Self taping screws into 3/16" steel

[thejon2524]

Im looking to fasten my 5/4 mahogany decking material to my truck bed this weekend. I want to use self taping screws and countersink them so they are nice and flush. However, I am affraid that if i do not pre drill them all they will just snap on me. They would be going into 1x2x3/16" c channel. Has anyone here had any experience using these screws on heavier steel is what I'm looking to find out? Any other ideas would be greatly appredciated.

 

[feralghoul]

I put super teks into 3/16-1/4 steel all day long at my work. http://garagedoorhardware.com/c6332-1000.html

Most will go right in, sometimes they get a but clogged up and you will have to turn them back, but if you dont want them to break on you after doing that just use a new screw as the tips can be prone to break off, and when they do they stick in the material so you have to start a new hole. To be safe i would pre-drill anyways, its not that much extra work to do it right.

 

[brianvantol]

I would highly recomend pre drilling them. The screws will snap and then they are a real pain to get back out. When I did my trailer I used carriage bolts which turned out nice. If you don't like the rounded tops get plow bolts from a TSC or farm store.

 

[OccupantRJ]

I drilled and tapped mine with a spiral pointed tap in a hand drill, then used stainless steel countersunk head bolts. Buff heads before installation for that chrome look.

 

[MP&C]

There are screws specifically made for semi-trailer decking that would screw right in, but may take some searching to find the shorter size for 5/4 boards....

http://abctrailerparts.com/Floor-Screws.html

 

[Ron Lombardo]

I bought them at FASTENAL 5/16"-18 x 2" 6-Lobe Flat Head Floorboard Thread Cutting Screw, Type F, Black Phosphate and Oil ... to fasten 11/4 white oak on my rack body ... i had to predrill them all prior ... but it worked great and I needed 36 volt Hilti to sink them ....

Ron

 

[vhol5]

There are screws specifically made for semi-trailer decking that would screw right in, but may take some searching to find the shorter size for 5/4 boards....

http://abctrailerparts.com/Floor-Screws.html

X2 on the screws. If you still want to use the self tappers, I have had good luck driving them in with a cordless impact driver. Very little breakage in thicker metals.

 

[klhitman]

all good advise above. we use self tapping screws all day long at work and when we do heavy gauge stuff some people like to pre-drill and some will run the screw a bit and throw it away and get a new one to finish the hole. if they break one they just starts a new hole. it gets covered up anyways.

but i would say pre-drill, it might take you longer but it will be better in the long run. no sense in fighting with a broken screw!

 

[rickb801]

I have put a lot of these in, I have found that predrilling the wood works best for me.

 

[mathil]

I've put in so many TEK fasteners that I think I've developed a "feel" for when they're about to twist apart. If I really don't want to dig a fastener out after it's broken I'll use one to do the drilling and part of the thread cutting and then switch to a new one to finish it off. Seems to drop my breakage percent. Pre-drilling to the size of the tip works as well, but you still get the same amount of stress when thread cutting. Frankly, once it gets to 3/16 you'll probably save time drilling with a proper drill bit than you would trying to do it with the tip of the fastener.

 

[Charles (in GA)]

The issue here is whether you are talking about thread cutting MACHINE thread screws like Ron Lombardo mentioned, which are generally not self drilling, or a self drilling, self threading "sheet metal" type screw.

You are doing a nice job, go all the way and finish the job properly. I'd drill and countersink every hole and use the self threading machine screws.

Charles