Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 96309 times)

Offline RReid

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1230 on: September 21, 2021, 12:22:19 AM »
Quote
But to do that, I want to use a 9/16” end mill.  I thought I had one of those, but it turns out, I don’t (or I can’t find it, which is essentially the same thing).
The perennial hazard of cleaning out the garage... :shrug:
Regards,
Ron

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1231 on: September 21, 2021, 10:49:12 PM »
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But to do that, I want to use a 9/16” end mill.  I thought I had one of those, but it turns out, I don’t (or I can’t find it, which is essentially the same thing).
The perennial hazard of cleaning out the garage... :shrug:

No joke!  I'll be finding where I sorted things into for years to come!
However, in this case, I think what I remembered is that I have a 9/16" ball nose mill.  I need a square end for this.

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1232 on: September 21, 2021, 10:53:01 PM »
Well, as I was brushing my teeth last night getting ready for bed, I realized that I’d made a complete guffaw with those absurdly little simple disks I made for the crossheads.  They were SUPPOSED to be 9/16” diameter, but I made them 5/8”.  I used 5/8” rod and forgot to shave it down to the required 9/16”.  That’ll be hard to do at this point.   

Anyway, so, the first thing I did this morning was to re-make those simple pieces. But THIS time I remembered to take them down to 9/16” before I cut them off.  I also realized that it would be a ton easier to drill the center holes on the lathe, so I did that too, prior to part removal.


THIS is what that final picture yesterday should have looked like.  I used my grooving insert tool to cut off the disks this time – it makes a MUCH cleaner cutoff than my big fat (probably not very sharp) cut-off tool.  So clean, in fact, that I couldn’t tell which side was the nicely faced side and which was the cutoff side.  So I scratched an ‘O’ on one face (the ‘outside’ face) to help me remember :)


Now I need the 9/16” end mill which hasn’t arrived (didn’t expect it to).

So, I’m going to work on some other little pieces needed for the crosshead assembly, namely the crosshead pins.

Chapter 15.5 – Crosshead Pins

These are a fairly simple turning exercise made from 1/4" 12L14 round stock.  Here I’ve cut the basic shape and just completed putting the 8-36 threads on the end of the pin, just before cutting it off.


And here are the completed set of Crosshead Pins.  Cute, aren’t they? :)


I’ll probably move on to the crosshead slippers next unless the 9/16” end mill arrives. Then I’ll do the actual crosshead itself. That’s the part that will require all the work in this sub-assembly.

Thanks for stopping by and taking a look!
Kim

Offline steamer

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1233 on: September 22, 2021, 12:23:35 AM »
YUP>..sometimes I sit and stare at the part and go hmmmmm  which side did I part....LOL    I'll get my scribe out next time

What kind of lathe do you have Kim?

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1234 on: September 22, 2021, 05:51:48 AM »
What kind of lathe do you have Kim?

I've got a Grizzly G709 - it's a good-sized import lathe.  It's my 'new' lathe. I got it new about 8 years ago (2013) so I guess it's not really that new anymore.  It replaced my Taig lathe (which I just gave to my brother following my garage clean out).

I really like the lathe.  I'm sure it's nowhere near as nice as some of the old iron people have but I'm quite happy with it.  I've had almost no issues with it and have received good support from Grizzly for the one part that I broke.

Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1235 on: September 22, 2021, 10:57:23 PM »
Chapter 15.6 – Slippers

Another little piece that we need for the crossheads are the Slippers.  These are essentially the linear bearings for the crossheads.

Kozo specifies phosphor bronze for the slippers but I used brass instead.  I assume that the bronze would wear better, but I couldn’t source any sheet bronze at a reasonable price and I already had the 0.040” sheet brass, so I just chose to use that.  If these become an issue I can always make bronze slippers to replace them.  But with how much runtime I anticipate this engine to have, I seriously doubt we’ll see any wear! :)

I had a small scrap of the 0.040” brass sheet so I just cleaned up the edges on that then used a slitting saw to slice off a couple of ~1/4” wide pieces.  I used the slitting saw because this small piece would be really hard (if not impossible) to hold in the horizontal saw’s vise.  And it was really easy in the mill.


Trimming it to the actual required width (0.235” I believe).


Then I sliced off 4 1” lengths on the scroll saw:


And squared up the ends and trimmed them to exact length in the mill (15/16”).


The final op was to drill and countersink holes for the 0-80 mounting screws.


And there you have it, four slippers for the crossheads:


And that was what I accomplished today!

Thanks for checking in on me.
Kim

Offline kvom

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1236 on: September 23, 2021, 12:21:07 PM »
On my build some of the most finicky work was getting the crosshead/slippers/guides/yoke to work smoothly together.  Your next parts on pages 98-100 need to be made very precisely. 

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1237 on: September 23, 2021, 06:56:52 PM »
On my build some of the most finicky work was getting the crosshead/slippers/guides/yoke to work smoothly together.  Your next parts on pages 98-100 need to be made very precisely. 

Thanks Kvom,
You're right, they will require extra special carefulness. But I'm actually really looking forward to the crosshead guides! Somehow getting those on there will make the mechanism all start to come together.  I've had those rods hanging there at the side of the chassis for months now.  But once I get the crossheads & guides on there, they'll have a place to go.

Kim


Offline Don1966

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1238 on: September 23, 2021, 11:00:28 PM »
More pieces to the puzzle added Kim. Always nice work……..did I say …..I………….likeeeeeee….. :Love:




 :cheers:
Don

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1239 on: September 23, 2021, 11:04:18 PM »
Thank you Don!  :cheers:
Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1240 on: September 23, 2021, 11:13:20 PM »
I’m coming up on another silver soldering operation so I decided it was time to mix up my new Citric Acid based pickle solution.  I decided to start with a ~60g per gallon solution – that turns out to be 1/4 cup of dry citric acid crystal/powder.  I weighed it out and a Tablespoon is about 15 grams.  So 4 Tablespoons, which is 1/4 cup, (don’t try and tell me you don’t love these English units!) came out to be ~60g.  That seemed reasonable with what I’ve heard others using.  If I want it stronger I can add more later.  The citric acid powder seemed to dissolve well into the room temp water, so that seems good.

You can see the 5 lb bag of Citric Acid on the welding table, and the big red Rubbermaid tub that I’m using for the pickle bath sitting on the floor (do not be confused by the red Coleman cooler that is sitting in the "to go" pile).  I put about 7 gallons of water in it so I’ve got quite a good-sized bath.  Should be plenty big enough for the boiler, which was my goal.  But the boiler is still some ways away yet.

All the stuff in the background sitting on and in front of the table saw is garage clean-up piles that are still in the process of moving out.  Hopefully, I’ll have my whole shop back soon!

OK, now, back to the Crossheads!  The 9/16” end mill came in yesterday so I’m all set to make more progress on this part.

I took the little steel chunk and drilled two holes for 3-48.


Then using a 7/16” mill I made holes 0.260” deep (that’s just over 2/3s of the way through the part).


Here’s where the 9/16” mill comes in. Using that magical new end mill I cut 9/16” holes 0.130” deep (that’s 1/3 of the way through).


With that done, I connected the 7/16” holes with 7/16” slot.


And then finally tapped the remaining holes 3-48.


This block will have the two previously cut 9/16” disks soldered into the 9/16" holes.  Then the part will be cut in half and that will be the basis for the two crossheads.


Here’s a shot with the disks in place.  You can also see what the crossheads will look like when completed.


But the soldering will be tomorrow’s job. This is where I call it a day.

Thanks for stopping by!
Kim

Offline crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1241 on: September 24, 2021, 01:04:18 AM »
I'm confused on that crosshead part - don't see how you get from that to what the picture shows.   :headscratch:    :noidea:
Guess I'll have to tune in to the next couple posts and see!   :popcorn: :popcorn: :popcorn:

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1242 on: September 24, 2021, 03:20:01 AM »
Chris- I think Kozo planned "dueling crossheads"  :Lol: the open sides face each other and the piston rod ends face outward at each end. My theory, anyway!  :cheers:

Looks like a two  :DrinkPint: job to make that.

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1243 on: September 24, 2021, 04:05:06 AM »
Yes, exactly as CNR said - they are facing each other.  And even after they are cut apart there's still a lot of shaping to go.  That 7/16" slot that went down 2/3's of the way will be the slot that the connecting rod fits into.  Hopefully, it will become more clear as the crossheads emerge.

Thanks for following along!
Kim

Offline crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #1244 on: September 24, 2021, 04:26:44 AM »
Guess I'll understand it when I see it come together - seems like a longer way to go than to just mill it out of a single piece, but I'm sure Kozo has a reason for it, he is always very good at working out procedures!  You got me hooked to come back and keep watching!   :ThumbsUp: