Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 327429 times)

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1020 on: April 17, 2021, 05:11:40 AM »
Great sequence, worked great!  On the counterbore, did you harden/temper it?

Thanks Chris!

I hardened the counterbore but didn't bother to temper, since I only needed it for two holes.  It has a very short useful life, so as long as it lasted for my two holes, I was set.  useful life is short.  And I always find it hard to keep the 'tempering' from getting too hot on the thin parts of the tool (like the sharp edges) which would start to draw away the hardening.  So I just skipped the tempering this time.

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1021 on: April 17, 2021, 05:13:24 AM »
Thank you for the encouragement Julian, Joe, Bob, Dave, and Craig!
Really appreciate the comments  :cheers:
Kim
« Last Edit: April 17, 2021, 05:17:01 AM by Kim »

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1022 on: April 17, 2021, 05:16:49 AM »
That's really nice work Kim, both the parts and the write-up.

It would seem that those little tapped holes would be for a small oil cup, but when I reviewed my copy of the book the bushings aren't shown as being drilled, so oil wouldn't get through anyway. Maybe a dummy oil cup was intended? I couldn't find a single photo or drawing showing the side rods assembled in anything other than a "rods down" position, in which case that area is always hidden from view. I imagine you looked too, but I got curious.

Thanks for the kind words Ron and for checking on those tapped holes.  Yes, I looked through the book several times and couldn't find anything to go in there.  I considered oil cups, but never saw any.  I also thought about a set screw to hold the bearings in place, but the threads don't go all the way through.  they only go partway in.  So I'm stumped. But I put them in because it was in the drawings! :)

I appreciate you looking too.  Maybe one of will figure out what those tapped holes are for someday!
Kim

Offline crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1023 on: April 17, 2021, 01:27:44 PM »
You may want to check this forum, the Kozo support group!
https://livesteam.proboards.com/board/3/kozo-hiraoka-support-group
Chris

Offline Roger B

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1024 on: April 23, 2021, 03:01:50 PM »
Excellent work on the rods  :praise2:  :praise2: It's interesting that suddenly a metric dimension appears  :headscratch:
Best regards

Roger

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1025 on: April 23, 2021, 04:40:24 PM »
Yes, I have found that interesting too!   Several of the internal diameters on the wheels are in metric.  I'm sure he just used those because they were convenient for him.  For the most part, everything is in inch units.  But those few really threw me for a bit!

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1026 on: May 16, 2021, 10:48:12 PM »
Time flies when you’re retired!  It’s been a month since my last update on this project, but I haven’t been idle.  I’ve moved one of my daughters and her husband to another state, I’ve been out camping a week, repaired the trailer, and the list goes on.  As has been said – I don’t know how I ever had time to work!

Anyway, I haven’t been totally absent from the shop… just mostly absent. Though I’ve made minimal progress I felt it was time to make an update so you’d all know I was still around and kicking.

Chapter 13.2 – Main Rods

Where the Side Rods connect the sets of main wheels together (the rods I just completed (if ‘just’ can be a month ago!)), the Main Rods will connect the wheels to the piston rod.

The process for making the Main Rods will be similar to the Side Rods, however, the main rods are not symmetrical as the Side Rods are.  They have some tapering which requires some additional work.

But for starters, it’s the same.  The main rods were made from lengths of 1/4" x 5/8" 1018 CRS.  I did the same steps here as with the side rods – stress relief, then mill it down to the required 0.200” thickness. No pictures here, as it is the same as before.

With the rods at the correct thickness, I drilled three holes.   The two for the part (big end and small end) and an extra hole PAST the small end just for holding things during machining.  Each hole is drilled and reamed.  The big end is 9mm, the little end, 6mm, and the extra hole is 1/4"  (notice Kozo again chose metric values for the holes for the bearings.)


Next, I narrowed the big end down to its final size of 9/16”.  I took a shave off one side, flipped it over and did the same on the other.  Took me a few tries to sneak up on it, but I got the right final dimension and doing it this way made sure it was centered.


Next, on the big end, I drilled and tapped holes for the fake cotter/bolt arrangement.  Those little pieces will be made later and will be threaded into these holes in the big end.  They provide no useful function, but make it look like the prototype.


The obligatory tapping picture (2-56) with my favorite little tap handle.


With the big end completed, its time to take the rod down to the final thickness.  Only the big end will remain at 0.200” thick.  The rest will be shaved down to 0.125”. This was done similar to the side rod, but now you can see the need for the extra hole since we need include the small end of the rod in the reduced thickness.  That extra hole provides a way to continue to hold the rod in the fixture while getting the entire small end down in size.


After shaving off one side, I flipped the rod over, added a few shims on the backside to provide some additional rigidity in the center, and shaved off the other side just the same.

And here’s a picture of one of the blanks thinned (lower one), while the other waits its turn (top one)  which will be next shop time since I was out of gas for the day.  Do note that the rods in the picture are backwards from what is shown on the drawing below.  I should have turned them over.  Sorry.


The piece of paper in the background shows all my trig calculations on it  that I will be using to make a jig for cutting all the tapered angles on the rod.  Took me a few tries to get consistent results, but I think I’ve got it now.  Guess we’ll see next time, eh?

Thanks for looking in,
Kim

Online cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1027 on: May 17, 2021, 05:40:52 AM »
Great start on the rods Kim!  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

PS rods I have made usually warp badly when I mill the opposite side. I think this is because my metal suppliers slip Bananium alloy into my order rather than plain black hot rolled steel I ordered.  Must be cheaper than black HRS.  :shrug:  :Lol:
"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 #1028 on: May 17, 2021, 05:07:53 PM »
Looking good, Kim! Somehow getting side and main rods done turns a rolling chassis into a locomotive chassis :).

By the way, I was looking at various compressed air engines yesterday and ran across your Radial-5 build. Went right out and ordered the book those plans are in. You did a great job on that one too!
Regards,
Ron

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1029 on: May 17, 2021, 06:08:34 PM »
Great start on the rods Kim!  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

PS rods I have made usually warp badly when I mill the opposite side. I think this is because my metal suppliers slip Bananium alloy into my order rather than plain black hot rolled steel I ordered.  Must be cheaper than black HRS.  :shrug:  :Lol:

Thanks CNR!
Yeah, I think they've shipped me some of that Bananium in the past too!  I have found that doing the stress-relief heating step really seems to help the CRS a lot.  I picked that trick up from people on this forum many years ago on one of my first engines that used steel.   That, and taking a shave off of one side, then the same off the other side, in multiple passes.  Not only does that keep the stresses more symmetrical, by doing it on alternating sides if it gets a tiny warp in it, it gets milled back flat.  Of course, this is only helpful for small warpage.

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1030 on: May 17, 2021, 06:10:45 PM »
Looking good, Kim! Somehow getting side and main rods done turns a rolling chassis into a locomotive chassis :).

By the way, I was looking at various compressed air engines yesterday and ran across your Radial-5 build. Went right out and ordered the book those plans are in. You did a great job on that one too!

Thanks Ronald!  (BTW, do you go by Ron, or Ronald?)

Yes, I'm really looking forward to having the rods and wheels on the chassis! :)

The Radial-5 was a very fun little engine.  Highly recommend it.  About the same time I did that, Bill Lindsey (another member of the forum) did a 1/2 sized version of the same thing.  That was a pretty cute little engine too!

Kim

Offline RReid

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1031 on: May 17, 2021, 06:17:01 PM »
Quote
Thanks Ronald!  (BTW, do you go by Ron, or Ronald?)

I normally go by Ron and please feel free to use that. I only use Ronald on the signature line to avoid confusion with the "other" Ron on the forum. :)
« Last Edit: May 17, 2021, 06:23:13 PM by Kim »
Regards,
Ron

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1032 on: May 17, 2021, 06:21:44 PM »
Quote
Thanks Ronald!  (BTW, do you go by Ron, or Ronald?)

I normally go by Ron and please feel free to use that. I only use Ronald on the signature line to avoid confusion with the "other" Ron on the forum. :)

Will do! Ron it is :)

Thanks Ron!
Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1033 on: May 21, 2021, 11:44:13 PM »
Continuing with the main rods, my next step was to make yet another jig to allow me to cut the taper on the rod.  As I’ve mentioned before, I did a page full of trig to get the right location for the holes.  And, as I also stated, I had to re-do my calculations a couple of times to get it right.  But while I was setting it up to do, I actually had to re-re-re-do the math because I realized I HADN'T done it right (don't you love math?).  Eventually, I got a number that actually seemed right, and produced the right angles when I checked them.  So I used those numbers to drill and tap 1/4-20 holes in three spots – one for the big end (on the right) and two for the ‘extra’ hole on the small end – one for the shallow angle, and one for the steeper one at the end.


With a part in place on the jig, I checked to make sure that the cut line followed the marked out line I made on the part.  And it did!  That gave me confidence that I’d done my math correctly (at least ONE of the times :)).


Then I cut the taper on one side, from the big end down to the inflection point.


Now, moving the little end of the rod to the OTHER hole, I checked this line, and it also looked right.


Then I cut from the inflection point to the end of the rod.


With my process proved out, I flipped the rod over and did exactly the same thing to the other side:


I realized that there was one other issue here.  The edge of the taper on the big end should match the place where the rod narrows.  I was off by about 0.020”.  I marked up the picture below to hopefully show what I’m talking about – the edge marked with the red line and the edge marked in yellow should touch at the corner.  And you can see, they don’t.


To fix this, I needed to extended the ‘thinning’ cut about 20 thousandths farther toward the big end.  So I put the rods back in the first jig, and took another smidge off each side.  I think it’s pretty close now.


I cleaned up the machine marks using the sandpaper over a steel dowel trick.


Finally, I centered up the rotary table and centered the small end over that. (There’s a protective piece of aluminum under the part to keep me from digging into the face of the RT.


Then proceeded to round off the end of the small end.  (You can see the extra length of the rod with the additional hole laying there in the lower right).


And there you have it, two completed main rods:


Thanks for sticking with me as I slowly move through my build.
Kim

Offline Dave Otto

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1034 on: May 22, 2021, 12:20:44 AM »
Nicely done Kim!
The rods turned out great.

Dave

 

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