Rules on Pilot Holes and Why do they work? - Woodworking Talk - Woodworkers Forum
 
Thread Tools Display Modes
post #1 of 7 Old 07-15-2008, 02:48 PM Thread Starter
Wood Butcher
 
Evil Scotsman's Avatar
 
Join Date: May 2008
Location: Philadelphia Pa M-F Bernville Pa S-S April - November
Posts: 95
View Evil Scotsman's Photo Album My Photos
Rules on Pilot Holes and Why do they work?

I know the purpose of drilling a pilot hole is to keep the wood from splitting. But how does it keep it from splitting? And what size pilot hole needs to be drilled? For example if drilling a 1/4" hole would an 1/8" pilot be correct?

Some people are like Slinkys.
Not really good for anything.....
But they still bring a smile to your face
when you push them down a flight of stairs.
Evil Scotsman is offline  
Sponsored Links
Advertisement
 
post #2 of 7 Old 07-15-2008, 02:59 PM
Senior Member
 
TS3660's Avatar
 
Join Date: Mar 2008
Location: Ft. Mill, SC
Posts: 1,463
View TS3660's Photo Album My Photos
Good question. The pilot hole should be the diameter (or slightly larger) of the root of the screw you're going to use. The best way to measure the root of a screw is with calipers because they can get between the threads. Or, simply hold the screw in front or in back of a drill and eyeball it up. In other words, guess at it. It also depends on what kind of wood it is. The harder the wood, the bigger the drilled hole must be. Basically, when the screw enters the wood, you only want the threads biting into the wood, not the shank of the screw.

Bud

"Veggie burgers aren't bad if you put enough meat on them"
TS3660 is offline  
post #3 of 7 Old 07-15-2008, 06:58 PM
Old School
 
cabinetman's Avatar
 
Join Date: Jul 2007
Location: So. Florida
Posts: 24,062
View cabinetman's Photo Album My Photos
Quote:
Originally Posted by TS3660 View Post
Good question. The pilot hole should be the diameter (or slightly larger) of the root of the screw you're going to use. The best way to measure the root of a screw is with calipers because they can get between the threads. Or, simply hold the screw in front or in back of a drill and eyeball it up. In other words, guess at it. It also depends on what kind of wood it is. The harder the wood, the bigger the drilled hole must be. Basically, when the screw enters the wood, you only want the threads biting into the wood, not the shank of the screw.

That's a very good answer. I don't use any fancy calipers as then I'd have to figure out the size measured to an appropriate drill bit. I just eyeball it like you described. I also don't use any wood screws that are tapered, and prefer screws that are threaded all the way to the head.






cabinetman is offline  
post #4 of 7 Old 07-15-2008, 08:25 PM
Senior Member
 
Juniperlampguy's Avatar
 
Join Date: Nov 2007
Location: Oregon Cascade Mountains 30 miles north of Crater Lake National Park
Posts: 231
View Juniperlampguy's Photo Album My Photos
Quote:
Originally Posted by TS3660 View Post
Good question. The pilot hole should be the diameter (or slightly larger) of the root of the screw you're going to use. The best way to measure the root of a screw is with calipers because they can get between the threads. Or, simply hold the screw in front or in back of a drill and eyeball it up. In other words, guess at it. It also depends on what kind of wood it is. The harder the wood, the bigger the drilled hole must be. Basically, when the screw enters the wood, you only want the threads biting into the wood, not the shank of the screw.
Ditto!! Glad to know I'm not the only one that does it like that. Eyeballing and guessing at it is the method I've been using for years.

Ron
Juniperlampguy is offline  
post #5 of 7 Old 07-15-2008, 11:36 PM
Senior Member
 
joesdad's Avatar
 
Join Date: Nov 2007
Location: The Land of Jersey
Posts: 979
View joesdad's Photo Album My Photos
Great topic. Great answers.

But the million dollar question is how many curse words do you mutter when you snap a pilot bit off in your project?.........

On the same note my favorite countersink bits are the Dewalt tapered. But that was when I used to be able to charge them on the old bosses account.
They're a little spendy.

Intellectuals solve problems, geniuses prevent them.
-Albert Einstein :http://armandj.com
joesdad is offline  
post #6 of 7 Old 07-16-2008, 10:22 AM
Senior Member
 
mmwood_1's Avatar
 
Join Date: Oct 2007
Location: corvallis, Oregon
Posts: 862
View mmwood_1's Photo Album My Photos
Quote:
Originally Posted by Evil Scotsman View Post
I know the purpose of drilling a pilot hole is to keep the wood from splitting. But how does it keep it from splitting?
When you try to drive a screw into wood without a pilot hole, the threads will cut in laterally, but the shank (or root, as it was previously called) has to have somewhere to go, hence it forces the wood apart. This is what can lead to splitting. If you have a pilot hole, the shank has an empty space to go into, while the threads cut laterally around that space.

Softer woods tend to be more forgiving about this, and nails driven into them can often penetrate without splitting. This is why framing can be nailed together without pilot holes for the nails. But harder, drier woods don't give as much.
mmwood_1 is offline  
post #7 of 7 Old 07-17-2008, 08:52 AM Thread Starter
Wood Butcher
 
Evil Scotsman's Avatar
 
Join Date: May 2008
Location: Philadelphia Pa M-F Bernville Pa S-S April - November
Posts: 95
View Evil Scotsman's Photo Album My Photos
Quote:
Originally Posted by mmwood_1 View Post
When you try to drive a screw into wood without a pilot hole, the threads will cut in laterally, but the shank (or root, as it was previously called) has to have somewhere to go, hence it forces the wood apart. If you have a pilot hole, the shank has an empty space to go into, while the threads cut laterally around that space.
Thank You ALL for your answers, I understand it now. Plus it actually explains how a screw works! Duh on my part. (Never really even thought about it before, just did it!)

I was under the impression that the cutters actually split the wood, but that all makes 100% perfect sense. Thank You all AGAIN for clearing things up for me!

Some people are like Slinkys.
Not really good for anything.....
But they still bring a smile to your face
when you push them down a flight of stairs.
Evil Scotsman is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Holes in work bench djonesax General Woodworking Discussion 8 11-19-2008 01:37 AM
House rules BHOFM Off Topic 3 11-17-2008 10:17 AM
3/8 dowell into 3/8 drilled holes Poppasun Introductions 11 11-08-2008 12:55 PM
drilling holes in dowels BigFishBite Joinery 6 10-28-2008 02:42 PM
need to know trim and molding rules (for furniture too) and other questions creative novice General Woodworking Discussion 2 07-26-2008 03:54 AM

Posting Rules  
You may post new threads
You may 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

 
For the best viewing experience please update your browser to Google Chrome