A blog about SCAMP (Small Craft Advisor Magazine Project) boats. Covering the build, sailing the boat and the scamp community that has formed around this little portly boat.

Sunday, October 5, 2014

Drilling the centerboard pin

I had what I thought was a brilliant idea to make some templates and drill guides for the centerboard pin. I had read this post and ordered all the bronze bushings and stainless hardware that I needed for  the centerboard and the rudder.

The bushings for the centerboard sides were for 1/2" shanks with 3/4" diameter and a 1" flange. That's a pretty burly bushing. And since the hole that was in the centerboard casing is only 1/2" hole, then I would need to drill it out. And since this is exposed to the water, it's best to drill the hole overly large, then drill it down to size. That way, there is no chance wood will ever be exposed to water.

The plan was to drill out 5 plates that all had aligning holes and centered holes, 1 with 1/2" hole, 1 with 3/4" hole, 2 with 7/8" holes and 1 of an end cap with a 3/4".
If I were to drill 1/4" holes through all 4 corners, then I could align all the plates with each other.

The 1/2" hole would go over the pin to align everything.
The 7/8" hole would be used as a guide to drill out an oversize hole in the CB.
The 3/4" hole would be used as a guide to drill the 3/4" hole through the epoxy plug in the CB for the bushing.
The original plan was too fill the two 7/8" blocks with epoxy, then drill them down to 3/4" to use as permanent plates on both the inner side and the outer side. However, it turns out I didn't use those.
The final plate was just a cap with a 3/4" hole that would go over the bushing that stuck out slightly proud of the surface.
Finally, the 3/4 plate or the 7/8 plate would be filled and drilled to 1/2" and would be the permanent housing for the pin.

In theory it was great. In practice, it mostly worked.

First, I took 5 plates and bound them together

Then I drilled out 1/4 holes for aligning

That seemed to work.

I drilled all the way into the plate so that I could align
Then I added a center hole
Now I had plenty of ways to align
In this shot, I'm using 1/4" drill bits to align.
However when it was in the boat, I used 1/4" dowels.
When it was all done, I had my plates.
I have a few picture later of how it all went, but we'll save those for later.
In short, it went pretty well. when I was all done, they were slightly misaligned. I think this is because the holes started misaligned. The bolt was very tight through the original 1/2" holes and I think I just compounded the problem by putting solid bronze bushings in there.
I did get it all working correctly though. I had to sand the pin just a little bit to get it to fit in well.

This was a long process to get it all done. I liked the way it all turned out. More pictures later.

(By the way, I'm actually about 2 weeks behind in this blog. I built most of this in mid September. I'm still trying to catch up with blog postings and hope to be live someday.)

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