# 6 Cylinder Radial



## ejcheli (Feb 26, 2014)

Well, I'm new to all this but I really have enjoyed starting building model engines. I built my first engine last month and now I am attempted to build a radial based on the design of* crueby* found: 



6-cylinder radial engine build log

I will be receiving a degree this spring in Metal Fabrication so I have a bit of machining experience and have access to CNC and manual lathes and mills making these projects possible. I will post pictures when able.

Eric


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## ejcheli (Feb 26, 2014)

Here is my first motor. Simple and plain but runs really well and has really good tolerances.


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## ejcheli (Feb 26, 2014)

Well here are all the parts I have completed as of today. For anyone who is familiar with crueby's engine, they will note some differences as I am taking the liberty of changing or adding a thing or two here and there but the heart and operation of the engine is entirely crueby's design.


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## crueby (Feb 27, 2014)

Hi Eric,

Looks like a very good start - loooking forward to seeing it progress!

Chris


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## ejcheli (Feb 27, 2014)

Thanks! Here is what I accomplished today.


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## ejcheli (Mar 4, 2014)

Remade my counterweight but used mild steel this time. It will fit perfectly but I don't like the super close pictures as they show every little defect hehe...

Keep in mind the end mill facing cuts across this piece were done with a .125" end mill, so its a really small part!


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## ejcheli (Mar 5, 2014)

Got all the cylinder blanks turned out today. Made a fixture as well which I will put into the CNC mill tomorrow and bore out the piston and valve shafts and also drill all the holes for the cylinder caps. Seems like cheating but I gotta make this a speedy as possible due to a massive amount of official class projects I have to build as well....


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## ejcheli (Mar 6, 2014)

Got all of the piston heads done today and cut out the engine block but its not finished yet obviously.


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## necchiom (Mar 6, 2014)

Very professional work: with compliment!


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## ejcheli (Mar 6, 2014)

I wasn't able to bore out the cylinders today like I thought but I made the previously mentioned parts on the machines that were available. The piston heads were actually all done on a CNC lathe which means they are all perfectly identical to each other with a 0.4975" diameter. I chose this because it was under .500" by 2.5 thousands but I wasn't sure how much clearance I should have for the pistons. I thought a .001" clearance may be too tight so my options at this point (unless I make more pistons) is a cylinder shaft of .499, .500, or .501" so... 1.5, 2.5, or 3.5 thousands clearance. What would you guys suggest for best performance?


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## ejcheli (Mar 6, 2014)

Here are my current plans of all the parts I built and plan on building. While basically the same as cruebys, these include my modifications if anyone is interested. I am doing this because I know how awesome free plans are. I will post higher resolution and cleaned up versions when I have completed this build as these plans have already undergone dozens of modifications and undoubtedly will receive a few more.


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## ejcheli (Mar 7, 2014)

Bored out all my cylinders today, the fixture worked great! I went with a bore of 0.499" and it worked great. When the bottom of the shaft is plugged and I dropped the piston in, it just slid slowly down... beautiful.


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## ejcheli (Mar 10, 2014)

I touched up some parts today and figured out a couple more things resulting in me posting page 1 of my plans in the download section found here: 6 Cylinder Radial. I believe that everything on this page should be 100% accurate.


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## ejcheli (Mar 24, 2014)

Well.... turns out I goofed up the cylinders. I suspected I may have when I finished them weeks ago but I've been on spring break and just got back into the shop today and really checked them out. I noticed some odd sounds during the CNC process and had to tighten the bolts mid way through and thought by some miracle I'd be ok, but it was as I feared... the cylinder bolts had backed themselves out and had become loose enough for many parts of the drilling and boring operations to be off center or worse. So... I spent most of my day today remaking 6 new cylinder blanks. These 6 are absolutely perfect as far as I'm concerned and will be bolted into a new fixture sometime this week. I plan on using some loctite and checking the bolts every step of the way this time.

Anyway, I hope to get this project completed within 2-3 weeks. We shall see...

Eric


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## ejcheli (Mar 27, 2014)

Here are my NEW cylinders... they are nearly perfect and I'm completely satisfied with them. The pistons slide down beautifully and every dimension that matters is spot on. I don't have pictures of the rest of my progress at this point but basically everything is done except for the connecting rods!


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## johnmcc69 (Mar 27, 2014)

I think it's looking great! That's going to be nice.

 John


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## ejcheli (Mar 31, 2014)

Thanks John.


Well, today I got quite a few pictures of the progress to date. Its really starting to look like something now!

Btw, the bottom picture of the faceplate is not finished, its just rough cut right now but I wanted to see how it fit and decided to share the pic.


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## ejcheli (Mar 31, 2014)

45 degree intake/outlet on cylinder


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## ejcheli (Apr 1, 2014)

Starting to put it together... its beginning to look like something.


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## ejcheli (Apr 2, 2014)

Got my motor mount nearly finished today.


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## ejcheli (Apr 9, 2014)

Was hoping to be done this week but its looking like it will be delayed until next week. Here is what I got done today.


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## ejcheli (Apr 22, 2014)

Very close now, only thing left is to finish the connecting rods and make the cylinder heads. I am certain it will be completed this week. Whether or not I can get it running by the end of the week I don't know, but every single part will be manufactured and I will try to get some pics tomorrow.


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## ejcheli (Apr 22, 2014)

Well here it is. Its not finished as I still need to make the cylinder heads and install the pistons and valves and then I still need to clean up some of the parts as I'm sure some of you will note scratches, grime, and other undesirable things. I just posted these pics to show you guys what its starting to look like.


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## ejcheli (Apr 23, 2014)

Sooo close now. I got all the pistons connected and turned out all the cylinder heads today. Just gotta drill the holes to mount them to the cylinders and finish the valve connecting rods. I'd be done tomorrow but I am touring a Boeing facility so... looks like next week, _again_.


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## ejcheli (Apr 25, 2014)

Every single part has now been machined. Its time to assemble and see if it runs!


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## ejcheli (Apr 25, 2014)

Its now assembled (1.5 hrs later) and its amazing! It freely turns with no binding issues whatsoever! Now to hook it up to some air and see if it goes...


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## ejcheli (Apr 25, 2014)

Here is a video of me turning it by hand.

http://youtu.be/kinSKJP0A2U


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## crueby (Apr 25, 2014)

SOOOOO close to seeing it go - gotta be some air around somewhere.....

What kind of hoses/connectors are those on the infeeds - have not seen that type before. Looks to be a modular and/or quick disconnect type?


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## ejcheli (Apr 25, 2014)

crueby said:


> SOOOOO close to seeing it go - gotta be some air around somewhere.....
> 
> What kind of hoses/connectors are those on the infeeds - have not seen that type before. Looks to be a modular and/or quick disconnect type?




There is in fact, at my grandfathers which is where I just was and it RAN!!!  

For about 10-20 seconds before it froze up , as the valves on cylinder 1 (master) and 4 (opposite) broke at the first thread on the .125" valve. I sort of expected it because I knew cylinder 4 could bind up if forced, but when I was spinning it by hand it never bound up so I figured it was ok. Guess not.

However, this isn't gonna get me down, if anything I'm stoked because I saw it run! I will turn out two new valves on Monday and in the meanwhile think about how to address the cylinder 4 issue. I believe the master rod broke because when cylinder 4 jammed, it put the master under pressure and snapped... or the master broke and jammed 4 before everything stopped working....thats my theory anyway.

About the air supply, 

These are called "push to connect" fittings and they are fantastic, found: 
http://www.amazon.com/gp/product/B0065RBIMQ/?tag=skimlinks_replacement-20

The hose was just some 1/4" OD hose I found here:
http://www.amazon.com/gp/product/B00B04UAIC/?tag=skimlinks_replacement-20here.


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## ejcheli (Apr 25, 2014)

So upon disassembly, everything is fine except those two valves, which leads me to suspect either A: It was running too fast (~25psi) through it didn't seem so, or B: The master valve rod failed and cyl 4 broke as it seized or vise-versa.

Next test when repaired will be far more cautious, I just didn't expect it to take off the first time air was applied. I stood there in shock for 10 sec or so in awe and then it all came to an end hehe.


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## crueby (Apr 26, 2014)

Great that it took off first try - you must have had a good setup on the valve positions. Mine did not take much pressure to run - you have 2 or 3 pistons pushing all the time with a reasonable size bore, so lots of power is there. If the pistons/valves are a good close fit, it only takes a few pounds to get going. One thing to double check on the valve rods is that they have the ability to rotate on the hub far enough, make sure the corner of the end does not rub on the hub .

Thanks for the link on the fittings - had not seen ones like that before.

Looking forward to a video of it running!


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## ejcheli (Apr 27, 2014)

Thanks for the info and I will get a video as soon as I can!

Also, my plans are now uploaded to the downloads section.


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## johnmcc69 (Apr 28, 2014)

Nice job! It look great!

& thanks for sharing the plans!

John


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## ejcheli (Apr 28, 2014)

Thanks!


Well, today I made some more valves, thought I'd figured it out, test ran it at school and it worked for another ten to twenty second run and bound up, then broke. Just cylinder 4 though as I was being careful. I then made another valve and tweaked some more stuff and brought it home to work on it. I spent 3 hours turning this engine to perfection and boy oh boy it spins soooo smooth now! No binding whatsoever!! 

There were multiple reasons why it was binding up before but the biggest was probably the fact that the pistons and valves were not lined up with the cylinders. Don't know HOW that even happened as I was sure I had already figured that out. Then there was a slight issue with the valve bushing spinning freely and some rods were slightly binding as crueby mentioned might be happening in a previous post.

Anyway, I would have a video of it running for you all today if I wasn't such a dummy and snapped another valve at home completely by accident.  So.... I will be making another valve tomorrow (getting good at that!) and probably a few extra that I'll never need but at this point... I'm not so sure heh.

Eric


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## crueby (Apr 28, 2014)

Mistakes are part of the game - make enough and you will have learned a lot (as long as it is not the same one over and over!  :wall.

One other thing to make sure of is to put in a little oil on the pistons/valves - brass parts moving on brass parts can add a lot of friction.


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## ejcheli (Apr 29, 2014)

A learning experience it definitely was!! 

I lubed it up and got everything working perfectly today... it runs like a dream!! Had a close call though... I barely caught it but the little set screws that I used as pins for the valve rods were backing themselves out! I have now applied locktite and am proceeding to set up a video of it running... will post later this afternoon.

Eric


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## ejcheli (Apr 29, 2014)

Here is a video of it running!

http://youtu.be/76om16YeguQ

Its short cause I didn't have much time but I will get more eventually. At least anyone interested can see it run now.

Eric


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## crueby (Apr 29, 2014)

Very nice!! Ticks over nice and smooth. th_wav
Congrats!


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