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Modeling the Tender

This part of the project has turned into a great learning experience.

I started off assuming that the NPC reused the tender from one of their wrecked 4-4-0's for the deck and running gear of No 21. So the tender that shipped with the Bachmann Spectrum 4-4-0 was an obvious candidate for creating the tender for No 21.

I had hoped to use a number of components from the Baldwin Spectrum in creating an early Baldwin 2-8-0. The Spectrum's tender could be used in production of the 2-8-0 with only minor modifications. I decided to scratchbuild No 21's tender, using the Bachmann tender as a direct takeoff model. But first I needed to locate suitable components. Also there is an excellent tender construction article in David Fletcher's MC 2001 series.

Acquiring Tender Components

Trucks

Hartford products makes an excellent set of archbar trucks in 1:20.3 that are very similar to those on the prototype. Here is a photo of the Hartford truck.

This is their truck in the 26 inch wheel size. Once I have 1:20.3 plans in hand, I can decide on wheel diameter as these trucks are also available in 22 inch and 24 inch sizes.

Detail Castings

The next step will be to run through the Ozark Miniatures catalog and select suitable castings.

Tender Construction

Tender Deck

In constructing the deck, I took the dimensions directly off the Bachmann Spectrum 4-4-0 tender. Here are the dimensions in millimeters. By the way I used a digital caliper from Harbor Freight that is frequently on sale for $20. Given that my eyes are no longer good enough to take accurate readings with a ruler, this tool is a joy to use.

Dimension	MM
Deck Length	240
Deck Width	95.7
Deck Thickness	2.56
Sill Height	11.3
Side Sill Length	236
End Sill Length	81.85
End Sill to Truck Pivot Centerline	55

Because MC 2001 involved building a Bachmann 2-6-0, I assumed that David's tender framing instructions would be more or less accurate for this tender. So I cut 2.5 mm thick styrene to the following dimensions (end sill less 5 mm because of overlap).

The deck was scribed to highlight boards. Wood grain will be added before painting.

Click photo for a larger image.

Structural pieces on the bottom were:

	Plastruct Square Beams - 9.5 x 9.5 mm
	Plastruct T Beams - 6.4 x 6.4 mm

Sorry for the lousy camera work. It looks much better than the photo shows.

Click photo for a larger image.

In the next step, the sills will be detailed. Then a trip to the paint shop is the next step. The following photos show the deck after detailing and painting.

	Here's the top of the tender deck. It's hard to see with the black paint, but the boards have been scribed with a razor saw to simulate wood grain.
	Here's a side shot. Bolts and nuts are real 4-56 bolts and nuts. I drilled holes, tapped the holes and screwed them in place. The rivets at the ends are HO Track nails with most of the shaft nipped off.
	This is the bottom. One thing I learned is that black paint hides plenty of imperfections. You don't see any of my mistakes, do you?

The Gotcha !!!

I hate it when this happens.

I was all ready to move on to the part of the tender mounted to the top of the deck, while the paint was drying, so I did some research. I pulled one of the drawings into ScalePrint and started taking off dimensions like the height and width of the oil and water tank. I was feeling pretty smug until, for the heck of it, I took off tender length. My scale takeoffs converted to 12.25 inches !!!!!! Can't be!! So I measured it again. My deck, out drying in the sun is 9.50 inches, 2.75 inches shorter than the measurement.

So I reacted the way many modelers might react in this situation. I freaked out. It wasn't until I returned to work the next morning that I realized the drawings were wrong. Here's the lesson folks. Before deciding to accept someone else's drawings, take the best photo of the prototype in your possession and double check the dimensions. You may have better information in front of you than the person had in preparing the plans.

On to the Tanks

The most obvious feature of the tender is the oil and water tanks. As I discovered in looking at original photos, (the water tank is larger in diameter than the oil tank. This is a difference that was not picked up in any of the three sets of drawings that have been published on No 21. Out of pure cussedness, I decided to model these tanks in different sizes.

Based on the drawings from the Gazette that Bob and Chris had blown up to 1:20.3 with a photocopier, both drums had a diameter of 3.6 inches. My takeoffs indicated that the oil tank had a diameter about 90% of the water tank.

Schedule 3" 40 PVC soil pipe has an outiside diameter of 3.5 inches. I figured after adding a styrene wrapper with embossed rivets I'd be very close to 3.6 Inches. But, how would I emulate the 4 inch water tank. The next jump in the soil pipe sequence is to 4 inches with an outside diameter of 4.5 inches ... way too large.

Then it hit me. What about the pipes used to join the 3 inch pipes. Yes, it turned out the joint pipe had a diameter of almost exactly 4 inches. Joiner height is 3.22 inches. Tank height is 2.9 inches. Yes !!! I had a match.

On the right is the oil tank cut from 3" Schedule 40 PVC sewer pipe. On the left is the water tank, cut down from a 3" PVC pipe connector.

Bob Baxter's method for modeling the tank top was to use the ends from a Bachmann tanker. That worked well with two 3.5 inch PVC tanks. I'd need a different method with different tank sizes as the Bachmann ends won't work with the larger tank.

Modeling Tank Tops

My first attempt will be to build a sandwich of round 2.5 mm styrene cut in circles slightly larger than tank end diameters. I'll insert a screw through a hole at the center of the sandwich with a washer on each side. A nut will draw the washers together. The screw shank will go in my drill press. I'll attempt to shape the top using sandpaper as the drill press spins the sandwich. Stay tuned for results.