[steamermeister]

Once the lead for the reverse states were adjusted, I created new sketches. This time the valve gear elements were set at the lengths that this first test calculated. The .0039 dimension in this sketch is being used to push the valve back as far as this geometry will allow to reveal what the actual lead of this state is, in this case .00388356 (SolidWorks rounds dimensions for viewing purposes). The "Measure Angle" annotation is exactly what it says.

 

[steamermeister]

Anyway, here are the values for actual valve travel and lead I was able to produce (values rounded to the nearest hundred thousanth of an inch). When set in forwards: Valve Travel = .21214, Front Lead = .00375, Back Lead = .00388. When set in reverse: Valve Travel = .21211, Front Lead = .00385, Back Lead = .00376.

I have tried more iterations to get more accurate values (.212 for valve travel and .00375 for lead) but the solution has remained elusive. It's probably doable much more investigation would be required. Overall, I'm satisfied with the results.

The process I have described only took a week to create and implement before it spit out this answer. That said, before I came up with it I had been beating my head against the wall for the previous three and a half weeks, working hard but getting nowhere. There are a lot of variables to the Walschaerts valve gear. Here's a shot of a more beautified version of the valve gear to end with.

 

[D&RGWC&S Fan]

Fantastic work! Your solidworks skills are inspiring, and that valve gear looks intimidating. Once you have the whole assembly finished (and have time to do it), a motion study clip would be super cool. If you don’t have time, I may be able to help with that.

 

[steamermeister]

While I would like to animate the motion, the solid model is very heavy (CAD speak for high computer processor load). I also have no time for it. If you'd like a crack at it, I can send you the data once I'm fully done working the chassis. I've taken the week off to handle some side projects that have been shelved for too long but I'll be back at it next week.

 

[D&RGWC&S Fan]

While I would like to animate the motion, the solid model is very heavy (CAD speak for high computer processor load). I also have no time for it. If you'd like a crack at it, I can send you the data once I'm fully done working the chassis. I've taken the week off to handle some side projects that have been shelved for too long but I'll be back at it next week.

No worries, I have a custom build PC at work for handling CAD and FEA which has handled multiple 300+ part assemblies and sub-assemblies. I am generally busy as well but would love to help out. Keep up the great work!

 

[JohnM]

As many times that I have driven past that place, I’ve never stopped in. I’m sure if you contacted them there’s gotta be an old coot in the group that could take photos, measurements as you needed them. It’s not really a town with a whole lot going on there…..

 

[steamermeister]

As many times that I have driven past that place, I’ve never stopped in. I’m sure if you contacted them there’s gotta be an old coot in the group that could take photos, measurements as you needed them. It’s not really a town with a whole lot going on there…..

Thanks but I have more than enough photo data to keep me going for now. A lot of the design is necessarily a compromise since there is a minimum size that various features and parts can be, below which they are unbuildable. This has knock on effects on other parts down the line as everything needs to work harmoniously.

 

[steamermeister]

No worries, I have a custom build PC at work for handling CAD and FEA which has handled multiple 300+ part assemblies and sub-assemblies. I am generally busy as well but would love to help out. Keep up the great work!

I’ll post again once I have the chassis model finalized and get you a copy of the CAD data.

Royce, same for you.

To everyone else, I’ll freely provide the CAD data. I’m thinking by USB stick in the mail. Just one catch, I need to know what your plan is for it. Some guidelines, I don’t want this information to be used for profit. Similarly you need to have real goal in mind, It doesn’t have to be a lofty one but just saying “I think it would be neat to have” wont pass. The drawings of course will be free for all, even if used as toilet paper but the models will be treated differently.

 

[Royce]

I’ll post again once I have the chassis model finalized and get you a copy of the CAD data.

Royce, same for you.

To everyone else, I’ll freely provide the CAD data. I’m thinking by USB stick in the mail. Just one catch, I need to know what your plan is for it. Some guidelines, I don’t want this information to be used for profit. Similarly you need to have real goal in mind, It doesn’t have to be a lofty one but just saying “I think it would be neat to have” wont pass. The drawings of course will be free for all, even if used as toilet paper but the models will be treated differently.

Nice work Sean. I just used prototype rod dimensions and used Charlie Dockstader valve design software for the actual valve/lap/lead/port issues. And keeping my fingers crossed that it will work. And I won't even know for quite a while.

 

[steamermeister]

Good luck man. I'm doing the best I can with the all my engineering experience I have to muster. Still, I'm merely attempting to predict the future. At it's base, any CAD software is not much different from a crystal ball. You do your best at the design, including allowances for your abilities, and later you hope you were right. If not, hopefully you have some contingency plans thought out.

 

[James Kuhns]

I have built SPNG 18 and 22. Kit-bashing Bachmann 10 wheelers for the engines and scratch building the tenders. No where near the detail you are putting into you project. The 22 was built over fifteen years ago, the 18 over ten years ago. They were great projects while recovering from foot surgery. I really enjoy running the SPNG trains on my railroad and I will be waiting to see you run yours and I hope you have as much fun with you and I have with mine.