Coleman 500 Making a new cleaning needle.

Discussion in 'Fettling Forum' started by ROBBO55, Dec 1, 2019 at 3:41 AM.

  1. ROBBO55

    ROBBO55 Subscriber

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    During the fettling of this 1951 Coleman 500 stove I found the cleaning needle was broken and needed replacing.

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    Here is my method I used for making a new cleaning needle for a Coleman 500. However this method can be used for many other makes of stoves.

    From my measurements.

    1. The original rod was made from 0.073” (1.85mm) steel rod.

    2. The thread on the end is 72 TPI with a major dia of 0.07” (1.8mm). This equates to a #1 UNF thread.

    3. I noted that the end of the rod was reduced in diameter to 0.055” which is the minor diameter of the #1 UNF thread. I believe this is done to assist the machining process during formation of the thread. It would help line up the rod with the die. (Pity I didn’t think of this until I was finished).

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    Materials.

    · Whilst the original was steel, I will be using a 2mm dia brass rod for the main body of the cleaner rod. It fits snugly within the spiral of the generator.

    · 1mm dia brass tube with nominal wall thickness of 0.3mm

    · 27 gauge hypodermic needle

    · Replacement pricker wire (0.21mm – 0.25mm) in my case the pricker wire is 0.21mm, No.8 stainless steel guitar string. (I don't know what the correct size is)

    · #1 UNF die (72 TPI).

    Method

    1. Measure the overall length of the original rod (excluding the pricker). In this case 147.5mm (5.8”)
    2. (Optional) set up the Dremel with a cutting wheel. I use this for all cuts and trimming made during this process.
    3. Cut the brass rod to length (In this case 147.5mm (5.8”).
    4. Reduce the diameter of one end of the brass rod to approx 1.8mm (0.07”) for a length of 10-12mm (1/2”).

    5. Thread this end of the brass rod (#1 UNF die). I had trouble centering the rod and keeping it straight during this process so I made a brass guide to fit in my die holder.

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    6. Using a lathe, centre drill the other end of brass rod.

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    7. Use a 1mm dia drill to drill a hole in the rod with a minimum depth of 6mm (1/4”).

    I use a pin drill to hold the 1mm drill. The pin drill is loosely held in the drill chuck on the lathe as a guide only. With the lathe running I control the drill by hand to drill the hole (broke too many drills determining this).

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    * Step 8 – 11 remember to remove the burs after each cut.

    8. Insert the 1mm brass tube into the drilled hole and mark the length. Cut the 1mm tube to length (don’t use side cutters).

    9. Cut the plastic end off the hypodermic needle. I find it is easier to remove the burs if you insert a piece of pricker through the needle before cutting (don’t use side cutters).

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    10. Make sure all the pieces are pushed together then cut the hypodermic needle to match the length of the 1mm brass (don’t use side cutters).

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    11. Remove the 1mm brass with the hypodermic needle inside. Insert a new pricker wire. Allow excess to be trimmed later. A little curl on the end of the pricker wire helps ensure it won’t pull out.

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    12. Reassemble and make sure all the pieces are pushed together (recheck length) then crimp the assembly in place. Remove any burs. My crimper is a pair of pliers with a 1.5mm hole drilled through the jaw face. The tips of the jaws are ground so I can place the pliers in a vice if necessary.

    12.jpg 12a.JPG

    13. Assemble. Adjust overall length (making sure valve closes) and trim pricker wire to length and remove bur.

    13.jpg

    Done.
     
  2. Tony Press

    Tony Press Australia Subscriber

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    Very nice work, Martin!

    Cheers

    Tony

    @ROBBO55
     
  3. presscall

    presscall United Kingdom SotM Winner Subscriber

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    @ROBBO55
    Good to see another ‘hypo’ repair. Nicely done indeed.

    John
     
  4. ROBBO55

    ROBBO55 Subscriber

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    @Tony Press @presscall

    Thanks Tony .

    Thanks John.
    Your many posts were the inspiration for this project. I just adapted to the situation at hand. :lol: