Essex Caloric Engine Build

[vederstein]

A thanks to Todd Snouffer for the link.

Continuing on with the build....

The prints call out some spherical ball end joints for the displacer rod. Alas, I don't have a ball turner. Therefore I went as far as I could as shown below. Because these parts (at least for me) are tiny I knew there'd be no way I could hold a cut to length round black for the milling operations. Therefore I turned the parts on the two ends of the provided barstock. This way once I was at the mill, hopefully I could stay at the mill.

Then placing the blank into my rotary table, I could locate, drill the holes and mill the side flats...




Then I parted off the end to length.

Then back to the mill. I turned the rotary table 90 degrees then rounded the end. This is a potentially dangerous setup and I recognized the risks and mitigated. When doing this, up-milling is critical so that the part doesn't grab into the mill and take your fingers with it. My fingers did not become a piece of stock for the endmill to cut.

A little filing to smooth the edges and I'm calling these parts done (Yes the parts have two difference hole diameters)...

 

[vederstein]

Ok, it's been a few weeks since I've posted anything about this thread. It's not that I stopped documenting it, it's that it's Summer and there's other stuff to do.

Continuing:

The plans call for an approximately 4" long x 5/32" dia rod to be turned down to 1/8" for about half the length. My 81 year old lathe doesn't have either a steady or following rest and there's no chance of my tooling making this part as designed.

So I went for a built up shaft. As shown in the following pictures, I reamed out the 5/32 rod to .125" and made a separate brass piece of 1/8" rod. After machining both pieces, I used Loctite 620 high temperature locker to hold the two shafts together.

While the Loctite was curing I continued on with the Displacer. The prints call for a piece of fine mesh lapped together into a cylinder and the lap held together with JB Weld.

Cutting the piece to size was easy enough with a straight edge and and utility knife. What I was unsure of was how to hold the lap together while the JB Weld was curing. After some thought, I found a piece of 7/8" diameter rod in the parts kit. I used this to wrap the mesh around. I then secured it with some masking tape.

After removing the rod, I could unlap the cylinder from the inside and apply the JB Weld. To (hopefully) get the part to the proper, "cylindrical" shape, I temporarily assembled the displacer ends and the displacer mesh onto the displacer shaft. That was it for the day...

 

[vederstein]

It's a few hours later and I removed the masking tape from the mesh. The results aren't perfect but serviceable.

 

[deverett]

I like your regenerator for this engine. I might see if I can incorporate it into the Myfordboy version when I get round to it.

Dave
The Emerald Isle

 

[littlelocos]

Ven. Great job on the regenerator.

Thanks Dave. That was one of my changes from the original design and what ultimately got my prototype running. Happy to answer any questions about the design or what's going on there.
Todd.

Littlelocos Model Engineering
www.littlelocos.com

 

[vederstein]

I have the lap and lapping compound on order. So in the mean time I worked on the furnace. But first an aside.

Part of this hobby is discovering new and novel ways to screw up. When I pressed the castings onto the center cylinder, I never gave the furnace any consideration. The press is so tight that if I tried to disassemble it, I'm sure I'd ruin the tube or worse. So I needed to recover via modifying the furnace design.

The furnace started with the top casting. I drilled/counterbored the flue socket per the print then flipped the part and bored the socket for the furnace body. It was pretty easy and machined well.

Then I needed to clean up the outside diameter. This was a bit tricky because there wasn't a good way to hold the part. So I put the part onto the furnace body and lightly clamped it into the lathe. I don't have a six jaw chuck so if I chucked to hard, I'd deform the brass tubing.

I used a live center to press the assembly axially and this was the significant clamping force. I thought I was taking light cuts, but even then the tube spun a bit in the chuck. (I didn't notice this until I removed it from the lathe). Other than the light marring of the brass tube, the setup worked well. I'll buff out the marks later....

...Ved.

 

[vederstein]

On to the furnace body....

After some thought, I realized that I must deviate from the original design because the furnace is pressed onto the shaft at the same time as the finned castings (no longer feasible). So the idea is to split the furnace into two sections across the centerline of the center tube. The issue was then how to secure the two sections together.

I created an aluminum sleeve to press fit onto one of the two sections. The OD was critical, the ID not so much (at least I hope so...)

After splitting the furnace body into two sections at the centerline of the tube, I pressed the insert into the smaller portion (just happens to be the upper portion).

I thought I could complete the work in the mill so after indexing the tool to position, I began to progressively drill the assembly. I soon realized I didn't have the tooling to complete the job in this fashion So back to the lathe. After indexing in the center, I bored the hole to 1.000in as shown tested with a piece of 1" barstock. In actually, I am a couple thousanths over, but I can't put the material back.

Then back to the mill to cut the slot for the flame.

And that's the assembly until it's time to assemble the entire engine. Eventually I'll need to split the two sections. When I do, I'll file down the excess aluminum insert material so that it can go over the center tube.

A day's work concluded.

...Ved.

 

[littlelocos]

Ved,
Nice work! Great job on the work-around for the furnace.
Todd.

Todd Snouffer
Littlelocos Model Engineering
www.littlelocos.com

 

[deverett]

Too late now, Ved but what you could have done to prevent crushing your brass tube is to insert a slug of some metal, or even wood that was a nice fit in the bore. Masking tape wrapped around the slug to improve the fit if it was loose.
Also wrapping masking tape on the outside where the jaws bear on the tube could have prevented damage by reducing the chance of slippage .

Dave
The Emerald Isle

 

[vederstein]

you could have done to prevent crushing your brass tube is to insert a slug of some metal, or even wood that was a nice fit in the bore. Masking tape wrapped around the slug to improve the fit if it was loose.

Yeah, hindsight's 20/20 although it should be better than that. The marks buffed out decently though.

I do have a question about descaling the burner. I've looked online and found several concoctions for descaling. Does anyone on this forum know of an effective and easily obtained formula?

 

[deverett]

Have a look at this link, Ved:
http://eirny.com/2013/06/03/removing-copper-surfaces-from-your-brass-or-bronze/

Let's know if it works for you!

Dave
The Emerald Isle

 

[Rickl]

Top job Ven. I like your initiative. Looking forward to seeing the end result.

Rick
Sth Australia

 

[fcheslop]

Citric acid available from most chemists or home brew shops
I used to use an American product Scale Kleen it came in 1kg bags and was just citric acid
It may leave the brass a little pink but it usually polishes up fine failing that vinegar and peroxide

 

[vederstein]

I tried the 3:1 mixture of H2O2 and Vingear from Devertt. It took about 15 minutes and worked as advertised....

 

[vederstein]

Then I inserted the wick, poured in some denatured alcohol, and lit the burner.

All was well for a few minutes, but I guess my soldering wasn't as good as I had hoped even though I thought I checked adequately for leaks with water.

There is an apparent leak at the bottom of the spout. Alcohol leaked on the work bench and then caught on fire. A bit of quick action avoided any real damage to myself or my house/workshop. Moving the burner to the concrete floor to burn itself out and a bit of patting the burning workbench with a rag put out the fire.

I have some sealing to do.

As I was experimenting, I have doubts that my engine is going to be a runner. I'll give it a worthwhile try, but Stirlings are always flaky. So it goes.

...Keep following...


...Ved.

 

[MRA]

Thanks for this warts-and-all write up. It's very encouraging when one's motivation goes, to watch someone else digging themselves out of the s*** with a cheery countenance

 

[vederstein]

MRA:

All of the builds I've documented here show my (sometimes enormous and expensive) screw ups. I've accepted it years ago, I'm just not that good of a machinist compared to other people here.

But that's ok! I'm still having fun with this ****. When it no longer becomes fun I'll step away from it for awhile. If it's still not fun after that, I'll sell my equipment. It's been over 10 years now, this hobby seems to be sticking around as long as I keep trying new things.

My next project will be my first dual cylinder, double acting steam engine. It will also be of my own design to which I'm I've started. It will have vertical shaft (like an inverted lawnmower engine). I'm going to cast the aluminum parts myself. The engine's purpose is my project for the 2019 Maker Fair season: a live steam powered spin art machine! Absolutely stupid in every way, but kids (and many adults) like stupid and whimsical things.

Usually when I build an engine, I'm just happy it runs. This next project will require an engine designed to actually perform a function.

...Ved.

 

[littlelocos]

"There is an apparent leak at the bottom of the spout."

Ved,
Before resoldering, etc. check to make sure you didn't overfill the burner. The spout of the little tea pot is lower than the cap. If you fill it to the rim, fuel will run out of the spout, down the neck to its base.

BTW, regarding how the engine runs. I've been really happy with it. If you have trouble there, also let me know as I'm glad to help.

Let me know what you find out on the burner.
Todd.

Todd Snouffer
Littlelocos Model Engineering
www.littlelocos.com

 

[vederstein]

Let me know what you find out on the burner.

It was a leak at the base of the spout. I unsoldered the joint, tried to clean the surfaces and resoldered.

The same thing happened, after cleaning, a small pinhole developed. So screw it, I plugged the hole with some JB weld on the inside. Outside the joint looks perfect so it's all good.

As for the engine running, it seems to want to, but not quite. So I'm close to a running engine. I now believe I overlapped the cylinder and made the piston a tiny bit too small. If I apply oil to the back of the piston and rotate the engine, I can see bubbles develop as air leaks around the piston. I also think the displacer is dragging a small amount against the cylinder wall.

I'll eventually heat up the piston to expand it and remove the displacer and try to find the contact point.

Thanks,

Ved

 

[littlelocos]

Hello Ved,
The video linked here should give you a good idea of the fit on mine.

Also check for leaks around the displacer rod.

I use Kroil as a lubricant in my Stirling and flame licker engines as it is super-thin; can take the heat; and doesn't gum up in storage. I use a dab of multipurpose grease or white lithium grease on the displacer rod as it helps with sealing.

The hot end of the regenerator will ride the cylinder wall; however, it gets enough oil from the power piston end to make this not a problem. This is different than if the displacer is used. It shouldn't touch the cylinder wall at all.

Set the lead angle at 90-degrees or a little more. I think mine is about 92 or 93.

Here's a video of the engine running:
It will pretty-much run like that all day on a low flame.

Thanks,
Todd.