Oshkosh Cement Mixer Part II: How to make spiral stripe

At first I tried free handing some painting masking tape on the drum, but could never get the spacing or the consistency of the spiral. After looking at the picture further I saw that there were in fact three separate stripes going around it. The problem that is most difficult to overcome is the fact that this is not a smooth symmetrical cylinder, it is basically two cones joined in the middle, with three separate angles on the cones. So I started thinking about it as I worked through the rest of the fabrication.

One day as I was walking through the living room I spied the answer to my problem-a candle holder I had made my wife over five years ago. It was one I had seen in a magazine and I became intrigued with it and long story short, bought a lathe and took a lathe class and made it.

I remembered that there were formula’s and geometry I had to do to lay out the spiral flutes. So I substituted stripes for flutes and believed I had the solution in hand-now all I had to do was find the magazine article that had the formula’s in it! Fortunately I keep all my magazines for just such an occurrence. A 30 minute search through the stack and wa la! I had the article.

So here is how to do it:

Strip, prime and paint the main coat of the barrel.

For ease of transferring the lines I knew I would need, I made a mount to put the drum on my lathe (yes the same one the candle holder was made on)

I then wrapped the entire drum with model paint masking tape, from one end to the other. Now we start the figuring by taking a piece of masking tape and wrapping it around the end of the drum with a little off set. With a pen, draw a line on the tape where it overlaps.

Remove the masking tape just marked and lay on a flat surface. The distance between the two marks is the circumference of the drum. Divide this distance into the number of flutes or stripes desired, in this case three. The distance was 4.5 inches, making the distance 1.5 inches.

Replace the masking tap back on the drum in the same place when you marked the line. I used the lathe tool rest to then transfer the three marks horizontally from one end of the drum to the other

Now take another piece of masking tape and place it on the drum from left to right and mark the ends of the drums.

Again lay that piece flat and divide it by the number of turns the spiral is to have. In this case I tried three and did not like the look, too slow. I then tried four and liked that, but went ahead and made a quick look at five and it was way too busy, so I choose four. Divide the distance between the marks into four, in this case 7/8” spacing.

Again, put the tape back on the drum and transfer the marks to the drum

Then rotate the drum around and with a steady hand and a little luck the line should connect to itself.

Now for the fun part, start at the end of one of the horizontal lines , and draw a line around, making your line go through the intersection of each of the horizontal and vertical lines until you reach the end of the drum. You now have your spiral pattern laid out!

I then used the width paint masking tape I wanted the yellow stripe to be, cutting them into short little 1.5 inch strips, I placed one edge along my spiral line. The reason I cut the tap into short pieces is to account for the changes in diameter and the transition from one cone to another.

Now, very , very carefully using a brand new blade in the xacto knife and using the edge of the tape as the guide, cut along the edge of both sides and remove the tape.

And you end up with a fairly decent looking set of spiral stripes ready for paint.

Before painting, I rubbed all the edges with a q-tip to make sure they were pushed down and then sprayed a coat of clear dull coat to seal the edges.

Apply the paint-thin coats building up layers slowly!

And after drying, carefully remove the tape. Now this is the crude version and I will clean it up a bit here and there. Because of the curves there is a leakage here and there, however I put the yellow on top so I can cut and remove the nib and touch up with the red and it will look perfect!

I hope you have enjoyed this narrative. I know I can be long winded, however I have learned so much here on this form from all of the master craftsman I thought I would share this as part of my debt to them!

Up next-assembly!!

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