# What's the name for a 2mm square hole in a screw head? **URL:** \ **Category:** Factual Questions\ **Created:** [May 27, 2015, 11:11pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999 "2015-05-27T23:11:29Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 27, 2015, 11:11pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/1 "2015-05-27T23:11:29Z")
This stove has a stainless top held on by 2 screws with square holes, about 2mm across. I can’t find the right term to buy a driver for this head. Why the stove company chose this, I have no idea. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 27, 2015, 11:14pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/2 "2015-05-27T23:14:03Z")
[Square drive.](http://www.homedepot.com/p/Unbranded-6-x-1-in-Stainless-Steel-Pan-Head-Square-Drive-Sheet-Metal-Screws-4-Pack-92298/100338713) ---
**Author:** ![Bones\_Daley](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@Bones\_Daley](https://boards.straightdope.com/u/Bones_Daley)\ **Post date:** [May 27, 2015, 11:16pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/3 "2015-05-27T23:16:54Z")
Also google “Robertson screws” … ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [May 27, 2015, 11:18pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/4 "2015-05-27T23:18:41Z")
As I understand it, Robertson screw heads are more of a Canadian thing… probably because they are a sensible design. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 27, 2015, 11:27pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/5 "2015-05-27T23:27:09Z")
I like that Home Depot link, but putting square drive 2mm into Ebay is getting me nowhere. Is there something else I should put in, do you think? ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [May 27, 2015, 11:28pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/6 "2015-05-27T23:28:40Z")
They are/were big in the RV field too. Very good for use with power drivers. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 27, 2015, 11:30pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/7 "2015-05-27T23:30:08Z")
> [@Cardinal](#): > > I like that Home Depot link, but putting square drive 2mm into Ebay is getting me nowhere. Is there something else I should put in, do you think? It’s probably not 2mm. Just put in “square drive bit.” ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 27, 2015, 11:31pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/8 "2015-05-27T23:31:38Z")
Square drive is getting me things everywhere that have the back end with a square hole, not the driver tip. ---
**Author:** ![excavating\_for\_a\_mind](https://avatars.discourse-cdn.com/v4/letter/e/e8c25b/32.png) [@excavating\_for\_a\_mind](https://boards.straightdope.com/u/excavating_for_a_mind)\ **Post date:** [May 27, 2015, 11:32pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/9 "2015-05-27T23:32:45Z")
Try “square bit” in eBay. I got 4,675 listings. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [May 27, 2015, 11:46pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/10 "2015-05-27T23:46:39Z")
> [@md2000](#): > > As I understand it, Robertson screw heads are more of a Canadian thing… probably because they are a sensible design. to be fair, Philips was a sensible design back when it was invented. It’s supposed to cam out of the screw head before enough torque can be applied to break the screw or ruin the threads. nowadays a Robertson/square drive makes more sense since most powered screw drivers have some sort of torque limit setting. but inertia keeps Philips going. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [May 27, 2015, 11:52pm UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/11 "2015-05-27T23:52:12Z")
I knew Robertson was a Canadian thing, but I thought EVERYONE knew the name by now. Best screw head ever. You can torque the shit out of it without stripping it. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 28, 2015, 12:06am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/12 "2015-05-28T00:06:23Z")
Robertson seems to be the clue I needed. Even my engineer dad, who owns almost every tool for the house, didn’t think of that name. The Wikipedia page on screw heads notes that Robertson had big legal problems with his patents outside of Canada, and the design didn’t make much headway in foreign markets. Is there a definitive list of what #2, etc means? The Robertson link here: [List of screw drives - Wikipedia](http://en.wikipedia.org/wiki/List_of_screw_drives#Robertson) seems to try, but skips over a 2mm hole in the screw head. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [May 28, 2015, 12:16am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/13 "2015-05-28T00:16:01Z")
Square drive screws are pretty common. I prefer then for big drywall screws, because they drive way better than Phillips. Most woodworker’s stores (e.g. - Rockler) have a large selection. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [May 28, 2015, 12:26am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/14 "2015-05-28T00:26:34Z")
> [@Cardinal](#): > > Robertson seems to be the clue I needed. Even my engineer dad, who owns almost every tool for the house, didn’t think of that name. The Wikipedia page on screw heads notes that Robertson had big legal problems with his patents outside of Canada, and the design didn’t make much headway in foreign markets. > > Is there a definitive list of what #2, etc means? The Robertson link here: [List of screw drives - Wikipedia](http://en.wikipedia.org/wiki/List_of_screw_drives#Robertson) seems to try, but skips over a 2mm hole in the screw head. Yeah, that’s kinda weird. I guess it’s either a yellow-handled, or a green-handled screwdriver. I just eyeballed my green-handled screwdriver with a measuring tape and think it would work. Both the driver and head are tapered, so there’s some leeway. The yellow-handled driver will definitely fit, but might have too much slack for hard torquing. There’s some overlap in sizes, just like Philips actually. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [May 28, 2015, 12:52am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/15 "2015-05-28T00:52:56Z")
For future reference, should you run across them, the six-point ones are called Torx head screws. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [May 28, 2015, 1:05am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/16 "2015-05-28T01:05:20Z")
Robertson heads come in 4 sizes: 0 (yellow) Found on #4 screws, tiny and not common 1 (green) Found on #6 screws 2 (red) Found on #8 and #10 screws, by far the most common 3 (black) Found on #12 and #14 screws, pretty damn beefy Contrary to what Leaffan suggests, I cannot recommend trying to use the wrong size driver with a Robertson screw. The next larger size will not enter the recess at all, and the next smaller size will do nothing but round out the hole. It’s also important to know that you can easily strip out Robertson screws while using a power driver if you don’t have the driver perfectly aligned. With hand drivers this isn’t an issue as you can feel when the alignment is off. If you like, I can hunt down my calipers and give you the precise dimensions of each size. ---
**Author:** ![FluffyBob](https://avatars.discourse-cdn.com/v4/letter/f/ecb155/32.png) [@FluffyBob](https://boards.straightdope.com/u/FluffyBob)\ **Post date:** [May 28, 2015, 1:19am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/17 "2015-05-28T01:19:15Z")
Yeah sounds like a Robertson #0. Robertsons certainly do strip, and the bits wear out quickly if they skip/strip at all. Using a six inch bit or extension greatly aids maintaining proper alignment. You can find multiple bit sets at Home Depot / Lowes etc. that will give you a selection of Phillips, Robertson, Torx bits and maybe hex bits, nut drivers and a few drill bits. Usually multiple options from multiple brands too. There are also some pretty nice multi bit screw drivers also such as Picquic that have models featuring a Robbie #0. There are always several to choose from on sale. Cheap. Something any one the least bit inclined to ever try to fix anything should have around the house. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [May 28, 2015, 1:28am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/18 "2015-05-28T01:28:33Z")
> [@Gorsnak](#): > > … > Contrary to what Leaffan suggests, I cannot recommend trying to use the wrong size driver with a Robertson screw. … I never suggested using the wrong sized driver at all. In fact I stated that the yellow-handle might not provide the desired results. 😕 ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [May 28, 2015, 1:41am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/19 "2015-05-28T01:41:40Z")
I’m told the micrometer measurement of the interior side to side distance is .083 inches. That’s why I’m a bit confused, using that Wikipedia table. So we’re looking at a #1? The local Lowe’s Hardware only goes down to a 4mm hole size, I’m told. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [May 28, 2015, 2:13am UTC](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999/20 "2015-05-28T02:13:56Z")
> [@Leaffan](#): > > I never suggested using the wrong sized driver at all. In fact I stated that the yellow-handle might not provide the desired results. 😕 Sorry, I took your “overlap in sizes” comment to suggest you could get away with wrong-sized drivers. [Next page](https://boards.straightdope.com/t/whats-the-name-for-a-2mm-square-hole-in-a-screw-head/720999.md?page=2)