Tender Trucks

04/03/05 -10/2/05

Making the Bolster Columns

A lot has been going on in my life (which is all good!) I've started back again on the A3 parts as I have some shop time again. You may have also noticed I changed the look of the web site introduction page. Trying to make it look a bit more professional. The T.E.Datum home page got a face lift too.

The parts here are for the center column of the truck sides where the bolster rides. Kozo calls them the "columns". Getting close to the first brazing (soldering) on the A3 with these parts.

These are parts for the bolster columns. The 1/16" thick brass strips are cut from the brass sheet shown here with a band saw. Two strips will do the job but I had to make three so they would fit the vise.

Here are the three strips in the vise being milled to the proper 5/16" width. A lot of the fun of gathering the materials is deciding what and how much to order of something that will be used to make what you really need.

The block to the right of the thin strips is the jig required when soldering the columns. It is as well made as the "for show" parts. I made it from brass so it will have the same expansion as the parts being soldered.

Well, it's been awhile but I am back to work on the bolster columns. The three in the back are already silver soldered (brazed) and I have one more left to do. The square block solder and drilling jig proves to be a very necessary part. It has to do a lot of work.

I made one flat strip to serve as the drilling jig. The extra long side and the layout dye serve to identify this jig. With the jig a standard drill press does an excellent job of making the holes with the #53 drill bit.

The tap here is very small. #1-72. Kozo calls out #1-64 but I could not find brass screws with that thread. These screws only hold parts together for the soldering and then are filed off and drilled out in the next step.

Here I an getting one end prepped for silver solder. The white paste is the flux. All surfaces to be joined are sanded clean before applying the flux. The secret to a good joint is a very good cleaning job and the flux helps to keep it that way in the heating process.

Here is the size of the torch I used and how I held the part. The torch when burning is about an inch or so lower. It takes a LOT of heat. I am investigating a new professional torch set like I used in my pipe fitter trade. However, once I got used to the big propane flame required, this job went very well with this torch head.

I just turned the torch off and the part is cooling a bit. From here it goes to a mild sulfuric acid bath that almost instantly cleans the flux residue off the part and brightens the brass.

Just out of the acid bath and ready to clean side two. Note how perfect the fillet formed on the first part. Actually a bit less silver solder could have been used. That's a perfect fillet job for a pipe fitter. The file will clean up the extra solder.

Ready to heat side two.

Side two soldered. The heat does not harm the first joint, even this close.

A second acid dip and we are clean again. I am really gonna like this silver brazing again. It is a ton of fun watching the flux turn into a clear liquid and then the solder suddenly melt and flow perfectly into the joint. Of course that is going to happen each and every time...

These screws have served their purpose and are now filed off. The PanaVice is a wonderful tool for holding this work. You just have to have one. Mine is a Standard.

Careful work and the screw heads are gone. yes, that is the same part.

Turn the part around and clean up all the sides as per Kozo's instructions. Another look at how the solder flowed. No doubt this is a good joint.

The same side with the overhang filed off. I am using Cadmium free silver solder and you can see it flows nice and does a very good job. Also the filing dust contains no Cadmium.

Here are all the bolster columns filed down and cleaned up

All the new holes drilled #47 and tapped #3-48 for the truss mount bolts. It sure is fun making nice looking components such as these. These parts are done.

I really liked doing this step. I am considering purchase of a professional acetylene/air torch. Mostly because I have used one for many years. However, I can see that propane/air can do the same job but the torch heads are going to be much larger for the same heat. It takes a LOT of heat to silver braze. No mater what the fuel.

The very first joint I made in this project I selected a propane head that was too small. I had to switch to my largest head as you saw in the photographs. If that first head had been acetylene, it would have done the job.

In my opinion (at this point) either fuel will work. It is just a matter of preference. Propane is a more familiar fuel to the hobbyist. I would think MAPP gas would be a fine choice too but I am not going there.

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