# Time for a Radial



## cfellows (Jan 13, 2011)

Figured it's about time for a radial engine. It'll be compressed air using my ball slave valve arrangement. Operation will be 4-stroke using a 2 lobe, coaxial cam turning at 1:4 ratio to the crankshaft. Here's the beginnings of a concept picture:







I started out rough cutting a hexagon out of 1.25" thick aluminum tool plate with my 4 x 6 band saw.  Then used a 1" arbor to chuck it up in my 5C hexagonal block. I used a 2" indexable carbide mill to face off each of the 6 faces.
















Wound up with what seems like a respectable hexagon 1.25" thick and minor diameter of 2.443" (Yeah, I over shot the target diameter of 2.500" :-[)






Chuck


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## b.lindsey (Jan 13, 2011)

Looks like a great project Chuck, and already off to a good start too. Will look forward to seeing it come together.

Bill


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## 1hand (Jan 13, 2011)

Chuck

I'm on board!  Whats the bore going to be?

Matt


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## dreeves (Jan 13, 2011)

Chuck, 

Just when I thought I was done with radials you had to hatch this plan. well Im in I need another :big: :big:

Dave


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## Brass_Machine (Jan 13, 2011)

Woot. Another one to watch! Go Chuck go!

Eric


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## cfellows (Jan 13, 2011)

b.lindsey  said:
			
		

> Looks like a great project Chuck, and already off to a good start too. Will look forward to seeing it come together.
> Bill



Thanks Bill, don't have all the design details worked out yet, but that's pretty normal for my builds.



			
				1hand  said:
			
		

> Chuck
> I'm on board!  Whats the bore going to be?
> Matt



Hey Matt, it'll be 5/8" bore x 3/4" stroke (give or take a few thou )



			
				dreeves  said:
			
		

> Chuck,
> Just when I thought I was done with radials you had to hatch this plan. well Im in I need another :big: :big:
> Dave



Thought you needed another project, Dave... 8)



			
				Brass_Machine  said:
			
		

> Woot. Another one to watch! Go Chuck go!
> Eric



Thanks, Eric, I'll try to keep it exciting!

Chuck


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## Metal Butcher (Jan 13, 2011)

Chuck. I'm looking forward to watching your build.

It's gonna be a dandy!

-MB


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## swilliams (Jan 13, 2011)

Looks like a fun build Chuck. I'll be watching

Steve


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## doubletop (Jan 14, 2011)

Chuck

I'm watching as well

Pete


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## cfellows (Jan 14, 2011)

I finished a prototype of one of the cylinders today. As you can see in the drawing, I've made a change in the design. Instead of using 2 long studs on either side of the cylinder to hold the cylinder and head in place, I decided to make the cylinder and the head one integral piece and use 4 SHCS's to faster the cylinders to the crankcase through a square flange in the base of the cylinder. I don't like the look quite as much, but it will be easier to build.
















I still have a little work to do to the cylinder before I'm finished with it.

Chuck


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## Brass_Machine (Jan 14, 2011)

That's a good looking cylinder. Whats the external diameter on that?

Eric


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## cfellows (Jan 14, 2011)

Brass_Machine  said:
			
		

> That's a good looking cylinder. Whats the external diameter on that?
> 
> Eric



Thanks, Eric. The external diameter is 1.125". The square base is also 1.125" on a side. The fins are 1/8" deep. Overal length of the cylinder and head is 2".

Chuck


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## cfellows (Jan 16, 2011)

I made a few more chips today. I'm proceeding cautiously since I'm still designing as I go along. The first thing I did was radius the edges of the fins and the head on the cylinder. I was trying to make a radius form tool but decided in the end I was overthinking the problem. I ended up just using a small file and sandpaper to make the radiused edges. I also started doing some milling on the crankcase. I may leave the outside profile this way or I may go ahead and finish radiusing the parts of the crankcase between the cylinders like the drawing. Finally, I started work on the master connecting rod spool. It was my first foray into machining 12L14 steel (a piece I inherited from Shred, I might add). Lovely stuff to work with.
















Chuck


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## ttrikalin (Jan 16, 2011)

Beautiful! :bow: :bow: :bow:

I admire you for designing it as you go. Undoubtedly a result of extensive experience and superior mechanical understanding and intuition. 

Take care, 

tom in MA


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## cfellows (Jan 16, 2011)

ttrikalin  said:
			
		

> Beautiful! :bow: :bow: :bow:
> I admire you for designing it as you go. Undoubtedly a result of extensive experience and superior mechanical understanding and intuition.
> Take care,
> tom in MA



Thanks, Tom. Mostly, I just find it hard to stay out of the shop. I get impatient and also have an easier time visualizing in the solid. Unfortunately, sometimes I get the steps out of sequence and make life difficult for myself.

Chuck


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## zeeprogrammer (Jan 17, 2011)

Very nice looking cylinders Chuck.

And I like your philosophy too.


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## cfellows (Jan 25, 2011)

Managed to squeeze in a little more time on the radial. I'm designing and making different components to see a)if I can, and b)whether they'll fit together as planned.

In these pictures, I'm making up the components of the connecting rod assembly. There is still a lot of finish work to do on the pieces, but there's some tips here I thought worth sharing.

First picture is an overall shot of what I'm trying to get to. You can see the master rod in the upper left. The 5/16" curve at the bottom fits snugly against the center hub of the spool. 






The three little pins are 1/8" diameter and are shouldered down on the end to accommodate a 2-56 thread. The pins slide through a 1/8" hole in the top of the spool and thread into 2-56 holes in the bottom of the spool. The pins will be cut off flush with spool and a screwdriver slot cut on the top end. This was the method Rudy Kouhoupt used on his 5 cylinder radial air engine.






So the first problem is to shoulder down the end of each pin to .085" for a length of 1/8" I wanted to use my minilathe for accuracy and to take advantage of the freshly sharpened tangential tool bit.






Since I don't (yet) have a carriage stop, I engaged the lead screw and used my leadscrew crank on the left end of the lathe to control the length of the cut. Since the leadscrew is 16 TPI, 2 full turns advanced the tool bit 1/8".






The next trick was to cut a 2-56 thread (squarely) on the shouldered end of the 1/2" long pins. So, I mounted the pin in the chuck of my tapping guide and laid the die, mounted in a die holder, on the table. This worked very well to cut the threads squarely.











Chuck


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## Captain Jerry (Jan 25, 2011)

Chuck

Thats a good looking design. Your 4 cycle style valving ought to add a lot of interesting detail. How do you plan to set up the gearing?

Jerry


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## cfellows (Jan 25, 2011)

Captain Jerry  said:
			
		

> Chuck
> 
> Thats a good looking design. Your 4 cycle style valving ought to add a lot of interesting detail. How do you plan to set up the gearing?
> 
> Jerry



Thanks, Jerry. Current thinking is that the valve gearing will be on the back of the engine, although I would prefer the push rods to be on the front of the engine. I also haven't made a final decision on the gearing. I'm currently leaning toward the option of using a 9 tooth pinion on the crank and 3 separate 18 tooth cam gears, 1 for each cylinder. The other option is to use 2 sets of 12/24 tooth gears with the primary, 12 tooth gear fixed to the crank and the final, 24 tooth gear freewheeling on the crank. This latter option would yield a 4:1 ratio and would require a cam with 2 lobes 180 degrees apart. The second option is more interesting and kind of apealling but requires more space.

Chuck


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## cfellows (Jan 25, 2011)

I'm pretty pleased with way the crank assembly is turning out, especially the 3 shouldered screws that hold the connecting rods in. This fiddly little pieces tend to give me problems, but I took my time and they turned pretty good. 











I plan to do some additional milling on the center spool to remove some weight. I may also do some light shaping of the connecting rods so they look less clunky.

Chuck


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## kcmillin (Jan 25, 2011)

Looking good chuck. 

I like your reverse tapping method. Gonna have to remember that one.

Kel


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## cfellows (Jan 26, 2011)

Today I shaped the Connecting Rod Master Spool (is there a proper name for this piece???) I used a 1.25" end mill to cut the curved part. As you can see, I used the crankcase as a fixture to hold and position the spool for cutting.












I'm going to leave the connecting rods alone for now. Next I'll be working on the crankshaft.

Chuck


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## Foozer (Jan 26, 2011)

Curvy, I like curvy, and you make it look so easy :bow:

Robert


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## krv3000 (Jan 27, 2011)

HI well i love it all ready can not Waite till its dun    bob   :bow:


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## T70MkIII (Jan 28, 2011)

Chuck, just backtracking a few posts and a slight thread drift - do you usually run your mini lathe without the gear cover on, and why the handle on the leadscrew? I see you've taken the chuck guard off too - very annoying piece of kit, and I'm thinking of doing the same (wearing safety glasses, of course).

Great looking radial so far!


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## cfellows (Jan 28, 2011)

T70MkIII  said:
			
		

> Chuck, just backtracking a few posts and a slight thread drift - do you usually run your mini lathe without the gear cover on, and why the handle on the leadscrew? I see you've taken the chuck guard off too - very annoying piece of kit, and I'm thinking of doing the same (wearing safety glasses, of course).
> 
> Great looking radial so far!



I leave the gear cover off for a couple of reasons. First, I never use the change gears on the minilathe. And, second, so I can use the crank I attached to the lead screw on the left. The crank is used for measured and repeatable movement of the carriage (1/16" per turn). I mounted it on the left so I wouldn't have to modify the leadscrew on the right side.

As far as the chuck guard goes, I've never bothered to attach it. As you say, it just gets in the way.

Chuck


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## T70MkIII (Jan 28, 2011)

All sounds good. Thanks, Chuck.


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## cfellows (Jan 28, 2011)

I hogged out the crankcase today and mostly finished the other two cylinders yesterday. Still have to round off the edges and fins on the cylinders and crop the base flanges down to size. If you like exercises, try centering a six sided piece on 3 opposing sides in a 4 jaw chuck. Had me scratching my head a few times.






You can begin to get an idea of what it's going to look like:






Chuck


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## Metal Butcher (Jan 28, 2011)

HI Chuck, your project its coming along real nice.

Your machined surfaces look great!

I can't wait to see it all together.

-MB


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## cfellows (Jan 28, 2011)

Thanks, MB.

Here's the last post for today. I got a good start on the front part of the crankcase. I still need to do some rounding, drill holes for the attaching screws and taper the nose piece. The crankshaft will be 5/16" running in some small ball races I had on hand. The bearings races are 5/16" ID and 1/2" OD, so they are not very heavy duty. I probably could have gotten by with a 1/4" crank, but 5/16" sounded better. I'm also considering drilling a radial pattern of holes in the front part so the inner workings of the crankshaft will be visible when the engine is running. Does anyone think that's a bit over the top???
















Chuck


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## 1hand (Jan 28, 2011)

Chuck,

I really like how it flows together, from the crankcase into the cyls.

Nice work!
Matt


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## compspecial (Jan 29, 2011)

Chuck, you are an inspiration, this engine has an elegance like the old Anzanis. I must confess I was absorbed by the pictures and assumed it was going to run on air, but when I read the text more carefully and found its a four stroke WOW its gonna sound great. hope you can find room for the valves in those heads


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## vascon2196 (Jan 29, 2011)

Great looking engine Chuck...looking forward to seeing it in action!

Chris


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## rleete (Jan 29, 2011)

Holes in the front, or even a clear cover is recommended. Gotta see the moving bits to make it more interesting! Why go to the work to shape your "master crank thingie" ( <-- technical term) if you're just going to hide it inside?

Hint: use cut up soda/beer cans to protect those cylinders when chucking in the lathe. Much less work than polishing out the jaw marks afterwards. Plain old masking tape works, but limits holding power a little.


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## cfellows (Jan 29, 2011)

1hand  said:
			
		

> Chuck,
> 
> I really like how it flows together, from the crankcase into the cyls.
> 
> ...



Thanks, Matt. Unfortunately, the cylinder flanges on the bottom 2 cylinders will be trimmed, so there will be a step there like the top cylinder shows.



			
				compspecial  said:
			
		

> Chuck, you are an inspiration, this engine has an elegance like the old Anzanis. I must confess I was absorbed by the pictures and assumed it was going to run on air, but when I read the text more carefully and found its a four stroke WOW its gonna sound great. hope you can find room for the valves in those heads



Thanks, compspecial. The engine will be run on air, but the valving will make it 4 stroke in operation, like the the opposed 4 engine that I built.

http://www.homemodelenginemachinist.com/index.php?topic=11641.30



			
				vascon2196  said:
			
		

> Great looking engine Chuck...looking forward to seeing it in action!
> 
> Chris



Thanks, Chris, you and me both!



			
				rleete  said:
			
		

> Holes in the front, or even a clear cover is recommended. Gotta see the moving bits to make it more interesting! Why go to the work to shape your "master crank thingie" ( <-- technical term) if you're just going to hide it inside?
> 
> Hint: use cut up soda/beer cans to protect those cylinders when chucking in the lathe. Much less work than polishing out the jaw marks afterwards. Plain old masking tape works, but limits holding power a little.



Thanks, rleete. I get in a hurry sometimes and wind up making things harder for myself later on. With the amount diet cola I drink there is no shortage of empty soda cans waiting for the recycler!

Chuck


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## cfellows (Jan 29, 2011)

Did a little softening and finishing work today. This first series of pictures shows the radial set of holes being drilled which will hold the front crankcase cover to the main crankcase. I thought the group might like to see the indexing fixture I have built into my drill press. I picked up this round table at a scrap yard a number of years ago. It already had the 24 holes in the sides (well, two holes on opposite sides are missing, but I work around those). I had to turn the spigot down to fit my drill press. Then I bored out the center to fit a 5C collet. Finally, I made an indexing pin and lever from some strap I had on hand.
















And here are some pictures of the engine in its current state:


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## Groomengineering (Jan 30, 2011)

Chuck, that indexing fixture is amazing!! I love it!! Makes me wonder what else you have stashed away... :big:

Your engines coming along very nicely. I just love the look and sound of a radial engine.

Cheers

Jeff


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## SBWHART (Jan 30, 2011)

Looking real well Chuck ;D enjoying following your thread.

Stew


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## Blogwitch (Jan 30, 2011)

Sorry I haven't commented before Chuck, I've been rather waylaid by other things.

It is coming along very nicely, just like all your other engines have done, and I am sure you will have everything 'just so' by the end of it.

John


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## Noitoen (Jan 30, 2011)

Nice build ;D. I was looking at your connecting rod assembly and I thought that on a radial engine, one of rods should be solid ???.
On your drill press, if the index pin's arm has 3 holes, you wont miss the 2 on the table


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## picclock (Jan 30, 2011)

Hi Chuck

That looks like a really neat build. In your first post on this engine you said 

"It'll be compressed air using my ball slave valve arrangement."

Any chance of an explanation of how this works or a pointer to a drawing ?

Many thanks

picclock


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## cfellows (Jan 30, 2011)

Groomengineering  said:
			
		

> Chuck, that indexing fixture is amazing!! I love it!! Makes me wonder what else you have stashed away... :big:
> Your engines coming along very nicely. I just love the look and sound of a radial engine.
> Cheers
> Jeff



Thx, Jeff. I've always tended to build as many of my own tools and fixtures as I can. For many years, I couldn't really justify the cost of commercially available stuff.



			
				sbwhart  said:
			
		

> Looking real well Chuck ;D enjoying following your thread.
> 
> Stew



Thx, Stew, always enjoy hearing from you.



			
				Bogstandard  said:
			
		

> Sorry I haven't commented before Chuck, I've been rather waylaid by other things.
> 
> It is coming along very nicely, just like all your other engines have done, and I am sure you will have everything 'just so' by the end of it.
> 
> John



Hey, John, I was wondering last night where you'd been. Hadn't seen any postings from you on the board anywhere. Hope everything is OK. Thanks for your words of encouragemet!



			
				Noitoen  said:
			
		

> Nice build ;D. I was looking at your connecting rod assembly and I thought that on a radial engine, one of rods should be solid ???.
> On your drill press, if the index pin's arm has 3 holes, you wont miss the 2 on the table



Thx, Noiten. One of the connecting rods is solid. The inner end has a concave radius which fits solidly against the hub of the spool.



			
				picclock  said:
			
		

> Hi Chuck
> That looks like a really neat build. In your first post on this engine you said
> "It'll be compressed air using my ball slave valve arrangement."
> Any chance of an explanation of how this works or a pointer to a drawing ?
> ...



Thx, picclock. I've developed several different versions of the slave valve arrangement and if you do a search of this site on slave valve, you'll get a number of hits. The arrangement I'm planning for this radial engine is here:

http://www.homemodelenginemachinist.com/index.php?topic=3026.0

Chuck


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## picclock (Jan 30, 2011)

Hi Chuck

Many thanks for the valve info, that's a really neat arrangement. :bow:

I love the simplicity of only having 1 port in the cylinder head, and the compact nature of the arrangement. Pure genius.

Best Regards

picclock


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## nh_eng (Jan 30, 2011)

Chuck,

I am new to the model making scene, and I am in awe of your skill. I really enjoy seeing your setups, as from my point of view, the biggest challenge I have in any machining operation is how to set it up/fixture it. They say that you learn by your mistakes, and if there is any truth to this I should be learning by leaps and bounds, because I am making mistakes at an incredible rate.

Keep up the good work and thanks for the great postings - you are truly an inspiration to me.

Thanks for sharing,

Paul


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## Brass_Machine (Jan 30, 2011)

I love the way it is shaping up. Looking good Chuck... I am enjoying it! :bow:

Eric


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## wareagle (Jan 30, 2011)

Chuck, you have a nice looking radial taking shape. I am eager to see this one running!

BTW Slick indexing fixture you have. Incredible find! May have to "hotrod" the drill press...


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## cfellows (Jan 30, 2011)

Thanks, everybody, for the kind words.

I spent most of today doing remedial work. Paying the price for getting in a hurry earlier on. I discovered the cylinder openings in the crankcase were .010" closer to one edge than the other. And, they varied in size by + / - .005". So I set the crankcase up again and enlarged all the openings so they were centered and equal in diameter. Of course, that meant that the spigot at the bottom of the cylinders was now too small, so I had to build them up by soldering short lengths of brass pipe on them and re-turning them to fit the new openings. Now they are all consistent and fit nicely. I feel much better now! 8)

So, finally some pictures with the engine in an upright position. They always look better when you get some fasteners in place. 

Yeah, I know, including the picture of the B-17 which adorns my shop wall is a bit over the top!












The overall diameter of the engine is a tad over 6". Here's a picture with a soda can for size reference:






Chuck


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## swilliams (Jan 31, 2011)

Looking great Chuck. The color from the brass cylinders gives a really nice touch.

Steve


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## tel (Jan 31, 2011)

Nothing to be ashamed of there, is there! Top notch job!


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## vascon2196 (Feb 2, 2011)

Those fasteners accent the engine nicely. That engine looks like it's going to scream!


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## ttrikalin (Feb 3, 2011)

the brass cylinders are fantastic.


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## cfellows (Feb 4, 2011)

Thanks guys, for the continued vote of confidence. Took a break from the small rotary table to get some work done on the crankshaft for my radial. Here it is, clampted into a v-block while the loctite cures (Thanks for the v-block idea, MB). Tomorrow I'll drill it out and insert a roll pin. A taper pin would be better, but I ain't got none of those nor do I have the needed reamer so a roll pin will have to suffice.






Chuck


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## vascon2196 (Feb 5, 2011)

This Loc-tite idea keeps the crank pin straight while curing?

Just last night I Loc-tited a crank pin into a crank disc but left it sitting flat on my toolbox.

Interesting....


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## cfellows (Feb 8, 2011)

Well, I've reached a momentary impasse on this project. The build has been super smooth and I'm very pleased with the fit and finish of everything so far. Now I have a decision to make - whether to use overhead valves with push rods and rocker arms or a simple rotary valve.

The overhead valves with rocker arms is probably 5 times as complicated. The added parts are 3 of each, valve lifters, push rods, rocker arms, valve actuators, extra ball bearings, and rocker arm mounts. And, routing the air supply to the top of each cylinder is more complicated. The head is more complicated also. On the positive side, there would be little to no air leakage between "firings" and visually, the engine would be much more realistic (and appealing).

A rotary valve, much like I used on my Opposed 4, is way simpler and the engine would look much less cluttered. But air leakage is much harder to control and there are many fewer visible moving parts which is less appealing from a model engine standpoint.

In the meantime, my shop time is stalled until I can make a decision. What to do, what to do...

Chuck


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## jct842 (Feb 9, 2011)

over head valves. Have seen a lot of your work Chuck so I know you can do it. I just love watching an out side valve train work. John


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## coopertje (Feb 9, 2011)

Very nice build Chuck! Hope to do a radial too in future, as so many other things...... Dont mind to work, but it just cost too much of valuable hobbytime ;D

Looking forward to your progress!

Regards Jeroen


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## rleete (Feb 9, 2011)

cfellows  said:
			
		

> Now I have a decision to make - whether to use overhead valves with push rods and rocker arms or a simple rotary valve.



One of each?


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## cfellows (Feb 9, 2011)

rleete  said:
			
		

> One of each?



Oooh, can't even imagine such a thing... but, then again...


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## cfellows (Feb 13, 2011)

I've decided to go ahead with the overhead valve arrangement on this engine. It will be 4 stroke in operation and will use a combination of my slave exhaust valve and a ball inlet valve similar in operation to the Liney Halo radial. High pressure air will be presented to the top of the cylinder where it will be stopped by a ball bearing check valve. To "fire", a valve stem which is an interference fit with the ball valve will open the valve by pushing it to the side when the stem is depressed. This will admit air into the head where it will push a second ball bearing to the side, exposing a hole which leads into the cylinder. This will push the piston in a manner similar to my other slave valve engines.

So here is the first series of pictures on work done the past couple of days. Here is one of the cylinders with the valve stem hole drilled down through the top into the and a 1/8" hole drilled radially all the way through.











Here I've milled a flat on both the intake and the exhaust sides to receive the input and exhaust pipe flanges. I've also enlarged the hole to several different sized. The intake side is 7/32" so the 3/16" ball bearing is a very loose fit. This allows air to flow around the ball bearing when it is unseated by the valve stem. Then the hole is stepped down to 5/32" where it passes around the valve stem. Finally, on the other side of the valve stem, it opens up to 3/16" so the slave ball bearing is a close sliding fit.






Inlet side, showing the step down to 5/32" around the valve stem hole.






This shows the inlet side on the left and the exhaust side on the right.






I will be attempting to emulate the layout of the Anzani radial engine as close as I can, perhaps without as much detail. Here, you can see that on the rear side of the cylinders, there is a tube going up the back into an elbow at the top which leads into the cylinder head. This is the air/fuel inlet manifold.






On my engine, the high pressure air supply will go up a tube on the rear of the cylinder and into an elbow, similar (or at least as close as I can get it!) to the Anzani. So, in the next series of pictures, I am making my version of the elbow.

I'm milling all three manifolds in one piece of brass and will cut them apart later. Here I'm using a 1/4" end mill with radiused corners to cut out the sides.






Next I use corner rounding bitto round off the top edges.






And, the finished manifold before cutting in to three separate pieces.






Here they are cut apart and the holes for the tube have been drilled. There is also a hole on the bottom which will lead into the cylinder head.






And, here they are with tube soldered on, mounting holes drilled and pretty much ready to mount, well, after I pickle them and get them polished up!






I'm still figuring this thing out as I go along, so progress is a little slow.

Chuck


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## SBWHART (Feb 14, 2011)

Comming along nicely Chuck.

Working on your own engine design certainly stimulates the old brain box.

Looking forward to the rest of the build

Stew


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## Deanofid (Feb 14, 2011)

Wow, it sure is looking good, Chuck. Really nice!


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## steamer (Feb 14, 2011)

I'm really liking the brass......Haven't figuried out the valve thing yet...but keep going...I'll catch on.

Dave


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## cfellows (Feb 17, 2011)

Thanks for the comments, Stew, Dave, Deanofid. After a lot of noodling and mind changing, I think I've worked out the details for the back end of the engine. The cam will have two lobes, 180 degrees apart and will turn at 1/4 the speed of the crankshaft. The cam will be coaxial to the crankshaft with double reduction gears 12/24, 12/24 to arrive at the 1:4 reduction. So here are a couple of pictures of the back crankcase cover. Here I'm machingin the back side and the timing gears will be inside the hollowed out part. The valve lifters will be set into the ring that has been formed. Further maching will be done on the ring and, in the end, it won't be a ring. Hard to explain what I have in mind, guess you'll just have to wait and see it. 












The ring part, btw, is 1 7/8" OD x 1 3/8" ID.

Chuck


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## cfellows (Feb 19, 2011)

Got some work done since the last post. Here are some pics of the timing gears. The two larger ones are 40DP, 24 teeth, 1/8" thick and about 6.5" OD. The smaller gears are on the 3/8" rod and haven't been parted off yet. They will be 12 teeth and are .35" OD. 






One of the 12 tooth gears will be loctited onto the crankshaft and drive a 24 tooth gear below it. The 24 tooth gear will be ganged to a 12 tooth gear, which will, in turn, drive the other 24 tooth gear which turns freely on the crankshaft. The double lobed cam will be attached to the second 24 tooth gear on the crank and will turn at 1/4 the RPM of the crankshaft.

Chuck


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## cfellows (Feb 21, 2011)

Got all the timing gears done. I decided to make the primary gear and shaft one integral unit rather than trying to loctite or solder the gear to a shaft. The second and third gears are ganged and soldered together. Then, the fourth gear rides on the crankshaft at 1/4th the speed of the crankshaft. The cam will be attached to the fourth gear, probably with a mechanism which allows for timing adjustments.





















Chuck


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## Captain Jerry (Feb 22, 2011)

Hi Chuck

That is really nice work! I was wondering how that first gear was going to work out on the shaft. Making it integral with the shaft is a great solution.

I have been watching this build with a lot of interest. You do a great job of explaining the design options and solutions. Your ball valve and slave exhaust valve is really interesting.

I have been kicking around the idea of implementing your valve on one of my oddball engines and have a few questions about the details. I'm not particularly concerned about making a four stroke operation and the sound is secondary. I'm mostly interested in avoiding the sealing problems associated with a rotary valve on the crankshaft.

The engine will be a two cylinder double-acting design with 90 degree offset for self starting. Its a little more complicated in that there will be no rocker arms. The valve actuator rods (push rods) will be in direct contact with the cam, sort of like an OHC design. 

Is sealing around the push rod a problem? Does the push rod need a separate return spring or is the spring tension against the ball enough? How well would this valve work for self starting and low RPM? What should the cam profile look like? Would a conventional eccentric work?

Lots of questions, I know. Hope you don't mind the distraction.

Jerry


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## cfellows (Feb 22, 2011)

Jerry, thanks for the kind words and your interest in the ball slave valve. Let me first say that my slave valve arrangement is mostly designed for the sound it makes and is not particularly efficient. However, to answer your questions, sealing around the push rod is not particularly important as long as the fit isn't really sloppy. You may get a little leakage, but you'll hardly notice since most of the air is going into the cylinder. Depending on which of my design's you're referring to, and there are many, you probably won't need a spring on the push rod. The valving arrangement works fair for self starting engines, but isn't 100%. For my engines, I like a very sharp cam profile with a short lift, but that's mostly for sound. A conventional eccentric would work OK as long as the inlet valve is completely closed by bottom dead center of the piston.

Since controlling air leakage is your first priority with self starting being a close second, let me suggest the following vave design. It runs quietly, can be made with virtually no air leakage, and produces a powerful engine. You could substitute a ball valve for the poppet valve if you want and it would work well.






As you can see, it uses a single push rod and a cam with a little higher lift than usual. As the cam (or eccentric) first engages the push rod, it closes the exhaust port. Futher motion of the push rod then opens the inlet valve and provides the power stroke. I don't have a video of this engine and have since modified it to use a slave valve, but it did run very well and I think it would be more suitable to your application.

Let me know if you have questions.

Chuck


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## cfellows (Feb 23, 2011)

I think I've wrestled all the remaining design questions to the ground so the worst part is over. Today I made the back timing gear cover or back cover for the back crankcase cover which is confusing, I know. I've also drilled and tapped the holes.
















Next, I'll be cutting away a significant part of the back cover and the sides of the ring to look something like this:






Chuck


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## rleete (Feb 24, 2011)

I saw the first pic and was just about to ask what happened to the open design. Glad to see you're exposing the inner workings.

Any plans for a clear cover, to keep out dust (and curious fingers)?


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## cfellows (Feb 24, 2011)

I'm not seeing any clear covers in finished engine. Leaving it open aids in the lubrication process. I don't think there will be anything dangerous to little fingers.

Today I got started opening up the timing gear cover. Milling, filing and sanding are not my favorite operations, but it did turn out OK.

Here you can where I've got the back part of the crankcase in a 4 jaw chuck on a rotary table. I'm using a 1/4", 2 flute end mill to do the hogging, taking .050" per pass.






Here you can see the whole lash-up.






For the last pass of the cut, I've switched to a ball end mill to give me a radius at the bottom.






Here I've moved over and am cutting out the waste on the other side.






I've finished up all the work with the end mill.






Several operations later, I've removed the rest of the waste, and filed and sanded to get it prettied up.






The next series of pictures shows the part on the engine in various positions so you can kind of see what it's going to look like.





















Still have a little refining and tuning to do, then I'll get on with cam...

Chuck


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## vascon2196 (Feb 24, 2011)

How do you do all of this so fast!!!

Great job Chuck!

Chris


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## kanvelchoudhary (Feb 24, 2011)

hi chuck
no doubt this project is as good as all previous ones and more challenging. 
nice job done.
i hope after this you might think about starting you glow plug engine design. 
you left it in mid way
will you be uploading the drawings and designs as you did of your 4 opposed cylinder compressed air engine.


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## cfellows (Feb 25, 2011)

vascon2196  said:
			
		

> How do you do all of this so fast!!!
> 
> Great job Chuck!
> 
> Chris



Thanks, Chris, it doesn't seem like it's going very fast to me, but, I am retired so I have quite a bit of time to spend on it.



			
				kanvelchoudhary  said:
			
		

> hi chuck
> no doubt this project is as good as all previous ones and more challenging.
> nice job done.
> i hope after this you might think about starting you glow plug engine design.
> ...



Thanks. I will get back to the hot tube engine eventually. I need to do some test builds of injector pumps and injectors to see if I can get them to work. Then, I'll get serious about the engine.

As to plans for this engine, I will probably put together some drawings.



			
				BigOnSteam  said:
			
		

> Very nice work Chuck.
> Thanks for sharing it.



Thanks!

Chuck


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## cfellows (Feb 25, 2011)

Tonight I made the cam for my radial. I was able to use my new rotary mounted chuck and it worked great. The cam is made from a 1.125" diameter brass disk about 5/32" thick. The lobes of the cam extend 1/16" so the disk diameter that is left is 1" diameter. In this first picture I have started cutting the disk. I advanced the disk .030" into the cutter, then turned the chuck with 28 turns of the crank. This rotated the cam 140 degrees. Then I raised the cutter above the work and turned the crank another 8 turns, rotating the the disk 40 degrees before lowering the cutter back into the disk.  Then I repeated the procedure to cut the other half of the cam. I made two more passes advancing the part .020" then another .015" for the final pass.






Here is a picture of the whole setup:






Here is a picture of the arbor setup I used to hold the disk for milling:






Here is the timing gear and cam setup as it will sit in the engine:











I still have to round off the cam lobe tips and fasten the cam to the final gear in the gear train. I will probably cut a radiused slot in the cam disk so I will have some timing adjustment available to me.

Chuck


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## tel (Feb 26, 2011)

Very pretty work Chuck - especially the gears!  Thm:


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## cfellows (Mar 24, 2011)

After a week of being sick and a couple of weeks working on projects deemed higher priority by the chief financial officer, I finally got some work done on this engine. I completed the profile on the cam disk, attached it to the final timing gear and made and fitted the valve lifters. Running the assembly with my drill proved it to be a smooth working assembly. I think this part is going to be particularly interesting to watch when the engine is running slow.











Chuck


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## cfellows (Mar 26, 2011)

The work I finished yesterday and today doesn't look like much, but I am happy to report that all the engine internals inside the crankcase are completed. Also completed is all the timing gear and cam assembly including the valve lifters. All that remains are the pistons, the the rocker arm assemblies, push rods, air supply hookups, and exhaust pipes. Fit and finish to this point all seem as good as I've ever done and the engine turns over smoothly with a drill, albeit, still a little tight.

Here you can kind of see the master connecting rod and a bit of the crank assembly.






Here's another shot of the cam gears and cam, lots of oil on everything.






The front of the engine, showing the beefy, 5/16 crankshaft.






And and overall side shot, again showing the cam and cam gears.






Later, I'll post some pictures of the engine disassembled to better show off the internals.

Chuck


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## agmachado (Mar 26, 2011)

Hi Chuck,

That's very cool... or better saying, absolutely fantastic! :bow:

Cheers,

Alexandre


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## swilliams (Mar 27, 2011)

Really nice Chuck, great creativity with the design :bow: :bow:


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## Noitoen (Mar 27, 2011)

Nice work. You could make a transparent cover for those gears and cam


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## vascon2196 (Mar 27, 2011)

Sweeeeeeeeet!!!!!


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## cfellows (Apr 15, 2011)

After a bit of a hiatus while I worked on another project, finishing my latest telescope in time to view Saturn which is now appearing in the late evening sky, I've gotten back to work on the radial. Here are some pictures of work being done on the push rod assemblies. The push rods are 3/32" drill rod, but I didn't have a 3-48 die, so I turned the ends of the push rods down to .081" so I could thread the ends 2-56. Here is the beginning of the 3 clevises which will attach the push rods to the outboard end of the rocker arm. These are made from 3/16" square steel and I used a 3/32" slotting saw to cut the slot in the end.







And here are the (almost) finished clevises threaded on to the end of the push rods with the 2-56 lock nuts in place:






Still have to drill the holes in the ends of the clevises to accept the clevis pin.

I'm getting pretty close to having this engine running. I still have to complete the pistons, exhaust manifolds, and the rest of the valve assemblies. Also gotta figure out what I'm going to do for a prop. I would like to make another steel prop for it's flywheel attributes. Still noodling around what I want to do.

Chuck


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## kcmillin (Apr 15, 2011)

Lookin good Chuck! 

I can totally understand your desire to see Saturn. It is an absolutely beautiful sight to see through a telescope. It puts the solar system in perspective, to actually see what is indeed an enormous object and not just a spec of light, amazing. 

BTW, are the rings at an easily viewable angle? I should really dig out my scope.

Kel


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## cfellows (Apr 15, 2011)

Thanks, Kel. Here is a link to a picture of Saturn taken about a month ago. The angle of the rings are pretty good. The scope I just built is a 10" F6 which is great for planetary viewing. The largest scope I ever built was a 16" F4.5, but the city lights just create too much light noise for a scope that size.






Chuck


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## cfellows (Apr 20, 2011)

Here's a picture of the roughed out flywheel. Looks suspiciously like a propeller, huh? It's made from 3/16" thick steel and is about 10" long. I wanted the look of the old wooden propellers, but also needed the weight of the steel. Still got some shaping to do, but don't want to remove too much of the weight. Also want to keep it nice and rounded on the ends and edges so if a finger gets in the way, it won't remove said digit.






I'm getting close now. Got the pistons and the exhaust manifolds done. As soon as I can sort out the air inlet manifold assembly, I'll be ready for a test run.

Chuck


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## Chaffe (Apr 20, 2011)

Looking good chuck, When you say it will be a four stroke does that mean it will induct on a downward stroke, compress on an upward stroke, "fire" by admission of air on a downward stroke, and finally exhaust on an upward stroke? is this more efficient than just a simple two stroke design where air is admited on the downstroke and exhausted on the up stroke? cant wait to see a video of this bad boy running! keep up the excellent engineering.


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## cfellows (Apr 20, 2011)

Chaffe  said:
			
		

> Looking good chuck, When you say it will be a four stroke does that mean it will induct on a downward stroke, compress on an upward stroke, "fire" by admission of air on a downward stroke, and finally exhaust on an upward stroke? is this more efficient than just a simple two stroke design where air is admited on the downstroke and exhausted on the up stroke? cant wait to see a video of this bad boy running! keep up the excellent engineering.



Thanks for the kind words.

The four stroke operation merely means that it has one power stroke followed by 3 freewheeling strokes ("fire", up, down, up, "fire", etc.). It isn't more efficient than a 2 stroke, but my goal isn't efficiency, it's to make an engine that runs on compressed air but sounds like a 4 stroke internal combustion engine.

Chuck


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## cfellows (Apr 21, 2011)

Here's a few pictures of the engine assembled. Still noodling around with the air supply manifold. I did finish up shaping and smoothing the propeller. Everything else is operational at this point. Soon as I get the air supply figured out and built, she'll be ready to run. Then I have to figure out a stand and add a few finishing touches.





















Chuck


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## b.lindsey (Apr 22, 2011)

Chuck, this has really come together beautifully!! Can't wait to see it all mounted up and running....bet its gonna sound as good as it looks!!!

Bill


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## vascon2196 (Apr 22, 2011)

FANTASTIC!


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## steamer (Apr 22, 2011)

It's got the great "Monosaupe" look with the lone valve.....it looks awesome!

Dave


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## cfellows (Apr 30, 2011)

It's finished! Watch for more photos and a video in the finished projects section later tonight.






Chuck


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## T70MkIII (May 1, 2011)

Congratulations, Chuck - looking forward to seeing the video.


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## dreeves (May 1, 2011)

Chuck,

Looking great I cant wait to see it run.

 :bow: :bow: :bow:

Dave


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## Chazz (May 1, 2011)

Wow, excellent work Chuck, a fine addition to any collection. Thm:

Kudos too to your presentation, I'm still trying to figure out 1. Remember the camera, 2. Remember batteries for the camera, 3. Remember to take pics, and 4. Trying to figure out what pics should be taken\posted. :-\

Cheers,
Chazz


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## vascon2196 (May 1, 2011)

Awesome!!!!!


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