Two Engines in One or Elmer Gets a Makeover

[Sshire]

Two Engines In One or Elmer Gets a Makeover

This is a cautionary tale about what happens when you decide to build an engine but don't like some of the design.

Elmer Verburg is probably looking down on this build and either thinking, "Hey, what's wrong with square blocks as cylinders?" or laughing uncontrollably. Or, perhaps, both.
Let me explain.

Elmer's Radial has square cylinders. Not actually a square cylinder, but a round hole bored in a square chunk of metal. Now a bunch of you are saying, "If it's good enough for Elmer..."
It bothered my sense of design. I wanted a round hole in a round chunk and if that isn't enough, I wanted some of those cooling fins in the round chunk. There probably isn't a time in the foreseeable future when this will run on anything but air so the cooling fins are nothing more than another skill to add on to the very short list of skills I've acquired in the last 11 months since I've started this hobby. (My 5th grade teacher would have cringed at that fine example of a run on sentence.)

Not willing to learn enough CAD to create a model, I jumped right in. In the process of "design-as-you go", I've created enough parts for, at least two engines. Hence the title of this build.

Since the only thing I've changed from Mr. Verburg's plans are the cylinders, let's begin there. This isn't where I actually started, so you may notice that some parts, like the crankcase, pistons, rods, etc. seem to have magically materialized. Believe me, they did not and I will get to the build steps for those in due course.

The simplest approach seemed to drill and bore the cylinder, as Elmer intended, in a square chunk of 6061. Then put it in the 4-jaw and make it round. So I did. Bad idea. The air passage was too close to the outer diameter of the cylinder to cut the cooling fins.

Aha! I'll offset the bore to leave more metal where the air passage is drilled.

Bad idea #2. Now there's not enough metal for the four through mounting holes. Plus ( or minus) the depth of the cooling fins is too wimpy.

Only one thing to do. Go upstairs and make a double-shot of espresso.

After thinking about this, I came up with two possible solutions (well, three actually but I disregarded, "quit and make more espresso.")
Plan #1. Increase the diameter of the cylinder (duh)
Plan #2. Forget the through holes for mounting and air passage and do them externally.
So I did both.

After turning a larger 6061 piece to 1.1" and boring the cylinder, I mounted it on a 5C expansion collet and milled grooves with a .125 ball end mill for the external hold down pieces.
The air passage hole near the bottom will also be a milled groove.

The cylinder, still on the collet, went over to the lathe and I cut grooves with a Warner grooving tool. I spaced the grooves equally with a dial indicator measuring the lengthwise travel and the depth with the DRO.

Three finished cylinders and they got to this stage in only 5 days of making "extra" cylinder variations.

My thought for the hold down pieces was to use .125 brass tubing. Cut to length, drill and tap 2-56. I would Loctite short pieces of 2-56 SHCS in one end and screws through the cylinder head at the other.

Now I needed to set of steps to make all of the tubing exactly (or as close to "exactly" as I can make them.)
So
1. Cut 12 pieces close to the finished length
2. Use a collet stop set for the length I needed. The 5C collet will be in a collet block.
3. Vise stop on the mill so I can return the collet block to the same position.

Clamped a straightedge to the jigsaw table. Fine tooth metal cutting blade in place. Cut all 12 pieces of .125 tubing about .1 over finished size. Deburred the ends.

I put one of the pieces into a ⅛" 5C collet, set a collet stop inside, put the whole thing into a square collet block. The block then went in the mill vise and I milled the end to split a line I had marked on the setup piece of tubing. I measured the piece in the 1"-2" micrometer and found that I was .009 over. Easy enough the use the DRO on the mill to move X over by .009. Now I locked everything down and did the remaining 11 pieces.

Done and all the same size.

And now, a short digression.

The crankcase has 24, 2-56 threaded holes to be tapped. Never passing up an opportunity to bolster the economy, a Tapmatic RX30 mysteriously appeared in the shop. After some research and a very nice discussion with an engineer at Balax (they make wonderful form taps), and some discussion here on the forum about tapping oils ( some of which, apparently, are quite "fragrant"), thread percentage and other mysterious topics, I did a few test holes to set the torque. A butt-clenching period followed while I tapped all 24, 2-56 holes in about 3 minutes with nary a broken tap. I was prepared to break a few in testing, so I had ordered 4. I still have 4.
End of short digression.

So here's where we are.

Stay tuned for the next part where I try to figure out how to get air into the cylinder and make more espresso.

Best
Stan

 

[arnoldb]

That's a great start Stan Thm:

Somehow I don't think Elmer would mind; in fact, I think he'd approve

Kind regards, Arnold

 

[rleete]

Nice. Metalbutcher did one with round cylinders several years ago, and I started to copy him. So, you aren't alone in thinking square cylinders should be made round.

 

[rebush]

Stan: Looks like it's going to be a good one, I'll enjoy watching you're progress. One thing baffled me ??? about the same time that a Tapmatic RX30 mysteriously appeared in the shop did you notice a decrease in the balance of the check book. If not you need to share that trick with the group. Roger

 

[steamer]

Great work Stan!

Dave

 

[Don1966]

Great work Stan I will be following along also. That tapmatic must of hit your checkbook hard all the ones I priced were way more then I can justify.

Don

 

[Sshire]

Thanks for the kind words. I came upon ( what I think) is an elegant solution to piping the air to the top of the cylinder. I'm putting the pix together for tomorrow's installment. Of course I won't know how elegant it is until I get to the point of trying to make it run.
About the Tapmatic. You bet it wasa expensive. I originally bought one on EBay. The previous owner had cut the stop rod to a 1" length which made it unusable. I was going to make ( or buy) a new part but decided to return it as it generally looked tired.
I bought the new one from Enco with a coupon and spare change. Everyday when I come into the house, all pocket change goes into a large can. I've been doing this for year's and it's amazing how it adds up. Long story short, with the coupon, the current crop of change ( about a years worth and a bit more, I had my RX30.
Stay tuned and thanks
Stan

 

[Troutsqueezer]

The cylinders are looking good. I am also building this engine although taking my own sweet time. Like Metal Butcher, I am making the cylinders round. Air supply is through a separate pipe. I'll post a pic in the next day or two.

Trout

 

[Blogwitch]

Stan,

I keep repeating this over and over, if you want to make yourself a unique engine from plans, as long as you stick to the basic critical dimensions, bore, piston stroke, porting etc, then everything else is fair game.

You can usually cut away half of the rest of the engine, support plates etc, without causing any undue concern.

Yours is starting to look very well indeed.

John

 

[bearcar1]

Hey Stan, you never know, Elmer might be watching and saying to himself "now THAT'S how I should have done it" ;D I like the slugs round, as opposed to being square (pie are square you know) *sorry Marv* :big: Should be a sweet looking engine when you are done.

BC1
Jim

 

[Sshire]

Trout
Anxious to see your photos. Im never above "borrowing" ideas.

John
I have absolutely read your posts about making unique versions and they obviously stuck. Look at the many, many variations of every engine posted here. Some people build beautiful engines precisely to the drawing while others just follow their own path.

Jim
It's a shame that Elmer can't see what he started with that book. Thousands and thousands of Elmer's Engines.

Stan

 

[Sshire]

Part 2 of

Two engines in one - I need air


When we last left our intrepid engine builder (after the magnificent engines I've seen here and at Cabin Fever, I'm not calling myself a Machinist), he was mulling over how to get air to the top of the cylinders.

I looked at a lot of other engines, build threads and photos that I took at Cabin Fever. Since my cylinders no longer have a through hole to carry air from the crankcase up to the cylinder top, it seemed the external piping is the only way. Due to the position of the already-drilled port in the crankcase, the "pipe with a 90 degree bend at the top" technique is not going to work.

After staring at the cylinders, and liking the look of the four half-embedded hold down tubes....Aha! Mill a fifth groove in the cylinder in line with the air port in the crankcase for another piece of .125 brass tubing and send the air through that. Not a new idea, MetalButcher used an air tube to the head in his build which I just found.

First, it would retain the consistent look of the cylinders
And
Second, I couldn't think of another way.

Milling the extra groove only required precisely placing the groove at a 45 degree angle to any of the existing four grooves. I already had a through air hole in the cylinder.

And I get to use that Shars 360 Degree Universal Bevel Protractor that was in Rick's thread a few months back. I have used it on a few other projects and it was how I learned to read a Vernier scale.

I drilled a hole at 45 degrees in the base of the 5C expansion collet for a locating pin, put the cylinder on the collet and ran a 1/16" brass rod through the port in the cylinder and into the locating hole. Then it was into the collet block, onto the mill and cut the groove with the same .125 ball end mill I had used for the other grooves. Quoting some other folks on this forum, it "worked a treat."

Now the question was, Alright, I've got air from the crankcase into a brass tube. How to seal it and how to port it to the cylinder?

Looking at the cylinder heads, I thought that I could do a .125 hole that the top of the air pipe could go into, a hole that would allow air into the cylinder, and a cross port to connect them.

I drew a 2X C.O.C. and measured, drew, erased and scratched out until it looked like it might work.

The length of the pipe was calculated by measuring the distance from the top of the crankcase to the bottom of the cylinder head and adding a bit for the counterbores that I would put in the head and crankcase.

The mill DRO was as useful as always in precisely positioning the air pipe hole and the center port.

Centering the head for drilling the cross port.

The cross port drilling went perfectly and I cleaned out the hole with this brush that I get from my dentist. You can also get them in the pharmacy in 10 packs.

Back to the collet block to cut the top of the tubing so that air can actually get into the cross port.

Back to the .125 end mill for the crankcase counterbore

The next group of photos are the test fit. I found that .125 tubing ranges from a measured .124 to a bit over .126. Another learning experience. Picking the larger size allowed me to put it in the lathe and use a 400 grit paper wrapped around a parallel until I got a very close fit in the crankcase and cylinder head counterbores. I'm hoping that this will be enough of a seal but, if not, Loctite should work.

The cross drilled hole will have a Loctited plug.

That's all for today. In the next installment, Elmer wants the fixed connecting rod to be perfectly aligned with the central hole in the hub. (he actually said "Try to make the rod centerline pass through the hub centerline.") Try? What happens if you fail to do so can't be good, so I made a fixture.

Best
Stan

 

[Troutsqueezer]

That is almost exactly how I did my intake pipe. There's not too many options to choose from, simple ones, at least.

 

[Sshire]

Trout
Were you able to get a good seal?
Best
Stan

 

[Troutsqueezer]

I haven't sealed it yet. You can see from the pics, I'm not too far along. I do have a tight fit. Considering using Locktite, but the kind you can release without too much trouble.

I drilled the port hole from the rear and used a set screw to seal the hole.

When I'm done, this will be a highly-polished version with the stand of my own design.

 

[miner49r]

Stan,
The square cylinders on Elmers Radial are a big turn off for me too. When fall comes and I get back to working in the shop the radial will be my next build after I finish #44. I will be watching with great interest.
Alan

 

[Sshire]

Trout
Looks great! I usually wait to polish until i have all parts completed. Otherwise, I scratch something and have to start polishing all over again.
Very nice idea with the screw to plug the hole.
The fun never ends.

Best
Stan

 

[Sshire]

Brick wall

Well I have a bunch more build pix and made all of the parts.
If I hold my thumb over the end of the cylinder, the piston stays in and when my thumb comes off, the piston slides out. I'm told this is a good thing.
I put the engine together, hooked up air and.....nothing.
It turns with nary a bind by hand, feels smooth. I "ran it in" on the mill for about two hours and still won't run on air. I switched the airbrush compressor for the shop compressor. Won't run. Doesn't even feel like it is trying.
I took the heads off and air is coming out of each air tube to the appropriate cylinder at the right time.
I read an old Madmodder post (pretty sure from Bogs) about the rotary valve being very touchy. I took a few thou off the valve housing to tighten up the tolerance until the valve wouldn't move then with 600 grit, sanded down the valve until it just moved again. No luck.
There seems to be a lot of air coming out the exhaust port, but even holding my thumb mostly over it to keep more air in the valve housing, nothing happens.

If anyone has another suggestion I'll certainly try it. I've reached the end of what I can figure out.
Help.

Thanks
Stan

 

[mzetati]

Providing I've found the correct intake (not sure about that) air should go the red way. Any chance it goes the blue way too, or the green way on wrong cylinders?

Removing the valve cover and applying air to the correct spot with the valve in the correct position should let You have it turning 120deg at the time, it may help solving the issues.
Removing the heads and closing each one with fingers at the right moment should do too, and will let You check for eventual unexpected flows on the other cyls.
HTH
Marcello

 

[mzetati]

Well, I see there's no valve cover, the valve housing being the cover itself.
This is an interesting engine, I still cannot figure how it would work.
Worth building.
Marcello