×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Screw Pull Out Force

Screw Pull Out Force

Screw Pull Out Force

(OP)
Need pull out force for a #6 x 2" coarse thread drywall screw embedded 1-5/8" into yellow pine.

Thanks,

TD

RE: Screw Pull Out Force

Test it.

Check with manufacturer....they MIGHT have data that specific, but usually more general.

 

RE: Screw Pull Out Force

(OP)
Thanks Ron,

Have emailed Hilti and Grip Rite.

Hope to have reply next week.

I remember reading a text that had general info on screw pull out strength, but can not remember the text.

May have to just test several screws with a pull out gage if I can not get any answers.

Thanks,

TD

 

RE: Screw Pull Out Force


Your best information will come from a series of tests.  

You could reference the 2005 NDS, Section 11 for more information - you will need to know the specific gravity of the wood.  For a #6 wood screw, the values vary from 38 to 209 pounds per inch of penetration into the side grain, multiplied by the appropriate adjustment factors in Table 10.3.1.  Your final calculated values from the NDS will likely be substantially less than your test results.  But then, your test results will also vary dramatically depending upon the nature of the grain that the screws are driven into.

None of the above considers the tensile strength of the screw itself.

Ralph
Structures Consulting
Northeast USA

RE: Screw Pull Out Force


Hilti and Grip Rite will likely tell you the strengths of their fasteners alone - the final value will depend on the wood.
 

Ralph
Structures Consulting
Northeast USA

RE: Screw Pull Out Force

I can't comment on NDS but the wood standard I use gives a withdrawal capacity of 170 lbs per inch of penetration for a No. 6 screw. It will vary depending on the quality of the wood. The thread doesn't come into the calculations for withdrawal from wood.

RE: Screw Pull Out Force

Drywall screws are not wood screws so the withdrawal values will probably not be the same. Without a ICC report on the withdrawal values of the drywall screws, I would use the nail values, knowing that the actual value would be higher.

As for testing, you will need to verify that the wood you are testing in meets the actual sg for that species as 95% of that species should be higher than the species sg. This is because of the 5% rule for determining the lumber values under the grading rules.

Garth Dreger PE
AZ Phoenix area

RE: Screw Pull Out Force

Agree with Woodman, Drywall Screws are NOT wood screws.  They are also very brittle, if you have any type of cyclic loading, the use of drywall screws is not realistic and should not be considered as a structural connector as they are not intended or tested to be such.   

RE: Screw Pull Out Force

OP:

I thought this was only applicable to dogs.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Screw Pull Out Force


Mike,

You are BAD!

(Had to think about for a bit)

Ralph
Structures Consulting
Northeast USA

RE: Screw Pull Out Force

Thank you..  Thank you..  Thank you very much.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Screw Pull Out Force

Mike:
Is that called a stuck stiffie?  What a bitch.
 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources