Thursday, June 18, 2015

A Microcar in Microcosm

My summer project is to rehabilitate the body of my second Heinkel car. This will be no small task since the car needs floors, sills, wheel arches, door tube, louvers, roof rails, and a gas tank supporting panel. In other words, it needs a lot of work.
Heinkel Cars and Cabin Scooters #Kabine
My second Heinkel Car
To outsource this kind of work is not really economical for me, so I’ve decided to do it myself.

Since my welding experience is very limited I decided that I really needed to get much better before I attempted anything that big and with places where my inexperience would be obvious. So, I decided to make a set of cooling tins for my engine.
Heinkel Cars and Cabin Scooters
Heinkel Engine Cooling Shrouds 

Cooling tins are not reproduced for 200cc cars. Close inspection of them shows why: The left hand shroud has 25 separate pieces, a cable-actuated heater gate, and a variety of curves, holes, bends, and welds. I brought one I had to my local tinsmith for an estimate and he gave me one of those looks that said “if you have to ask you can’t afford it”.  I got to thinking that it really was a microcar in microcosm; lots of little pieces that have to fit together in a certain way and will require a lot of fidgeting.

Step 1: Reverse engineering
I couldn’t find a plan for making cooling tins, so I looked at my original and decided to reverse engineer a copy. I made components out of manila file folders. Manila file folder material is easy enough to get, relatively easy to cut, and is sturdy enough that I could use it to craft a 3D prototype. 

Cardboard Mockup of Heinkel Shroud
With the prototype completed I needed to add tabs and determine the parts layout so I could cut, bend, and weld it easily.

Step 2: Steel:
I decided to use 22 gauge steel to fabricate the pieces (gauge refers to the number of pieces stacked together that it takes to make a one inch high pile). I went on line to and had the steel in 2 days. I could fabricate the entire cooling shroud out of 4 square feet of steel.

Heinkel Cooling Tin Parts laid out on metal for cutting

I purchased a 2 foot square piece. In retrospect I would have purchased a 1x4 foot piece. I’ll explain why in a minute.

Step 3 (really step 1!): Tools:
I forgot to mention that this project is a good opportunity to buy some tools? If you’re going to fabricate body panels you can go overboard on tools. Just go to and look at some of the things they sell there. 

Unfortunately a lot of metalworking tools are too big, heavy, not portable, and expensive for a hobbyist. I decided on snips and a 3 in 1 metal machine to do the tasks required. 
3 in 1 Brake Shear Roll Metal Machine

The snips let you cut straight, left, or right. Left and right refer to the direction the waste falls off (or curves around) when you cut your metal. The reason I should have purchased a 1’ wide piece is then I would not have to cut a 2 foot piece. Snips are good for small cuts and not long pieces.
Snips- usually they are red (left) yellow (straight) and green (right)

Step 4: Cutting, Bending and Shaping the Metal:
I learned quite a bit here. Rule #1: cut as little metal by hand as possible. It is extremely difficult to cut a straight line with a good edge using snips.  Snips do well if you are cutting small straight cuts or curves. Either way you need to look out for hanging edges that will slice your fingers.

The 3 in 1 is actually a lot of fun. It’s pretty easy to cut metal once you get the hang of it.  Clean bends are easy, and rolling circles is a piece of cake.

I referenced a sheet metal fabrication book in order to make my round piece transitions. For the air deflector I cut a circle in the main piece, and then cut a wavy edge in the second and everything lined up pretty well. I also experimented with making a “square to round” transition for for heater takeoff, but the 22 gauge metal and small sizes were difficult for me to work with.  I came up with a pretty good solution though.

Step 5:  Welding:
This was what I was hoping to practice on. I had to do a variety of joins including right angles, lap joints, and butt jointing. I decided to tack everything first and then go back and try to lay down some nice bead lines.

Heinkel Cars and Cabin Scooters
Test fitting tack-welded pieces on Heinkel engine

Like anything else the beginning welds were not so attractive. I eventually did pretty well and by the end I was able to make some decent beads. I have a new appreciation for what takes to lay down a good weld.

Not the best welds but they will do!
Step 6: Grinding:
I used the grinder to clean them up the ugliest of the welds.  There are some tricks to learn with grinding too.  I never knew you were only supposed to grind at right angles to the work.

Step 7: Constructing the Heater Gate:
I had to add some extra pieces to replicate the gate. I used an angle iron as it was about the right thickness of the original, then I drilled extra holes for the springs and the cable holder.

Step 8: Paint:
I used hammered paint. The originals seem to have come in a bunch of colors, but I used hammered black since it helped cover up some of my earlier mistakes.
Completed Heinkel Shroud

Head on View of  heater pipe takeoff

Heinkel Cars and Cabin Scooters
Heinkel tin- backside

Heinkel Cars and Cabin Scooters
Exhaust end of shroud
I’m as ready as I’ll ever me for car body welding. I’ll start with my undercarriage where no one can see, and as I get better move on up to the showiest bits!

No comments:

Post a Comment