Opposed 4 Compressed Air

[cfellows]

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

 

[stevehuckss396]

I like it!!

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

 

[rleete]

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

 

[cfellows]

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

 

[radfordc]

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

 

[cfellows]

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

 

[cfellows]

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

 

[Bernd]

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.

 

[cfellows]

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

 

[stevehuckss396]

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

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.

 

[cfellows]

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

 

[Brass_Machine]

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

 

[steamer]

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

Dave

 

[Maryak]

Go Chuck,

Neat trick with the boring head :bow:

Best Regards
Bob

 

[cfellows]

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

 

[putputman]

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.

 

[cfellows]

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

 

[cfellows]

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

 

[ksouers]

This is going to be interesting, Chuck.

Following along.


Kevin

 

[NickG]

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

Nick