Metal Screws For Holding Wood Planks To Frame.....

[Utopia Texas]

I have a 2X6 plank on my new trailer that has warped and popped two screws in half that I need to replace and need some advice. These screws are tapered at the end but are not self drilling and have the wide flat heads that are driven with a star shaped bit. When I drill the new holes through the wood plank and into the metal frame below the wood should the drill bit be one sized smaller than the diameter of the screw? I have never used this kind of screw before and am not familiar with its application. Thanks.....

 

[Soundguy]

You need to leave some metal for threads to bite, so don't use a drill bit the same of as the screw.

 

[dfkrug]

What I like to do is drill the hole in the wood just large enough so the threads on the fastener do
not grab the wood at all. This means pretty much right at the thread OD. I then predrill the steel
at the optimal diameter for the threads to bite properly and pull the head into the wood.

I see you already bought your screws. I bought stainless self-drilling bugle heads to attach my
PT plywood to my steel joists. The steel was too thick for the screws to drill through without a
pilot hole.

Using a 120V hand drill and two 18V impact screw guns made the work go pretty quickly.

 

[Soundguy]

when I redecked mine last time, i laid my new wood down and then marked all the holes underneath with a pencil and drileld them, that way all my crossmembers didn't look like swiss cheese.

about ready for a 3rd deck on one of my old trailers..

 

[Utopia Texas]

What I like to do is drill the hole in the wood just large enough so the threads on the fastener do
not grab the wood at all. This means pretty much right at the thread OD. I then predrill the steel
at the optimal diameter for the threads to bite properly and pull the head into the wood.

I see you already bought your screws. I bought stainless self-drilling bugle heads to attach my
PT plywood to my steel joists. The steel was too thick for the screws to drill through without a
pilot hole.

Using a 120V hand drill and two 18V impact screw guns made the work go pretty quickly.

I have not had the chance to buy the new screws yet. I was just describing what the broken off screws looked like when I threaded them out of the wood plank. I assume I could buy self drilling screws to do the job. I only need to re-set this one board. All the rest look good.

 

[2458n]

If the self tappers do not work use some carriage bolts. I had some left over from another project,and they have held up well. Drilled from underneath so there is some frame work left,and of course bolted from the bottom. Just using what I had around.

 

[Diamondpilot]

We never drill anything. The screws we do drill, tap, and fasten all in one step.

Chris

 

[Stimw]

Typical semi trailer and straight truck flooring is fastened with what are referred to as "Floor Screws".
They are either 1/4" or 5/16" with a countersinking head with a Torq 30 or 40 drive hole. They are VERY HARD!
For the 1/4" you drill a 7/32" hole and they self tap.
For the 5/16" you drill a 9/32" hole and they self tap.
A good bolt supplier should know what you are looking for.
I have replaced many dozens of semi trailer floors, I would start with a 50 lb box of screws! Sometimes needing more.
I even have a CP Drill that I fabricated a long handle to it so I could stand up and drill the holes.
If the old screws are too rusted to back out easily you just break them off and try not to hit the old screws with the new.
I spent 30 years working on Semi trailers, supervised 3 shops in two states!

 

[mikegt4]

I used "thread forming screws" like Stimw said. I got mine from McMaster Carr, 1/4"-20 x 2-1/2" (91087a132). They worked great for 2X wood over angle iron cross members.

McMaster-Carr
bottom right of the page

 

[kwswan]

We never drill anything. The screws we do drill, tap, and fasten all in one step.

Chris

How about a link to these screws or brand & part number?