Essex Caloric Engine Build

[vederstein]

Now that I've completed Rudy K's open column steam engine, double sized and with cast components it's on to the next project.

If you remember I did Rudy K's engine double sized because I'm not a real fan of making tiny, fiddly engine parts.

So, at the NAMES show I purchased the half scale Essex Caloric (Stirling) Engine from Little Locos. Wouldn't you know it: It's full of tiny fiddly bits!

So be it. I'm only going to document the parts that are/were difficult for me. Nobody needs another picture of a shaft getting turned down or threaded. On with the build...

 

[vederstein]

I have some tooling on order for this engine, so I needed to start with parts to which I already have tooling. The connecting rod seemed like a reasonable pain in the butt to start with.

First I made a fixture plate to which I bolted the barstock. This allows flipping the part and maintaining locations.



After indicating in the plate centered on the four jaw lathe chuck.Second I turned down the barstock for the webbing. This required several flips of the part.





The print calls out the webbing cut to a 3 degree angle. I used a angle adjustable combination square to fixture the plate to the angle. This way I can flip the part and maintain the angles. So when I screw up and my cut is off, at least I can be off consistently.





After that the ends needed rounded, the holes reamed to size, and oil holes drilled.





And after two-three hours of work I had a conrod. I had one boo-boo when the mill grabbed the part, but life will go on.



...Ved.

 

[Blogwitch]

Hi Ved,

Myfordboy also does a casting and build set for this engine, just a little more refined.

http://myfordboy.blogspot.co.uk/p/the-essex-hot-air-engine.html

I think this engine has a full build sequence on Youtube, so it might help you with a few of the risky setups.

I have bought myself a set for his Aermotor, very reasonably priced and he ships rather cheaply to anywhere in the world. The castings that I received are the best castings I have ever handled, despite him doing them himself at home.

His site is well worth a visit if you are looking for something different.

John

 

[vederstein]

Next up are the cylinders. There is a 1" OD stainless steel tube that gets pressed into the castings. The tube is really the cylinder, these castings are heat exchangers.

The castings are pretty good, so I felt confident just clamping them into the 3 jaw lathe. The process was facing, drilling, reaming, boring the index pilot, then flipping and facing the opposite side.

I purchased a 1.000 reamer for this operation. I'm none too happy about the finish of the bore and why a new, never used reamer would not give a smooth finish. Luckily finish really isn't that important.











Then off to the mill. The hardest part here is clamping and indexing the castings. I used a 1/4" rod as shown in the photo. This way I could calculate the centerline of the reamed hole. Then I could face off the base and drill the mounting holes.





That's it for today.

...Ved.

 

[vederstein]

The piston is a strange beast and being made of cast iron can be either a good or bad thing. Because piston fit is critical, I put in a new carbide insert in the turning tool. The piston has two diameters so I did those in the same set up.

The piston is then bored to two diameters. Based on the way I started, I had to flip the part in the lathe chuck to do the larger bore.

Then to the mill for drilling out the wrist pin hole.

 

[vederstein]

Regenerator/Displacer Parts!!!!

The displacer end caps looked like a never ending source of frustration and failure. Given the age and quality of my machines (and my abilities), I thought these would suck to no end. Amazingly I got them on the first try.

I chucked 1.00 dia brass barstock in a 5C collet then chucked that into the four jaw lathe chuck. From there I could index the part center then offset .257" for the air passage holes. With the offset part, I drilled the .344" diameter holes. In actually my Chinese 5C collet set isn't symmetrical, so I had to re-index to center every time I rotated the collet holder.

Then I switched up to the three jaw chuck and turned to the proper OD. After that I turned down the nipple.

There is trepanning operation to which I don't have tools. I do have a carbide ID O-ring cutting tool. It was close enough to the print requirements that I used that instead.

From there I drilled out the center and tapped #5-40 per the print. Then I could use a parting tool to cut off the part.

The second part was made on the same chunk of barstock with the same steps. After both were created, I chucked them in the lathe reversed to cut off the extra bit from the parting operation.

Thus I quit while I'm ahead...

...Ved.

 

[nautilus29]

Wow nice job! Hard parts to make with a limited setup, but you found some nice work arounds.

 

[vederstein]

Thanks for replying. I was wondering if anyone was watching this thread.

If anyone is remotely aware of "The Cathedral and the Bazaar" will understand that Internet forums, chat rooms, Facebook, open source software, etc. all rely on feedback, positive feedback. All people are narcissistic even if they don't realize it. (e.g. when looking a a photo, most people will try to find themselves first).

It takes effort to create these build logs. If there's no feedback it may not be worth it and the forum will die.

Thanks again.

...Ved.

 

[deverett]

I've got a set of Myfordboy's Essex castings gathering dust in the attic. I'm watching your progress and it may give me the impetus to get off my backside and do something about getting the dust off them.

Dave
The Emerald Isle

 

[vederstein]

Well, I screwed up. Part of the piston assembly is a cap silver soldered to a brass tube then secured with Loctite to the cast iron piston. My soldering skills aren't great, but I got there. Where I screwed up is that the thin walled tube pulled out of the lathe chuck ruining the part.

So after contemplating life, I decided to try again with a solid piece of 1" diameter 360 brass. I turned it to the proper length then turned the OD to size.

Next I drilled and bored out the center. This was no so easy because the final wall thickness is very thin and I kept losing position on my boring bar. The cutting tool would move and my dial on the lathe cross feed would stick. So it was a lot of small cuts and trial fits until I was satisfied.

In the end I got there. The bore isn't near as nice as I'd like, but I believe it's functional and it's hidden inside the engine anyway. That's enough for the day...

...Ved.

 

[rlukens]

Ved, I, along with many, enjoy your efforts. Creativity is the mainstay of a true machinist. Nice work.

 

[vederstein]

Thanks . Is that an Austin Healy Sprite?

Cute car. My money pit is a 65 Corvair.

 

[deverett]

Looks like a Triumph TR3A. Great cars in their day, but couldn't quite do the 'ton', even if there were suitable roads. A 2 litre modified tractor engine powered them.

Dave
The Emerald Isle

 

[vederstein]

Anyone that has the plans for this engine and is following this thread probably knows that I'm jumping all over the place. In no way am I starting with the first drawing and continuing in order to the last. I look at a part and decide if it's something I'm willing to tackle for the day. So today the crankshaft looked like a challenge worth attempting.

Expecting to screw up at least once, I used a piece of 1" leaded cold rolled instead of the CRS supplied with the kit. This way I expected to use overall less material. First I turned the part to the proper OD (.875") and square the end.

Then I drilled/reamed the bore. I broke a center drill. (Crap!) The drawing calls out .188" for the final bore. I don't know why it wasn't .1870" for a press fit, but it didn't I followed the print. In the end, the material supplied in the kit didn't press fit into the bore. So it was the old dimple the shaft and red Loctite route.

I don't see why this part couldn't have been a simple disc, but it wasn't. It's counterbored then a comparatively large internal 45 degree chamfer. I don't know why it's designed that way, but I went ahead following the prints. In this process I found a piece of HSS that I could use as a boring bar. I used the same HHS bar for machining the chamfer. Chatter was of the order of the day. Oh well...

The print calls out for a .125" diameter "ring groove" on the outside diameter. I guess it was used on the full sized machine for a belt or something. This detail had me scratching my head for some time. Before I started the build I looked for a carbide tool ground to a .125 diameter. No luck. Theoretically I could ground a piece of HSS for the profile. But I know that I'd have a snowball's chance in Hell for that to turn out ok. So after finishing the part to size, I transferred the part to the mill and set up my rotary table.

Once the part was indicated in, before I tackled the groove, I drilled/reamed the .093" hole for the crankshaft throw.

Then I rotated the rotary table and used a .125" endmill to create the groove. I'm sure this isn't a "sanctioned" way to do this, but it worked for the tooling I have available.

This one little part took about three hours. Therefore enough for the day.

...Ved.

 

[jimsshop1]

Hi Ved, I'm watching your progress and am amazed at the ways you come up with for holding parts. We all can learn something from posts like this so please don't think it is a waste of time. I'm still very much an inexperienced model builder even though I have a couple steam engines that run well and I managed to get 2 Hit-Miss IC engines completed and running all from bar stock. I haven't worked on any cast engines yet but am going to the Cool Springs Museum swap meet this Friday and may come home with a casting kit of some kind. Keep on posting your build as you are doing a fine job!

Jim in Pa

 

[vederstein]

I wish I could make an IC engine. My previous attempt was disastrous. I could never get the poppet valves to seal.

At some time in the future I'll try again, but I'm still intimidated about putting in all that work/effort only to fail.

...Ved.

 

[vederstein]

Ok, I've been away from this thread for a few weeks. Hey it's Summer and there's other things to do. Anyways today I did get some shop time for two parts. The first part was a cylinder cap which was entirely a lathe part. Not hard and no pictures taken. The second was the Crank Stand, and it was a head scratcher. It's an aluminum casting with no obvious starting or grabbing point.



So after some thought, I figured facing the base would be the best course of action, so eyeballed the part in the lathe and cut away...

Then off to the milling machine. I still had my setup from the crank disc which means my rotary table was still installed and indexed in. Not that if I didn't have this already set up, I may have worked on this part an entirely different way.

So I chucked the part into the rotary table and used a combination square to get the thing "square" with the table. (Ok I eyeballed it, but it's the best as can be done with the tools available).

Then I drilled/reamed the crank journal.

The drawing calls out specific distances off the center of the casting to face off the front and rear ends of the crank journal. To do this I indexed off the edge of the rotary table chuck and lowered the tool for the cut. Then I rotated the part 180 degrees and machined the other side.

I'm running out of picture allowance. So I'll finish this part in a subsequent post...

 

[vederstein]

Crank Stand Concluded....

I loosened the vise and placed the rotary table facing up. This way I maintained squareness for drilling the mounting holes. In actually, something got off because my first hole wasn't centered. So it's not a perfect part, but then none of my builds are perfect... And that concluded the day's work.

 

[vederstein]

At this time I thought I was far enough along to see how the engine fits together. So I made the wooden base plate out of maple. As usual, not everything went to plan. The crank bearing spacing was off, so I placed it where I thought it should go, marked, & drilled the holes in the plate. So I have some extra holes in the plate. I'll probably need to make it after I'm done, so I'm considering this plate a prototype.

I found that the piston was a little stiff in places, so I made lap with a piece of oak roundstock. In the end the piston move fairly smoothly but there's a bit of sticking at the end of stroke, top dead center. Does anyone have suggestions on how to cope? (The bore is 0.920" in diameter).

...Ved.

 

[littlelocos]

Hello Ven,
I'm just finding your series in the last week or so and will continue to follow along. Great job so far!

The piston fit is absolutely critical to the engine running well. I use an expanding lap purchased from McMaster Carr. Here's the link to the 1" diameter lap. Turn the OD to closely match the ID of the cylinder sleeve and then lap with a fine grade lapping compound. I use the oil-based Clover lapping paste.
https://www.mcmaster.com/#4548a29/=1dmzjt4

I'm happy to support and respond to any questions you or anyone else may have.

Enjoy!
Todd.

Todd Snouffer
Littlelocos Model Engineering
www.littlelocos.com