Robertson Square Drive

NW Modeling List nw-modeling-list at
Mon Nov 1 17:57:58 EDT 2010

I brought this topic up for discussion at a building session this weekend and no one working on the layout could remember stripping or breaking any square drives when building the benchwork. Considering this is a pretty large layout that's a pretty good result.

I can attest to the fact that Lowes and Home Depot, at least in my area, didn't have much of a selection of square drives, that's how we ended up at McFeely's. And Gary thanks for reminding me of Fastenal, there is one no more than 3 miles from here that I always forget about.

Since I use TORX on a daily basis at work I've grown to despise them, now Triple Square Drive or XZN they're awesome, but that's another story.
Doug Langlitz

-----Original Message-----
From: NW Modeling List <nw-modeling-list at>
To: 'NW Modeling List' <nw-modeling-list at>
Sent: Mon, Nov 1, 2010 12:19 pm
Subject: Robertson Square Drive

Actually, boys, the drywalls screws are the weakest of the screwtypes in general use. They are made specifically for the attachment ofdrywall to wood studs or the thin C-section metal studs used in partitionwalls. They also are specified to have a BUGLE head which really only hasthe volume to hold a Phillips-type socket. The bugle head is made to‘sink’ into the paper and gypsum without tearing the paper. The screws have the minimum of corrosion resistance in the black or grayphosphate coating and they have the lowest strength possible by using a verylow alloy steel and a very thin case hardness.

The Robertson drives are usually used in screws that requirehigher strength or more drive torque- the square drive does not cam-out likethe Phillips drives do. McFeely’s sells to mainly woodconstruction, but there is a whole family of square drive screws used for cold-formedsteel construction in load bearing connections- See Grabber or Buildex for someof these screws. There are some other drive sockets used that are similarto TORX type sockets in these screws.

In general, the wood screws with 82 or 90 degree countersink headswill require predrilled and countersunk pilot holes. (Use a combination drilland c’sink.) Bugle heads in lower density woods like white pinewill mostly sink in flush, but will not in yellow pine or fir especially ifthey have dried out for a while; the wood will be too hard.

If you cannot find square drive tips at Lowe’s or HomeDepot ( not untypical) go to the ‘professional’ stores especiallythose aimed at the commercial construction market as commercial constructiondoesn’t use wood that much, but does use a lot more cold-formed steel andsquare drive screws. Look for Fastenal, Grabber, White Cap orHILTI. Also these guys will have long drive bits used in tools usingcollated screws ( screws in long plastic strips for feeding automatically) togain access into cramped quarters.

Gary Rolih
A screw guy in Cincinnati

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