Model of a Bessemer Hot Tube Oil Field Engine

[cfellows]

Thanks, Rob.

Today I finished up the water jacket. I started with 2" OD DOM steel tubing. After turning both ends square, I mounted the piece in my milling machine vise to drill the holes for the threaded bushings. First a 5/16" hole...

Then I used a 3/8" diameter end mill to create a shelf.

Here's a couple of pictures with both bushings silver soldered into place.

Here I've cleaned it up and threaded the bushings with a 1/4" model pipe taper thread.

The hot water will exit out the top, front of the water jacket, the cool water will enter at a 45 (135) degree angle from the back lower quadrant.
Tomorrow I'll shape the front part of the cylinder. Then I'll either press or heat shrink the water jacket in place on the cylinder. Gonna be tense!

Chuck

 

[aonemarine]

Chuck, I just love the work you do and the way you think. Maybe one day you will be at the cabin fever expo so I can meet you in person. I am sure there are many others on here that would like to meet you there as well.....

 

[cfellows]

Chuck, I just love the work you do and the way you think. Maybe one day you will be at the cabin fever expo so I can meet you in person. I am sure there are many others on here that would like to meet you there as well.....

Thanks, your comments mean a lot. Never been to Cabin Fever, but maybe I'll give next year's expo some serious thought.

This morning I finished shaping the cylinder for the water space and got the water jacket pressed into place. A little tense and scary, but it worked out perfectly in the end.

I started by cutting the cylinder to .010" larger than the ID of the water jacket, then began cutting out the water space.

Here's a photo of the shaped cylinder and the water jacket. The outboard end of the cylinder is .010" smaller than the inboard end and the ID of the water jacket is also .010" smaller on the outboard end. This let me slide the water jacket most of the way over the cylinder and line up the water exit with the exhaust port before pressing it into place.

I pressed the water jacket onto the cylinder using my 20 ton hydraulic press. Fortunately, it wasn't much of a struggle, so I think the .010" interference fit was about right.

I think I'm at a point where I can reassemble the engine.

Chuck

 

[cfellows]

I think it's going to be a runner!!! It's back together and I've gotten it to fire a few times. Just need to put together an air bleed for the vapor fuel tank/carb and I think it will run! I'm pumped!

Chuck

 

[cfellows]

Looks like I'm going to have to install one or more piston rings. Turns out I don't have enough compression without squirting some oil in the cylinder. Unfortunately, it's going to have to be pinned so the ring gap won't pass over the exhaust port. Anybody got information or a link to making a pinned piston ring?

Chuck

 

[johnmcc69]

I've seen roll pins installed radially in the ring grooves & the rings radiused on the ends to wrap around the pin. Half dia. Opposite on each end of the ring.

John

 

[cfellows]

I've seen roll pins installed radially in the ring grooves & the rings radiused on the ends to wrap around the pin. Half dia. Opposite on each end of the ring.

John

Thanks, John, think that's exactly what I'll do.

I'm following a write-up in Model Engine Builder that details making rings both from steel and cast iron. The write-up goes into a lot of detail about theory and is a bit over my head. But I think I've got enough out of it to give it a go. Basically, instead of cutting the ring to a finished diameter then expanding through heat treating, the article advocates turning the ring to a finished diameter that is oversize, then cutting a gap that will allow squeezing the ring down to the cylinder bore.

I'm using cast iron since that's the only material I have on hand that is about the right size. The cylinder bore is 1.260" and here I've turned the outside diameter to 1.294". Here I've begun boring out the center.

In this photo I've finished boring the center to the desired ID of 1.106".

And here I have parted off two rings. I plan to only use one, but fully expect to break or otherwise damage one of them. I also have enough turned stock left to make another 5 or 6 rings if needed.

Chuck

 

[cfellows]

Against all odds, I got the piston ring made, the pin installed in the piston and the whole assembly put back together. And I even managed to do it all with 1 ring, didn't have to go to the second one. Here's a picture of the ring after I cut the gap with a dremel tool and abrasive cutoff blade.

Don't have pictures, but next I mounted the ring in my milling vise and used a 1/16" end mill to cut the ends of the gaps back to the right distance and with a 1/16" diameter contour on ech end. Here's a picture of the ring inserted into the cylinder bore and the pin inserted into the round gap.

Next I drilled a 1/16" hole in the ring groove on the side of the piston.

Then I pressed the 1/16" roll pin into the hole. I used my Dremel tool with a cutoff blade to grind the pin down below the surface of the piston.

After reassembling everything, I have better compression, but still can't get the engine to start. It pops and will sometimes fire several times on it's own but won't keep running. The next thing is to install points and spark ignition. Since it's a 2 stroke of somewhat unique design, I'm not sure how consistently the fuel mixture is getting to the glow plug. I think the consistency and controllability of spark ignition will make a difference. And from there, I need to install a real carburetor instead of the vapor fuel tank.

Still got a few things to try and I'm still confident I'll get it running.

Chuck

 

[Generatorgus]

Hi Chuck, I'm probably not the one to be giving advice about the pinned ring, or rings at all for all that matters, as I got an F- in the ring making class.
But, in my experience with real size antique engines, the pin does not interfere with the normal end gap on the ring, but is fully encompassed by the ring.
I think what I mean that the pin should be smaller diameter and the ends of the ring should form the gap independent of the pin, and let the ring do it's own thing.
I'm guessing the pin would normally be no more than half the width of the ring.
You may lose compression at the double gap it causes and over the top of the pin.

I wish I could have said that before you did all the work, but it may be a non-issue anyway.

GUS

 

[cfellows]

Hi Chuck, I'm probably not the one to be giving advice about the pinned ring, or rings at all for all that matters, as I got an F- in the ring making class.
But, in my experience with real size antique engines, the pin does not interfere with the normal end gap on the ring, but is fully encompassed by the ring.
I think what I mean that the pin should be smaller diameter and the ends of the ring should form the gap independent of the pin, and let the ring do it's own thing.
I'm guessing the pin would normally be no more than half the width of the ring.
You may lose compression at the double gap it causes and over the top of the pin.

I wish I could have said that before you did all the work, but it may be a non-issue anyway.

GUS

Yeah, I agree that would be better. Unfortunately, the smallest roll pin I had was 1/16" and I don't know if they even make anything smaller. I didn't want to make the ring any wider as I had already made it about .010" wider than recommended and that would just increase the friction. The ring gap ends are radiused to match the pin, but not deep enough to form a complete circle.

I had cut a 1/8" deep cup in the top of the piston to lower the compression ratio some and in retrospect, that may not have been a good idea. If all else fails, I may have to fit a plug to raise it back up. Or, I may cut the top of the piston off and go to a two piece piston, separated at the ring gap. I've seen other folks do that and it sure makes installing the ring a lot easier. I probably came real close to breaking that ring getting it installed.

Chuck

 

[t.l.a.r. eng]

Perhaps a much smaller hardened steel pin pressed into the piston ring land is needed. Most 2-cycle engines use very tiny hardened pins pressed into the ring land.
Drill the hole in the ring material before cutting off to accommodate the pin, then splitting the ring at the drilled hole when the ring is cut to width.

Some engines I have seen offset the pin to the top or bottom, don't remember which at the moment, of the ring land as to leave more ring material to butt together.

Hope that makes sense?

 

[myrickman]

Nice build Chuck! I like how you attached the water jacket. Being a loop-scavenged engine you should have good purging of the spent fuel/air. These engines are finicky on the fuel to air ratio. I have the full sized version with a 7.5x12" bore and stroke and it refuse to run unless the mix is in one sweet spot.
You might have better luck on propane but making the mixer is another device to fabricate. I feel your single ring should be adequate... If you are at say 4:1 compression ratio or better, it should go. Again, enjoying your build. I have a soft spot for the engines of the oil patch.

 

[Generatorgus]

Chuck, a small piece of one of your old number drill bits or a new one for all that matters, should probably do nicely. I really don't think there is much shear stress involved.

This is from the webpage of the guy I buy my full size rings from.
Good tips about groove and end clearance and should apply to our small engines.
http://www.ringspacers.com/tips.htm

 

[cfellows]

Thanks for the link, Gus, and to all for the comments and suggestion. Very helpful and much appreciated.

So, today I got the points installed and decided to work some more on the engine frame/base before trying to start it again... tired of it moving all over the place when trying to start it, not to mention the banged fingers and knuckles!

I'm thinking of adding the 3" tall steel pieces to raise the engine so the flywheel clears whatever it's sitting on. It also adds some weight.

Thought I'd see if anyone has any strong opinions, one way or the other, before I move ahead. Don't be shy!
Chuck

 

[Brian Rupnow]

Chuck--My vote is for anything that makes it easier on you and your fingers. It looks just fine raised up like that to me. I am following with rapt attention to see how this critter develops.----Brian

 

[cfellows]

Chuck--My vote is for anything that makes it easier on you and your fingers. It looks just fine raised up like that to me. I am following with rapt attention to see how this critter develops.----Brian

Thanks, Brian. Guess that makes it unanimous 2 to zip.

I welded up the base.

The sides are made from 3" channel iron with one side cut off.

The ends are made from 1.5" x 3" x 1/4" angle iron.

I'll bolt the engine to the base through the angle iron end pieces.

Chuck

 

[larry1]

Chuck, Im with Brian, whatever the easier for you. I like it sitting up, too.

 

[Generatorgus]

That makes a very respectable looking sub base, and also way easier to work on.

I like your use ordinary structural steel. But it's got to be a pain to cut the leg off. Do you use a cutting torch, band saw or abrasive blades? The abrasives would be my choice.

GUS

 

[cfellows]

That makes a very respectable looking sub base, and also way easier to work on.

I like your use ordinary structural steel. But it's got to be a pain to cut the leg off. Do you use a cutting torch, band saw or abrasive blades? The abrasives would be my choice.

GUS

I used my 4 X 6 band saw. It wasn't too bad. The channel iron was 11" long. With the saw in the vertical position, I used a machinist clamp to clamp a piece of aluminum plate to the small existing table. The top jaw of the clamp was beside the blade, slightly in front of the teeth. After laying out my cut line, I held the channel iron horizontally on the table with the bottom pressed against the clamp jaw. Then I began tilting the top of the piece forward into the blade by lifting the back. I continued to lift, tilting the iron more and more until it hit the top blade guide. At that point I was a little over half way through so I removed the piece, rotated it 180 degrees and repeated the process from the other end.

It sounds and felt a little dangerous, particularly since the blade was trying to pull the work into the blade. But I took my time and never really felt like it was going to get away from me. I took me less than half an hour to completely cut through both side pieces. Then went over each cut surface with an end mill and finished them off with my horizontal belt sander.

Chuck

 

[bobsymack]

Chuck why is it necessary to pin the rings ,I remember the 2 stroke detroits had a series of exhaust ports and the rings were never pinned.Excellent build by the way.
Vince