Wake 101
Home   Articles   Pics/Video   Gear   Wake 101   Events   Community   Forums   Classifieds   Contests   Shop   Search
WakeWorld Home
Email Password
Go Back   WakeWorld > Boats, Accessories & Tow Vehicles

Thread Tools Display Modes
Old     (johndk)      Join Date: Aug 2008       05-18-2013, 8:29 PM Reply   
I'm installing a trim tab, and have one pilot hole drilled so far (which I probably need to redo since it's offset, as I wrote in another thread).

I'm using 1/4" pan head sheet metal screws, and what I've read is that I should use 3/16" pilot holes. (The MB trim tab kit itself had no instructions.)

But when I tried to screw the screw in, it stopped with about 1/8" left to go, even with my corded drill. It was so tight, the drill couldn't back it out, and I had to grasp a screwdriver with a pair of pliers to do it. The pilot hole was longer than where the screw got stuck.

So, is 3/16" really the right diameter pilot hole for 1/4" screws, and I'm just doing something wrong? Or should I drill thicker holes, such as 13/64" or 7/32" or 15/64"? I will also be using 3M 5200 adhesive sealant.

In this video, the guy is just using a screwdriver... there's no way that would be possible in my case:


Last edited by johndk; 05-18-2013 at 8:31 PM.
Old     (johndk)      Join Date: Aug 2008       05-19-2013, 8:20 PM Reply   
13/64" worked. I actually got gel coat cracking around the 3/16 hole I tried (I hadn't done the countersink yet, but was just trying to briefly test the screw... now I know to never put in a screw even temporarily until you've countersunk the surrounding gelcoat off first).
Old     (fman)      Join Date: Nov 2008       05-19-2013, 8:40 PM Reply   
Also a good idea to use a Chamfer bit and round off the holes to prevent gelcoat cracking from the screws.
Old     (johndk)      Join Date: Aug 2008       05-19-2013, 8:43 PM Reply   
I just used a much larger bit (run in reverse) to countersink it and grind away the gelcoat about 1/16" around the hole. I saw that tip somewhere - hopefully it's as good as using a specific bit like you mentioned.
Old     (fman)      Join Date: Nov 2008       05-19-2013, 8:57 PM Reply   
I think you will be fine, you just want to round off the hole which sounds like exactly what you did.
Old     (rallyart)      Join Date: Nov 2006       05-20-2013, 12:06 AM Reply   
Fibreglass is much tougher than wood, or sheet metal, and you may need a bigger hole than normal for a screw. If it's too tight it will bust the screw and that is a real pain. The threads will hold very well in glass compared to wood or sheet metal, even if the hole is a bit bigger.
Old     (johndk)      Join Date: Aug 2008       05-20-2013, 12:13 AM Reply   
Yeah, I just don't understand why the various sources I watched/read said to use 3/16", even though it was clearly too small.


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

All times are GMT -7. The time now is 7:14 PM.

Home   Articles   Pics/Video   Gear   Wake 101   Events   Community   Forums   Classifieds   Contests   Shop   Search
Wake World Home


© 2016 eWake, Inc.    
Advertise    |    Contact    |    Terms of Use    |    Privacy Policy    |    Report Abuse    |    Conduct    |    About Us