Pennsylvania A3 Switcher (Kozo)

[cnr6400]

 

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. 

[Don1966]

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

[Kim]

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? 

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

[Kim]

Now I’m ready to see if I can slice off the back (which is really the front) and make it look more like a driver!  I’m a little worried that the spacer I left on the bottom might have gotten accidentally soldered to the spokes or something.  I’ve just never done something like this, so I’m 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, I’ll 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 didn’t 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 wasn’t nearly as pronounced as you see in this picture.  By the time I thought to take the picture I’d 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!


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


Here’s another shot of the backside of the wheel – this side will be painted, except for the rim and the hub.  And you won’t see those gaps anyway, since it's on the inside (that was one of the reasons for making it upside down).


And here’s the top side. You can still see the spot where the solder was along the inside of the wheel weight (just right of center).  It’s not quite as jagged, but it still doesn’t make the smooth line it should along there.


And just in case you’re wondering, I’m 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

[crueby]

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?

[FKreider]

That's a lot of work and dedication! 

Just goes to show you can build just about anything out of bar stock!

[matthew-s]

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!

[cnr6400]

Wheel looks great! 

[kvom]

One down, 3 more to go.   

[joe d]

Kim

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

Cheers, Joe

[Kim]

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   

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

[Kim]

The first task on my list today is to make the 7/16” mandrel needed for turning the drivers.  Not a lot of pictures here because it’s a straight forward turning job.

I made it from 4” of 7/8” 12L14.  The last half inch or so is threaded 7/16”-28 (yes, I single point threaded it! Kinda fun, you know?)


I didn’t have any 7/16”-28 nuts so I made one.  Standard 7/16” nuts are 3/4" wide between flats.  I didn’t have any 3/4" hex, so I made my nut 5/8” across flats.  And tapped it 7/16”-28, of course.  I also made it extra tall, at about 1/2" tall.  Figured it would help hold things in place better.


Here’s the test driver all setup on lathe installed on its new mandrel.


I punched a mark on the mandrel that lines up with a mark I’ve made on my collet chuck.  That way I can be sure to get my mandrel in the same orientation if I ever take it out.  And I am also using that same mark to line up the pin hole of the wheel. That way I can re-install the driver in the same orientation if I need to do more machining.


I turned the wheel down to 3 7/16” diameter.  Then cut the tread part of the wheel down to 3.25 leaving the last 3/32” for the flange.



Next, I used a 60^o threading tool and cut a groove right at 2.75” radius. This makes a nice groove ‘separating’ the weight from the rim, and it leaves a bit of a chamfer on the inside of the rim.  The trick here was to make sure I got the tool set to exactly 2.75” diameter.  To help with this I drilled a very tiny spot right in the center of the mandrel. This helped me center the tool.  Then I used the DRO to move out the specified distance.  It worked out pretty well.


With the cross-slide set to 3^o I cut the angle on the tread.


Then cut the 10^o angle on each side of the flange.  I also took a little chamfer around the outside of the rim and rounded over the top of the flange with a file.


And finally, the beauty shot of my completed driver prototype.  Actually, I still need to drill out the pin hole a little larger.   But that shouldn’t be too hard.


Thanks for following along!
Kim

[Dave Otto]

Looking good Kim!
A small blast cabinet would sure be nice to clean the wheels after silver soldering.
Did you ever try boiling water to remove the flux?

Dave

[propforward]

Wow - lovely work Kim. I have to agree - single point threading is fast becoming my favourite turning job. Don't know why. Something about knowing what's going on synchronizing everything on the lathe that is just fun.

Top shelf job - really impressive work!

[Don1966]

Nice job Kim......



 
Don