Pilot hole...

Reply

  #1  
Old 04-23-13, 06:04 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Pilot hole...

Hi, I want to screw an antenna mount in the attic. The mount comes with hex-head screws that have a "root" of slightly less than 3/16 of an inch. Including the thread, the size is 1/4 of an inch. The head fits in a 3/8 hex socket.

What is the size of the pilot hole I must drill in the wood to properly torque the screw in the wood?
 

Last edited by alesan; 04-23-13 at 06:42 PM.
Sponsored Links
  #2  
Old 04-23-13, 06:19 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
I would use a 1/8 or 5/32" bit. You want it not to split the wood, but leave enough bite to hold.
 
  #3  
Old 04-23-13, 06:48 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
So small??? Will I be able to actually screw it in without breaking it? It sounds like I will have to put a lot of force... Should I lubricate the screw?
 
  #4  
Old 04-23-13, 07:04 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
So according to this table, a screw that has a thread diameter of about 1/4" is a #14:

Bolt Depot - Wood Screw Diameter and Number Table

And according to this other table, a tapered #14 screw on softwood would need a 15/64" hole, that is more than 3/8"... I am thoroughly confused!

Bolt Depot - Pilot Hole Sizes for Wood Screws
 
  #5  
Old 04-23-13, 07:21 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 44,398
Right.... a 1/4" is roughly a # 14

For a # 10 screw I would use a 1/8" bit
For a # 12 screw I would use a 3/32" bit
For a # 14 screw I would use a 3/32" bit

Usually my 3/32" is broken and I use 1/8" for everything.
I buy 1/8" bits by the box of 100.

Technically putting that screw into the center of a 2x4 shouldn't split it without pre-drilling.

So if you use either of the two sizes we mentioned you'll be in good shape. If you are really concerned about binding......use a little soap or candle wax.
 
  #6  
Old 04-23-13, 07:25 PM
Member
Thread Starter
Join Date: Jan 2012
Location: USA
Posts: 190
Oh wait, these are the screws I have:

[ATTACH=CONFIG]11870[/ATTACH]

And it seems they are NOT tapered... so the table I linked suggests a 5/32" like you said, chandler. Thank you and sorry to have doubted your expertize!
 
Attached Images  
  #7  
Old 04-24-13, 03:09 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
That's OK. I'm married. Good luck on the install, and welcome anytime!!
 
  #8  
Old 04-24-13, 06:02 AM
Member
Join Date: Oct 2008
Location: New England
Posts: 9,937
Just a correction, 15/64 is less than 1/4, not more than 3/8. Moot point as you have the correct advice.
I know I'm too picky .

Bud
 
Reply

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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'