Steam Loco Spoked Wheel Making

[victor miranda]

solder paste will work.

 that with an oven and a brass fixture will be a bad combo.

use the aluminium fixture if you pop it in the oven.

v biting his tongue miranda

[peteski]

v biting his tongue miranda

I think that I'm just as amused by this thread as you are.  E-Z Bake oven anyone? 

The problem with solder paste (and I've used plenty of that stuff when reworking SMD computer chips with 100s of pins, using a hot air nozzle) is that the paste thins out and separates before the solder melts.  Solder paste is composed of micro-spheres made from solder (tin/lead) and paste flux.

That is not a problem when reworking printed circuit boards (since the solder is supposed to melt on the flat horizontal solder pads).  But on spokes the heated (but with solder micro-spheres still solid) the solder paste will mostly flow to the bottom and three won't be many micro-spheres left around the spoke to create a solder joint.  If the spokes were in contact with the alignment plate the capillary action might wick some melted solder back up to the joint, but that is not guaranteed.

[victor miranda]

! wow peteski,

I did assume... since I have seen joints flow solder upward
that the solder would stay in the joint.

It did not cross my mind that the paste would run down and carry the solder down with it.

I am trying hard not to tell Max, or anyone who wants to do this,
that the attempt is full of perils.  It has to be possible somehow.

believe me I will, very likely, try what works.
  I've tried what doesn't work...

I can see a 5 spoke wheel in my future...
adding ten more spokes will be fun!

victor

[mmagliaro]

Flux, solder, a hot iron, and a little luck.
You can solder joints without having to heat up the whole jig.  It has been working for me
on brass pipes and boilers, so it should work here too.  The flux makes enough heat conduct into the joint
fast enough that the solder flows and bonds without having to heat up the whole jig.

Anyway, that's my story and I'm sticking to it until I try it and it doesn't work.

That will be a few weeks away, I expect.

How's this for comedy modeling?
What if there were a way to
- tack that tire in place on a metal plate, around the hub, just by eye
- chuck the axle (which is through the hub and the plate, as we've been discussing) in the mill
- just spin the thing on the axle in the mill, and ride the dial indicator against it,
- you could just nudge the tire with a toothpick until the indicator shows zero runout and you'd be done. 

If the tire were tacked by
a little adhesive, it would now be in the perfect spot.  Just put a couple drops of ACC on it, let that harden,
recheck with the dial indicator, and then solder in your first two spokes.

As funny as this sounds, I think it would work, except that I don't think any temporary adhesive would
stand up to the slight pressure of the dial indicator riding against the wheel.  It would keep moving
around.

[peteski]

! wow peteski,

I did assume... since I have seen joints flow solder upward
that the solder would stay in the joint.

It did not cross my mind that the paste would run down and carry the solder down with it.

Not all the solder will flow down - some will remain at the joint area. But I don't think it will be enough for a solid solder joint.  I guess one way to find out would be to try it.  The upwards flow you saw is the molten solder being wicked by the capillary action into the gap in between the parts being soldered.  That is after the solder metal is melted.  Personally I have not tried to use solder paste in the way being described here. I'm just theorizing (which I often in the online forums). 

[VonRyan]

Here's a thought. Take a ceramics mold and in the negative space mill a mold for the wheels you want and then melt the solder into it.

Max, if you want I can send you some flat ceramics molds that would be perfect for something like that.

[victor miranda]

ceramics...
hmmmm

you can do spokes in a wheel in
ceramics?

like a mold? made of
ceramics?

ummmmm?

any chance it can survive pouring pewter in it?

we can skip the spokes soldering then...

miranda

[wcfn100]

I think I've kept up with this thread but if this is not pertinent (or has been mentioned) I apologize.

If you're considering casting the centers, instead of trying to cut the spokes, cut the mold for the spokes (with the rim and hub), it would seem to be much easier in this case.

If you can machine something like this:



Then cast cast the pieces.

Just a thought.

Jason

[VonRyan]

ceramics...
hmmmm

you can do spokes in a wheel in
ceramics?

like a mold? made of
ceramics?

ummmmm?

any chance it can survive pouring pewter in it?

we can skip the spokes soldering then...

miranda

My grandmother used to own a small ceramics business and she had 2000+ hard plaster molds for various things. Plenty of them are flat and would easily lend itself to having a mold milled out for spoked wheels.
The more molds I get rid of, the happier I become.

[mmagliaro]

I think I've kept up with this thread but if this is not pertinent (or has been mentioned) I apologize.

If you're considering casting the centers, instead of trying to cut the spokes, cut the mold for the spokes (with the rim and hub), it would seem to be much easier in this case.

If you can machine something like this:



Then cast cast the pieces.

Just a thought.

Jason

The exact problem is that I cannot mill something like that.  Those slots for the spokes have to be only about 1/64" wide.
Running an end mill that fine would probably be hopeless in my mill at only 2000 rpm or so, and only by manual control.
Everything that follows from the opening page of this thread has really been exploring ways to do this that would avoid having to mill slots that fine.

Another complication is that the bottoms of those slots have to be a little narrower than the tops.  The spokes have
to be slightly tapered in order to look good.  I plan to handle that by just running a strip of brass through the mill
with an angled cutter to put a tapered edge on a whole long strip at once.  Then I can cut the little pieces off and
they will all have an identical taper.

Another tricky thing is that even if I cast the centers using a mold like that, I still have to bore out the center and insert
a brass hub, and now I still need a jig or other way to get the hub, wheel center, and rim to all go together concentrically.
No matter how accurate we draw and mill, when that thing goes together, it's going to be a little off, so there needs to
be a way to assemble and correct it.

[mmagliaro]

I've been thinking about how to make a form to hold the wheel while soldering it.

I think I know how to cut a perfect circular recess into something, into which I will place the wheel.
I'll show that later on after I try it and see how it goes.

Question:
What about using a piece of PC board?  Flip it over, copper side down, and cut the circular recess into the
phenolic material.   That stuff is pretty hard, but not as hard as metal, so it should be fairly easy
to cut the recess, and it would be resistant to soldering without absorbing so much heat as to make soldering difficult.

What do you folks think?   (It isn't very thick, but I have some 1/16" thick stuff that should be sufficient.  There just needs
to be a little circular recess cut into it to hold the wheel still.  The whole wheel is only .065" thick, which is barely 1/16",
so I'm thinking I only want a slight recess, perhaps .010" or .020" deep.

[peteski]

PC board material (either phenolic or glass-epoxy) should withstand soldering temperatures for few seconds.

Do you have a rotary table for your mill?  That would make it easy to mill a circular shape (and even milling out slots for the spokes).

[Sokramiketes]

I've been thinking about how to make a form to hold the wheel while soldering it.

I think I know how to cut a perfect circular recess into something, into which I will place the wheel.
I'll show that later on after I try it and see how it goes.

Question:
What about using a piece of PC board?  Flip it over, copper side down, and cut the circular recess into the
phenolic material.   That stuff is pretty hard, but not as hard as metal, so it should be fairly easy
to cut the recess, and it would be resistant to soldering without absorbing so much heat as to make soldering difficult.

What do you folks think?   (It isn't very thick, but I have some 1/16" thick stuff that should be sufficient.  There just needs
to be a little circular recess cut into it to hold the wheel still.  The whole wheel is only .065" thick, which is barely 1/16",
so I'm thinking I only want a slight recess, perhaps .010" or .020" deep.

But phenolic isn't rated for the heat!   

[mmagliaro]

But phenolic isn't rated for the heat!   

Heh... believe me, I remembered your post about the jig.  But I am not sure about "phenolic" always being the same
stuff.  There are a variety of materials that circuit boards can be made from.  I know from soldering to
PC boards that I can touch an iron to that PC material directly for a few seconds and it won't melt.

In any event, I'll give it a try... after I try out my scheme for machining the circular recess in it (and no, I don't have a
rotary table, although I've been considering laying out the money for one).

[peteski]

In any event, I'll give it a try... after I try out my scheme for machining the circular recess in it (and no, I don't have a
rotary table, although I've been considering laying out the money for one).

It would be very helpful for this project (and I'm sure many future projects)!  If you can afford one, this is project is a perfect excuse to get one.    Heck, you could use it to machine the entire wheel - spokes and all.