Go Back  Offshoreonly.com > General Discussion > General Boating Discussion
How do I drill Gelcoat without cracks >

How do I drill Gelcoat without cracks

Notices

How do I drill Gelcoat without cracks

Old 08-26-2021, 04:40 PM
  #1  
Registered
Thread Starter
 
Join Date: May 2018
Location: Western Pennsylvanoa
Posts: 483
Received 76 Likes on 59 Posts
Default How do I drill Gelcoat without cracks

Going to install 2 strap brackets for Bimini with #10 screws. Best I can figure final drill size is 5/32. What technique for drilling without cracks.

thanks
PA.WOODCHUCK is offline  
Old 08-26-2021, 04:56 PM
  #2  
Registered
 
Join Date: Jul 2008
Posts: 574
Received 22 Likes on 16 Posts
Default

Originally Posted by PA.WOODCHUCK View Post
Going to install 2 strap brackets for Bimini with #10 screws. Best I can figure final drill size is 5/32. What technique for drilling without cracks.

thanks
Easiest methods Iíve found are donít use an extremely sharp bit, go in reverse to burn through the first layers, lightly counter sink the hole before you run the screw in. If you donít have a counter sink or are lazy to change your bit you can also use your phillips screw tip as a small counter sink haha
lavey jr is offline  
The following 4 users liked this post by lavey jr:
350scarab (09-03-2021), bajaman (08-26-2021), Dave3fl (08-26-2021), Gimme Fuel (08-27-2021)
Old 08-26-2021, 05:56 PM
  #3  
VIP Member
VIP Member
 
Join Date: Nov 2005
Location: Wichita, Kansas
Posts: 421
Received 169 Likes on 87 Posts
Default

Originally Posted by lavey jr View Post
Easiest methods Iíve found are donít use an extremely sharp bit, go in reverse to burn through the first layers, lightly counter sink the hole before you run the screw in. If you donít have a counter sink or are lazy to change your bit you can also use your phillips screw tip as a small counter sink haha
Quoted for truth...THIS is the best way.
__________________
Baja 252 Islander
bajaman is offline  
The following 2 users liked this post by bajaman:
Dave3fl (08-26-2021), lavey jr (08-27-2021)
Old 08-26-2021, 06:00 PM
  #4  
*
Platinum Member
 
madbouyz's Avatar
 
Join Date: Nov 2002
Location: PortRoyal Bermuda
Posts: 954
Received 109 Likes on 64 Posts
Default

Originally Posted by lavey jr View Post
Easiest methods Iíve found are donít use an extremely sharp bit, go in reverse to burn through the first layers, lightly counter sink the hole before you run the screw in. If you donít have a counter sink or are lazy to change your bit you can also use your phillips screw tip as a small counter sink haha
X's 3
And use a very light touch !
madbouyz is offline  
The following 2 users liked this post by madbouyz:
Dave3fl (08-26-2021), lavey jr (08-27-2021)
Old 08-26-2021, 06:01 PM
  #5  
Registered
 
Join Date: Jan 2004
Location: Northern NY
Posts: 5,283
Likes: 0
Received 48 Likes on 23 Posts
Default

Do not run the screw into the glass without an appropriate counter sink. Best done with a stone so as to not create any rough / sharp edges. Just want a smooth bevel, and do not over tighten the screw and pull the gell from the glass substrate.
RaggedEdge is offline  
The following users liked this post:
Keith Atlanta (08-26-2021)
Old 08-26-2021, 06:03 PM
  #6  
Platinum Member
Platinum Member
 
Too Stroked's Avatar
 
Join Date: Apr 2010
Location: Rochester, NY
Posts: 1,923
Received 110 Likes on 39 Posts
Default

Originally Posted by lavey jr View Post
Easiest methods Iíve found are donít use an extremely sharp bit, go in reverse to burn through the first layers, lightly counter sink the hole before you run the screw in. If you donít have a counter sink or are lazy to change your bit you can also use your phillips screw tip as a small counter sink haha
^^^^ This, plus one more hint based on years of experience. Normally, when sizing a hole for wood or something similar, one goes slightly smaller than the root diameter of the screw when sizing the drill bit. For fiberglass (topped with gelcoat), it's a bit different. Size the drill bit exactly for the root diameter or even a bit bigger. Although this theoretically reduces the strength of the hold down, it also prevents stress cracks.
Too Stroked is offline  
The following 3 users liked this post by Too Stroked:
Dave3fl (08-26-2021), lavey jr (08-27-2021), liberator221 (08-26-2021)
Old 08-26-2021, 08:58 PM
  #7  
Registered
 
Join Date: Jul 2009
Location: USA, PA
Posts: 495
Received 153 Likes on 89 Posts
Default

i always put down masking tape on the fiberglass before drilling, reduces cracks/chunks.
remove after drilled.
SabrToothSqrl is offline  
The following 3 users liked this post by SabrToothSqrl:
Ryan00TJ (08-27-2021), tmmii (08-26-2021), Ton (08-26-2021)
Old 08-26-2021, 09:52 PM
  #8  
Ton
Registered
 
Join Date: Jun 2021
Posts: 17
Received 5 Likes on 4 Posts
Default

Originally Posted by SabrToothSqrl View Post
i always put down masking tape on the fiberglass before drilling, reduces cracks/chunks.
remove after drilled.
I totally agree with this...A masking tape on the fiberglass before drilling does the trick.
Ton is offline  
The following users liked this post:
tmmii (08-26-2021)
Old 08-26-2021, 09:56 PM
  #9  
Gold Member
Gold Member
 
Join Date: Jul 2008
Location: Delray Beach, FL
Posts: 3,562
Received 624 Likes on 231 Posts
Default

Why dont you thru bolt it?
Keith Atlanta is offline  
The following users liked this post:
Dave3fl (08-26-2021)
Old 08-26-2021, 11:07 PM
  #10  
Registered
 
Join Date: Aug 2014
Posts: 835
Received 98 Likes on 66 Posts
Default

Masking tape and then counter sink
tmmii is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.