#302 Over the last few days I have been applying coats of a wax free shellac sanding sealer to the wood bases. Each coat was sanded off before another was applied. The purpose of all the coats is to fill in and seal the grain. The finish will be three coats of Varathane Profesional semi-gloss. A few years back I found out a that wood must be sanded with the grain. In the picture below I show the 'block sanding' style I use with a Formica covered board to level the woods surface. The sides are done the same way. For the routed part of the edges I use a short piece of scrap metal wrapped with sand paper.
#303 In this picture you can see how the frame of the engine looks sitting directly on a wood base. Mounting the engine this way would leave the center-line of the carburetor needle to low for the fuel level at the top of the gas tank.
#304 In this picture I added an aluminum base to raise the carburetor up, and at the same time add a minor cosmetic detail to the engine's frame. The engine base was a detail that I felt was missing.
#305 I used an end mill to create a counter sink under the wood bases. This will conceal the nuts and washers that will go on the bolts, that will secure the engines and gas tanks on top of the wood bases.
My milling vise is too small to hold the bases so I had to eye ball the locations for the end milled areas. To make this easier I made a brass button to pencil mark the locations making the end mill line up a bit easier.
#306 Here's a base already milled out for the gas tank mounting bolts. I went .150" deep with a 3/8" end mill to allow plenty of clearance for a 4-40 nut and washer. The engine mounting holes and countersinks were done previously. For those I used a 1/2" end mill and went .200" deep for 6-32 nuts and washers.
#307 I started the assembly of the fuel tanks by soldering the gas cap nipples on first. I used small pieces of 60/40 soft solder placed on the inside of the tank, and applied the heat to the nipple from the out side. The solder is attracted to the heat and pulls through the joint using this method.
If you use this method with the intention of adding the end caps latter, its best to use a high temperature soft solder or a high temperature silver solder, for the first soldered on part to avoid melting the solder used on the nipple when you add the end caps. I didn't remember this, and one of the threaded nipples let loose and had to be re-soldered as a last step. The repair made a mess and created a wider spread of the visible solder joint. This can be seen in a picture further along in this post.
In the back ground one assembly is cooling down. I set the nipple over a stepped rod held in a vise to hold it up while I soldered it together.
#308 Using the same set up shown in the previous picture, I stood the vise on end to solder on the end cap with the fuel line nipple pressed in place. I used a snug fitting rod from underneath, to hold the end cap up and in place. After all the contact surfaces were fluxed I set small pillows of solder around the inside perimeter of the end cap and applied heat from the out side and all around till a hint of solder came through the joint.
I wrapped the assembly with aluminum wire before soldering as a safety precaution. The last thing you want is a hot piece of pipe landing in your lap!
#309 After good cooling the assembly was preped with sanding and flux, and installed with a 160 degrees rotation on the fixture rod. An end cap was prepped with flux and solder pillows, and then installed from underneath supported with a steel rod.
#310 Again the heat was applied just till the first hint of solder could be seen. With the soldering finished the tank is ready for the final clean up and finishing steps.
#311 The soldering of the five tanks is finished. It took the better part of the day with most of my time spent waiting for the cool downs.
#312 Here's how a tank looks after a little sand papering. I would love to copper plate these to hide the solder joints. Maybe by next time around, when I find the time to research this idea.
#313 The filler neck nipple shifted (melted) and had to be re-soldered on one on the left.
-MB