Tuesday, November 8, 2011

All about drills, or, using your powers for good or evil

Actually, according to one of my favorite characters - Strongbad - you can only use your powers for good or for awesome.  Today, I'm eagerly awaiting a fascinating new machine - my taper bore countersink drill bitts with stop collars.  Kind of sounds like a Red Rider BB gun with a compass in the stock, doesn't it?  And like Ralphie, I have no shortage of people telling me I'll shoot my eye out, in one form or another.  The bitts cost a pretty penny - $90 plus $14 shipping for a set of 4 bitts and other assorted goodies - and like a kid at Christmastime, I'm waiting to rip open the package.

So why are these bitts so important that I'd spend that kind of money on them?  The Jamestown Distributors (quickly becoming my most loved and hated vendor at the same time) website explains it best:

Taper Point Drills were engineered to be used to pre drill the pilot holes for the shank and threaded portion of a wood screw. The object, of course, is to use the proper size drills and drill to the proper depth to insure the best holding power from the wood screw. This is critical when the fastened joints have to support a heavy weight or pressure such as when fastening planks to form the hull of a boat. A less critical application would be fastening a wood floor in a house or building cabinets.
Yeah - so take THAT Bob Vila!  Actually it's rather interesting but when you're dealing with something so sensitive as the interface between planking and frames - arguably the connection wherein the boat achieves much of its strength and stiffness - the difference between holes created by a straight drill bitt and a tapered one can be fasteners that begin to work loose on first launching or fasteners that hold fast for 107 years - as some of the originals undoubtedly have.  And when you're playing in that arena - do it right or half ass it - this is one thing that shouldn't be compromised on.  So expensive drill bitts it is!

Now, this doesn't cover the myriad other holes that will need to be drilled in this boat, and in 9 out of 10, the principle conforms to the cartoon above.  When the existing material is sufficiently stalwart or the existing fastener comes out nicely, a smaller hole can be drilled for a smaller fastener.  We'll see prime examples of this in most of the keel, stem and sternpost - where in areas that we have lots of, well, area, to select the placement of fasteners, we can do a good job of distributing the loading over smaller fasteners. 

Other areas, such as the keel alongside the centerboard slot - which was devastated by the use of iron drifts that rusted in seawater to scale twice the size of the original fastener - actually have to be chewed away with a router and replaced wholesale before we can get in there and apply proper fasteners that will hold up to the strain.  Remember the comment about shooting my eye out?  How about being under the boat, upside down, holding a router against the keel chewing out the old mess?  No matter how well my goggles fit, I always seem to end up with sawdust in my eyes.  If done properly, the section I 'chew' out is then replaced with a piece of wood shaped to fit the void - called a 'dutchman' and epoxied in place.  We can then fasten into the dutchman as we would anwhere else on the hull and proceed accordingly.

Needless to say, I am the only 'evil dentist' in the Dockyard - nobody else is going under the hull with a router like that.  Do as I say, not as I do sort of thing.


Wednesday night's and Saturday's working session will be drilling and fastening the frames we've bent into place, and ripping out other frames for replacement.  We also need to plane down more stock, rip into frame blanks and start bending up frames to install 'cold' as soon as the boat is ready for them.  If all goes well, I hope to have frames 10-14 replaced by close of business Sunday.  That will make my graphic a little less dismal, and the boat a hell of a lot stronger.


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