Quote:
Originally Posted by KSagal
one other potential factor to consider is the type of tool you use to determine the amount of torque you are applying.
I use a torque wrench at work that has a pivoting head, in that when you reach the dialed in torque, the head will 'pop' or pivot about 10 degrees. This action is pretty noticeable, if you are looking for it.
Unfortunately, this type of torque wrench does not quit applying torque at that point. It is designed to tell the operator it has reached the dialed in torque, but you can easily continue to tighten bolts till they snap.
I have used better torque wrenches in the past, where they will simply ratchet freely after the dialed in torque is reached. In other words, you cannot over tighten bolts with this type.
A third type of torque wrench exists, and I have used them in the past, but not for decades, is a wrench that has a scale and long pointer that indicates the torque on the shaft of the wrench. The harder you push, the farther the needle moves. I believe you need to be careful with this type, as you can over toque pretty easily. The needle may not be reflective of the actual torque involved.
Just curious. What type to you use, and do you agree or not with me on some of my observed differences in these tools?
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Mine is the cheaper 'beam' style that indicates with a needle how much the shaft is bending. They're undoubtedly less accurate than the click types, but cheaper, and probably close enough for Segway work. ;-)
This is the first and only torque wrench I've owned, and I bought it just for the Segs so I could torque the bolts to the proper spec. Then I didn't bother double-checking to see if I remembered right what proper was.
I just removed the damaged gearbox in preparation for the new one, and managed to punch out the broken bolt after grinding the threaded part flush with the flange. The head has a raised 6-lobe pattern that keeps it from turning in the recess in the flange.
I tried again to drill new holes, and it wasn't as hard as I thought. I used cutting oil and went slow. I even managed to tap one of the holes. So my idea could have worked, but one of the other bolts is so obviously twisted and stretched, that I'd worry that it's next to go. I'm afraid to look at the bolts on the other side, or those on the other i2, so I won't. Ignorance is bliss.
I'll just periodically check to see that the nuts are staying tight.
I was happy to see that the elastomer looks just fine. It's lasted at least twice as long as the first ones, which basically turned to sticky dust, so I think they improved the material.
Edit:
I was in too big a hurry drilling the holes to realize that, with the bolt out, I could just glue a nut into the recess where the head had been, using steel-based epoxy.
I'll use thread-lock and a lockwasher, and think this will work just fine. Since the new gearbox has already shipped, I'll keep it as a spare, but I probably won't need it. If another bolt breaks, I'll fix it the same way.
Should be back on the road tomorrow morning.