Chris's Mann Wagon Build

[crueby]

Chris:

Obviously, the next part on the todo list is the Turbo Encabulator.

Don

With the optional Fetzner Valve

[cnr6400]

Not the gyrolyzing hablifier ? (with nucleating rheological feedback passageways)

[crueby]

Not the gyrolyzing hablifier ? (with nucleating rheological feedback passageways)

You've been mixing Elfensteiner beer with Oreos again...

[cnr6400]

That's amazing! How could you tell?    

[crueby]

That's amazing! How could you tell?   

Because you spelled 'gyrolyzing' correctly!   

[crueby]

Holy Swarf-Pile, Batman!   That long-lost package that I've been waiting for for almost a month finally arrived today, in perfect condition. I had put in a 'wheres-my-mail' complaint form a few days ago at the post office, and this morning the package magically went through the last couple depots locally, which normally can take several days. My bet is that they found it under a bench in the back, or were using it to prop open a door... 

Anyway, it finally made it!

No work on the Mann truck for a couple days, I've been doing other things, like a photo shoot of the Lombard model - the magazine series in Live Steam on that build is wrapping up in the November issue, and they needed some more pictures of the completed model (may be on the cover again). I am thinking of doing the wheels for the Mann truck next...

[cnr6400]

Glad you received the package at long last.    Look forward to when you get a round - to the Mann wheels. 

(no Elfensteiner, Oreos, or Navy rum today, just in a good mood , things going well generally, amongst all the hoo ha out there) 

[crueby]

I've been putting some thought into how to make the wheels for the truck - bit large to carve from solid (rear wheels are 5-3/8" OD x 1.26" wide, Front are 4" OD x .625" wide), so I am going to try piecing them up. After some experiments with the ring roller, I am just not confident enough with it to make the rims from flat stock and get things round enough, so I ordered some short lengths of pipe to cut the rims from. The rears will be steel rims, the front aluminum since I could not find steel in a close enough size. There will be a rolled piece of narrow flat stock screwed to the inside center, which the two sets of spoke flanges will bolt to - Mann used two plates cut to the spoke shapes, seperated and bolted to the hub and rim. The plates are tapered, farther apart at the hub than at the rim. So, I needed a way to shape the plates consistantly. What I came up with was a pair of wooden formers with a shaped punch for the center to push the plate out into shape.

To make the formers, started with some hardwood discs, one bolted to the faceplate, and the other screwed to that first one. Then milled out the opening for the punch through the top wood block:


Then removed the top block, and milled the recesses in the lower block (doing it this way ensures the openings are all concentric, and the screws will locate the blocks together consistantly). One outer level for the tapered section, then another lower ring for the hub:


Cut some squares of heavy copper roof flashing that I have a sheet of, screwed them one at a time between the wooden forms, and whacked in the punch which has a step turned on one end:

Here are the four plates for the front wheels after that shaping operation:

Giving the copper some raised shape really stiffens it up a lot. Next I need to find out if this sheet will be strong/stiff enough for the wheels, will set up to mill the spoke and hub openings in one, and see how it is when clamped up as a unit. If not rigid enough, I'll go to some thicker sheet stock and try again - I have a variety of copper and brass available. I tried a bit of aluminum, but its too hard to bend like this well. Once the front wheels are made up, the same wooden form can be modified for the rear wheels, same basic setup but a deeper offset and a larger diameter at the outside.

[Kim]

Very interesting process, Chris.   
I'm excited to see how it will all come together here! 
Kim

[crueby]

Very interesting process, Chris.   
I'm excited to see how it will all come together here! 
Kim

Got the first one shaped out, I think its going to work out. The finished plate looks quite slender, but with the dished shape to the spokes, it is surprisingly rigid, and will have a steel rim around between the two plates at the outside edge, plus a spacer at the center hub.  Here is a photo sequence of making the first one:

First, centered up the 'punch' arbor on the mill using the co-axial indicator (very handy gizmo)

Held the plates on the arbor and center drilled to mark the middle - the middle depression plates self center well on the arbor

Then slipped the wood form over the arbor to hold the plates level, and clearance drilled to match the hole in the arbor:

Did those steps for all four plates (two for each front wheel) before moving on. Next screwed the first plate in place, with some washers underneath to lift the plate up so it would lay flat on the wood, but be held tightly on the arbor. Moved the table out and went around the inner and outer ends of the spokes, plunge cutting with a 1/4" end mill to lay out the corners inside all the spokes. I had laid out all the distances and angles on the 3D CAD model in Fusion, so this was straightforward. Its basically the same method that Don has posted in a spreadheet in the past.

Then switched to a smaller (1/8") end mill, and went around the edges connecting the holes. For the cleanest results, I make the first cut away from the final dimension, then took a couple of light cuts to finish it off. Started with the outer edge, then started down the spokes:

The spokes are tapered, so the mill table was offset to one side and the starting angle found from the CAD model to connect the rims of the holes. Finished the spokes by cutting the second side, and then across the base at the inner edge:

Last went around the outer rim, cutting away the excess. This cut was done out from the final dimension, the small end mills have a tendancy to flex just a little as they make a full width cut.

and finished with a few light cuts around the rim to take it to final size:

A few swipes of a file to take off the little burs on the edges, and test fit in the pipe that the front wheel rims will be made from:

A piece of steel flat stock will be rolled to fit the inside of the pipe, and will get screwed into the pipe. The spoke pieces will screw to that at the end of each spoke, one plate on either side. The hub will fit between the plates at the center. Still need to bore out the center hole in the plates to match the hubs.

So, that one plate worked out, next will go back and make three more of them. The rear wheels will be a similar setup, but they are a larger diameter - may use thicker plate stock for those, I have some slightly thicker brass plate that should work out (have to test, see if it needs to be annealed before forming, the copper sheet was already annealed when bought).

[cnr6400]

Hi Chris, the appearance of the wheel is great!  I do have a concern about strength though. Is there any plan to reinforce the copper spokes , ie doubling them up or adding a rib soldered to the backs of them to make a T shape, or something? I'd hate to see someone lean on the wheel or a kid sit on the truck and have a wheel collapse sideways, wrecking all your work. Annealed thin copper is not too strong against bending, particularly when it has been pre-formed. Just food for thought. I would not be worried if the wheel centres were 16 ga steel sheet, reinforced with rolled strips as you mentioned.

[crueby]

Hi Chris, the appearance of the wheel is great!  I do have a concern about strength though. Is there any plan to reinforce the copper spokes , ie doubling them up or adding a rib soldered to the backs of them to make a T shape, or something? I'd hate to see someone lean on the wheel or a kid sit on the truck and have a wheel collapse sideways, wrecking all your work. Annealed thin copper is not too strong against bending, particularly when it has been pre-formed. Just food for thought. I would not be worried if the wheel centres were 16 ga steel sheet, reinforced with rolled strips as you mentioned.

I've been debating the same thing, they just look so slender, but they take a lot of force without bending due to the taper that was formed in. Remember that the annealing was done before forming, not after, so I dont follow your 'pre-formed' comment. Putting in a narrower steel spoke between the two might work out - that spoke could be straight rather than tapered, and would not be very visible. Hmmmm..... Have to experiment with that idea! The steel discs could fit against a step in the hub, or maybe be separate spokes, sort of like what Brian has been doing on his Stephenson build....   
 

[Brian Rupnow]

Chris--I was amazed and delighted by how well the wheels I made for the Rocket turned out. I found it kind of neat to see that you and I were designing and making wheels at almost the same time. I'm enjoying your project.---Brian

[Admiral_dk]

I wouldn't be surprised if two of these 'opposing each other' (domes facing away from each other) would be strong enough if both are soldered in place .... but I have no clue if this idea ruins the 'original look' 

Nice work as usual Chris        

[cnr6400]

Hi Chris, what I meant with the pre-formed comment was just that doing any forming to a piece of sheet or rod stock makes a point where bending will happen first if load is applied later. Good analogy is the crease on a car fender. If any force is applied later it will bend at the crease. With an unbent sheet it is hard to say where bending may occur under load.

Another way to think of the loading, although not the same as your wheels, is  wire formed bicycle spokes. They are very small and very strong and work beautifully to support huge loads for the size of the wire. However if they are ever bent or kinked in the span between rim and hub they will bend and fail there with loads later.

Hope this helps.