# Help! Can you identify this screw head
**URL:** https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188
**Category:** Factual Questions
**Created:** [August 24, 2019, 10:35pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188 "2019-08-24T22:35:15Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)
#### Post date: [August 24, 2019, 10:35pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/1 "2019-08-24T22:35:15Z")
I’m doing some renovating of a manufactured house and need to remove/back out a lot of these screws…
[ ](https://s3.amazonaws.com/gs-geo-images/977759e2-3781-4df2-8356-1fd4dd0151ae.jpeg)
[ ](https://s3.amazonaws.com/gs-geo-images/a519ef24-d8e2-4a37-962f-bb11973e1142.jpeg)
… and can’t find a screw tip. Tried local HD, etc with no luck. Anyone?
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### Author:  [@california\_jobcase](https://boards.straightdope.com/u/california_jobcase)
#### Post date: [August 24, 2019, 10:40pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/2 "2019-08-24T22:40:25Z")
That’s a clutch head screw. Try a local mobile home parts store or a Harbor Freight (where it’ll be one of a big set of bits). [Clutch Head Screw Bits](https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm)
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### Author:  [@kayT](https://boards.straightdope.com/u/kayT)
#### Post date: [August 24, 2019, 10:42pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/3 "2019-08-24T22:42:51Z")
I love the dope; five minutes to a solution.
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### Author:  [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)
#### Post date: [August 24, 2019, 10:44pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/4 "2019-08-24T22:44:08Z")
> [@california\_jobcase](#):
>
> That’s a clutch head screw. Try a local mobile home parts store or a Harbor Freight (where it’ll be one of a big set of bits). [https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm](https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm)
Brilliant! Thank you.
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### Author:  [@friedo](https://boards.straightdope.com/u/friedo)
#### Post date: [August 24, 2019, 11:06pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/5 "2019-08-24T23:06:28Z")
> [@california\_jobcase](#):
>
> That’s a clutch head screw. Try a local mobile home parts store or a Harbor Freight (where it’ll be one of a big set of bits). [https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm](https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm)
And I thought I was an expert on screw heads. That’s some obscure fastener trivia, there.
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### Author:  [@california\_jobcase](https://boards.straightdope.com/u/california_jobcase)
#### Post date: [August 24, 2019, 11:17pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/6 "2019-08-24T23:17:31Z")
> [@Lucas\_Jackson](#):
>
> Brilliant! Thank you.
You’re welcome. Back in the ‘80s, I lived in a 10’ x 60’ 2 bed trailer for 9 years. It still had the tongue on the front and painted-over tail lights on the back. It was held together with clutch head screws.
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### Author:  [@EinsteinsHund](https://boards.straightdope.com/u/EinsteinsHund)
#### Post date: [August 25, 2019, 12:10am UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/7 "2019-08-25T00:10:11Z")
I guess those screws never made it to Europe, never have seen such a screw head. It also looks not very effective for transmitting torque.
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### Author:  [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)
#### Post date: [August 25, 2019, 4:18am UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/8 "2019-08-25T04:18:04Z")
> [@friedo](#):
>
> And I thought I was an expert on screw heads. That’s some obscure fastener trivia, there.
Yeah, I searched around a bit before asking here.
And they are pretty impervious to hacking. I tried to file down a flathead to get one out with no success. What I don’t understand is why even bother inventing something like that. These things are holding up a furrdown. It’s not like they are securing some important thing.
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### Author:  [@Melbourne](https://boards.straightdope.com/u/Melbourne)
#### Post date: [August 25, 2019, 11:19am UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/9 "2019-08-25T11:19:58Z")
> [@Lucas\_Jackson](#):
>
> Yeah, I searched around a bit before asking here.
>
> And they are pretty impervious to hacking. I tried to file down a flathead to get one out with no success. What I don’t understand is why even bother inventing something like that. These things are holding up a furrdown. It’s not like they are securing some important thing.
I think it was just one of the many invented to avoid the problems of slot and philips: that in production it is difficult to keep the tool ingaged. In the competition of life, this one lost out. It doesn’t look like it’s any worse that square, triangular, hex, or torx: the tool is harder to make than a square, but also harder to damage.
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### Author:  [@enipla](https://boards.straightdope.com/u/enipla)
#### Post date: [August 25, 2019, 1:42pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/10 "2019-08-25T13:42:34Z")
> [@california\_jobcase](#):
>
> That’s a clutch head screw. Try a local mobile home parts store or a Harbor Freight (where it’ll be one of a big set of bits). [https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm](https://www.vintagetrailersupply.com/Clutch-Head-Screw-Bits-p/vts-578.htm)
Yup. We used to own a mobile home park. They used those on mobile homes a lot. Actually a good head. Can’t strip them out.
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### Author:  [@Terry\_Kennedy](https://boards.straightdope.com/u/Terry_Kennedy)
#### Post date: [August 26, 2019, 4:21am UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/11 "2019-08-26T04:21:04Z")
> [@Melbourne](#):
>
> I think it was just one of the many invented to avoid the problems of slot and philips: that in production it is difficult to keep the tool ingaged.
The Philips screw was intentionally designed to “cam out” when fully seated, to allow semi-automated production on assembly lines. They then came up with ACR Philips to try to eliminate this design ‘feature’. The problem with Philips is that maximum torque is applied by the driver to the fastener at exactly the spot where there is the least metal contact.
And then there is the JIS (the screw head looks like a Philips but has a small dimple in one of the quadrants). They have a different angle on the bevel and have been jokingly referred to as “Japanese Incompatible Screw” and are quite common on electronics.
The worst fastener abomination has to be the one found on modern North American wiring devices (light switches, outlets, etc.). It started out being a simple slotted head. Later Philips was superimposed over that (for the electrician who was too lazy to flip the bit in his electrician’s screwdriver?) Some time in the last decade or so, someone had the bright idea to add square drive to that. I joke that they should just machine a nicely tapered cone as it will be faster to manufacture and won’t be any more annoying to customers as the current abomination.
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### Author:  [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)
#### Post date: [August 26, 2019, 8:02am UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/12 "2019-08-26T08:02:36Z")
> [@EinsteinsHund](#):
>
> I guess those screws never made it to Europe, never have seen such a screw head. It also looks not very effective for transmitting torque.
I think that’s the purpose – to avoid over tightening.
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### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [August 26, 2019, 10:06am UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/13 "2019-08-26T10:06:30Z")
> [@EinsteinsHund](#):
>
> I guess those screws never made it to Europe, never have seen such a screw head. It also looks not very effective for transmitting torque.
It’s a fair sight better than Phillips. But then again, so is just about everything else.
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### Author:  [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)
#### Post date: [August 26, 2019, 1:32pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/14 "2019-08-26T13:32:28Z")
Thanks again to CJ, I managed to secure a clutch bit and complete my project. I called a few hardware stores (including Harbor Freight) before I found a local independent that had them. I spoke with them on the phone in the evening and was assured they had them. The next morning I dashed over. When I asked for a clutch head bit. The two employees looked at me like I was from Mars. Told them my story and they explained the guy who worked there last night was off today. After an exhausting search I finally found them. The older employee twirled it in his hands and said, “ I’ve worked here for 9 years and have never heard of or seen them”.
> [@enipla](#):
>
> Actually a good head. Can’t strip them out.
I can tell you from experience that’s not technically true. 😉
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### Author:  [@CurtC](https://boards.straightdope.com/u/CurtC)
#### Post date: [August 26, 2019, 8:11pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/15 "2019-08-26T20:11:39Z")
> [@EinsteinsHund](#):
>
> I guess those screws never made it to Europe, never have seen such a screw head. It also looks not very effective for transmitting torque.
I guess they never made it to Texas either, 'cause I’ve never seen one.
Actually after reading this thread I’m sure Texas has more than its share, since we have more than our share of mobile (trailer) homes.
I thought I knew screw heads pretty well. The ones I know:
Flat
Phillips
Pozidriv
Allen
Robertson
Torx
Then there are those I’ve seen on bathroom stalls, that look like a Torx but have a big “punt” in the middle of the indentation, I presume to keep bored people who happen to have a Torx with them, from taking it apart.
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### Author:  [@jz78817](https://boards.straightdope.com/u/jz78817)
#### Post date: [August 26, 2019, 9:40pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/16 "2019-08-26T21:40:08Z")
Tamper-resistant Torx, yes.
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### Author:  [@Atamasama](https://boards.straightdope.com/u/Atamasama)
#### Post date: [August 26, 2019, 10:37pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/17 "2019-08-26T22:37:58Z")
> [@jz78817](#):
>
> Tamper-resistant Torx, yes.
Also called “Security Torx” (though tamper-resistant is a much better descriptor). I was taught to call the bits for these screws “security bits”.
I think Torx screws are my favorite. Very easy to work with and you can put a lot of torque in them. Much less likely to strip than Phillips and you’re not slipping the screwdriver out of them constantly like a flathead. In a perfect world they’d be the standard head. My WAG is that they’re too expensive to be common (due to patents, manufacturing difficulties, or a combination).
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### Author:  [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)
#### Post date: [August 26, 2019, 10:58pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/18 "2019-08-26T22:58:22Z")
One big problem with Torx: you can engage a Torx head and turn it with a driver that’s one size too small. The small driver then easily strips the head. You can often still get the fastener out with the right-sized driver, but still, this is annoying. It matters more in a production/assembly environment than it does for the home mechanic, of course.
Fastener heads are always a compromise—none is perfect. I like conventional hex heads between 4-10 mm and Torx for anything smaller, but cogent arguments can be made for other driver shapes.
The sociocultural aspects of fastener heads are kind of interesting too. To me, slotted fasteners can seem crude, while cross-head fasteners (including Philips) seem more finished. But a socket-head cap screw (a fastener with a pocket to accept a hex driver) seem a lot more finished still, whether “pure” SHCS or the flat-head (countersunk) variant.
I know others who strongly prefer Philips-head screws because they own screwdrivers but not hex wrenches. This drives me nuts, but I care about this stuff way more than the average person. I’m aware that I’m a freak in this respect.
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### Author:  [@Atamasama](https://boards.straightdope.com/u/Atamasama)
#### Post date: [August 26, 2019, 11:22pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/19 "2019-08-26T23:22:33Z")
> [@EdelweissPirate](#):
>
> One big problem with Torx: you can engage a Torx head and turn it with a driver that’s one size too small. The small driver then easily strips the head. You can often still get the fastener out with the right-sized driver, but still, this is annoying. It matters more in a production/assembly environment than it does for the home mechanic, of course.
Now that you mention it, I think I have done this before with a powered screwdriver. ☹
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### Author:  [@enipla](https://boards.straightdope.com/u/enipla)
#### Post date: [August 26, 2019, 11:58pm UTC](https://boards.straightdope.com/t/help-can-you-identify-this-screw-head/839188/20 "2019-08-26T23:58:25Z")
> [@Lucas\_Jackson](#):
>
> Thanks again to CJ, I managed to secure a clutch bit and complete my project. I called a few hardware stores (including Harbor Freight) before I found a local independent that had them. I spoke with them on the phone in the evening and was assured they had them. The next morning I dashed over. When I asked for a clutch head bit. The two employees looked at me like I was from Mars. Told them my story and they explained the guy who worked there last night was off today. After an exhausting search I finally found them. The older employee twirled it in his hands and said, “ I’ve worked here for 9 years and have never heard of or seen them”.
> I can tell you from experience that’s not technically true. 😉
Huh. That’s a surprise. Back in the day all of the aluminum siding that went on mobile homes where 1/4 drives. Those where good as well. I liked the clutch drive, provided you had the tool to drive them. Now, about, 45 years later, I’ve run out of my supply of both 1/4 drives and clutch drives. Of course the tools to drive them have improved vastly.
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