Stephenson's Rocket--Working Model

[dsage]

Nice looking wheels. Hard to tell their condition from the photo - but you should probably take them all apart again and clean all the metal bright and shiny before attempting to tig weld them. TIG is VERY fussy about cleanliness.

 

[Brian Rupnow]

So, here we are with one big wheel and one little wheel welded. The wheels haven't been removed from their jigs yet. They look nasty/ugly, but remember, all of the brown smoky stuff is going to disappear. The side with the welds on it is going to face inwards, so very little of these welds are going to be visible. I will post another shot of the same wheels later today after I get them cleaned up. I used my new tig welder for this job, because it is the only welder I have that can deposit a small controlled puddle of weld where I want it.

 

[Brian Rupnow]

I have discovered something that is a problem, and I have a solution for how to solve it. No matter how much care is taken with the jigs and set-up, there will end up being visible "wobble" when the wheel is rotated on the center hole in the hub. This can be addressed by taking "truing cuts" from the outer edges and sides of the wheel as the wheel rotates if the wheel is supported on an "axle" which fits into the hole in the center of the hub.
I was just in the process of doing that, when I had a thought. I would strongly recommend that anyone who sets out to build fabricated wheels like this, put a bore thru the hub center 1/16" less than what it will end up being. This lets you build a fixture which accommodates the smaller center hole. Then when the wheel is removed from the jig, set it up in the lathe so that the chuck is gripping the outer diameter of the wheel, and that it is rotating "true" with no visible wobble or run-out. Then re-bore the center hole in the hub to the correct size. That is much easier than trying to re-machine the outer diameter and sides of the wheel to make it run true.

 

[Richard Hed]

I have discovered something that is a problem, and I have a solution for how to solve it. No matter how much care is taken with the jigs and set-up, there will end up being visible "wobble" when the wheel is rotated on the center hole in the hub. This can be addressed by taking "truing cuts" from the outer edges and sides of the wheel as the wheel rotates if the wheel is supported on an "axle" which fits into the hole in the center of the hub.
I was just in the process of doing that, when I had a thought. I would strongly recommend that anyone who sets out to build fabricated wheels like this, put a bore thru the hub center 1/16" less than what it will end up being. This lets you build a fixture which accommodates the smaller center hole. Then when the wheel is removed from the jig, set it up in the lathe so that the chuck is gripping the outer diameter of the wheel, and that it is rotating "true" with no visible wobble or run-out. Then re-bore the center hole in the hub to the correct size. That is much easier than trying to re-machine the outer diameter and sides of the wheel to make it run true.

Even doing that, however, might not be enough as welding generaly warps things in more than one dimension: twists, warps, turns, so if you are planning to weld and needs high accuracy, leave a small amount of extra metal anywhere that you will be able to true up later. The hole in the center being the most important as you will clean it up FIRST then true up the rest after, using a mandrel or whatever.

 

[Brian Rupnow]

This is a "trial assembly" of the welded wheels fitted to the chassis. When I get some yellow paint on those wheels, it's going to look awesome!!!

 

[Peter Twissell]

Looks really good, Brian.
I still think it really needs that brass chimney crown to top it off.

 

[RonW]

Looks really good, Brian.
I still think it really needs that brass chimney crown to top it off.

Yep! And wheel spokes need to be red.
Actually Brian, any colour you choose and to hek with the rest of us. Good job!
RonW

 

[Brian Rupnow]

Three wheels done, one to do yet. The good side which faces out away from center looks fantastic. The inside of the wheels which face towards the center are ugly as Hell. This is one of the few times I wish I had a little sandblasting cabinet. After I finish the last wheel, I will have to make a decision whether to spend a bit more time on the inside faces of the wheels with a bit of body-fill, or maybe just clean them up with my Dremel tool and leave it at that. The tig welder is perfect for making tiny welds on the ends of the 1/8" square spokes where they connect to the hub and to the outer rim.

 

[awake]

Even doing that, however, might not be enough as welding generaly warps things in more than one dimension: twists, warps, turns, so if you are planning to weld and needs high accuracy, leave a small amount of extra metal anywhere that you will be able to true up later. The hole in the center being the most important as you will clean it up FIRST then true up the rest after, using a mandrel or whatever.

Agreed. Even though TIG welding can create a smaller HAZ and induce less warping than other processes, I have learned the hard way that even just a skinch* of welding will take the precision out of a precision-machined piece.

*skinch: a term I learned from my parents' Missouri dialect, indicating just a little itty bit.

 

[Brian Rupnow]

This is something I've wanted to check, but couldn't until I had the drive wheels machined and assembled. My computer shows me that I have about 1/16" clearance between the clevis on the center shaft and the outside of the wheels outer rim. The computer is like having an old friend who lies once in a while. You want to believe everything it says, but you feel a lot better after you've actually verified that it did tell the truth. Sure enough, there is clearance there. Not very much, but enough. The lever is at its maximum travel here, and from where I show it, it only swings back in the other direction away from the wheel.

 

[Badhippie]

Brian
Is there a reason you didn’t machine the entire wheel and skipped most of the fab.work of corse the fab work would have turned into machine work. Which probably would have been the same amount of time and the same amount of pulling hair lol

 

[Brian Rupnow]

Yes, there is a good reason. I wanted to keep the same look as the original Stephenson's Rocket wheels, and that is very difficult to do with machining alone.--And---I spent many, many years of my life building hot-rods from the ground up, which included a lot of chassis fabrication. I know far more about fabrication than I do about machining.

 

[Badhippie]

Yes, there is a good reason. I wanted to keep the same look as the original Stephenson's Rocket wheels, and that is very difficult to do with machining alone.--And---I spent many, many years of my life building hot-rods from the ground up, which included a lot of chassis fabrication. I know far more about fabrication than I do about machining.

I fully understand now and btw I forgot to say very nice job they look great.

 

[RonW]

Hi Brian,
I guess either you copied Hornby or they copied you. Sam's trains just put out a "road test" of Hornby's Stephenson rocket model. If I got the address correct its at
They endorse your colour scheme except for the funnel.
RonW

 

[RonW]

Th

Hi Brian,
I guess either you copied Hornby or they copied you. Sam's trains just put out a "road test" of Hornby's Stephenson rocket model. If I got the address correct its at
They endorse your colour scheme except for the funnel.
RonW

It says the video is unavailable but I just watched it. Fat thumb must have got in the way somewhere.
RonW

 

[Brian Rupnow]

This is a view of the "Belly of the Beast". I've spent the entire day reassembling, adjusting, adding a bit of clearance here and there. Right now one engine runs and one doesn't. Tomorrow I will try and get the second engine set up to run correctly. I'm down to the point where I am just about ready to paint the wheels, but not until I have everything adjusted properly. After the wheels are painted and reinstalled, I have to fabricate a prettier air supply.

 

[Brian Rupnow]

TA-DA!!!--It is alive and running on both engines. It is standing on end right now, which gives me much better access to the eccentrics so that I can adjust the valve timing.

 

[werowance]

looks great Brian. i really like the wheels.

 

[Brian Rupnow]

Today was wheel painting day. Very nice yellow from Tremclad, same as the boiler. Now I have to figure out the pressure line plumbing for the cylinders. That is not going to be a simple thing. I have something in mind, but have to do some cad work now to see if it's going to be possible.

 

[Brian Rupnow]

Things are going to get really strange in order to get air pressure into the cylinders and still have everything "look right". There is a bit of work in this, but it is almost the last work I have to do before remounting the wheels.