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Final Drilling Powder-coated Parts

EJWash

EJWash

Active Member
Hi All,

Working on my -14 vertical stab. Before permanent installation, there is one hole in each of the six rudder hinge brackets that are final-drilled to #12. Of course, doing so removes the powder coating inside the hole. So, the question is: Is anything applied to the inside of the hole after removing powder coating/paint to stave-off rust/corrosion? What practices are out there?

Thanks in advance.
 
Last edited:
EJWash said:
Hi All,

Working on my -14 vertical stab. Before permanent installation, there is one hole in each of the six rudder hinge brackets that are final-drilled to #12. Of course, doing so removes the powder coating inside the hole. So, the question is: Is anything applied to the inside of the hole after removing powder coating/paint to stave-off rust/corrosion? What practices are out there?

Thanks in advance.
Click to expand...
At installation time I use Duralac. Duralac is a jointing compound to protect against corrosion between dissimilar metals and is commonly used in boats.
 
One additional thought -- use a reamer instead of a drill when final sizing a hole. Drilling (push/feed into the material) will tend to create a slightly epitrochoid shaped hole larger than what is desired. Using a reamer (pulled through the material) leaves the finished hole of the desired size.

If you can't get a gas tight seal around the attachment hardware, and/or you're concerned about water incursion accelerating the oxidization of the material, put a little primer on a q-tip and run it around the inside of the hole.
 
bjdecker said:
One additional thought -- use a reamer instead of a drill when final sizing a hole. Drilling (push/feed into the material) will tend to create a slightly epitrochoid shaped hole larger than what is desired. Using a reamer (pulled through the material) leaves the finished hole of the desired size.
Click to expand...

I'm using chucking straight flute reamers to final size all holes. Piloted tips for #30 and larger, unable to find a piloted #40.

bjdecker said:
If you can't get a gas tight seal around the attachment hardware, and/or you're concerned about water incursion accelerating the oxidization of the material, put a little primer on a q-tip and run it around the inside of the hole.
Click to expand...

In the case of these vert stab-to-rudder hinge brackets, the holes are for 10-32 bolts. Too-small for a Q-tip, but a primer-dipped pipe cleaner will fit. That'll be downline when the rudder gets attached.
 
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bjdecker said:
One additional thought -- use a reamer instead of a drill when final sizing a hole. Drilling (push/feed into the material) will tend to create a slightly epitrochoid shaped hole larger than what is desired. Using a reamer (pulled through the material) leaves the finished hole of the desired size.
Click to expand...
Now *there's* a good word :).
 
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