Self-drilling screw into 3/8" steel?

Reply

  #1  
Old 10-02-16, 01:02 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,548
Self-drilling screw into 3/8" steel?

The "self-drilling" (2 1/2" long with 3/16" shank) screw pictured below is the type that was used (among several others like it) to secure the top plate of a wood-framed wall to the bottom flange of a steel I-beam of 3/8" thickness. My inquiry here is whether once these screws have been used, as just described, if they could be expected to be re-used and the tip would still be sharp enough to drill through into the steel again or are the tips pretty much spent after one such use and I'd need to use new ones. Also would I necessarily need a power drill stronger than mine which happens to be an 18-Volt, 380-Watt motor cordless?

 
Sponsored Links
  #2  
Old 10-02-16, 02:45 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
That type screw will still require a pilot hole, as it is self tapping, but not self starting. I would not re use the screws, as the shank has been compromised due to torque on the original install. They can't be that expensive. It is also better to use an impact driver for such installation.
 
  #3  
Old 10-02-16, 02:54 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 44,369
Another reason not to reuse the screw is that you can see the starting threads are worn flat.

Name:  IMG_3644_zpsnx2sfn9f.jpg~original.jpg
Views: 120
Size:  30.2 KB
 
  #4  
Old 10-02-16, 03:11 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,083
I have had some success using self-tappers into 1/4" steel posts but not 3/8". Here is the method I have used:

Use a drill bit the same size of the self-tapping end of the screw to drill a pilot hole through the 3/8 steel. Then run the screw through the wood and into the steel.

Another option is to shoot nails through the wood into the steel using a powder actuated nail gun. That is how I see commercial carpenters attach steel studs and track to steel building structure. Although they are using very short pins as the steel studs are only 24 ga. Just make sure to wear hearing protection!

Is this at home or at your work? If it is at work, I am wondering why you are not using steel framing?
 
  #5  
Old 10-02-16, 03:13 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,548
That type screw will still require a pilot hole, as it is self tapping, but not self starting.
If the shank is 3/16" what would be a proper size pilot hole? The hardware store has "cobalt" drill bits should that drill through 3/8" steel, with my drill? I need to drill about eight holes for eight screws into the I-beam.

It is also better to use an impact driver for such installation.
I don't have an impact driver available; but regardless please describe why the impact driver would be better for such installation. Could my drill still do the job without significantly more difficulty than the impact driver?

thanks
 
  #6  
Old 10-02-16, 03:20 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,548
Another reason not to reuse the screw is that you can see the starting threads are worn flat.
Not sure how you can see that PJ. Upon close-up examination (of the screw itself, not the photo) I cannot really see that the starting threads are worn flat at all; the first few threads look pretty much the same as the rest of the threads I see no flatness...

Not that I will be attempting now on trying to re-use the screw(s) (per chandler's advice), but just sayin'....
 
  #7  
Old 10-02-16, 03:27 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,548
Use a drill bit the same size of the self-tapping end of the screw to drill a pilot hole through the 3/8 steel.
I measured the end of the self-tapping screw; it's 3/16" so guess I drill a pilot hole that size. If I can, through that thick steel...

Is this at home or at your work? If it is at work, I am wondering why you are not using steel framing?
It happens to be at my work. I dunno the original builders used wood framing for this (non load-bearing) wall, above which is a steel I-beam to which the top plate is attached with those type screws. I'm removing the wall due to some water damage (cause now fixed) and was just gonna re-do it the way they did it, with the wood framing.
 
  #8  
Old 10-02-16, 03:51 PM
Member
Join Date: Oct 2015
Location: usa
Posts: 541
I would use screws that have a standard SAE thread and diameter, I would purchase a thread tap (for SAE screw), a tap drill for the steel and a clearance drill for the plywood. Drilling 8 holes in steel and plywood with a battery powered drill should not be a problem. Have the plywood in place when drilling the holes in the plywood so the clearance drill marks the tap hole location in the steel. Use engine oil on the drill and tap when drilling and tapping the steel. Good luck
 
  #9  
Old 10-02-16, 03:52 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 39,968
"Cobalt" is just a come on name, to make you think it is made of Kryptonite or something. Likewise with "Titanium". You can drill 3/16" pilots, but buy a few bits just to be on the safe side. Metal is tough on today's bits.

Your drill will bottom out or stop spinning when a certain torque is reached. An impact driver does not stop spinning, adds impact and added torque per hit to assist in putting the screws in place.
 
  #10  
Old 10-02-16, 04:11 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,548
Good luck
Thanks. ^ I'll need it.
And thanks for all the helpful replies.
 
  #11  
Old 10-02-16, 04:24 PM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 12,083
It happens to be at my work.
The reason I asked, around here carpenters are mostly required to use steel framing or wood framing that has been fire treated in commercial spaces.
 
  #12  
Old 10-02-16, 04:43 PM
sgull's Avatar
Member
Thread Starter
Join Date: Nov 2007
Location: AK
Posts: 2,548
The reason I asked, around here carpenters are mostly required to use steel framing or wood framing that has been fire treated in commercial spaces.
Ah I see. I'm fairly certain in my neck o' the woods though that's not any absolute requirement. I could be mistaken but don't think so.
 
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
'