Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 327496 times)

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #735 on: July 21, 2020, 05:49:01 AM »
Maybe just a dab of "Super Glue" on the screen?

 John
Yeah, that's what I'm currently thinking :)
Kim

Offline john mills

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #736 on: July 21, 2020, 09:55:07 AM »
i like the cup over the screen to hold it in place if it is brass it would solder easily and you will know it will stay on
it could be crimped over a little . if you use super glue you will not know if it falls off .loktite is not really a glue
to stick things on like an epoxy glue and again if it falls off you won't know.      john 

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #737 on: July 21, 2020, 12:12:20 PM »
Hi Kim, +1 on John's cup idea to retain the screen. I would not depend on Loctite or Superglue to hold the screen forever immersed in water. Seen superglue fail in water immersed jobs several times.

In Kozo's earlier designs of locomotives he showed a groove around the pickup funnel and the screen retained by a wire wrapped around and twisted tight. That would also work, but the screen would have to be very thin and compliant to get it formed over the end to start with.

You are making great progress! enjoying your build pics!   :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:
"I've cut that stock three times, and it's still too short!"

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #738 on: July 21, 2020, 06:07:52 PM »
Thanks John and CNR,
I appreciate the thoughtful input.  I'll continue pondering and think about a more positive retention mechanism.  Seems that the superglue/Loktite solution isn't as good as I was thinking...  :thinking:

Kim

Offline Roger B

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #739 on: July 21, 2020, 07:13:05 PM »
Still following along and enjoying  :praise2:  :praise2: Ball valves are tricky things  ::) The bore of the seating is also important, it should at least be reamed if the seating is flat or raised as in Achim's drawing.
Best regards

Roger

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #740 on: July 22, 2020, 08:38:42 PM »
Still following along and enjoying  :praise2:  :praise2: Ball valves are tricky things  ::) The bore of the seating is also important, it should at least be reamed if the seating is flat or raised as in Achim's drawing.

Thanks Roger!
The D-bit I made for this has a 15o angle on the end, so there should be a good raised seat for the hole to sit on.

I'm looking at going with the Silicon Nitride balls that Kerrin (and others) mentioned a few posts back.  I've got a few on order and we'll see how they work out :)  I decided to go that direction rather than the softer Nitrile balls.  One reason is that I've already drilled the holes, and advice is that if you go with the softer balls you need to make the hole slightly undersized.  I'm too late for that!  So I'll give the super-hard ones a try.

Kim

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #741 on: July 27, 2020, 12:39:11 AM »
I’ve got a couple of parts for my update today.  First, we have completing the link for the hand pump.

I’d just rounded off the ends using filing buttons last week.  So, this week, I set it up in the mill and used a slitting saw to make two cuts to remove a chunk leaving a 1/8” wide slot on each side:


And here’s the final part:


Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #742 on: July 27, 2020, 12:57:50 AM »
After completing the link, I went back to considering how to attach the screen on the Suction Valve.  My previous attempts at soft soldering didn’t go to well.  I just couldn’t get the solder to adhere to the screen.  I think the problem is that I was unable to get the screen hot enough without scorching the flux, so the solder would never adhere.  Usually, you can heat up one side of the metal and the other side gets hot enough to do the job.  But with the screen, it doesn’t work that way.  Plus, I was very worried bout melting the screen.

So, in the end, I went with making a cap to go over the end of the suction valve to hold the screen.

I started with 7/8” brass rod (360).  I used a series of drills to make a hole about .2” deep, then bored it out to 19/32” to match the bottom of the suction valve.


Then I bored a .75” hole .125” deep, like so:


Just big enough for the big end of the suction valve to fit into:


Then cut it off 5/32” long, leaving me a 1/32” thick lip all around the edge to hold the screen in place.


With that done, I drilled and tapped a hole for a #0-80 screw to hold the screen retainer in place.  I was going to do two, but once I got there, I figured 1 would be plenty!  It’s not like its going to be under a lot of stress.


I got a bright shiny screen out of the bag of 100 that I’d got off Amazon and used that in the final assembly.  And here’s out it turned out:


This is a deviation from Kozo’s plans, but I think it turned out mighty nice looking!  And this way I can change the screen if it gets too clogged from excessive use! (yeah right :))

With that, I am calling the Suction Valve assembly complete.
Kim

Offline crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #743 on: July 27, 2020, 01:09:55 AM »
That came out great!

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #744 on: July 27, 2020, 01:11:04 AM »
Thanks Chris!  I think this was your idea, so you should take credit :)
Thank you!
Kim

Offline john mills

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #745 on: July 27, 2020, 01:12:52 AM »
that looks good

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #746 on: July 27, 2020, 01:13:10 AM »
Chapter 8.7 – Lever

My last part for today was the Lever for the hand pump.

This was made from a piece of 1/8”x1/2” 303 Stainless flat bar.  First operation was to chuck it in the 4 jaw and center it as best I could, face it, then cut a 3/4" length down to 5/16” diameter:


Back to the mill to cut to length, then add 2 pivot holes – reamed to 1/8”.


After shaving 1/32” off each side (to bring the width down to 7/16”, per the plan), I used 3/32” spacers on the narrow end and milled each side to an angle.  To get 3/32” I used a stack of feeler gauges (on the back side) and a 3/32” slitting saw (on the front).  A bit unusual, but that’s what I could find for 3/32” spacers!


Lastly, I rounded the narrow end using files & some 1/4” filing buttons and it was complete:


Here’s a pump family shot.  Only a few more parts to go, like the handle and some pivot pins!  But I’m getting close to completing the hand pump (believe it or not).


Thanks for visiting my shop today!  (and for maintaining an acceptable social distance :)).
Kim

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #747 on: July 27, 2020, 01:13:52 AM »
that looks good
Thanks John!
You were part of this solution too.  I appreciate the input!  And the results speak for themselves :)
Kim

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #748 on: July 27, 2020, 12:29:55 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Top notch work! The cup / screws for screen retention look great and make it serviceable, which is a great feature, I think.
"I've cut that stock three times, and it's still too short!"

Offline Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #749 on: July 28, 2020, 04:57:42 AM »
Thanks CNR!  :cheers:
Kim

 

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