Pennsylvania A3 Switcher (Kozo)

[RReid]

Great idea and well executed plan for filling those gaps Kim. I've never done that with copper (or brass), but I have used steel bits to fill a gap for oxy-acetylene welding. Worked in that case too!

[internal_fire]

A little late, but 

Kozo's wires are not very effective for closing the shell tightly. Much more effective is the use of worm-drive hose clamps to close the shell. (I believe the Brits sometimes call these Jubilee Clips.)

When the shell is tightly closed, and then the joining strip is riveted, the gaps will not appear when the clamps are removed before soldering.

Gene

[Kim]

Thanks Chris, Per, and Ron!

Gene,
Yes, I can see how hose clamps would have been a MUCH better solution for holding the tube closed than the twisted wire.  I kept breaking the wire when I'd try to twist it tighter.  A little frustrating, but I eventually got it to work OK.  But hose clamps!  That's a brilliant idea!  Have to file that away for next time.

Thanks again!
Kim

[Don1966]

Nice recover Kim….


Don

[learn2turn]

Congratulations on a job well done Kim.  The boiler is coming along nicely.  I think your approach on filling those gaps was very resourceful and it looks like it worked great.  Now I sit and wait for the next update.

[PJPickard]

Interesting to compare you and Blondihacks...she did the exact same with her last video and had the exact same issue of the solder not flowing where you had the same issue. She was able to reheat and get it flowing. I will be wanting to make a boiler soon so this is very useful stuff! Thanks for posting it

[Kim]

Thank you Learn2Turn and PJPicard.  Glad to have you following along and I appreciate the comments!

Yes, I watched Blondihacks video the other day.  It always makes me feel better to know that, not just that others struggle with the same things I do, but that they can find ways to make it work!  It gives me optimism that I can do the same

Kim

[Kim]

Chapter 23.11 – Truing and Facing the Shell

Now Kozo has you true up the freshly rolled and soldered shell.  You do this by forcing a round form through the shell tube.  This has been mentioned earlier by Gene I believe, and now I’m going to do it.

Interestingly, Kozo had you make the front tube shell backing plate the EXACT right size for this operation. But before I could use it to size the tube I had to take a little notch out of it to clear the joining strap.


Unfortunately, when I put the form in the end of the shell, it pretty much just fell through… well, not quite.  But it was far too easy.   In this picture, I’m using a dowel rod to just push the form through the tube.


So I measured the inside diameter of the tube.   It was pretty close to what it should be (3.555”) but it was out of round by 20 thou or so. The out-of-roundness wasn’t surprising, since that's what we're trying to address here.  But the fact that the disk moved through the tube so easily even when it was out of round – THAT was what was surprising.  So then I measured the diameter of the disk.  I had thought I’d sized it very carefully to Kozo’s specified dimensions.  However, it was clearly 15 thou undersized.  It was about 3.540”.  Not sure why.  I wondered if my pounding had caused some size change?  The formed part (front tube sheet) came out the right size – but wait – this was just the backing plate, which had no bearing on the size of the formed part.  I'm betting I just wasn’t as careful with the backing plate thinking that its size wasn't really critical.  And it wasn't, for the forming.  But it was because Kozo had other uses for the backing plate!  Shows I should always listen to Kozo! 

Off to make another forming disk.  I need a second one anyway, for the next operation of facing the ends of the tube.  This time I used an actual 1/4" mandrel instead of a 1/4" bolt. Worked much better!  I should have done that the first time (I just happened to have a 1/4" mandrel in my stock of previously made jigs and such - guess I didn't even bother to check the first time!  How silly of me!).


This time when I pushed the form through the tube, it actually did its job!  It took some effort to pound it through the tube.  I’d move it a bit then pound on the sides that looked a little high. Then move it a bit more.  After doing that a time or two, the tube was much more round!  It was awesome!


And as a quick check, I tried fitting the front tube sheet in place.  And it’s a nice snuggish-but-not-too-tight fit.  I’m pleased with that!


Next, we need to face the ends of the tube to make them square and even, and get the tube to length.

I fit the two former circles I had into each end.  The slightly small one needed a few wraps of masking tape to provide a good friction fit, but it worked just fine.  Then, starting with the end that was most uneven, I faced it off using very small cuts of about 5 thou per pass.


Once one end was true, I measured the overall length of the tube to see how much length I had to play with. I still had another 45 thou to remove.  This was good.   I also needed to make sure that the joining strap ended 3/16” from the front end of the shell. This is important as the front tube sheet needs to recess into the front end that far.

So I shaved another 20-25 thou off this end to bring it down to where that recess was correct.  I had to back the center out of it’s place in order to measure the recess there, but would always put it back before I took another facing pass!  (You can kind-a see where the joining strap sticks out along the back of the tube next to the blue tape sticking out there.)


I also made sure that I had enough length left to face off the other end of the tube so that it was even and square.  Which there was. 

After facing off the other end, here is the finished shell – trued and faced!

[steamer]

that's looking the business Kim!    Nice solder job!   It's always satisfying when a solder job goes well.

Dave

[Kim]

Chapter 23.12 – Silver Soldering the Bushings and Studs

You may have thought I was all done with the woodworking, but no!  I’ve still got some more of that to do!

A few days ago, Chris sent me an email suggesting a good way to hold the boiler tube while drilling it.  I liked his suggestion so much, that’s what I’m going to do!  So, using the time-honored technique of taking excellent advice from others and making it look like your own, I’m going to show you what I did. 

First, I cut a couple of chunks from a scrap 2x6 I happened to have laying around.  Standard dimensioned lumber is certainly not that accurately sized, nor does it have very tight grain and it splinters a lot!  But for this application, I think it will work just fine.  I guess we'll find out at least, eh?


I drilled two long holes through each end of the two chunks of 2x6, spacing them so that they would fall right over the T-slots on my mill.  Then I took the largest hole saw that I had and cut a hole in the center of each of them.  You can see the plug I just drilled out of it there in front.


Next, I moved them to the lathe and bored out the hole to a nice sliding fit for the boiler shell.  You can see here, I’ve zip-tied my shop vac hose to the boring bar.  This worked quite well for keeping most of the wood swarf off the lathe bed.


Then I went back to the table saw and cut them in half.  Now I have a great pair of clamps to hold the tube in place during the soon-to-come drilling operations! Thanks for the great tip, Chris!


Next, I made the handrail studs.  These will be soldered into the boiler shell and will be used to fasten the handrail to, eventually.  They were made from 3/8” bronze.  They are 1/4" in diameter and the very tip is threaded 1/4-32 for threading into the boiler shell. Then I put a 3-48 threaded hole in the center for fastening the handrail.  Then cut it off the parent stock.


Here are all four of the handrail studs, completed.


This covers the last couple of days of work and brings you up to date on my build.

Thanks for looking in!
Kim

[Kim]

that's looking the business Kim!    Nice solder job!   It's always satisfying when a solder job goes well.

Dave

Thanks Dave!

Isn't it though?

This one took me at least 3 tries. That's how I'm seeing most of my boiler work going though... multiple retries to get the joints that I think (hope) will make a successful pressure vessel!  I know you know what that's like - you've certainly done it before! 

Kim

[crueby]

Great job on the clamps, I think you'll like how they work.

[vtsteam]

I like the tube straightening method and wooden jig a lot. Thanks for showing those! 

[Kim]

Great job on the clamps, I think you'll like how they work.

Yes!  I think I will when I actually get around to using them

I like the tube straightening method and wooden jig a lot. Thanks for showing those! 

Thank you Steve!  Yeah, I was surprised at how well it actually worked!

Kim

[Kim]

No shop time over the weekend. Had lots of family duties. Wonderful duties, but they kept me out of the shop all the same.

But today I was able to continue making the shell bushings and studs.

I started with the steam dome base.  This was turned from a piece of 1.5” bronze rod.  Here I’m in the process of parting it off.  It’s a pretty good-sized hunk of bronze!


After parting, I flipped it around and faced off the parted end so that it was flat.


Then to the mill where I found the center of the part using the axial indicator (always fun!)


And proceeded to spot and drill a bunch of holes.  The four smallest holes around the outside are blind holes and will be threaded.  The other four are all through holes.  Two for the pressure gauges (front and back), one for the throttle (left side), and one for the steam passage to the cylinders (right side).  This would be the view from the front of the engine, not the engineer's position, so don’t be confused!


Here I’m threading the four holes 8-32.  These will be for holding the throttle body onto the steam dome base.


Next up was the Blower Pipe Bushing.  This is not actually for the boiler shell, it will eventually be soldered in the backhead. But I’m just turning up all the bushings now while I’m at it.


This one has 1/4”-32 threads on the outside of the bushing for hooking up the blower valve.


Interestingly, I wanted a bottoming tap for this op, but didn’t have one.  In fact, I couldn’t find a 1/4”-32 bottoming tap anywhere!  So I got a second 1/4"-32 taper tap and just ground the taper threads off of it.  I started with the taper tap, then switch to the ground one to clean up those bottom few threads. Seemed to work pretty well.  At least in this bronze, which is quite easy to work with.  Though I kinda think it would work in steel too!  I mean, what really, is the difference between a taper tap and a bottoming tap other than the bottoming tap doesn't have the taper threads on the end, right?


And here’s my work for the day.  The Steam Dome Base and the Blower Pipe Bushing (for the backhead).


More bushings and studs to come in the near future.

Thanks for stopping by!
Kim