Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 283450 times)

Offline Krypto

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3495 on: November 19, 2023, 04:00:11 PM »
A milestone has been reached! Congratulations, that must have been very satisfying to start to see the engine become operational.
My Workshop Blog:  https://doug.sdf.org/

Offline Michael S.

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3496 on: November 19, 2023, 04:02:06 PM »
Kim, I congratulate you.
It can be regulated well. Emotional vaping is possible.

 :cheers:

Michael

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3497 on: November 19, 2023, 04:52:49 PM »
Thank you everyone!   :cheers:

Yes, it was quite the thrill to see it hold air and just take off running like that. Very exciting indeed!  :cartwheel:

Kim

Offline scc

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3498 on: November 19, 2023, 09:01:22 PM »
Wonderful      :cheers:     Well Done Kim


Offline Don1966

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3499 on: November 19, 2023, 09:56:31 PM »
Awesome KimÖ :Love:

 :cheers:
Don

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3500 on: November 20, 2023, 05:14:04 AM »
Thanks Terry and Don!  :cheers:

Kim

Offline AdeV

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3501 on: November 21, 2023, 05:12:07 PM »
It looks amazing Kim!

Erm - is the front wheel supposed to be jumping up & down like that?
Cheers,
Ade
--
I'm just a poor old man. I have no time for law-breakers. My legs are grey. My ears are gnarled. My eyes are old and bent.

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3502 on: November 21, 2023, 05:43:06 PM »
It looks amazing Kim!

Erm - is the front wheel supposed to be jumping up & down like that?

Thanks, Ade!  :cheers:

Well, yes and no...  The axle for the front wheels pivot in the center. So when the engine is suspended in mid air like it is on my test bench, there's nothing to keep the wheels straight. So on every power stroke the axle moves up and down.  If it were supported by track, it wouldn't be wobbling like that.

I'll have to figure out some way to hold the wheels steady when I'm suspending it like that.  I think last time I put some tape around the axle to help hold it more steady, but that looked funny.  Or maybe I'll just have to make a real test bed with bearings for the wheels to sit on :)

Kim


Offline AdeV

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3503 on: November 21, 2023, 06:58:01 PM »
Ah, cool, that explains it! Good to know it's not something that's about to explode in a cloud of balls and springs  :Lol:
Cheers,
Ade
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I'm just a poor old man. I have no time for law-breakers. My legs are grey. My ears are gnarled. My eyes are old and bent.

Online crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3504 on: November 21, 2023, 07:03:45 PM »
For running my New Shay on air on the bench (and sitting on the short section of bridge trestle I display it on) I made some cradles that fit under the axles bearings between the rails, to raise the wheels just off the rails. Painted them dark brown so they don't show in the shadows under the engine.

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3505 on: November 21, 2023, 10:30:14 PM »
That's a good idea, Chris.  I'm just seeing the ends of the frames on 2x4s  :Lol:

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3506 on: November 23, 2023, 02:23:05 AM »
Chapter 29.1 Ė Steam Dome

On this engine, the Steam Dome's main goal in life is to cover the throttle and safety valves.  It is made up of two major parts; the saddle, and the dome itself. And for the past several days Iíve been working on the Steam Dome Saddle.  Not dramatically different than the saddle for the smoke stack, but itís quite a bit bigger, which makes it more challenging.  For one, itís harder to hold on to.  Itís a big, relatively thin round part.   I spent some time trying to figure out how to do most of the work while it was still attached to the parent stock, but then I couldnít figure out how to hold it and finish the backside at the same time. Actually, I could figure it out, but it didnít do any good to have additional stock that needed to be cut off because I'd still have to hold the skinny puck to clean up the backside anyway, so it didn't buy me much.  Consequently, I just decided to slice off the puck and go for it.  Itís a 2 3/4" diameter by ~1 1/4" thick slide of 12L14.


The best method for holding that I came up with was the 4 Jaw. Luckily, one end was very perpendicular to the sides, so I used that to set things up against.  I should have made a nice lathe spider to simplify this setup, but I didnít. I used a stack of various parallels between the face of the chuck and the back of the part during setup (held in with some tape, so they wouldnít fall out as I rotated the chuck).  This worked to get things centered up and tightened in the chuck. Once that was done, I took out the stack of parallels before turning things on.  Then I faced the end and turned the first feature on the saddle. This will become the ring that the steam dome registers on eventually.


Next, I drilled out the center in steps, up to 1Ē (my largest drill).


Then bored the hole out to 1 15/32Ē diameter Ė just large enough to slide over the valve body.


The last thing I needed to do in this setup was to make a 5/16Ē radius profile around the top edge of the saddle.  My original idea was to use a 5/8Ē diameter ball end mill as a form tool.  I tried this, but it was just very hard going.  The ball end isnít really a very good form tool.  The cutting edge around the nose of the mill isnít flat, it varies.  Hereís a pic of the tip of the 5/8Ē ball end mill. You can see that the business edge of the mill isnít flat, like a good form tool should be so the whole edge canít be on the centerline of the cut.  I set it at a bit of an angle to try and average the height difference so some would be a little above center and some a little below.   I made a red line just above the cutting edge to highlight my dilemma.


When it became clear this would be too hard to do I made a step-off chart and approximated the 5/16Ē radius pattern, like so:


I tried the ball end mill again here, thinking that with most of the heavy cutting out of the way, I could use it to clean up the stair steps that were left.  I used my fat blue Sharpie to color the whole thing so I could see how I was doing.  However, even this proved to be too much for my poorly-shaped-make-do radius form tool.  Guess this is just too much to ask of it, eh?


So, I went old school and used some files to clean up the stair-steps.  At least a some.  Itís not super clean but Iíve got a ton of filing on this part in my future anyway, so Iíll clean it up then.


The next setup was to reverse the part in the 4-jaw.  I used the same ďstack of parallelsĒ trick to make sure the part was square with the jaw face and centered it up using the inside of the bore as the reference.  Then I faced off the back side to get the part to the correct thickness of 1 - 1/16Ē


Finally, I bored out most of the hole another 1/16Ē.  The boring went really well and I was getting a finish I was very pleased with.  However, about halfway through the finishing pass a chip must have gotten stuck on the cutting edge because thereís a weird streak on the bore.  You can barely feel it, but you can sure see it!  It wonít matter in the slightest, but it made me kind of sad anyway.


That completed all the lathe work I could do using these setups.

Next, Iím going to have to make a faceplate setup to turn the inside face of the saddle.  Last time I did this (for the smoke stack) I set it up on the rotary table and did it on the mill.  Unfortunately, this part is too deep for me to do that way. I donít have a mill that could reach all they way across it.  The longest mill I have is just over 3Ē and I need a 2 3/4" reach!  So using the boring bar on the lathe seems like the right way to go.  And it will be a new experience for me since Iíve never used the big faceplate on the lathe before!

But before I can do that, I have figure out how to set it all up. So thatís the next task.

One of the things I need is a nice little plug that will fit in the hole on the saddle to bolt it in place.  So I made that.  My intention was to make it from some 12L14, but what pulled out of the 12L14 pile seemed more like cast iron.  It turned easily but didnít make chips like 12L14.  It made little chips Ė almost dust much of the time Ė more like cast iron would do. Plus (and this should have been my first hint) the bar was a bizarre size.  Bigger than 1.5Ē, but not 1.625Ē.  It was something like 1.578Ē to 1.582Ē.  Not very even round ether.  So I think it was a cast bar (i.e. cast iron).  So I relabeled it when I put it in the CI pile when I put it away.

Anyway, hereís the mounting plug for the saddle, just as Iím cutting it off.


I did check the size and even did a test fit on the part, but I was going for a nice close fit...  I guess I got it too tight.  I couldnít even get it to fit all the way through the hole.


So, I used my little taig 3 jaw to hold the plug and carefully touched it with a file to shave a thou or so off.


And now it fits very nicely. Still a very good fit, but I can get it in and out (with some work).


Hereís what it looks like from the top.


So that brings my build up to date.   Believe it or not, thatís what Iíve gotten done this week.  Doesnít seem like much, but itís taken me some time to get here.

The next step will be to figure out that faceplate setup. Iíve got a picture in my mind, I just have to get there. And yes, itís going to look a lot like the setup Kozo suggests, so donít be too surprised! But even at that, I have to figure out how to get it all held in place at the right spot on the faceplate.  So thatís my next challenge.

Thanks for looking in.
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3507 on: November 23, 2023, 02:50:55 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Online crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3508 on: November 23, 2023, 03:17:15 AM »
Great work Kim!  Amazing how much goes into what is (for the purpose of this model) 'just' a cover!

 :popcorn: :popcorn: :popcorn:

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #3509 on: November 23, 2023, 05:25:38 AM »
Thanks Jeff and Chris!  :cheers:

Amazing how much goes into what is (for the purpose of this model) 'just' a cover!
Ain't that the truth!  :Lol:

Kim

 

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