Pennsylvania A3 Switcher (Kozo)

[Steamer5]

Hi Kim,
 Sorry for the slow reply, re the balls! Ok so these are what I’m talking about...

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=silicon+nitride+balls&_sacat=0

The reason to go for these over stainless is they are ROUND......stainless may not be, well not quite as round!
How hard they are shouldn’t be an issue as a non return as they dont open / close at a quick rate, hence beat the seat.

To quote Lukas..

Hi

The mentionded balls are made of silicon nitrile (not nitiride)  ==> they are soft "rubberlike".

Lukas


These are the ones I’ve tried, what I found is if you swap them out with your stainless ones, they will work fine...........for a while! You will then find that sometimes they work & sometimes they don’t work so well! I was getting frustrated with this !

I was at Dads & we were trying to figure out what was going on, with little success. I had the fitting out, when the phone rang, Dad can be gone for a while! Anyway, I tried the suck & blow test method! Same issue as on the loco, changed the ball all good, hmmmm I did the suck blow test for a while & all was good. Time for a closer look, out with the magnifier it was just possible to see indentation in the ball that had been in the non return......had to be the issue!
Sometime latter I read that to make these work you need to provide a bigger seat.....remember bigger in this sense is the difference between a sharp corner that has been “modified” by a wack,(given that the stainless ball you are likely to be using may not be round) & a controlled taper.

The NITRIDE ball can be used to form the seat in a controlled manner by using a press...aka vice....you can then use the same ball in the non return.
Hope that helps

Cheers Kerrin

[kvom]

Collets by 1/64?  That's a major investment!   

[Kim]

Hi Kim,
Sorry for the slow reply, re the balls! Ok so these are what I’m talking about...

https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=silicon+nitride+balls&_sacat=0

The reason to go for these over stainless is they are ROUND......stainless may not be, well not quite as round!
How hard they are shouldn’t be an issue as a non return as they dont open / close at a quick rate, hence beat the seat.

<snip>
Cheers Kerrin

Thanks Kerrin,
This is great!  I may end up trying the Silicon Nitride balls.  I've got stainless ones, but having used them in the past, I can relate to the hit & miss nature of them.

Thank you for the link!
Kim

[Kim]

Collets by 1/64?  That's a major investment!   

Yeah, well, it was part of a Christmas present to myself one year

Kim

[Kim]

I’m delinquent with my update from last weekend, so I’ll post that now before I go out and enjoy some shop time.

As mentioned before, I’m on a series of small parts for the tender hand pump. Today I made the plug and started on the suction valve.


Chapter 8.4 – Plug

The plug screws into the top of the pump body and holds the spring against the check-ball in the outlet side of the pump.  It's made from 5/16” Hex rod of 360 brass.

Here it is pretty much done, being cut off.


And the completed plug.


As I said, simple parts.

[Kim]

Chapter 8.5 – Suction Valve

Next up I started on the Suction Valve.  This part screws into the bottom of the pump body and is the seat for the inlet check-ball.  The inlet side doesn’t have a spring, depending on gravity to keep the ball in the right place.

The suction valve is made out of 3/4" round 360 brass stock. I turned the basic shape on the lathe. The narrow end is where the ball will seat.


Then used a die to cut the 1/4-32 threads.


And here’s the part so far, after cutting it off from the parent stock.


Still a bit more work on the suction valve, but that was what I got accomplished last week!

See you all in a bit, after some good shop therapy!
Kim

[Kim]

Today I finished up the Suction Valve, or, at least mostly finished it…

Picking up from where I’d left off, I held the big end in the hex collet holder and shaped the hex section of the part.


Back on the lathe, I turned the part around and faced off the big end (which is the bottom).


Then I drilled a cone shape in 1/32” increments. This worked well till I got bigger than 1/2" and then I had to move to 1/16” increments.


With most of the material removed, I used my smallest boring bar and smoothed up the edges of the cone.


With that, the machining is complete.  All that was left was to soft solder a screen over the big end.  This didn’t go so well.  I tried it 3-4 times.  My best attempt was to tin the bottom of the cone with solder, then try to heat every thing up again, but the solder still didn’t adhere to the screen.


So, here’s where it’s at for the moment.  I think I may just clean it up and use Loktite to hold it in place.

[crueby]

Soft solder? I've never had much luck with soft solder onto stainless steel, hard solder is fine on it, but it might melt the screen. Maybe a couple 0-80 screws?

[Kim]

Yeah, that's what I was worried about, Chris - melting the screen.  Which is why I didn't consider hard solder (at least not much ).
Do you think Loktite would work?  Seems like a filter screen on the intake isn't stressed THAT much. And it certainly won't be hot!
Kim

[crueby]

Yeah, that's what I was worried about, Chris - melting the screen.  Which is why I didn't consider hard solder (at least not much ).
Do you think Loktite would work?  Seems like a filter screen on the intake isn't stressed THAT much. And it certainly won't be hot!
Kim

Maybe one of the thicker loctites, like 638, the wires dont give much contact patch. Maybe a better way would be to make a cap with an open center, would not need to be thick, just enough to hold the screen in place, and the cylindrical sides would give surface area for the solder or loctite.

[Kim]

Hmm.... I'll have to think about that.

Thanks for the thoughts, Chris!
Kim

[Kim]

Chapter 8.6 – Link

Next up is the link. This will provide the pivot point between the handle and the body.

It’s another simple part.  I started with a length of 1/4" 303 Stainless, milled it to length then drilled the pivot holes, turned int 90^o and drilled some holes for the end of the slit.


Before I cut the slits, I used some files and filing buttons to round over the end of the link.


And that’s where I’m stopping today.  Didn’t get the link complete as I still have to cut the slits.

Thanks for looking in!
Kim

[matthew-s]

Yeah, that's what I was worried about, Chris - melting the screen.  Which is why I didn't consider hard solder (at least not much ).
Do you think Loktite would work?  Seems like a filter screen on the intake isn't stressed THAT much. And it certainly won't be hot!
Kim

I ordered some brass screen from McMaster hoping that it will stick to solder. Not sure if it is too fine a mesh or not. That could be an option, I hope?

[Johnmcc69]

Coming along nicely Kim!
 Maybe just a dab of "Super Glue" on the screen?

 John

[Kim]

Yeah, that's what I was worried about, Chris - melting the screen.  Which is why I didn't consider hard solder (at least not much ).
Do you think Loktite would work?  Seems like a filter screen on the intake isn't stressed THAT much. And it certainly won't be hot!
Kim

I ordered some brass screen from McMaster hoping that it will stick to solder. Not sure if it is too fine a mesh or not. That could be an option, I hope?

Yeah, I bought a pack of 100 "brass pipe screens" that are 3/4" round.  It was cheap that way, but I'm not sure it was the best idea?  It was something like this (if not exactly this): https://www.amazon.com/Brass-Pipe-Screens-Screen-Filters/dp/B073JP7SFR/ref=sr_1_6?dchild=1&keywords=3%2F4%22+brass+screens&qid=1595306798&sr=8-6
Kim