[GreenKeys] 14 TD help

[John, W9DDD]

The problem seems to be fixed.

I couldn't find a nice side view of the clamp, but here's a fuzzy one. 
In this side view you can see a slot in from the right end all the way 
to the hole for the shaft.  Above the slot a vertical clearance whole is 
drilled.  Below the slot the vertical hole is drilled and tapped for 
4-40.  So a screw dropped into that hole will slide into the clamp until 
it reaches the portion below the slot. At that point it engages the 
threaded portion and as you screw it in it will attempt to close that 
slot and make the hole for shaft tighter.

While playing with it without being on the shaft I was getting 
resistance like the clamp was real hard and wouldn't flex like needed.
My experience reminded me of the experience of trying to use a screw 
with the wrong thread pitch into a tapped whole.  If the pitches are 
pretty close you can get a few turns of the screw until it get harder 
and harder to turn.  Either a light bulb turns on, or you twist off the 
screw. (AFAIR I don't think I was ever that stubborn)

I finally tumbled the fact that the clearance hole had a burr in it. 
Apparently they didn't run the drill quite far enough into the hole. 
The burr would act like a thread. As you started to put pressure to 
close the slot it would in effect change the thread pitch.

I didn't have the exact drill size they used, but with a slight smaller 
one I seem to have gotten enough of the burr removed that I now can get 
the clamp to hold.

Why wasn't this noticed before?  This part was a rescue from a different 
TD, maybe the other shaft was slightly larger in diameter?  It would 
have only take a few thousands difference.

Well, that's my theory and I'm sticking to it.

---
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The above comments or recommendations are SWAG. Use at your own risk.
John, W9DDD

On 5/29/2021 8:21 PM, John, W9DDD wrote:
> This might work better with a more common file format.
> 
> I can't seem to get the tape arm to hold adjustment.
> 
> Screw 151685 is supposed to tighten down enough to cause the clamp to 
> not slip on the 89481 shaft.
> 
> I'm considering replacing the fillister head 4-40 screw with a allen 
> socket head so I can get more torque on it, unless someone has a better 
> idea.
> 
> 
> 
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