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Old 03-13-2016, 05:12 PM
86c's Avatar
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I hear you on the opposing forces.

Prior to using epoxy to hold the barrel in centered and up I milled a spare v-block flat and did some experimenting with the set screw from below, the extra long rail screw from above, the flat retainer block with and w/o the roll pin in the mouth.

EDIT: When I did the flat retainer instead of filing the tongue, I used the set screw from below in conjunction with the td screw to hold the barrel in where I knew for a fact it was exactly where I wanted in both planes. I put the action in the vice but clamped it by the tip-off rail not the sides of the casting. Then I milled the tongue and tang together for a perfect match at the correct final position. It was true to center and way higher then I even wanted it as a result. I don't see how I could have possible done a better job but maybe so.

That is when I discovered the temperature problem and the problem with the screw from above. I will try to explain it at a later date. It is simple. Writing it up not so much.

The opposing forces created by a set screw from below in the tang and from above thru the rail is much easier to explain.

The thought was the rear screw from above help hold the tail end down while the front props the whole deal up adding stability and such. Nice theory, did not hold water.

The short version is that the epoxy bedded tongue with NO helpers after cure with a V-block tight as possible was the best stability. I did absolutely go thru it both ways multiple times over both measuring the instability in the shop with a laser on paper and also field testing. Lack of torque on the v-block allowed it rise and fall too much over a relatively small temp change. The flat block was way, way worse than the v-block at low torque settings.

I am not saying others don't get good results with this that or the other thing. I am saying I have gotten my best results with the cheapest, easiest, fastest method which took me a LONG time to figure out just how simple and easy it really is when I know how.

Apparently Swiss figured it out a long time ago.

WHY he did not tell me sooner I don't know but now that I think of it he is on my ........

Thanks Swiss, I guess you figured I'd be better off figuring it out the hard way, eh.

Last edited by 86c; 03-13-2016 at 05:31 PM.
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