Author Topic: Pennsylvania A3 Switcher (Kozo)  (Read 63667 times)

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #900 on: January 10, 2021, 09:43:12 PM »
 :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

More progress and more learning! Latest result looks far better.  Do you have or could you borrow a second torch to add more heat on the opposite side you are working? That can help when silver soldering deep or heavy assys. Just food for thought. Even an additional Spitfire type air/propane mixer tube  plumbing torch can help.  :cheers:

Offline Don1966

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #901 on: January 10, 2021, 10:31:45 PM »
Looks a lot better Kim and the learning curve on this is great. What I would of first done was to solder the inter spokes since there is less mass there and the heat would not of transfer to the outer rim very much. After completing the inner then I would concentrate on the outer rim with heat specifically in spots like two spokes at a time then move to the next two etc... just my two cents ..
Your work has been very intuit.

Regards Don

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #902 on: January 11, 2021, 05:36:14 AM »
Thanks tghs, Matthew, Cnr, and Don!

I wimped out and bought the casting - and finishing those nearly killed me!

Getting the castings is certainly not wimping out!  It's still not out of the question for me.  But as I said earlier, or some intangible reason, I really want to do the whole thing without castings.  Not sure of the reason.  It's not really cost - it may be a tad cheaper to fabricate them, but purchasing a foot of 3.5" 12L14 was not cheap!  Though I'll still have most of it left over after I make the wheels, so I guess it is cheaper material wise, but certainly not time wise.  Luckily, I'm doing this for fun, so whatever I think is fun is what I get to do :)  Don't you love hobbies?  :Lol:

Do you have or could you borrow a second torch to add more heat on the opposite side you are working? That can help when silver soldering deep or heavy assys. Just food for thought. Even an additional Spitfire type air/propane mixer tube  plumbing torch can help.

This is a good idea, though the only other torch I have is one of those BernzOmatic torches.  Maybe I'll get that in the mix and see if it helps with the heating.

What I would of first done was to solder the inter spokes since there is less mass there and the heat would not of transfer to the outer rim very much. After completing the inner then I would concentrate on the outer rim with heat specifically in spots like two spokes at a time then move to the next two etc... just my two cents ..

Good process inputs.  I'll have to think about the best process for my next try.

The black flux helped a lot by staying in place longer. But it sure is a booger to get off!  It leaves a thick black crust on the part.  The white stuff leaves more of a clear crust.  Guess its not TOO much different, but the black stuff makes it look uglier for sure!

Thanks for all the helpful input everyone!
Kim

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #903 on: January 17, 2021, 09:31:09 PM »
Now Im ready to see if I can slice off the back (which is really the front) and make it look more like a driver!  Im a little worried that the spacer I left on the bottom might have gotten accidentally soldered to the spokes or something.  Ive just never done something like this, so Im excited/apprehensive to see how it worked.

First, I centered it up on the back side (the side where the spokes were exposed already), faced it flat, and then took 1/16 out between the main hub and the rim of the wheel.


Then, I flipped it around and centered it up again.  This will be the final setup using the four jaw chuck.  After this, Ill be turning using a mandrel on the axle hole so everything looks concentric when it's going around in circles.

The first thing I did on this side was to open up the 1/4" hole to 3/8 with a drill. Then I used a small boring bar to bring it out to just under 7/16, to make sure the hole truly straight and perpendicular.


And finally, the 7/16 reamer.


With the center hold complete, I moved to shaving off the 1/16 that I left on the bottom of the fabricated part, which, as I said before is really the outside of the driver.


I took off the full 0.062, then a few thou more because I didnt seem to be through.  I was debating if I should take off a little more, but then I noticed the pattern here I could see a subtle line around the outside and the hub.  It wasnt nearly as pronounced as you see in this picture.  By the time I thought to take the picture Id already poked and prodded it with some tools trying to get it to come out. When I realized it would, I stopped and took the picture.


Then I continued my poking, prodding, and prying, and it finally came off, sort-of like those pull top lids!  There was one spot where I had to kind of tear the metal you can see the jagged spot along the weight edge some solder dripped there and made it not come out as easily there.  It will take some filing work to clean that part up. Regardless, it came off!  And the resulting wheel looked pretty good!


Heres another shot of the peel-off lid and the wheel.  Ive done some cleaning up on the wheel to get rid of the sharp edges. But it still needs more cleaning for sure.


Heres another shot of the backside of the wheel this side will be painted, except for the rim and the hub.  And you wont see those gaps anyway, since it's on the inside (that was one of the reasons for making it upside down).


And heres the top side. You can still see the spot where the solder was along the inside of the wheel weight (just right of center).  Its not quite as jagged, but it still doesnt make the smooth line it should along there.


And just in case youre wondering, Im quite pleased with how it came out!  Still have to shape the rim so it looks like a train wheel, but the method of fabricating the part so it looks like a driver seems to have worked!

Couple of things I'll do differently on the REAL wheel fabrication:
  • I'll leave the circular spacer on the bottom of the wheel a little taller and cut a notch in it with the 1/8" ball nose mill. This will help keep the spokes aligned during soldering.
  • I'll leave the bottom section a little thinner than 1/16", or maybe, I'll make the starting puck 1/32" thicker, so that I can leave a 1/16" bottom (to shave off later) and still have a little extra to work with.  I can shave it down an extra 32 thou which will help get rid of any solder pooling on the bottom.  Not sure which would be better - make the bottom layer thinner or leave it the same thickness and just add a bit to the overall height of the part.  The plus side of making it thinner is lower thermal mass.  The potential downside though would be that if it's thinner it might warp during the soldering process.
  • I'm also debating on whether I should make the top four spokes shorter - I made them all the same length for simplicity.  But that's a LOT of metal to shave off with a 1/18" mill when I don't have to. And it might make soldering them easier if I only have to solder it 1/8" or so into the weight rather than 1/2" or more.

Thanks for checking in,
Kim

Online crueby

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #904 on: January 17, 2021, 09:38:17 PM »
Love the pop-top trimming!  I must have missed something, you mention doing this all again on the 'real' wheel? Was this a practice one to work out the techniques?

Offline FKreider

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #905 on: January 17, 2021, 10:06:18 PM »
That's a lot of work and dedication!  :cheers:

Just goes to show you can build just about anything out of bar stock!
-Frank K.

Offline matthew-s

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #906 on: January 17, 2021, 10:10:17 PM »
Great work. That really looks the business! I've looked at a good number of build logs and I don't think I've seen anyone do it this way yet!

Offline cnr6400

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #907 on: January 17, 2021, 10:36:04 PM »
Wheel looks great!  :ThumbsUp: :ThumbsUp: :ThumbsUp: :popcorn: :popcorn: :popcorn:

Offline kvom

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #908 on: January 18, 2021, 12:05:10 AM »
One down, 3 more to go.   :ThumbsUp:

Offline joe d

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #909 on: January 18, 2021, 01:47:31 AM »
Kim

I like that "Pop-top" wheel!  Looking good for a proof of concept piece.

Cheers, Joe

Online Kim

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Re: Pennsylvania A3 Switcher (Kozo)
« Reply #910 on: January 18, 2021, 05:47:37 AM »
Thanks Chris, Frank, Matthew, CNR, Kvom, and Joe!
Really appreciate your comments :)

Chris, I started with just one, even though I needed four.  I wanted to prove the technique before I went to all the work (and material!)  of carving up four of them.   I had hoped that this was just the first of four, with three to come up in parallel next.  But once I got to the soldering and one of the spokes came out crooked, that's when it became the prototype driver, rather than the first of a production run    :embarassed:

I've learned a lot with this one and I will jump into the real four, all in parallel, next.  I'm debating about whether I should do five, but I'm kinda thinking I'll just do four and do another one if I need to.  Which I hope I won't   :-\

Matthew, I've never seen it done this way before either.   I was just trying to figure out a way to do it that would somewhat minimize the machining (i.e. I didn't want to machine 12 spokes out of the solid).  My first plan was to do it in more of a Kozo method where every piece was screwed to a base plate, and that plate would be machined away.  Then I came up with the idea to just machine the backing plate as part of the rim.  And leaving the hub there helped keep the rim and hub concentric during soldering.  The last innovation I had was to do the rounding of the spokes and put them in from the back.  I really liked that idea because I think it will make the finished drivers look more cating like to have the rounded spokes rather than have a square edge on the spokes from my original plan.

The Pop-Top part, that wasn't part of the plan.  My idea was to machine the whole thing off.  But I think what happened was that as the metal got thin, it bent in under the pressure of the cutter and the last few thou didn't shave off.  Only the parts that were thick & held ridgid cut off.  That's why I'm making the next ones with another 1/32" or so to cut off.  I think it will get rid of the pop-top lid :)

Kim