# Coal-Fired C-25 build notes



## lenicheck (Jan 8, 2008)

Never thought I'd fall in love with coal-firing, let alone build one but I have been working on scratchbuilding a D&RGW C-25 now for over a year. Yea, it's going rather slowly. I have, however, made substantial progress which I am going to outline here, mainly because people have been asking how it's going. 


You might have noticed that Accucraft recently announced a release of this model and have seen the drawing in their ads:









They call this engine a "Baby Mudhen" because of it's looks and it's ability to pull almost as much as a K-27, the "Mudhen". (The "25" and "27" designation refers to the engine's tractive effort.)


Prior to cutting any chips I did most of the design in a 3D CAD program called Solidworks. I strongly urge anyone who is going to make a model of even moderate complexity to bite the bullet and do this design step (using Solidworks or any of the other CAD programs out there). BTW, I really like Solidworks because all of the parts are modeled in 3D, allowing you to make sure everything fits before you make it. 

I decided fairly early on in this build that I would have the frames made this time around rather than cutting them out myself. The frame material is 3/16" steel stock. It would have been a fairly easy job for someone with a CNC machining center do to this but I did not at the time know anyone who did this work, only needing the two frame sides. Turns out I did make contact with a guy who arranged to have the frames wire-EDM cut, which gives a very precise dimensional tolerance. All I then had to do was to drill the holes in the frames for the various shafts and pins needed. This pic shows the frame plus the firebox extension, as on the prototype.











BTW - the frame is equalized, which explains the small hole locations. More in this in the next edition. Bedtime for Bonzo...

Rob


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## David BaileyK27 (Jan 2, 2008)

Rob, you may remember I built a coal fired C25 and took it to Diamonhead, I still have some parts available and can supply a complete etch for the Tender and Cab etc, also have all my noted and designs for the boiler etc.
David Bailey DJB Model Engineering Ltd


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## rodblakeman (Jan 2, 2008)

Hi Rob, Nice looking work again. If you did want some parts from David as offered above, I could bring them with me in January ?


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## lenicheck (Jan 8, 2008)

So, continuing, since I wanted to make the running gear equalized I had the problem of needing to make the driver leaf springs functional, or at least stiff enough to withstand the engine's weight. As of now I am not planning on using any springs. Two years ago in DH I found out about 3D printing in stainless through a conversation with Dan Rowe. All I needed was a 3D part design sent online to Shapeways who would then print it up at a very nominal cost. The result:








You can see that the surface finish is not great but you can't tell that from 6 ft away. (Don't think I use this method for anything I'd want a good finish on unless I could machine it smooth. But this method would really work well for making wheel blanks provided they could print it up that big.)

The next step was to make the cylinders, crosshead guides, etc. The cylinders are 9/16" bore and .985 stroke. I used Dockstader's valve gear program to design the valve gear, which is a between-the-frame full Stephensen's. This software is quite impressive and it's free. If you're interested take some time to download the package and play with it. You will learn a bunch about how valve gears work.

Here is the site: http://www.billp.org/Dockstader/ValveGear.html

Moving right along, the cylinder and parts:








I designed the cylinder manifold so that the steam intake line and the exhaust run though it. This may mean that the cylinders will take a bit longer to clear but it's a lot cleaner then using pipes because the cylinders and manifold plop into the frame as a complete unit when bolted together.

This is what the running gear looked like as of last Jan in DH:









You can now see the center pivot levers and all the appurtenances which make up the equalization. 

On to the rods:









And, finally, the rods and counterweights attached to the axles. Great story about the counterweights. Wanted to use Loctite to secure them but didn't think to provide a well at the back of the counterweight for the excess Loctite to flow. So because the clearance was so tight between the journal and the counterweight I managed to Loctite those together as well in some cases. Thank goodness Loctite is reversible with heat. 


















Now for probably amounts to the most difficult part of the build the valve gear, built according to the dims which came out of Dockstader's program:









And finally a look at the mostly complete valve gear and pretty much where I am today in the build. I'll update again when I get the timing done and, hopefully, working.


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## Steve S. (Jan 2, 2008)

* Wow, thats awesome work. !!*


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## Steve Shyvers (Jan 2, 2008)

Hi Rob, 

You've been a busy guy! Published in SitG. Explorer of the great Northwest (Staver's). And doing a beautiful job building the C-25! 

Steve


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## Dwight Ennis (Jan 2, 2008)

That's looking terrific Rob!! You never cease to amaze me with the stuff you make, and all manually to boot! Far better than I could do.


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## Phippsburg Eric (Jan 10, 2008)

I had wondered about the odd spacing of the drivers...the reason is obvious when you look at the last photo...you need room for the Stephenson valve gear! Some of the Maine two foot gauge 2-6-2's have the same odd spacing for the same reason.


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## Larry Green (Jan 2, 2008)

Rob, please keep the photos and commentary coming. I look forward to seeing your progress at DH. 

Larry


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## placitassteam (Jan 2, 2008)

Hi Rob, I found this after the e-mail you sent. It is fun to see all the bits and pieces anfter seeing it run. The equalization is really neat too. Keep up the good work. Maybe we can see the finnished product next year at Don's.


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## Taperpin (Jan 6, 2008)

Rob, 
That is lovely work! very,very,high class something to have great pride in having made I look forward to seeing it in the metal some day. 

Gordon.


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