Ron's Rudy's Radial Five

[crueby]

Those look great. Really like the way you painted before cutting the fins, great end look.


 

[Kim]

What Chris said!  The cylinders and black-lined fins look really cool!

Kim

[RReid]

In the vernacular of the times when radial engines were common in aviation - Thanks Fellas!

Just drilling and generally piddling around today. And being careful not to knock the paint off.

[RReid]

The cylinder mounting flange was drilled using the same drill jig that was used to drill the matching tapped holes in the crankcase. A similar jig was made for drilling and tapping the cylinder tops. These also gave me a way to hold the work without marring the paint on the cylinders. Here it's held in the vise while one cylinder top gets tapped.


And with the flanges drilled I could do a trial assembly and a progress shot.


With that fun out of the way I turned my attention to what Rudy calls the rod bearing. Brass for a change – WooHoo!


The rod bearing is drilled and reamed on centerline to ride on the crank pin, and will get five steel pins screwed in around its circumference that act as the connecting rod journals. Those pins will be the next job.

[Kim]

Great work, Ron!  Love your progress shot.  It's always fun to see all the pieces together  

Kim

[Don1966]

   


 
Don

[joe d]

Looking good Ron!  I like those "where we are so far" shots too!

Cheers, Joe

[galland]

Great looking engine Ron. Earlier when you were figuring out what fin spacing you wanted someone asked what the holes in the fins were for. For what its worth they are not needed in these engines as they will run just as good without them. This is a miniaturized 9 cylinder and runs fine.
   Gary

[RReid]

Thanks guys, I really appreciate your comments!

Earlier when you were figuring out what fin spacing you wanted someone asked what the holes in the fins were for. For what its worth they are not needed in these engines as they will run just as good without them. This is a miniaturized 9 cylinder and runs fine.

That's very interesting, Gary, good to know. I'm wondering if Rudy put them there mainly for acoustic effect, as the valve controlled "secondary" exhaust would apparently be functionally adequate alone?

Great looking engine too, by the way!

[crueby]

Sounds (pun intended) like a great experiment once its running - wrap some string or something around over the holes and see what difference it makes.
 

[RReid]

Sounds (pun intended) like a great experiment once its running - wrap some string or something around over the holes and see what difference it makes.

Yeah, my thought exactly. Well, not exactly. I'm thinking maybe some tape, or an appropriate rubber band. Or some elf snot.

[RReid]

Since my last update I've gotten journal pins done and fitted to the rod bearing. I used some nominal 3/32” (0.09375”) 304 stainless I have on hand, simply because it has a nice surface, but is actually slightly undersize at 0.093”, which is the dimension Rudy calls out on the plans to fit into a drilled #42 (0.0935”) hole.


Before I could cut the screwdriver slots in the ends though, I had to pause to make an arbor for a 1/32” slitting saw, with a 3/8” shank to fit into a collet.


Then I could almost duplicate the picture JC posted earlier today in his MEM Corliss build.


In addition, the beginnings of the connecting rods have been roughed out and drilled. A little shaping on the mill and they should be ready for action.

[Kim]

 

You're making good progress, Ron!
Kim

[RReid]

Continuing with the connecting rods, the rough cut blanks were screwed to a piece of ali from the scrap pile and milled to length and width.


The master rod gets a concavity milled into its inner end to match up with the hub of the rod bearing, which serves to hold it rigidly perpendicular to the crank axis. Lacking a 5/16” end mill for the job, I used a 5/16” wood boring bit instead. Aluminum is nice that way.


To round off all the other rod ends, I used one screw of the holding fixture as a pivot, used a machinist's clamp as a handle, and rotated each against a spinning endmill by hand.


The last shaping step was to neck down the web between the pins to produce a dog bone shape. I could have used the holding fixture for this too, but I wasn't all that happy with it, so I set all five up at once as shown below. The downside of doing it this way is the sharp inside corners left by a flat end mill, which can be a breeding ground for cracks. The machinist (me) checked with the consulting engineer (I), and I convinced me that with this being a lightly stressed compressed air engine, it would be perfectly fine. Of course a ball nose end mill could be used to mitigate this question, but I don't have one of those on hand either. Cheapskate!


Here are the finished rods and rod bearing assembly.




And finally, a short silly video of the Radial Engine HappyBottom Dance. The movement looks jerky because I'm just turning with my fingers while also holding the camera. Mechanically it's nice and smooth.
<a href="https://www.youtube.com/watch?v=4FdfSpPXKCk" target="_blank">http://www.youtube.com/watch?v=4FdfSpPXKCk</a>

[Kim]

Gotta love the happy dance!   
Looking good, Ron!
Kim