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I mostly use M2.5 size screws. I got some brand new Torx screws but when I tightened them for the first time, either they stripped or the bit of the screwdriver got twisted. What could be the reasons? I used to use hex head bolts. This is my first time to use torx screws. Among Torx, Hex, Philips and Slotted, how are they ranked among each other in terms of difficulty in getting stripped?

lovedrinking
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    Torx is supposed to be more difficult to strip than even hex, especially at smaller sizes. If the screw driver is twisting but the screw is not stripping, it means the screw driver is crap or you are over torquing. Phillips and slotted aren't even in the running. – DKNguyen Nov 23 '22 at 23:16
  • One or two Torx brand new screws got stripped when I tightened/untightened them from threaded inserts the first time. The screwdriver is from a Husky 22-piece precision ratcheting screwdriver set. Any recommended screwdrivers brand/product? I use M2, M2.5 and M3 screws. – lovedrinking Nov 23 '22 at 23:33
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    Bondhus is the common standard in North America for hex (and probably Torx too). I believe Wera is on the same level. Beyond that are the boutique brands like PB Swiss (especially PB Swiss) or Wiha (or at least they used to be, I've had my suspicions since they changed their product line up but they do have lots of easily available precision screw drivers). The problem with PB Swiss is they are too nice to use. I have the older Wiha System 4 with full length blades but they have changed their product line up so I have my doubts about them now. But they still offer System 4 with bits. – DKNguyen Nov 24 '22 at 00:07
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    what do you mean when you say `they stripped`? ... are you saying that the threads stripped, or that the screw head slot stripped? – jsotola Nov 24 '22 at 00:11
  • Screw head slot stripped. – lovedrinking Nov 24 '22 at 00:16
  • How about LIFEGOO from Amazon? For M2.5 screws, am I supposed to use T7 or T8? – lovedrinking Nov 24 '22 at 00:19
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    please clarify your question – jsotola Nov 24 '22 at 00:25
  • I mean is the LIFEGOO brand of screwdriver any good? The Bondhus ones are either out of stock or sold at inflated prices by 3rd party sellers. Am I correct that I should look for T7 or T8 size screwdrivers as my screw is of size M2.5? – lovedrinking Nov 24 '22 at 00:33
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    If you don't recognize the name it's probably an import which was the problem int he first place. You need to look up a table of drive sizes because the drive size depends on the screw type. An M2.5 set screw has a different drive size than an M2.5 socket cap head screw, etc. Thorp is another good brand used by model helicopters. Oh, it's also possible the problem is that your screws are cheap, not the drivers, or over-torquing. – DKNguyen Nov 24 '22 at 00:38
  • Thank you. The screws I am using are button head torx screws. Will stay away from brands you didn't mention. As for over-torquing... When should I stop tightening? Ideally, I want to tighten the parts as much as I can to merge the parts without stripping the head slot. – lovedrinking Nov 24 '22 at 00:47
  • https://www.tien-i.com/blog_detail/1080-torx-screw-and-star-socket-size-chart Here is a confusion. The table shows that both T7 and T8 can be used for M2.5 screws. Why it is not standarized? – lovedrinking Nov 24 '22 at 01:16
  • @lovedrinking When the allen key starts to flex. If you're using precision screw drivers and not allen keys you normally can't apply enough torque to strip steel hex or torx screws if they are any good but this might not be true with with very tiny screws. – DKNguyen Nov 24 '22 at 02:10
  • @lovedrinking That table is confusing. There is more than one type of screw. There are set screws, socket cap head screws, countersunk screws, and others. Each with a different sized head that will only fit a driver so large. Also note that Torx and Torx Plus exists and they look similar and not necessarily interchangeable. – DKNguyen Nov 24 '22 at 04:02
  • I think thet Philips screw head was designed for high-volume manufacture in a time when powered screwdrivers didn't have good speed control or torque limiters. The clever part of the design was that the bit would cam out of the head at a torque determined by the pressure applied - a skill that would improve with practice on an assembly line. – Transistor Nov 24 '22 at 15:55

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If you stripped a Torx screw you probably didn't have the right driver or bit.

Resistance to stripping? Torx, hex, flat, Philips. Torx allows application of more torque than hex because the hex tool is smaller, and Torx has more points of contact. Robertson square drive is a fine option, primarily used in cabinets and Canada in North America.

"As much as I can" [from your comments] is not a torque spec. Figure out what the torque should be for the fastener you are using. Over-tightening produces a weaker connection. Mechanics have a feel for this, but there are charts to tell you, and torque wrenches to verify.

Tiger Guy
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