I always use pin driving fluid, which is phenolic Resin, ie. the basis for Modern Varnish, without the "Driers". I get it from Rhodda Paints, at their Factory. Their people at their stores just give you a blank look when you talk to them about the stuff. :-( It is thinned with "Synthetic Reducer", which has some pretty nasty chemicals in it, so use proper precautions. Years ago I did some experiments with and without. I found that the torque was about 20% higher without the pin driving fluid. Of course, if you drill to a proper torque not using it, that will work too. However, It has been my experience that the pin blocks that fail are those that are drill all the way through, ie exposing the inner block to the elements below the pin. I like to use Pin driving fluid, as it is, after all a type of varnish, to seal the wood below the pins. Also, I NEVER drill a pin block all the way through. Another thing I do, is to take some of the scrap material, left over from the pinblock just made, and test many different drills for the ideal fit. When I do this, I make sure that the drilling process, with a warm drill bit, cooled with air, etc, is exactly like the whole drilling process. Further, I ALWAYS seal the entire pinblock, outside, with Varathane, (at least 2 coats). Hope this helps. Regards, Joe Garrett, RPT, (Oregon) P.S. If anyone is interested in my "Specs Chart", that lists torques, tuning pin diameters, pinblock drills available, wire sizes (US & Euro converted), and some other stuff, it is available for the asking. Please do it off list so's we don't clutter up the list.
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