Chariots of Fire

An update on progress. A trip to the local fire department where this rig ls housed helped in locating the steering arm, pivot rod and connecting arm. A few #90 bolts and nuts hold all together.

There's not much chance of making duplicates of the rig I've started. Lots of hours in it already and the engine, drivetrain, cab, front end, winch, body, brush bars and pump are still to go! The cab is not hard to scratch build. The biggest problem is going to be getting the hood right. The M series hood has two reverse curve sections at the front corners o they have to be figured out. The rest is basically square pieces to make up the fenders, doors, windshield and cab sides and back. Best way to do that is make up a drawing to scale and use it as a template for the various pieces to be glued up.

Too bad there isn't a decent kit out there as well. There is a Czeck company, I believe who did a CCKW in 1/25 scale but it predates the M series by a lot. I don't think it would even come close. The resin parts in some cases were very brittle. A friend built one a while back and had some issues with it. Ultimately it came out ok but not without a lot of tinkering. 1/35 scale seems to be where it's at. Wish I had a plastic enlarging machine!

Tom: You familiar with a company called V-Tech? Think they are in Brattleboro. They have built a lot of brush rigs for towns in our area. They took over where Farrar and E. J. Murphy and Maxim left off.

This may not seem like much but there are many pieces that went into each front hub assembly. There is the hub itself with a brass tubing insert that acts as a bushing. I filled the inside with some two part resin to sturdy it up. The center of the original mounting had to be drilled out to accept the tubing and otherwise would have left it very weak. In addition there is the main internal hub assembly that acts as the pivot point for turning the front wheels. The brass pieces in the center go together and fit inside the white plastic tubing just to the right of center in the photo. The other one is fully assembled and is on the long brass axle insert. In front is the tie rod that attaches to the arms on each hub assembly. The small screws and washers fit inside each hub and hold it on the brass axle of the assembly. Two pieces that do not show here are the guards that fit on the front of the hub assembly. On the real truck they help to deflect debris away from the hub where there is a rubber boot to keep out dirt and mud. (I tried but I'm not adding the rubber boots!)

Got a bit more done in the last few modeling sessions including the front axle. There is a small amount of warp in the frame which I attribute to my soldering surface not being flat any more. It's enough to make it aggravating but I think with enough weight finally on the frame and all it will settle down ok. With the front axle set in position the ends were made up to allow the front wheels to turn. There is still much to do around the hubs to include the brackets for the tie rod and steering arm. Fortunately I have photos and TM drawings that give me enough information to do a reasonable job of replication. As with the rear hubs, the front ones are held on with a small screw and washer that sit inside. They will eventually be covered with the center hub cover.

Nice job on the plow, Alain. Do you have any photos of old V plow and wing plow frames that you could post? I have a couple for the Coleman but not nearly enough detail to do a creditable job. Charlie

Resin casting is not hard. Complex pieces can be a challenge but there are so many parts that can be made with just a single mold to pour the resin in. For example the axles on this truck were done it two separate molds. I glued each half to a piece of plastic and then built a box around each one to hold the RTV. Mold release was painted on the part and on the box sides. RTV was poured in making sure that the RTV covered the entire axle half. You have to plug the ends of the axle halves because you don't want the RTV to get inside. Use a bit of modeling clay for that. The mold will cure in 3-4 hours. Break the mold box apart and remove the axle master. Then mix up two part resin and pour it in the mold Make sure the resin coats the inside of the mold without any visibie air bubbles. Wait for it to cure and pop out the new part! MIcro-Mark has a good assortment of RTV and two part resin materials. Not cheap but you can get a lot of molds and parts that way.

Got the front springs done yesterday, all except for securing the mounting pins. That will be last after the frame is painted. Parts will be painted separately and then put together. The rear suspension is now complete except for the drive shafts.

Got a bit more done on the rear suspension. Torque rods were used to connect the main pivot point with the axles to keep them in alignment. There's a bit more done on the rear of the frame as well but I will post that when I get more done on the front suspension. Just started by soldering on the front spring purchases.

Been a while since I posted progress. Shops have been busy with the frame and rear suspension for the M-52. Good thing I have the TM's for this rig. Without them I would be lost! Even found additional info on line which has been a big help. Tomorrow I get to crawl under the real rig to get additional details for the inside of frame suspension parts. Springs are made from 1/64" x 1/8" brass strip stock. Brass tubing makes up the pivot point. Still to be made up are the torque rods that keep both axles in alignment.

Here is a photo of the simple drawing to show the frame and tire layout in plan view. With a drawing like this things can be kept in scale and proportional. The rear axle is now to the correct length. Still to go is the other axle for the tandem rear end. The front axle will have to wait until I get more photos of the actual truck. I also painted up two of the tires to see how they will look. Not bad but they can be better. 3D printing does have its limitations and they are evident here with a rougher sidewall surface than I would like. A little sanding after the first coat of paint is applied will make some difference.

Hello Arnd! Thank you for your kind words. The tires are 11:00 x 20 actual size and are 41mm diameter by 10mm wide. The inside diameter is 20 mm.That represents a real tire that is 41" high.

Been working on some basic drawings for the truck. In previous projects I depended too much on the way some kit pieces come out of the box. For instance the rear axles that are in the above photos are simply too wide (not the brass inserts, they are just temporary length). So by knowing from actual measurements the track width of the rear tires, I drew out a plan view of the frame and tires. Having had the tires cast to a predetermined width, they had to fit within a certain parameter. That meant that the distance that is between the two inner tires had to be enough for the frame width and the springs. So far so good. One rear axle has been adjusted and the tires and wheels checked for overall width. Now to do the same thing to the second axle. More photos soon.

I don't consider myself an expert in casting so what I explain probably goes against every proper way to do it. That having been said if you look at the last mold of the small 8 spoke rim the mold have next to the master is quite deep and includes most of the casting details. Resin is poured into this half of the mold and brought to overflowing. Then the top is put on squeezing out all but what makes up the mold cavity with the top on. Sometimes air bubbles do get trapped. (Maddening!) But most times they do not. After the resin sets the two pieces are broken apart. Same method was used for the tires for the brush truck project. If I had a pressure pot to introduce about a 10 lb. vacuum it probably would help a lot in expelling the air.

To: 426-Hemi: Here is the grill that you inquired about. It is resin and has a slight curve to it but it will straighten easily. There are also two clear resin lenses for the holes in the grill. The headlight bezels are separate but are the same as what are in the Linberg L700 kit.

After a bad start on making a mold for the tires, a new one was made up and 10 tires and wheels are now ready for the build. I was concerned that the deep tread might cause some problems for the mold tearing away when I separated it from the master but it held up fine. The secret was really swashing on the mold release so the small parts of the mold would not stick. Two part resin was made and poured in. Very little clean up was needed although on some of the castings there was a air pocket that needed filling afterward. Nothing in the tread area which was good. Next is to clean up the wheel pieces and begin on the frame so I can locate the springs. In this one the base of the mold has been completed. Next up is to pour the top of the mold. The mold box is complete and has the first resin pour in place. After the resin sets the mold will be separated. And here are all of the tires and wheels awaiting setup and final painting. JeffH is working on a 1919 Federal and needed some 8 spoke rims. The Mack AC kit has 5 spoke wheels in the front and 7 spoke wheels for the rear. What to do? He broke apart two 5 spoke wheels and drew up a circle with 8 segments. He trimmed the 5 spoke sections until they came together into a configuration of 8 spokes. He asked if I would make up a mold and voila! 8 spoke wheels for the Federal! In this photo, the resin has set and the mold has been separated to reveal the new casting. The original 8 spoke master is to the right. The resin casting is out of the mold. This was an easy mold to make but it took 4 steps to complete. 1. Build a box and fill the bottom 1/3 with RTV. Let set. 2. Make up more RTV and pour in just enough so that when the master is set in, the wheel is sitting on the first pour and the new RTV is even with the middle of the spokes of the wheel. Let set. The master is now secure in the mold. 3. Make up a third batch of RTV and pour it on the outside of the wheel only up to the top of the rim. Let set. 4. Coat the entire mold and wheel master with mold release and pour the last of the RTV over the wheel and up and over the wood plugs in the corners. The plugs will help allign the two mold halves so that the casting will be centered.

On the Scale Firehouse forum site there is a section called the Parts Bin. Look for Shapeways Store. Matt is a CAD guy who has been doing up detailing pieces for fire apparatus models. I sent him a photo of the tire tread I wanted and the dimensions of the tire for 1/25 scale. He took it from there, made the 3D drawing and shipped to Shapeways. He let me know that it was ready and gave me the link. I simply purchased the finished tire from Shapeways. He gets a small amount of the purchase price for doing the 3D workup. Kind of a neat thing.

Hah! Didn't even notice that! Must have been when I put new batteries in the camera.

Hmmmm! Didn't realize I was that quick! Also helps to be retired from full time work!

Now that the 1929 Coleman is nearly completed (I'm in a slump about building the hydraulics and dump body) there is a new project on the board. This big 1957 Diamond T M-52 military tractor was turned into a brush rig for an adjoining town. I've been asked to build a model of it for someone who was instrumental in getting the chassis and seeing the construction completed. This has just been started after taking a number of photos and some basic measurements to come up with a side view of the cab and chassis. The axles were taken from an Ertl ALF kit and modified for the military style differential. The transfer case I made up some time ago for the Type O-5 Crash Truck. The tires were 3D printed by Shapeways based on a photo and dimensions I provided. They are quite well done and I was able to simply snap in the resin wheels with only very little sanding. Lots to do on this scratch building project including a Continental R6202 gas engine. I can see myself making several trips to see the real rig to get more info in the coming weeks!

NIcely done!

That's some nice work. Very impressive. If you don't mind telling, where did the tires and axles come from?

Everybody starts somewhere, John. Welcome back to a great hobby!

Thought of that but I think it is just a little to big and not quite flexible enough. The wiggly worm is just about the best except for that one flaw. I'll give it a few more days and if the paint doesn't cure I'll wipe it off and try the alternative.