You Can’t Fix What You Don’t Measure

… maybe the title should be “Two Stupidities A Week”, but since both stupid actions had to do with measurement, or rather the lack thereof, let’s stick with the proverb.

Selfmade rotorpuller next to old oneStupidity #1
Last Saturday my brother and I went to a motorbike scrapyard for some advice, and maybe a new rotorpuller we could borrow. While talking to the guy, it became clear that either I am treating the rotor with too much love and care, or this guy turns into the Hulk when he pulls rotors. He gave us the advice to try again, and:

“Don’t force it, get a larger hammer!”

So we set out to get the larger hammer. While getting the hammer I got the brilliant idea to only use the outer bolt of the rotorpuller, so that it sat against the flat outer end of the crank. That way we could hit it harder without the risk of tearing up the threads inside the crank.

I turned the puller into the rotor, tightened it, and started hitting it with the hammer. Nothing happened. After hitting it, I could hardly remove the puller from the rotor. It appeared to be forged shorter and thicker by the hammering. The threads looked strangely damaged. When I overlooked the damages a day later, it occured to me that the rotor puller was rather short. And yes, mesaurements confirmed that it never could have touched the crank. It turns out that I was actually hammering the rotor onto the crank, and killing the puller in the process. The thread in the rotor still looked pertty intact. Phew.

Stupidity #2
The rotor puller now being officially useless, I started browsing the internet to see what type of bolt I would need to pull the rotor of a Kawasaki KL650B block. I found a site, telling me I needed a 20mm bolt, with 1.5mm thread. That’s an ISO fine M20x1.5 bolt. So I set out to get one. 20mm bolts are not common in your local hardware store. One hardware store could actually find where he could order it, but refused to do that (I will never walk into WALCO hardware store next to Haarlem Central Station again). I would have gladly payed any shipping costs, he had no idea, and he never asked.

Since I have a lathe, I decided to put some time in it. My local favourite hardware store had 20mm round steel (the thickest they had) , so I bought a meter of it. With my lathe I cut the 1.5mm thread onto it, which actually worked quote nice. I only broke a cutter on the last pass, stopping too late. I have to find out how to prevent that from happening the next time.

I removed the workpiece from the lathe, and tried to screw it into the rotor. Guess what? It was too small! If I had taken 15 seconds to measure the rotor before buying the steel, I would have saved myself a lot of work. After uploading this story I will try to order a puller online, because I can’t find larger steel rods today, and the rotor puller is nothing more than a $3,00 bolt.

Or maybe I feel like using my lathe again next week, who knows… But then I will use my measure calipers first, last, and very often in between, because: You Can’t Fix What You Don’t Measure!


5 Responses to You Can’t Fix What You Don’t Measure

  1. rolfje says:

    Just found out that the puller costs 9.90. As long as the link works, you can see it here:

  2. rolfje says:

    .. and motionpro seems to think that the world stops at the water, so shipping to Europe will be a problem, because ofcourse it doesn’t exist. Tsjeez. Nice doing business with you.

  3. rolfje says:

    Yeeeha! Found a store that ships the damn thing to Europe! It’s part MP11 of their kit:

    So, the shipping is a stunning 17 dollars for a single bolt, but it will save a lot of frustration. Can’t wait to see it arrive!

  4. rolfje says:

    Yes the comments are dated 2 years after the article, I know. It’s a side effect of the migration process from my old blog, sorry.

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