Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 327582 times)

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #690 on: June 30, 2020, 08:33:44 PM »
Let's see... since you did your Shay you've only completed another 143 metal working projects, several dozen carvings, nine RC Submarines, and multi-dozen other projects... and you didn't remember if there was an o-ring?  :thinking: I don't think you need to worry about your memory, Chris!  You remember more about projects you did 7-8 years ago than I do about the one I'm doing right now!  :ROFL:

Kim

Offline crueby

  • Full Member
  • *****
  • Posts: 18555
  • Rochester NY
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #691 on: June 30, 2020, 08:48:28 PM »
Let's see... since you did your Shay you've only completed another 143 metal working projects, several dozen carvings, nine RC Submarines, and multi-dozen other projects... and you didn't remember if there was an o-ring?  :thinking: I don't think you need to worry about your memory, Chris!  You remember more about projects you did 7-8 years ago than I do about the one I'm doing right now!  :ROFL:

Kim
:cheers:
And it was only 141 metalworking projects...  :ROFL:

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #692 on: July 04, 2020, 04:13:06 PM »
I had the day off for the 4th of July weekend, so got to have some extra time in the shop today!

Continuing where I left off with the handpump body, I clamped the assembly into the 4-jaw chuck and proceeded to drill a #22 hole all the way through to the vertical hole in the column.  Then I followed that with a near 3/8” hole, followed by reaming at 3/8”:


The outer 7/16” was bored to 0.508”.  This will be for an o-ring to seal around the plunger.


We’re getting to the final steps on this complex piece!
In the opposite end, I drilled and tapped a hole for a #1-72 screw. This is to keep the inlet check-ball in place.


Then drilled and reamed the 1/8” hole in the pump handle lug.  I also rounded the lug, but no picture of that operation.


I drilled and tapped a couple of #1-72 holes for screws to hold the base in place during silver soldering.


And last for today, I cut the base plate and milled it to dimension, then drilled through holes for the mounting screws and for the #1 screws used for soldering.


That’s where I ran out of steam and left things for the day.  Couldn’t quite get the part finished, but it's close!

Kim

Offline matthew-s

  • Full Member
  • ****
  • Posts: 59
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #693 on: July 04, 2020, 04:30:07 PM »
Nice work. I was also working on the pump body this weekend. What a stressful part as there are some tricky (to me) steps and a lot of time and material $ goes  into the pump body. Unfortunately I could not hold the 0.375 cylinder bore on my sloppy 7” lathe. I ordered some 10mm 303 stainless stock that I’ll need to turn down a hair to save this assembly.

You did a really nice job on this, and are flying compared to me!

Offline crueby

  • Full Member
  • *****
  • Posts: 18555
  • Rochester NY
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #694 on: July 04, 2020, 08:01:30 PM »
Great progress Kim - hope you dont make the mistake I did on first pump, and you use stainless spring and ball bearings! Mine worked at first, then rusted.   :wallbang: Got right materials for reworking it. 

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #695 on: July 05, 2020, 05:17:42 AM »
Nice work. I was also working on the pump body this weekend. What a stressful part as there are some tricky (to me) steps and a lot of time and material $ goes  into the pump body. Unfortunately I could not hold the 0.375 cylinder bore on my sloppy 7” lathe. I ordered some 10mm 303 stainless stock that I’ll need to turn down a hair to save this assembly.

You did a really nice job on this, and are flying compared to me!
Thanks Matthew! it does have a lot of steps!  I tried not to think about how much work it would be to re-do if I screwed up.  Just tried to focus carefully on each step as I went.  Hopefully I did OK. Guess we'll see soon!

That sounds like a pain, to have to turn down stock to 3/8".  But hopefully it worked for you!

Kim

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #696 on: July 05, 2020, 05:19:49 AM »
Great progress Kim - hope you dont make the mistake I did on first pump, and you use stainless spring and ball bearings! Mine worked at first, then rusted.   :wallbang: Got right materials for reworking it.
Yes, I was very careful to select stainless balls and stainless wire for the springs.  Made it a big harder to source, but it seemed like an important detail :)
Kim

Offline fumopuc

  • Full Member
  • *****
  • Posts: 3231
  • Munich, Germany, EU
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #697 on: July 05, 2020, 07:01:25 AM »
Hi Kim, nice progress.
This valve ball/check valve story is mostly not so easy.
Very important is the design of the ball seat.
If it is not possible to do this so perfect as required, these type of balls will help a lot.
https://www.bengs-modellbau.de/en/material/seals/157/grafi-sil-valve-balls
This is a German source, but I am sure there will be also a US dealer.
A quick check at McMaster-Carr showing me this
https://www.mcmaster.com/silicone-rubber-balls
Good luck for your further steps with this excellent build.

Kind Regards
Achim

Offline fumopuc

  • Full Member
  • *****
  • Posts: 3231
  • Munich, Germany, EU
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #698 on: July 05, 2020, 08:19:22 AM »
Hi Kim, here an explanation what I understand by not so easy to make.
Left side, standard ball seat with a 118° drill bit made.
Right side the best shape for sealing, but much more difficult to make.
Kind Regards
Achim

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #699 on: July 06, 2020, 05:51:39 AM »
Thank you for the info, Achim!  I'm wondering if there's any US distributor that has those Silicon balls?  Those look like they'd be really good for these type of ball-check valves.

I did use a D-bit to create the seat, so hopefully it looks like the more ideal case in your excellent drawing.  But it can be hard to get a good, smooth seat there.  I may see if I can find some of those balls like that.

Thanks,
Kim

Offline crueby

  • Full Member
  • *****
  • Posts: 18555
  • Rochester NY
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #700 on: July 06, 2020, 03:43:03 PM »
Thank you for the info, Achim!  I'm wondering if there's any US distributor that has those Silicon balls?  Those look like they'd be really good for these type of ball-check valves.

I did use a D-bit to create the seat, so hopefully it looks like the more ideal case in your excellent drawing.  But it can be hard to get a good, smooth seat there.  I may see if I can find some of those balls like that.

Thanks,
Kim
Closest I have seen are these from McmasterCarr - not the same compound as he linked to, but meant for same use:
https://www.mcmaster.com/rubber-balls/durometer~70amps/


Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #701 on: July 06, 2020, 08:37:16 PM »

Offline crueby

  • Full Member
  • *****
  • Posts: 18555
  • Rochester NY
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #702 on: July 06, 2020, 09:15:35 PM »
Look like the same things - I suspect Carr's shipping will be cheaper than the $15 that PBS lists, worth an email to them to find out (since Carr does not show shipping in the shopping cart, but will respond with a shipping quote by email before ordering).

I've never used them for check valves, but it looks worth a try. Seems like they would form to the shape of the opening nicely, question is do they release easily or stick when squished in. For a few bucks, worth a try (especially if combined with a larger order for something else to dilute the shipping cost). For the rubber balls, seems like the shape left by a standard drill bit would work fine.

Offline Steamer5

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1272
  • The "Naki" New Zealand
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #703 on: July 07, 2020, 09:42:30 AM »
Hi Kim,
 I’ve tried the nitrile balls in the non returns on my loco. Worked great for awhile then I had issues, changed them out for new ones & had the same problem. By chance I found that they had deformed.
I have since found that using a square faced hole isn’t the way to go for nitrile balls, you need a tapered.
The other way to go is nitride balls. These are extremely hard & round, unlike stainless ones, the usual idea is to put a ball in the hole against the seat & give it a wack to create seat, throw the ball & use a new one. With the nitride ball you can use the same ball as they are so hard. Instead of a wack use your vice with a suitable length of rod & put a controlled squeeze on the ball to form the seat
When I get sorted I’m heading down this road, I got the balls via EBay.

Cheers Kerrin
Get excited and make something!

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7860
  • Portland, Oregon, USA
Re: Pennsylvania A3 Switcher (Kozo)
« Reply #704 on: July 07, 2020, 04:59:49 PM »
Thanks Kerrin!
Now I'll need to look into Nitride balls too :)
Kim

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal