Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 327632 times)

Offline Admiral_dk

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1245 on: September 24, 2021, 11:30:25 AM »
I had to think about it too - but CNR's comment helped quite a bit.

So will you mill the slots in the top and bottom (that are the long thin sides right now), before you cut the two appart ?
I'm even thinking about doing it before soldering - but that is probably a bad idea, as it might warp more when soldering ....  :thinking:

I really enjoy following your build Kim - but there are so many commenting, that adding more might be fluf ....

 :cheers:      Per

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1246 on: September 24, 2021, 07:00:09 PM »
Thanks Per!  I do appreciate the comments :)  And what's a little fluff amongst friends?  You can NEVER have too much fluff!  :Lol:

Yeah, I thought about cutting the grooves in the top and bottom before cutting them apart.  That might have been my first thought, but it isn't the order Kozo does it in.  He does that last.  And after more thought, there is a step where I need to mount the separated parts in the 4-jaw chuck in the lathe.  That will be easier to do if I don't cut the grooves first, so I'll probably go ahead with Kozo's suggested order on that.

I'm about to go out and do some work on those parts today - we'll see how far I get :)

Thanks for your comment Per!
Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1247 on: September 24, 2021, 11:21:49 PM »
The first mission today was to silver solder the crosshead parts as shown yesterday.  So I cleaned them up, added a few center pings to provide a little space between parts, added flux, and used little brass 3-48 screws to hold the disks in place.  Unfortunately, I forgot to take a picture of my silver solder offering before I burnt it to a crisp.  In fact, I did it three times!  Somehow, I thought I could do both disks in one heating.  Wrong.  By the time I got to the 2nd side, the flux had all disappeared. I used the white flux and I should have used the black.  That was a mistake.  Would I have been able to do it in one heating?  Maybe, or maybe not.  But it couldn’t have hurt.  Also, it was very hard to heat from behind because there was a big air gap between the back of the part and the disk.  So I had to do some heating from the front. This really zapped the flux too.

Anyway, I got one side done then I cleaned it up and did the other side, and tossed it in the pickle bucket.  Oops – I didn’t wait for it to cool and I heard it sizzle as it hit the water – and I realized I may have just hardened the part being as it’s all-steel (not an issue if it were brass).  So I fished it out of the bucket and heated it up to red hot yet again.  This time, I let it cool before I soaked it in the citric acid.

So, that was my exciting time with silver soldering today.  Sorry, I was so engrossed in my mess that I forgot to take pictures.  But it was truly ugly.  Nobody would want to see THAT!  I’d even melted the brass screw heads :(

After that excitement, I milled off the heads of the screws and took the whole thing down to 0.360”.  And it looked much better after that:


Next over to the bandsaw to cut it in half:


And here’s the state of play at the end of shop time today.  Two nascent crossheads.


By the way, for anyone interested, I feel that the citric acid bath did a very respectable job of cleaning up the part – it ate away a lot of flux and really helped the part immensely.  I’ll try to get some pictures going forward.  I just completely spaced on that this time.

Thanks for looking in on my incremental progress!
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1248 on: September 25, 2021, 12:29:34 AM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline RReid

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1249 on: September 25, 2021, 12:50:49 AM »
Nice job, Kim.
Assuming that's mild steel, you needn't worry about quenching it. It doesn't have the carbon content to harden.
Regards,
Ron

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1250 on: September 25, 2021, 05:45:58 AM »
Thanks CNR and Ron!

Assuming that's mild steel, you needn't worry about quenching it. It doesn't have the carbon content to harden.

It was 1018, which I thought was considered carbon steel?  Now that I look it up I see it is a mild, low-carbon steel.  So, what I'm learning is that 1018 won't quench harden because it doesn't have enough carbon? That's pretty cool to know.  I knew it wasn't tool steel (like w-1 or o-1) but didn't realize I didn't have to worry about it hardening.

Thanks Ron!  I learn something from you guys EVERY DAY! :)

Kim

Online john mills

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1251 on: September 25, 2021, 07:48:41 AM »
which quenching the mild steel its more a matter of distortion and worst getting splashed of spat at by hot spots of water .
john

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1252 on: September 25, 2021, 05:25:30 PM »
which quenching the mild steel its more a matter of distortion and worst getting splashed of spat at by hot spots of water.
john
Luckily, I didn't seem to have gotten much distortion.  So that's good! :)
Nor did I get splashed! But yeah, I can see that being an issue to watch!
Thanks,
Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1253 on: September 26, 2021, 11:42:09 PM »
Next step on the crossheads is to drill a few holes.  The center hole is the datum used to define everything else for the crossheads.  I located that, drilled, reamed and counter sunk that hole, then drilled a couple of smaller holes that will help define the shape of the crosshead.


With the center hole defined, I cut the front side of the crosshead to length.


Then flipped it around and did the back end – all in relation to the center hole.


More shaping: using a 1/8” end mill I cut some slots on each end at an 8o angle.  Here’s the first one.  I did this on the opposite side of the same end too.


Then I flipped the part over and did essentially the same thing (not quite as deep) to the other end, both sides.


And that is where the crossheads sit today.


There’s a lot of ops in these little parts, but they are really neat looking.  They may not be the most prominent feature on the engine, but I feel they really help bring out the steam engine look!

Kim


Offline samc88

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1254 on: September 27, 2021, 12:14:55 AM »
Looking good so far Kim. I was looking at the cross head castings on my Tich which look like they'll be "interesting"

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Online crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1255 on: September 27, 2021, 12:20:17 AM »
Okay, now I'm seeing where this sequence is going. Clever.

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1256 on: September 27, 2021, 05:51:51 AM »
Looking good so far Kim. I was looking at the cross head castings on my Tich which look like they'll be "interesting"

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Yes!  I saw you've been able to get back to your Tich build, which is great!  I'm looking forward to seeing your crossheads and other progress! :)

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1257 on: September 27, 2021, 05:55:10 AM »
Okay, now I'm seeing where this sequence is going. Clever.

Yeah, wish I could claim any process brilliance here, but I'm just following Kozo's well-documented build.  I have made a few minor changes here and there (like the drivers, for instance!) but mostly, I'm just learning a ton from following his process outlines.

But you know Kozo's books.  Very good drawings and very good explanations.
Kim 

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1258 on: September 28, 2021, 11:35:10 PM »
I’ll be moving forward a bit more slowly for a while here.  My father just passed away and I’ve been spending time with my mother and family helping with arrangements there.  But I did have some time in the shop today (very therapeutic) and made a little progress.

I’m going to round the ends of the crossheads that connect to the piston rod using the lathe.  But to make it easier to center on the lathe, I used the mill to find and mark the center.


Then moved this to the lathe and centered in the 4-jaw using that mark.


I spent considerable time carving a narrow round end tool to use for this operation.  There's not a lot of space between the inner boss and the outer protrusions.
 Anyway, I got it done and it seems to have worked!  You can see my fancy tool here and you can also see that it has successfully been used to round off that boss.  Kozo specifies 5/16” diameter for this, but I took it down just a bit farther since at 5/16” still had some mill marks from cutting those grooves.  It ended up about 10 thou under (0.302”) to get a nice clean look on the boss.  I felt that was a much better look than having it exact size but with a little divot showing.  Looks much better and nobody will even know about the slightly reduced diameter!  (sh… don’t tell anyone!)


I also took the outer ends down 1/32”, as shown in the plans.


And drilled and tapped 8-36 to receive the piston rod.


Here is where we are with the crossheads.


I still have some shaping to do on both ends, and of course, cutting the grooves for the slippers.  But I’m making progress.

Thanks for checking in,
Kim

Offline samc88

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1259 on: September 28, 2021, 11:39:33 PM »
Sorry to hear about your news Kim, thoughts with you and family

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