Pennsylvania A3 Switcher (Kozo)

[Kim]

Hmm.... somehow a 'space' crept in between some of the letters in the path name for the picture.  Sorry about that!  the pic should show up now.

Thanks Per!
Kim

[crueby]

Nice recovery!!

[cnr6400]

 

[Dave Otto]

That looks good Kim, I'm glad that you were able to recover from this little setback.

Dave

[Kim]

Thanks Chris, Jeff, and Dave!

I've got LOTS of mistakes to go before I finish this project!  Can't let a little thing like a severely misshapen boiler stop me, can I? 

Kim

[Kim]

Chapter 23.19 – Silver Soldering the Foundation Ring

Next up is the foundation ring.

I dry-assembled the major sub-assemblies of the boiler again, showing where the foundation ring will be going.  I chose to tackle it one side at a time, starting with the section between the firebox tube sheet and the throat sheet.


I took careful measurements here and drew up a diagram of what I wanted to end up with, then cut a piece of 1/8” copper and roughed the shape out using a 1/2" end mill.  Here’s my drawing and the part I roughed out.  I planned to do all the fine-tuning with files.


But then I had a brilliant idea!  The forms were made with a 1/16” radius, so if I used a 1/8” round-nosed mill I could nicely cut the inside rounded shape.  So That’s what I did.


When fitting I realized my mistake; the form would have been the inside curve of the sheets – so the outside curve (the one I’m fitting to here) would be greater than 1/16” radius.  Probably closer to 1/8” radius (but not quite - it'd be 1/16" plus the thickness of the copper sheet (0.080")).

I did some additional shaping with files and it fits OK, but there are pretty big gaps at those inside corners. The straight edges aren’t really as bad as they look here.  I put a slight bevel on the inside edge there – something Kozo says to do to help the solder pull down into the joint.


I may end up re-doing this part if I have enough copper stock (I’m getting pretty short on 1/8” copper sheet).  If not I’ll just plug the holes with copper wire and shavings.  That will work. But it would feel better if I had a closer fit there.  I’ll see what my copper situation is and decide after that.

Thanks for stopping by!
Kim

[Prowler901]

Your boiler is really looking good, Kim.  Nice save on the interior backhead.  And, the mud ring looks like it's going to be some fun and finicky work.  I look forward to your continued progress.
My own engine has had some minor progress.  I'm about to do the final shaping of the main rods.  I'll post on my log when those are done.

Todd

[Kim]

Thanks Todd! 

Looking forward to seeing your progress too! 
Kim

[cnr6400]

 

[Kim]

Thanks, Jeff! 


I reviewed my 1/8” copper sheet situation and as it turns out, I did have enough to re-do that piece of the foundation ring.   I knew I was running close on that, but luckily, I had enough.  I tend to overestimate my need a little when ordering material and I try to be somewhat more efficient when I actually go to cut parts.  So, yay, I have a little bit to spare. 

So, that’s what I did today – remade that piece of the foundation ring at the base of the throat sheet.  I used essentially the same process as before but was more methodical and careful about it.  I started on one side, got it to basically fit, then worked on the other side till it, basically fit.  Then I fine tuned the depth of the long channel. Here I decided that one end was a little narrower than the other end so I used a feeler gauge as a shim while fine tuning that part.


Then a few dozen more file/test iterations and I had a fit I was mostly satisfied with. Though not perfect, the fit on this one is quite a bit better than the first one. 


Next, I wanted to add some hold-down screws for the newly fitted piece of the foundation ring.  I couldn’t figure out a way to hold this setup in the mill so I ended up drilling the holes through the throat sheet with my cordless drill.  I used minimal stick-out on the tiny #52 drill (1-72 tapping size) and drilled through the throat sheet just to where it just started into the foundation ring piece.


Then I took the foundation ring piece out and moved that to the mill to finish drilling the holes deep enough.  I found this much less worrying than trying to drill drilling a 1/4" deep hole in copper using the cordless drill. 


After tapping those holes, I opened the two holes on the throat sheet to #48 (1-72 close-fit through holes).

My next move was to add screws to hold the backhead in place. The backhead won’t be soldered in for some time yet but I want to have a secure way to hold it in place as I fit the remainder of the foundation ring.

So, I clamped the backhead into place.  I spent a fair bit of time positioning the backhead. I wanted it to be as perpendicular to the sides of the boiler as possible, and at the right distance out from the outside firebox sheet so that the boiler would be the correct length overall.  And of course, I needed the firebox door ring and the stays to all protrude through their respective holes enough.  I think I got a decent compromise on all fronts.  This, of course, was made harder by my bone-headed soldering mishap earlier, but I think I'll get past it. Here I've just drilled the 1-72 tapping hole through the outside firebox sheet and the backhead (again, using the cordless drill).


After tapping the holes in the backhead and opening up the ones in the outside firebox sheet, I assembled all the pieces in place.  You can see the throat sheet section of the foundation ring (in the lower left of the picture) and the back head all fastened together here.


Unfortunately, I forgot to put the actual firebox in there, so I’ll have to do that first thing tomorrow.  Hopefully, I won’t forget the firebox on final assembly! 

That’s where I finished up for the day.  I hope to complete the foundation ring tomorrow. Or possibly the next day. Or the one after that. Each step of this boiler has taken longer than I had predicted. So I hesitate to make any predictions at this point!

Thanks for looking in!
Kim

[crueby]

Very fiddly work, but coming out great!  After the boiler is done, you can go into making copper jigsaw puzzles!

 

[Kim]

After the boiler is done, you can go into making copper jigsaw puzzles!

Actually, I've done quite a bit of that, though, not in copper. I've made lots of wooden jigsaw puzzles!  Fun to do, but it looses its luster after doing several dozen puzzles...  I don't know how people do that for a living (cut jigsaw puzzles, that is - and yes, some people do!)

I've used several different cutting styles.
A curly one:


A long style:


And a slightly more standardish knob style.


I don't do grid style. It's just so boring.

I do, however, embed lots of cool figure pieces in them!  That makes them extra special and fun!


Though, I've never done it in copper before!
Kim

[crueby]

Wow - those look like amazing puzzles, the patterns are fiendish!

[Admiral_dk]

Interesting Jigsaw Puzzles - I'm sure John my Brother in Law, would love to solve a few of them 


Per                  

[Kim]

Thanks Chris & Per!
Yes, they are very fun to assemble.  Doing a wooden jigsaw puzzle has a whole different feel to it compared to a cardboard puzzle (which I also enjoy).  The wooden pieces are very satisfying to put into position!   

Kim