Help me Center the Blade of my 172

D

Don M

Joined
Apr 30, 2000
Messages
846
I left my Mayo 172 in my wife's car and it sat in the glove box for a couple of months (in Utah, in the sun). Now the centering is way off. It was never perfectly centered, but now it nearly touches the scale opposite the lock bar. I figure the heat made the plastic washer creep under the pressure from the lock bar.

I took it apart and checked the washers, and found one was a little thinner on one side (by just a little - checked with a micrometer). I reinstalled with the washer rotated 90 degrees, but it did not help the centering. I also tried loosening the screws, snug the pivot a little, and pushing the scales one up the other down, then retightening the screws in the position that moved the blade the right direction, and it helped a little, but not enough.

The lock is a little sticky now, which it never was before.

Apart from getting some oversize bronze washers, do you have any suggestions?
 
I think the best thing to do is contact the factory. they may want you to send it to them for repair.
 
I replaced the washers with bronze washers and that helped. It is definitely tighter now, though not as slick as the original Teflon washers. On close inspection, it looks like the blade is not perfectly straight, which is why the tip is not centered when it is closed.
 
Since you've had it apart already I'd take it back apart and put the blade on some kind of a straight edge and check it to see if it's actually bent or not. If the centering is worse than when you first got it the blade wouldn't have gotten bent just laying in the glove box. Also check the scales on a glass surface or other known, flat object and see it something has gotten warped.
 
The centering is back to about where it was when new. I would not say it is bent - it might have warped slightly in heat treat, or been ground slightly off center. I can see a slight offset when I sight down the blade. I will check it and the scales for flatness the next time I have it apart.
 
Tom Mayo said to take the knife, open the blade, and push the tip in the direction of the handle scale toward which it points when the blade is closed. It worked for mine, but with the bronze washers it may not. Won't hurt to try it.

The real question is how you could leave it unattended for months in a glove compartment. Have you no shame?
 
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