Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 129393 times)

Online samc88

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1395 on: October 30, 2021, 07:06:57 PM »
Interesting looking slide valve, all the ones I've seen so far just have a relief milled around the outside, nice work Kim

Sent from my G3121 using Tapatalk


Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1396 on: October 31, 2021, 04:45:34 AM »
Thank you, Sam!  :cheers:
Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1397 on: November 04, 2021, 09:32:32 PM »
Chapter 17.3 – Valve Spindles

Next up is the Valve Spindle – that’s what Kozo calls it anyway.  I’d have called it a valve rod. But what do I know?

Regardless of what you call it, it’s a fairly simple part.  The only challenge here is turning a 1/8” rod down to 0.086”.  I did that by supporting the end with a live center and taking really small cuts.  And it worked.


Then I removed the live center, cut the taper using the compound slide, then threaded the rod 2-56.


After cutting it off at the specified length, I flipped it around and threaded a short length of the 1/8” end to 5-44.


And here are the two valve rods:


Slipped into their home positions with the valve nuts and valves:


Next up will be the valve spindle yokes (which I would call the valve rod clevis.)

Thanks for looking in!
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1398 on: November 04, 2021, 09:42:05 PM »
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Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1399 on: November 12, 2021, 10:53:47 PM »
Chapter 17.4 – Valve Spindle Yokes

Last weekend I started the Valve Spindle Yokes (the valve rod clevises).  I got about half done and was going to finish on Monday.  But my Monday took a different direction.  So instead, I finished them on Friday.  If you’re interested to hear more about my adventure, I posted a summary in the Chatterbox sub-forum.

But back to the Pennsy!

The valve clevises are small little forks that will thread onto the end of the valve rod. They were made from 1/4" x 3/8" 1018 CRS bar stock.  I cut off a piece a little over 1 1/8” long to make the two clevises from.  I will be making one on each end, then cut them in half.

The first op was to shave the part down to the right thicknesses – 0.200” x 23/64”.


With that done, I measured 0.100” in from each side and drilled & reamed a 5/64” hole all the way through.  This will be for the clevis pin.


After centering up the RT, I used a gauge pin to center the end of the part over the RT and clamped it in place.


And rounded off the end.


Then, tipping it up on end, I carved out the forks by making a 0.204” wide gap centered in each end.


At this point, I cut the part down the middle(ish) and cleaned up the ends to the correct length:


The final step was to drill and tap 5-44 to match the end of the valve rod.


And here are the completed clevises:


Now, mounted on the valve rods.


That’s one more piece down!

Thanks for stopping by,
Kim

Offline MJM460

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1400 on: November 13, 2021, 12:24:59 AM »
Hi Kim, nice work on the clevis’s.  Good to see progress again despite the inconvenient interruption.

I always look forward to your updates.

MJM460

« Last Edit: November 14, 2021, 01:01:28 AM by MJM460 »
The more I learn, the more I find that I still have to learn!

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1401 on: November 13, 2021, 06:11:57 AM »
Thanks MJM!
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1402 on: November 13, 2021, 01:07:51 PM »
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Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1403 on: November 13, 2021, 07:41:07 PM »
Thanks CRN  :cheers:

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1404 on: November 19, 2021, 12:07:29 AM »
Chapter 17.5 – Combination Levers

This week I’ve been working on the Combination Levers.  These are the short levers that connect the valve rod to the rest of the valve gear (the Radius Rod and the Crosshead) and produce that combined motion that is characteristic of the Walshaerts valve mechanism.

Just so I don’t confuse people who may be following Kozo’s book, this is NOT the method he shows to use for this part.  I charted my own process here.  I did use some of his techniques though, as you’ll see later.  But he did most of this part in a completely different way.

To start with, I cut some 1/4" square 12L14 bar then did some stress-relieving.  Not sure if 12L14 is as prone to go banana as the 1018 CRS is, but I figured it was easy to do.  The two short pieces are for the Combination Levers. The longer pieces are for the Radius Rods which will be coming up shortly.  Figured I’d just do the stress relief at the same time.


After shaving the 1/4" square down to 0.200” square I drilled some #49 holes in the right place.  These will be reamed out to 5/64” eventually, but for now, this size will allow a nice close fit for some 1-72 screws to use to hold the part in a jig for shaping.


Next, I made a jig using some 1/2" aluminum.  I drilled & tapped holes in the right locations to hold the rod in place.  This jig will be used in both horizontal and vertical positions for various operations in the making of this part.

Here I’m using it horizontally to mill the neck of the ‘small end’ of the combination lever.  Hopefully, this will become more clear later.  I milled this 1/4", but if I were to do it again, I’d probably use 3/16” instead.  I think 1/4” was just a tad too big for this radius.


With that done, I turned the part sideways (sans-jig) and drilled a #45 hole (0.082”) as the termination for the slot.


And then proceeded to cut the slot from the end to the hole just drilled.  I did this by using an 0.040” saw, positioning it to produce the right with of the upper fork.  After slicing the upper side, I flipped the part over and did it again to get the other side (which was now the upper side again of course, since I flipped the part). This way the slot was centered and I had the same with of tines on both sides of my fork.  This operation was surprisingly satisfying.  I would have normally just gone to a 1/16” end mill for this operation, but Kozo showed doing it this way and I decided to give it a go.  I was super impressed with how well it worked!  :Lol:


Back to the jig, where we mount it vertically in the mill vise and use a 5/32” mill to narrow the bulk of the lever.  The just-completed one is mounted in the jig, and the second one is sitting on the vise below, waiting his turn.


There’s a notch that has to be cut into the small end of the lever, so I did that next.  I wanted to make sure and get that done BEFORE I cut the taper on the rod (which would make it a lot harder to hold!  I also did a double and triple check before doing this operation since the lever is no longer symmetrical - Wouldn't want to notch the wrong side!  :o


And now, the taper.  This is a very shallow taper.  I calculated that it was around 1.5o.  To do this, I drilled another hole on the right side that was 0.048” thousandths lower than the centerline.  I had to use the second hole from the right.  If I’d used the first one, the hole for the taper would have overlapped the hole for mounting it straight.  By using the second hole, I didn’t have that problem.  But I did have to make sure I did my trig calculations for THAT hole and not the other one.  It’s hard to see here, but the taper has been cut on the topside, but not the bottom.  To do the other side, I had to flip the part over.  This jig only cut the taper correctly on one side.


Here’s a better view of the part in the jig, post tapering.  It’s hard to tell, but the part is at a bit of an angle, and after the tapering, the top is now flat/straight.


And finally, I made some 0.200” filing buttons and rounded the ends of the combination levers.


Here they are completed!


Oh, wait!  I forgot to ream the holes out to 5/64”! :embarassed:  Guess I’ll do that tomorrow.  But they are essentially done!

Thanks for taking a look,
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1405 on: November 19, 2021, 01:55:45 AM »
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Offline Don1966

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1406 on: November 19, 2021, 03:50:32 AM »
Making progress Kim and very nice work…..


 :cheers:
Don

Offline Steamer5

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1407 on: November 19, 2021, 07:54:08 AM »
Nice work Kim,
They have come out lovely!

Cheers Kerrin
Get excited and make something!

Offline kvom

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1408 on: November 19, 2021, 12:35:50 PM »
I'd counsel against 12L14 as it's very prone to rust, and you won't be painting these parts.

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1409 on: November 19, 2021, 06:24:09 PM »
Thanks all, for the encouragement.

I'd counsel against 12L14 as it's very prone to rust, and you won't be painting these parts.
Kvom,
So, are you saying that 12L14 is more prone to rusting than 1018?  I have 1018 that has rust on it too, but that's interesting if that's the case.  I was planning to spray all the unpainted parts with some clear coat after they're all buffed up to keep things from rusting.  Hopefully that will help?

Kim