Pennsylvania A3 Switcher (Kozo)

[cnr6400]

Nice recovery Kim! The base looks good. The form tool looks repairable. 

(it's no accident that my scrap bins storage bins for things to be used later have a number of broken tools of various sorts - it happens to most of us I think.)

[Kim]

Thanks Chris and Jeff!

Yeah, a lot of filing to go for sure!

I'm thinking I may use the small wheel attachment on my nifty belt sander to help out shaping the stainless.  We'll see.  I don't want to get too aggressive, but with the right size wheel and the right speed, I think it will help quite a bit!

Kim

[Kim]

The next big step is to curve the bottom of the stack base so that it fits on top of the smokebox.   To do this, I needed to make a little holder piece. I made this from a scrap chunk of 1” 1018 that I had in my bits & pieces bin.  I’ll be using a 3/8-16 machine screw to hold it in place.


Here’s the holder piece stuck in the center of the stack base.


Next, I needed to make a fixture to hold the part in the correct orientation while I carve the saddle shape.  For this, I used a 3” length of 1/4" x 2 1/2" angle iron (hot rolled). I wanted to make sure the important sides are truly 90^o so I started by flattening the base:


Then I clamped the base down and trimmed the side of the upright that I’ll be using.  This way I know it is truly at a right angle to the base. (I had just put my RT on the table and this seemed like the easiest way to hold it at the time.  But it worked  ).


Now, back over to the vise where I drilled a 3/8” hole in the upright part to hold the stack base. After flipping the part in the vise, I used the DRO to measure over the specified distance from the surface of the upright and drilled & reamed a 1/4" reference hole.  I’d originally hoped that I could just do this in the angle iron itself, but turned out it wasn’t quite long enough.  So to remedy that, I just double-sticky-tapped a scrap of aluminum in place to extend the length out far enough that I could make the 1/4" reference hole.  This hole will take no stress. I just need it for locating things on the RT.  I did, however, use a clamp to aid the double sticky tape during the drilling operation.  The sticky tape didn’t hold to the hot rolled steel very well due to the mill scale.  But it held well enough for this operation.


After zeroing in the RT, I used a 1/4" gauge pin to locate my holding fixture and clamp it in place.


I then used the RT to cut the curved bottom on the stack base.  I would have preferred to use a carbide EM here, but the only thing I had with enough depth of cut was this 3/4” HSS end mill.   It worked, but it was a bit of a chore!


After cleaning up the burrs, here’s the base up to this point.


And where it will go sitting atop the smokebox!


Next up is the stack itself.
Kim

[crueby]

Great fit on the smokebox. Amazing how much work can go into one curve on a part.
 

[RReid]

That came out really well! You should be well pleased with how it fits. Looking forward to the stack, nothing says "steam locomotive" like a good smoke stack (or chimney)!

[cnr6400]

 

If you hear a very faint grumbling when you go in the shop next Kim, it's probably gonna be a perturbed gnat who can't even get one eyelash between the smokebox and the stack base!   

Top notch fit. 

[Kim]

Thanks Chris, Ron, and Jeff! 

It does take a lot of work for those rounded parts. But they sure look nice when they fit right, don't they?

Kim

[tzkelley]

Looks really good, Kim! And so does the smokebox door--sorry, been gone for a while.

[Kim]

Thank you Doug! 

Kim

[Kim]

The stack was started from a ~4” length of 1.25” diameter 303 Stainless rod.  I faced it off to the required length, then proceeded to drill it through.  However, all my good drill bits are machine screw length, so were not long enough to go more than about halfway through the bar.  So, I drilled a blind hold halfway through, starting at 1/4":


Then step drilled in 1/16” increments up to 1/2".


At which point, I turned the bar around and did the same process again.  By doing this, the holes from each end met in the middle.  I was worried about the holes from each end not being aligned but figured it would be close enough for a smoke stack.  Seems to have worked out pretty well.  I can’t feel an edge between the two holes, so I’m happy.


Now, I wanted to go up to 5/8”.  And my cheap HF Silver & Deming bits are long enough to go all the way through.  So I stepped up to 9/16” then 5/8” which went well.


Next, I brought the outside end of the stack down to 7/8”.  This will be the part that sits in the base.


Like so – only, the base is upside down in this picture… Oops…


Then I bored a length in the end up to 11/16”.


And added a 60^o chamfer to the inside bottom of the smokestack.


I flipped the stack around holding the 7/8” diameter in a 5C collet.  Next, we’ll be tapering the inside of the stack. To do this, I carefully adjusted the compound to 1.95^o.  To get the required accuracy, I used the X-offset over Z-distance method to set the angle precisely. 1.95^o sounds rather arbitrary, but it’s really just what is required to connect the two inside dimensions with a single taper.


Then I proceeded to actually bore the taper.  This took a lot of long cranking sessions moving the compound slide back and forth.  No power feed on the compound!


I then added a small 60^o chamfer on the top of the stack (sorry, no pic) and used a live center to help hold the part steady while tapering the outside.  I started by defining the top radius of the stack, just below what will be the decorative ring.  I did this with the grooving tool.


Then I used my favorite tangential tool to take off the bulk of the material before actually starting the tapering.


And after carefully setting the compound taper to its new required value of 1.05^o, I tapered the outside of the stack.  I had to switch to the lefthanded tool to get the last bit of taper up to the top of the stack.  Now, all of the outside dimensions up to this point are about 1/64” over their final size.  After soldering we’ll take down that last bit to clean things up and blend the two parts together.


And here we are AFTER silver soldering the two parts together.   Annoyingly, I forgot to take a picture of the stack piece before soldering.  But hopefully, you can imagine what it might have looked like.


The part is now being pickled.  Tomorrow we’ll move forward with the final shaping of the smoke stack!

Kim

[Dave Otto]

Coming along nicely Kim!

Dave

[crueby]

Smokin!  Thats a lot of work, looks great!

[cnr6400]

 

[Kim]

Thank you Dave, Chris, and Jeff! 
Kim

[Steamer5]

Hi Kim,
More trials & tribulations behind you! Well done, coming along nicely!

You need to sort out your top slide power feed, cranking the handle to do long parts like that looses its appeal quite quickly........ sure youve got a battery drill sitting in the corner .... you know the one its got the sign over saying...."PICK ME!"

Welcome to the "had covid club!" Best advice when your body says sit down i need a rest, do it! Both my wife & i found that once we had eaten all we wanted to do was sit... took a couple of weeks for that to pass.

Cheers Kerrin