On Friday I finished drilling through the new steel mast step, in the process learned some valuable lessons about steel as the subject of drilling. When you’re putting in a 3/4″ hole through 1/4″ steel from underneath (or another thick, hard material….) it pays to:
- buy a good drill bit
- keep it sharp (use a bench grinder and roll the bit along it’s natural curvature and sharpen each outside edge)
- drill pilot holes, if it’s a big hole drill multiple
How did I learn these things? I needed to drill four holes in the new mast step and elected to use the old holes in the lead keel. Drilling up through the countersunk holes allowed me to keep my angle right. I did not have a drill bit the right size, nor did the boatyard. I wanted the hole to be slightly smaller than the bolts so I could tap the hole so the bolt would be threaded into the step itself and a nut.
We made a run out to the local True Value, about 15 miles away and bought a bit. I came back and assumed the position. I crouched under the boat and held drill above my head at about a 70 degree angle and well….drilled. A lot. By the second hole the woman who works their store offered me a stool, I of course declined until I looked up what felt like 15 minutes later and had only gone through half of it…….that seat suddenly seemed like a good idea.
The seat didn’t make the drill any faster, when I finished the hole I checked out the bit and it was totally rounded off on the sides. If I’d sharpened it, that second hole wouldn’t have taken anywhere near as long.
lesson #917,126
When I finished the first hole, the drill stuck in the hole and kicked. I dropped the drill, if I’d had a bad grip or wasn’t paying attention I could definitely have been popped in the head….After the second hole I learned how to sharpen the bit. The third hole went quickly and easily. The last hole was going quickly like the third until the bit split enough. That’s where the pilot holes come in. Right…..
Drill bits are designed to cut around the outside. I was putting a lot of weight on the point and the steel was pushing back, all that pressure and motion eventually cracked the bit in half.
Anyway….holes drilled and tapped, I cleaned out the holes with my Dremel. Then threaded in the bolts and tightened them about 90% of my strength (only a slight grunt, not battle cry tight) with a whole lot of 5200 in the hole and around the head of the bolt. 5200 holds….I don’t like using it because getting it off is like battling a 20 minute mayonnaise jar lid with a jigsaw and pry bar. I let that sit over the weekend to form a gasket.
Then I went and got two Tyvex suits, breathing masks and heavy duty gloves to sand the bottom with 6″ sanders attached to giant shop vacs. Lara was shockingly not too enthused about spending the afternoon dressed like she was doing a crime scene clean up, sanding off paint designed to poison shellfish and other would be colonizers. So I was stuck by myself to finish off my Friday afternoon shoulder work out.
While sanding I discovered more work….or created some. The bottom had several blisters, I followed these instructions by Don Casey, who incidentally knows what he’s doing. Though he skipped the “flatter your artistic girlfriend and convince her to fill the blisters because you make a giant mess with any available medium and you don’t want to end up having to sand off stalagmites of epoxy” step.
Pictures below
