lbhsbz
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As I'm de-rigging the back of my new-to-me Lavey 18'10", I'm finding that most of pieces fastened using flat allen head screws are fucked up. The tunnel tabs for one...and I've noticed on a lot of boats I've played with, the tab braces always seem to be loose due to wallered out holes.
Here's why. SAE flathead screws typically use a 82° angle on the underside of the head...not 90°, not 100°. I've measured a few of the holes that are not fucked up, and they were all countersunk to something other than 82° by whoever made these parts. If the angles don't match, we will have effectively a point load situation which...especially in aluminum, will become loose over time and under load. Use the right cutting tool, unless you're dealing with wood, then it doesn't matter.
I'm making some new side plates for the outboard bracket today (to shorten it so I can run a hyd. jack plate). I have a couple 82° countersinks, but of course, they are nowhere to be found...so we have to wait for McMaster to show up tomorrow.
Here's why. SAE flathead screws typically use a 82° angle on the underside of the head...not 90°, not 100°. I've measured a few of the holes that are not fucked up, and they were all countersunk to something other than 82° by whoever made these parts. If the angles don't match, we will have effectively a point load situation which...especially in aluminum, will become loose over time and under load. Use the right cutting tool, unless you're dealing with wood, then it doesn't matter.
I'm making some new side plates for the outboard bracket today (to shorten it so I can run a hyd. jack plate). I have a couple 82° countersinks, but of course, they are nowhere to be found...so we have to wait for McMaster to show up tomorrow.
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