Ringbom 1: Tim's Ringbom Stirling Engine Build

[tvoght]

A few days ago I showed a video of my Ringbom Stirling engine "Ringbom 1" running. I thought then that I might not do a build log, but I have reconsidered. I have a lot of build photos for some parts, but I imagine some parts will have little or no photos. I'll do the best I can.

Before you make any comments about how fast the build is going, remember the engine was essentially complete 3 years ago. I'll put this photo here as a reminder:



I'm going to attach a .pdf drawing with the log of each part.
Here we go!


--Tim

[tvoght]

The power cylinder and cylinder head were made first. They are of cast iron. The horizontal bandsaw was used to slice off pieces to arrive at stock closer to the finished shape.
The various slabs went into the junk box for future projects.




The larger piece just above the part numbered 1 was to become the cylinder head. Here it's shown in the 4-jaw having a boss turned which will extend into the cylinder bore.



Then excess was sawed off creating more scrap box fodder. Focus!


The flange portion was then milled to thickness.


Now with the main cylinder stock placed in the mill vice, the mating flange to the cooler was cut. Since the sides being clamped are not parallel after the sawing operation, A sheet of paper was folded into multiple layers and placed between the movable jaw and the part to take up slack.



With the broad milled side as starting reference, The other surfaces of the cylinder block were milled.





The cylinder block then went to the lathe for drilling and boring.
It seems there is no documentary evidence of the boring.


Back at the mill, the head was temporarily super-glued to the cylinder for placement of mounting holes.



The head flange and cylinder werre drilled to depth with a 4-40 tapping drill, then only through the head flange for clearance. Finally the cylinder was tapped with the head still in place since the tap cleared the clearance holes in the head. A screw was placed before proceeding, and the remaining holes were done in a similar way.




The cooler mounting face previously cut for reference was then cut to final dimension with a face mill for a decent sealing finish.



Mounting holes for the cooler were drilled through, and then the port hole cooler-to-cylinder was drilled through to the bore.



The next cuts are decorative to give the cylinder some character.




And that's about it for the cylinder and head (until the bore is lapped).

[crueby]

Not seeing any pictures here...

[RReid]

I'm seeing the pictures.

[tvoght]

Picture are seen on Firefox browser and not Chrome. I just checked an old build of mine and the pictures aren't showing there either. Something has changed.   --Tim

[crueby]

Yup, I am using Chrome on my tablet, not seeing them. Will check with firefox on the pc. All the browsers have changed thier rules on linked content, its really hard to diagnose. Usually something to do with whether all content, or none, is a secure link, https, or not. Mixing them causes lots of odd behavior lately.

[tvoght]

The chrome debugger revealed the problem. MEM is now https, but my self-hosted pictures are on an http server. It's not immediately obvious how I can fix this. I may not be doing this build log     --Tim


P.S. For interested techies:    https://love2dev.com/blog/chrome-mixed-content/


The only solution is probably to switch the server I'm using to https. I'll have to check into it.

[MJM460]

Hi Tim, all the pictures are showing here on iPad plus Safari.

I do hope that you will be able to continue somehow.  Perhaps. The standard attachment method will work.  It would be a pity to not be able to proceed.

Thanks for the pictures so far.

MJM460

 

[PJPickard]

Yeah I hope you continue as well. I have one of these on my eventual list. I have Senft's book, but I like the design of yours better.

[tvoght]

First, thanks crueby for your help in troubleshooting this.My solution will be to transition my server to https. This could take a couple of days, and it's unclear to me whether I will need to change all the links in my prior builds so that they can be seen with Chrome also.

MJM460, it's likely that this is only a problem with recent versions of Chrome, but it's probably only a matter of time before other browsers take this measure. The standard attachment method will not remedy my existing builds here which have the same problem, and I don't like the text first, then pictures format.
PJPickard, I have built Senft's "Tapper" as well, and I also like mine better .  I stole some of Senft's design ideas, though. I am attaching drawings as I go, and will eventually place them in a .zip in our plans section.

--Tim

[tvoght]

The cooler (in 6061 aluminum) came next. A chunk of 2 inch square stock was cut slightly over-length and centered in the 4-jaw, then a hole was drilled and reamed clear through for the displacer rod bushing. That hole can be seen at the bottom of the larger displacer cavity that had been bored to depth here.
The hole was bored ever slightly deeper than required and then the end was faced to establish the design depth.



A recess was bored to accept a flange on the hot cap.



This shows that a form tool was made to cut a groove for a sealing o-ring at the bottom of this recess. Ultimately, a wider square-section o-ring was used here and the groove serves no function.



The cooler was clamped in the CNC mill for a fin-cutting operation. The clamps to the sides served to ensure no lateral movement.



A 3/32" saw was used with a CNC program to cut the fins. A slow operation compared to cutting these in the lathe, but good luck has been had with the method, and some frustrating bad luck trying to do it with a lathe.
Also -as you'll see- some of the fins do not extend entirely around the cooler, so a lathe operation would not have worked for those anyway.



In the lathe, the cooler was centered on the hole that had been previously reamed for the displacer rod bushing. A boss was then turned, No photo is shown of that operation.



Here in the mill vice you can see the boss that was turned, and that holes have been drilled and tapped to match up with those previously made on the mating face of the cylinder. The hole in the middle provides direct connection from the cylinder bore to the displacer bore in the cooler. Plenty of cleanup still needed.



A corner was rounded off to build character for this part. It was decided to use a coarse step in the round off to give this scalloped effect. An observer at a show asked in a surly tone why in the heck it was like that. To each his own.
You'll also see the adjacent corner was truncated for appearance.



This photo shows a now-favorite tool, this edge-finding device. It is mounted in a dedicated tool holder and then adjusted to eliminate runout. It is a very accurate tool. Here It's being used to find the middle of that bore using the Osborne maneuver. What's not shown is why: holes were drilled surrounding the hot cap flange recess. Those will be for a clamping ring which will hold the hot cap.



That's all the existing photos of cooler operations, but one more step taken was to mill each of the 4 flat sides with a face mill just to cleanup the extruded faces and any clamping marks.

[crueby]

No pictures yet in chrome. 

[tvoght]

I'm sorry to anyone who's looking. All that I succeeded in doing is partially fixing this for Chrome, and completely breaking it for other browsers. I've at least restored it to work with other browsers, but I won't be posting anymore until I get this figured out (if ever).
If I have bad days on my day job, it is quite often because I'm dealing with browser compatibility issues (but I get paid for that). Meanwhile I have far too much day job work to do to spend so much time on this.
--Tim

[crueby]

Yeah, just checked in Firefox, no pics there again either.   

[RReid]

Using a laptop running Windows 10 I see the pictures in Firefox, but not in Chrome.