HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
(OP)
The ICC-ES report Link for the HILTI Kwik-Flex 1/4-20 fastener states that the maximum self-drill capacity is 0.5" thick.
I have an application where it has been specified that a aluminum handrail post (with patch plate), be attached to the 3/8" thick web of a mild steel channel and wanted to check how readily such a web thickness can be self-drilled with these fasteners.
I have never directly used these fastener types before and thought they were only used for cold formed steel but I guess they get specified for bi-metal applications too.
I have an application where it has been specified that a aluminum handrail post (with patch plate), be attached to the 3/8" thick web of a mild steel channel and wanted to check how readily such a web thickness can be self-drilled with these fasteners.
I have never directly used these fastener types before and thought they were only used for cold formed steel but I guess they get specified for bi-metal applications too.






RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
I've just had occasion to add some steel angle reinforcements (#14 gage) to the bottom of the frame, using 1/4-14 self-drilling screws that I got from Home Depot.
You know how the point of a new twist drill bit is sharp enough to draw blood?
Self-drilling screws are not that sharp.
Using my Craftsman Nextec 1/4" impact tool (wonderful tool), it took a couple of minutes to drive each screw through ~3/16" of steel. If I had to do more, I'd probably drill pilot holes. The impact tool had zero trouble driving the threaded portion of the screws in, but actually drilling the metal required that I push _really_ hard on the back of the tool to cause the screw's drill point to make chips.
If you expect someone else to put a self-drilling screw into 3/8" of steel, you really need to go drive a few for yourself, to understand what you are asking.
Have you settled on a thickness for the aluminum baseplate? I'm not seeing how you get full strength of the screw if the plate is more than 1/8" thick, and a plate that thin won't survive the high school cheerleaders, much less the football team.
Mike Halloran
Pembroke Pines, FL, USA
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
BA
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
Thanks for your input.
The preprinted alum patch plate that is prewelded to the vertical handrail post is at least 1/4" thick.
I have drilled TEKS into 1/4" steel without any problems, but it did take a bit of pushing, as you indicated.
I too thought it would take about a minute per fastener, but according to a data sheet I found via Google that compares comparable fasteners Drill-Flex (same as Hilti Kwik-Flex) to TEKS they state the time is seconds.
We are going to get the contractor purchase a few of the fasteners and trial drill a few to check production. The original design (by others) calls for SS through bolts and the contractor wishes to substitute for the self-drill fasteners.
BAretired:
According to the tech sheet, these fasteners are designed for dissimilar metal use, and specifically alum and steel.
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
It was not too bad. Took about 30 to 45 seconds per screw IIRC.
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
To get a drilling time of seconds, you would need a power-feed drill press, or a very burly craftsman bearing his or her full weight on a big portable drill.
In my case, I was pushing up against the trailer frame, with my elbow bearing on the driveway beneath, so chip clearance was not a problem, but drilling force was limited by my wrist.
Separately, I witnessed the techs at the trailer dealer using somewhat larger (~5/16") self-drilling screws to install a 'load equalizing' hitch. (Trailer dealers must love self-drilling screws.) For every one of those screws, it took a minute or more to drill the hole, and seconds to tap the hole and seat the screw, using a hand-held impact tool, through ~1/4" of mild steel in the trailer tongue.
Maybe the TEKS or Hilti screws have sharper points than the ones I have used, or the ones the trailer dealers used, so I am curious to see the results of your contractor's test.
Mike Halloran
Pembroke Pines, FL, USA
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
It appears that the major manufacturers of these fastener types all state drill times that seem exceptionally optimistic. Stated values of 6 seconds to SELF DRILL a 1/4-20 in 3/8" thick steel seems awfully quick!
We are going to get the contractor do a few field trials and report back to us there findings.
Thank you for your help.
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
B.E.
You are judged not by what you know, but by what you can do.
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
Mike Halloran
Pembroke Pines, FL, USA
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material
I imagine the screws from home depot are no match for the quality of screws designed for commercial work.
I have used the wood to metal screws from Home Depot to attach 2x4's to a 1/4" tube steel column. They definitely did not cut like the Buildex Tek5's
RE: HILTI Kwik-Flex 1/4-20 fastener through 3/8" thick material