

> Chuck,
> 
> I really love the way you can come up with these small engines 'simulating' the real thing.
> 
> ...



Thanks, Blogs, I tend to favor the old internal combustin engines of all kinds, from marine, to aviation and industrial. However, getting a model to run, idle, and sound like the full size jobbies is a real struggle. Compressed air gives more control and more realistic scale performance. 

I remember the engine you built using my slave valve design and was quite flattered that you found it worth investigating. I look forward to seeing the changes you make to it. There are a number of things that can be changed to alter the sound and the performance. Some include how quickly the inlet valve is opened, the open dwell time, and of course the timing. I also like my engines to make a little noise to sound more like IC engines. To that end, I've found keeping the slave valve pretty loose helps. The sound of air escaping past the slave valve when it "fires" enhances the overal sound. Also, in later engines, I've replaced he sliding piston slave valve with a simple ball bearing.

Thanks for the kind words. I also have a v-twin and a radial engine of similar operation in various stages of completion. So many projects, so little time!

Chuck


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## Blogwitch (Jan 31, 2010)

> So many projects, so little time!



I know exactly how you feel Chuck.

I have been working on that engine for a few weeks now, and today I managed to get the flywheels almost sorted. It has only taken me about a two weeks to get them done. Normally, they would have been finished in an evening. When I do eventually get it finished (don't hold your breath), I will take a picture or two.

Blogs


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## NickG (Jan 31, 2010)

Coming along nicely Chuck. I agree, I was mesmorised when I first saw one of your compressed air engines, sounding like the real deal. I think at least one of your engines will make just about everybodies list of projects.

Nick


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## kcmillin (Jan 31, 2010)

Chuck,
  Wow, that thing is beautiful. those parts are so well blended. They look really nice together. 

kel


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## Deanofid (Jan 31, 2010)

Still looking good, Chuck.
The rotary valve running with timing gears in order to mimic a cam is a neat idea.
Are you going to make your own gears? : )

Dean


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## cfellows (Jan 31, 2010)

Deanofid  said:
			
		

> Still looking good, Chuck.
> The rotary valve running with timing gears in order to mimic a cam is a neat idea.
> Are you going to make your own gears? : )
> 
> Dean



Yep, I will be making the gears shortly. The will be a 15 tooth & 30 tooth, 24 pitch. I have a pretty complete set of commercial gear cutters for 24 pitch.

Chuck


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## slick95 (Jan 31, 2010)

Very Nice Chuck :bow:

Closely following your build...

Jeff


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## kcmillin (Jan 31, 2010)

Chuck,
I find the four stroke design of your compressd air engin verry interesting. you say it help the way it sounds, this may be a dumb question, but how does it affect the sound? I too like the sound to be more "authentic", does this method creat a vacume in the motor and then release with a nice "pop" or is it something els?

kel


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## cfellows (Jan 31, 2010)

kcmillin  said:
			
		

> Chuck,
> I find the four stroke design of your compressd air engin verry interesting. you say it help the way it sounds, this may be a dumb question, but how does it affect the sound? I too like the sound to be more "authentic", does this method creat a vacume in the motor and then release with a nice "pop" or is it something els?
> 
> kel



The authenticity comes from several factors. The four stroke design has a minor impact on the sound, but does introduce engine mechanical sounds between power strokes, like most full size engines. The slave valve design, because of the way it works, has a much larger impact on the sound. It forces the engine to run at higher pressures which more closely resembles the sounds of internal combustion. When the inlet valve admits air into the head, it pushes a slave valve to one side, against spring pressure. All this mechanical motion plus the movement and release of the high pressure air creates sounds similar to IC engine operation.

Here's one of my earlier engines that operates on compressed air, in 4 stroke mode, with a slave valve in the head.

[ame=http://www.youtube.com/watch?v=CXH2nNLmBXo&feature=related]http://www.youtube.com/watch?v=CXH2nNLmBXo&feature=related[/ame]


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## kcmillin (Jan 31, 2010)

Wow that really does sound good. I like the time inbetween pops. 

Thanks for the vid.

kel


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## BigBore (Feb 1, 2010)

Blogwitch  said:
			
		

> *..............You really do make extraordinary engines out of ordinary materials. A great credit to you*.
> 
> Blogs



Couldn't have said it better. I'm a motivated student of your work as well as the other artisans on this forum. (per wiktionary: Artisan _ _ A skilled manual worker who uses tools and machinery in a particular craft__._)

Thanks, Chuck!

Ed


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## cfellows (Feb 2, 2010)

Thanks Ed, Kel, I do appreciate the kind words.

Today I fabricated and fitted brass manifolds. The brass tubes leading to the cylinder heads will be soldered into the holes showing in the sides of the manifolds. I'm including a few pictures of the everything I've made to date assembled... partly cause I wanted to see how it looks and partly so I can fit the air tubes.





















Chuck


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## Metal Butcher (Feb 2, 2010)

Lookin good Chuck!

Are you going to make small 'bolt on' flanges for the tubing to be soldered to on the cylinder heads?

-MB


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## Deanofid (Feb 2, 2010)

I sure like it, Chuck. Looking really good!

Dean


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## cfellows (Feb 3, 2010)

Metal Butcher  said:
			
		

> Lookin good Chuck!
> 
> Are you going to make small 'bolt on' flanges for the tubing to be soldered to on the cylinder heads?
> 
> -MB



Thanks, MB. Yeah, I've already got the flanges made. They will be soldered onto the end of the tube going into the head.


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## cfellows (Feb 3, 2010)

Deanofid  said:
			
		

> I sure like it, Chuck. Looking really good!
> 
> Dean



Thanks, Dean.


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## cfellows (Feb 3, 2010)

I'm contemplating tapering the fins on the cylinders to make installing and removing the cylinder screws easier.

Like this:


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## NickG (Feb 3, 2010)

Chuck, this is looking fantastic, I like the tapered fins idea. Can't wait to hear the sound of this thing!

Nick


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## SAM in LA (Feb 3, 2010)

Chuck,

I really like the way you made the square cylinder with the fins. 

I'm not so sure about the tapered look.

I can't wait to see the finished product.

SAM


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## spuddevans (Feb 3, 2010)

cfellows  said:
			
		

> I'm contemplating tapering the fins on the cylinders to make installing and removing the cylinder screws easier.



Have you thought about turning the taper on the lathe? The transition between the top square fin to a round bottom fin might look pretty neat, and would give that extra clearance for the cylinder screws.


Great build by the way, I always enjoy following your work.


Tim


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## cfellows (Feb 3, 2010)

Thanks everyone for the appreciative comments. I'm putting the tapered fin idea on hold for now. At this point I'm getting pumped at the idea of making a steel, 4 bladed propeller, like this drawing...






It would be about 7 1/2" in diameter and I'm thinking of making it from steel. Haven't decided whether it would be made from one solid piece or built up, but would probably be built up to save material and make machining easier. I'm thinking this kind of prop would have good flywheel properties as well as being attractive.

Chuck


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## ariz (Feb 3, 2010)

Chuck, I see great progress here, can't wait to see it running


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## slick95 (Feb 3, 2010)

Very Nice Chuck. I'm an airplane nut and your engine just has aviation written all over it. Keep those pics coming Please 

Jeff


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## gbritnell (Feb 3, 2010)

Hi Chuck, I like the idea of the tapered cylinders. I think it would give it more of an aircraft engine look. Kind of like a Continental flat four. I'm curious as to how you're going to create the prop out of steel.
gbritnell


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## cfellows (Feb 3, 2010)

slick95  said:
			
		

> Very Nice Chuck. I'm an airplane nut and your engine just has aviation written all over it. Keep those pics coming Please
> 
> Jeff



Thanks, Jeff, got another picture coming in a minute!



			
				gbritnell  said:
			
		

> Hi Chuck, I like the idea of the tapered cylinders. I think it would give it more of an aircraft engine look. Kind of like a Continental flat four. I'm curious as to how you're going to create the prop out of steel.
> gbritnell



The vote is still out on the tapered cylinders. But I do agree that the straight sided cylinders make the engine look kind of blocky and heavy.

As far as the prop goes, I'm still noodling on how to do it. I've been experimenting with cutting a slightly angular slice out of a PVC tube to fashion each blade. This gives me a slight twist and the back side of the blade would be cupped. Of course, I would make the real thing from a steel tube, but so far I haven't found a shape that pleases me. I've also thought of making each blade from a piece of 3/16 x 1/2" steel and welding them together in the center with each blade rotated slightly then grinding the airfoil on the front. Just not sure, yet, how I'm going to do it. In the end it will probably be brute force grinding and lots of hand work including (shudder) filing.

If you have any ideas, I sure would welcome them!

Chuck


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## cfellows (Feb 3, 2010)

Got the air tubes cut, bent and dry fitted today. Will probably solder them up tomorrow. 






Or, I may decide to try loctite. Got a new bottle of 620 that I'm itching to try out.

Chuck


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## SAM in LA (Feb 3, 2010)

Chuck,

Looks great.

I like the blocky look.

SAM


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## stevehuckss396 (Feb 3, 2010)

Looking good Chuck. Looking forward to seeing the 4 blade prop.


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## Deanofid (Feb 3, 2010)

The air tubes look just great, Chuck. Very uniform.
It does look good with square cylinders. I think the tapered style would look even better.

You're the boss! Either way, it's a neat looking engine.

Dean


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## NickG (Feb 4, 2010)

Yeah, it looks brilliant either way.

NIck


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## zeeprogrammer (Feb 4, 2010)

Nice Chuck. Looking great.


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## cfellows (Feb 4, 2010)

Thanks Zee, Nick, Dean, Steve, Sam.

Didn't have much time for the shop today, but did manage to get the air inlet manifold finished. Soldered up the assemblies, then drilled & tapped the heads and bolted it all up.

Heres a few pictures:
















Gotta see what else I can squeeze in before the wife convinces me I need to get started on refacing the kitchen cabinets! :

Chuck


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## Maryak (Feb 4, 2010)

Chuck,

I really like your engine. :bow: :bow:

The prop as a flywheel is a great idea. :bow:

Personally, I like the cylinders as they are. 

Best Regards
Bob


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## Kermit (Feb 4, 2010)

Chuck,
I may have overlooked it, but I'm wondering what you use between the brass manifold an the aluminum valve housing. Is it just a lapped metal to metal joint? The picture shows a tight seam there where the two meet.

I'll go back to lurker mode now. Beautiful engine too.


Thank you,
Kermit


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## cfellows (Feb 5, 2010)

Kermit  said:
			
		

> Chuck,
> I may have overlooked it, but I'm wondering what you use between the brass manifold an the aluminum valve housing. Is it just a lapped metal to metal joint? The picture shows a tight seam there where the two meet.
> 
> I'll go back to lurker mode now. Beautiful engine too.
> ...



Actually, Kermit, it's not even lapped. Just flattened on some wet or dry sandpaper over a piece of glass. We'll see how air tight it is when I get the engine running.

My biggest problem with air leakage is usually around the rotary valve and its housing. I tried to get a really close fit on this one, so we'll see.

Chuck


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## kustomkb (Feb 5, 2010)

Great progress Chuck.

Its looking pretty sweet!


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## cfellows (Feb 5, 2010)

Maryak  said:
			
		

> Chuck,
> 
> I really like your engine. :bow: :bow:
> 
> ...



Thanks, Bob. The prop will be more for aesthetics and I will probably not have much of a pitch on it. I'm more interested in having some weight and not so much on actually pulling air. Having said that, I don't want it to look to bulky. 

I found a piece of cold rolled steel plate, 6" x 6" x 3/16" thick, so I'm planning to carve the whole thing out of that one piece. Going corner to corner, I should get a prop just under 8" from tip to tip. I'm still thinking about the best way to transfer the pattern to the steel blank. Once I figure that out, I'll use the band saw to cut the rough X shape out, then use the belt sander to shape the profile of each blade. At that point, I may put a small twist near the base of each blade. Next, I'll grind the air foil using an angle grinder, then shape and smooth with a file. We'll see how all that looks before I worry about final smoothing and polishing. 

Chuck


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## ref1ection (Feb 5, 2010)

Very nice looking engine. Can't wait to see it all come together. I also feel that you can't go wrong on the cylinders, tapered or not, still gonna look right.

Ray


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## cfellows (Feb 5, 2010)

Got the propeller cut and smoothed to the profile today. For some reason, it looks like it's made of aluminum in the photo, but it's actually cut from 3/16" thick cold rolled steel. The prop is 8" diameter from tip to tip.

Here's the prop with the paper pattern still glued on. This is after I cut it out on the bandsaw and sanded up to the lines on my belt sander. I've got it mounted in the mill on my rotary table getting ready to mill out the thinner sections connecting the blade to the hub.







Heres a picture with the milling done and some filing also done to smooth up all the edges.






Now I have to noodle over what and how much will be done to it to finish it.

Chuck


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## putputman (Feb 5, 2010)

Daaang Chuck, yesterday you were just talking about the prop and today here it is. :big: ;D :bow:

Can't wait to see & hear this one run. Always fascinated with your air engines.


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## Deanofid (Feb 5, 2010)

Nice start on the prop, Chuck. It's quite a hunk of iron, and should give a fine flywheel effect.

Dean


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## cfellows (Feb 5, 2010)

Well, I screwed up my courage, clamped the prop in my vise and put a 20 degree twist on each blade. Think it tuned out pretty good. Now I have to pull out the grinder and grind the proper airfoil curve on each blade.


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## joe d (Feb 5, 2010)

Chuck

That's looking good! Do NOT get you fingers in the way of that one :big:

Joe


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## cfellows (Feb 5, 2010)

joe d  said:
			
		

> Chuck
> 
> That's looking good! Do NOT get you fingers in the way of that one :big:
> 
> Joe



Thanks, Joe. Yeah, it's a bit of a brute. I'm planning to knock off all the sharp edges and corners so hopefully if I do get my fingers in the way, it'll just be a bruise.

Chuck


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## cfellows (Feb 5, 2010)

This is actually going faster and easier than I thought it would. It's all hand work at this point, but I forgot how much I enjoy the hand work. I did a bit of wood carving a few years ago and, of course, a lot of wood carving as a kid. You can really get lost in this kind of stuff. I understand how GBritnel can get wrapped up in the file work.

I ground and shaped the leading edge of the prop blades in the last hour and a half or so. I used my 2" belt grinder to do the rough shaping, followed by draw filing to even it up and remove the grinder marks, followed by a light sanding with 220 grit wet or dry paper. Tomorrow, time permitting, I'll shape the trailing edges and smooth them up.


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## cfellows (Feb 6, 2010)

Here's the prop, pretty much finished. Still have to balance it and decide on a finish. I've got it sitting on the engine crank to give an idea of size & scale. My first impression is the prop should be bigger. Any opinions? Regardless, I'm probably not going to make another one.  :big:






Chuck


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## slick95 (Feb 6, 2010)

Chuck, 

Actually the diameter looks just right. Typically a four blade prop would be shorter/smaller (like yours) diameter due to the added load from the additional blade(s). Also, a polished prop is generally only polished on the front (side away from the engine) and painted flat black on the other side (reduces reflection to the pilot).

Looking real nice. You're putting in some significant shop time in the this project. Thank for the pics...   

Jeff


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## Metal Butcher (Feb 6, 2010)

cfellows  said:
			
		

> Here's the prop, pretty much finished. Still have to balance it and decide on a finish. I've got it sitting on the engine crank to give an idea of size & scale. My first impression is the prop should be bigger. Any opinions? Regardless, I'm probably not going to make another one. :big:
> Chuck



That,s a mighty fine lookin prop there Chuck! What you could use is a spread water tower style stand with a wooden base, hint ,hint. ;D

And it looks plenty big to me.

-MB

-MB


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## stevehuckss396 (Feb 6, 2010)

cfellows  said:
			
		

> Here's the prop, pretty much finished. Still have to balance it and decide on a finish.




send it out for chrome!!!


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## Maryak (Feb 6, 2010)

Chuck,

Lovely job on the prop, (and the engine too). I agree with others. It looks proportional, (making it a pee pee i.e. proportional propeller), to the engine. :bow: :bow:

Best Regards
Bob


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## NickG (Feb 8, 2010)

Looks brilliant! :big: :bow:


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## stevehuckss396 (Jul 3, 2010)

Hi Chuck!!

I am going back thru some of the old threads. Where are you at with the engine? Is there any plan to get back to work on this one? Just wondering.


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## cfellows (Nov 28, 2010)

If you get the idea I'm jumping all over the place with my projects, you're right. I'm kind of working on different things as the mood hits me. This is an opposed 4 cylinder compressed air engine that I started a couple of years ago. Yesterday I completed the larger timing gear and got it installed. Today I made the pistons. I am very close to having this engine running (assuming it runs! :-[). I'm intent on getting this thing finished before I go on to something else, so I may actually get it running within the next few days.











Chuck


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## NickG (Nov 28, 2010)

I remember this build well Chuck, the propeller is amazing and it's going to sound fantastic! Can't wait! :bow:


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## swilliams (Nov 28, 2010)

Looks great Chuck. Hopefully she runs without too much messing about

Steve


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## stevehuckss396 (Nov 28, 2010)

This is great! I was hoping you would get back to this one!!

If/when it runs, will there be plans available? I really like this engine and wouldn't mind having one for myself (hint)

Steve


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## cfellows (Nov 29, 2010)

Tonight's the night!


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## cfellows (Nov 29, 2010)

Well the good news is, it runs. The bad news... well, there is no bad news! It runs great! Self starting, nice sound. Here's some pictures while I'm waiting for the video to finish uploading.





















Video should be up in half an hour or less.

Chuck


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## cfellows (Nov 29, 2010)

And the video...

[ame=http://www.youtube.com/watch?v=SYugS_vvPrQ]http://www.youtube.com/watch?v=SYugS_vvPrQ[/ame]

I will have to make a little nicer video after I've completely finished the engine.

Chuck


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## GailInNM (Nov 30, 2010)

Very nice looking and a beautiful sound, Chuck. A very nice addition to your collection. 
 Thm: Thm:
Gail in NM


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## ozzie46 (Nov 30, 2010)

Looks and sounds great Chuck. Seems like the prop is balanced fairly well too.

  Ron


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## Metal Butcher (Nov 30, 2010)

Chuck, congratulations on you successful build! :bow: :bow: :bow: :bow: :bow:

I love the styling, and it sounds just like a full size small airplane engine.

When you first started the project it caught my attention, I'm glad you were able to get back to it and finish up.

-MB


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## joe d (Nov 30, 2010)

Chuck

Great sound, great looks... what's not to like?

congrats! Thm:

Cheers, Joe


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## kjk (Nov 30, 2010)

It's a beauty Chuck. Are the slave exhaust valves built in to the exhaust pipe flanges?


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## dreeves (Nov 30, 2010)

Chuck, Great sound on the engine. Im back to my Liney rv2 just got to finish up the intake system. It looks like you used the ball valve on this engine am right.

Dave


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## kustomkb (Nov 30, 2010)

Wow, "nice little pop" is right! Beautiful job Chuck!!


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## arnoldb (Nov 30, 2010)

Well done Chuck - it looks great and sounds awesome :bow: :bow:

Kind regards, Arnold


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## spuddevans (Nov 30, 2010)

Looks and sounds just great, well done.

Tim


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## seagar (Nov 30, 2010)

Congratulations Chuck,wonderfull work . :bow: :bow: :bow:
I would love a plan for Christmas. Thm:

Ian (seagar)


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## Artie (Nov 30, 2010)

Chuck, thats a beauty, it sounds surprising like an aero engine... im impressed! ;D


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## ref1ection (Nov 30, 2010)

I had all but forgotten this build. Great to see it completed as it looks and sounds terrific.

Ray


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## stevehuckss396 (Nov 30, 2010)

That was fast!! What did you have left to finish? Great engine!


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## NickG (Nov 30, 2010)

Well done Chuck, it's brilliant as usual! :bow:


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## swilliams (Nov 30, 2010)

very nice engine Chuck, sounds great too, Congrats :bow: :bow: :bow:


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## cfellows (Nov 30, 2010)

Many thanks to all for the kind words. For those that asked, the engine does use a ball bearing slave valve which is located in the head. Here is a diagram:







The performance and sound of the engine can be varied by changing the type of spring. A heavier spring lets the engine run faster and makes for a beefier sound. Right now, the springs I used are pretty light weight making for slower speeds with less air pressure.

Chuck


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## ttrikalin (Nov 30, 2010)

what a sound! 
What do you mean you want to do some more work? Looks pretty finished to me. :hDe:

take care, 

tom in MA


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## cfellows (Dec 4, 2010)

Been thinking about the stand for my engine and started work on it tonight. I made it from a piece of magnesium I've had laying around for a few years. Gotta say, that stuff is a dream to machine. It's (a lot) lighter than aluminum and it doesn't gum up or stick to your bits at all. Nice, crisp shavings and beautiful finish, even with carbide end mills. It does cut slower than aluminum with my 4 x 6 bandsaw, not sure why. Yeah, I know it can cause a pretty exciting fire if ignited, but the kindling point is 883 deg F. so it's not likely to spontaneously combust. Too bad it's not more available.

This piece will mount to the underside of the engine, hollowed side down.






Chuck


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## Blogwitch (Dec 5, 2010)

Very nice build and runner Chuck, just what we come to expect from you nowadays.

You've really cracked that system of operation now, the skies' the limit.


John


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## cfellows (Dec 7, 2010)

Here's another video of my opposed 4 engine. As you can see, I've finished the base for it. From the bottom up, the first piece was made from 3" channel iron. The next piece was carved out of chunk of aluminum, 1 3/4" x 3/4" x 4" - the holes are 3/8" diameter. The vertical piece and the piece supporting the engine are both made from magnesium. Again, I really like machining that stuff.

[ame=http://www.youtube.com/watch?v=nFs24p4jYvQ]http://www.youtube.com/watch?v=nFs24p4jYvQ[/ame]

Had a bit of excitement in the shop yesterday. I was grinding and polishing the steel base for the engine on my belt grinder, and I forgot that I had been grinding and sanding the magnesium pieces on the same belt grinder. A few seconds after the sparks start flying from the steel piece, I had a wall of fireworks move across the top of my bench. there was quite an accumulation of magnesium dust on my bench top and it made quite the sparkler. Luckily there was nothing flammable on the bench top and the fireworks didn't really generate enough heat to cause any damage, but it was breathtaking for a few seconds.

I also had one of the silver solder joints on my built up crankshaft let go a couple of days ago. I cleaned it up and locktited it back together. I also pinned it with a 3/32 roll pin. I think it will hold now.

Chuck


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## Metal Butcher (Dec 7, 2010)

Hi Chuck. Sure sounds sweet. And I really like the stand, its very creative!

I would love to build one. Hint, hint. ;D

-MB


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## ozzie46 (Dec 8, 2010)

Neat! Sounds like J-3 taxiing out for take off.  :big: :big: :big:

  Ron


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## Groomengineering (Dec 8, 2010)

Hi Chuck.

A great running engine and fireworks, what more could you ask for. :big:

Cheers

Jeff


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## CallMeAL (Dec 11, 2010)

Wonderful work. Unique design and great presentation.

Thanks for all your efforts.


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## Deanofid (Dec 11, 2010)

What a good sound, and a great runner, Chuck. Really aircraft-like in looks, too. Nice job!


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