5 ms·

IIRC Phillips was designed to cam out on purpose to avoid over-torquing. I personally disagree with that design decision (inconsistent max torque between users

IIRC Phillips was designed to cam out on purpose to avoid over-torquing. I personally disagree with that design decision (inconsistent max torque between users and tools, cam-out strips screws, etc). Using the "wrong" pairing (pozidric screw + Phillips screwdriver or vice versa) results in easier cam-outs in my experience, without alerting the user that they're using the wrong screwdriver. I personally like Torx and (less so) hex heads.

hug 4y ago
It's a good design decision, and a terrible choice to have used that design where it was used. The design was intended to be used in industrial automation settings where you'd very much rather cam out and possibly destroy a single fastener rather than having it destroy your entire part, or jam your line, or possibly blow up your tool.
- derefr 4y ago
  > industrial automation settings In what context are you doing industrial automation, but have to worry about overtorquing a fastener? Wouldn't you almost always solve this problem by having a pilot-drilling + tapping step and then using machine screws? In what industry do machines drive self-tapping screws into things? (I suppose you could dramatically overtorque a machine screw and end up shearing the head off or something; and that this could have been more of a concern before there was any sort of torque limiting built into drivers. But torque-limiting drivers have been around as long as electric drills/screwdrivers have been.)
  - daniel_reetz 4y ago
    Just because torque limiting drivers are available, does not mean they are used, or used appropriately, or used outside the OEM factory.
DannyBee 4y ago
Only refined phillips (post-1949) was designed this way. Early on, phillips was not designed to cam out, and instead was designed to have better ability to be torqued than slotted. The whole "phillips was designed to cam out" has been retconned :) Wikipedia actually goes into this: https://en.wikipedia.org/wiki/List_of_screw_drives#Phillips https://en.wikipedia.org/wiki/List_of_screw_drives#Phillips The truth is that it was already pretty hard to mass produce a phillips recess (vs a slotted one) back then. Once everything transitioned to being stamped, and stamping was easy, phillips became the worst choice for roughly every application.
- RobertRoberts 4y ago
  I found the original designs that are part of the patent, it was designed to cam out. Edit: I guess the very original patent was edited to _add_ the cam out? I may be wrong on this, but my research showed that the automated screwdrivers on assembly lines did not have good torque controls and therefore were wrecking screws (early 1900s?) and so the cam-out feature was added to help with this problem.
  - DannyBee 4y ago
    What you've found in your research is the common story, but there is not a lot of evidence to back it up, AFAIK. Like if you actually go read the references, there isn't a lot of history from the early 1900's that agrees with the narrative. Also, slotted screws (that they were using) actually cam out before phillips (and aren't self-centering). It's more likely the self-centering part was more useful to the automated screwdrivers back then.
    - RobertRoberts 4y ago
      I am really surprised people are calling this a story or narrative. I found factual statement made by the designers in their own patents that "throw-out" (their phrasing similar to cam-out) is intentional to protect against wrecking screws or tooling with use with clutched automatic screw drivers. Sections 7.35 to 7.55 discuss this here: https://pdfpiw.uspto.gov/.piw?PageNum=7&docid=02474994&IDKey=14D96AF311E8&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D2474994.PN.%2526OS%3DPN%2F2474994%2526RS%3DPN%2F2474994 https://pdfpiw.uspto.gov/.piw?PageNum=7&docid=02474994&IDKey... Edit: As a side note, they point out that _all_ screws have throw-out, and the only way to not is to have "zero vertical angle is used on all engaging driving faces or the friction between the driver and the recess walls is greater than the axial component of the driving torque." (Section 7.15 in the link above) They acknowledge that it's possible, but it's not done in their design intentionally.

hug 4y ago

It's a good design decision, and a terrible choice to have used that design where it was used. The design was intended to be used in industrial automation settings where you'd very much rather cam out and possibly destroy a single fastener rather than having it destroy your entire part, or jam your line, or possibly blow up your tool.

derefr 4y ago
> industrial automation settings In what context are you doing industrial automation, but have to worry about overtorquing a fastener? Wouldn't you almost always solve this problem by having a pilot-drilling + tapping step and then using machine screws? In what industry do machines drive self-tapping screws into things? (I suppose you could dramatically overtorque a machine screw and end up shearing the head off or something; and that this could have been more of a concern before there was any sort of torque limiting built into drivers. But torque-limiting drivers have been around as long as electric drills/screwdrivers have been.)
- daniel_reetz 4y ago
  Just because torque limiting drivers are available, does not mean they are used, or used appropriately, or used outside the OEM factory.

DannyBee 4y ago

Only refined phillips (post-1949) was designed this way. Early on, phillips was not designed to cam out, and instead was designed to have better ability to be torqued than slotted. The whole "phillips was designed to cam out" has been retconned :) Wikipedia actually goes into this: https://en.wikipedia.org/wiki/List_of_screw_drives#Phillips https://en.wikipedia.org/wiki/List_of_screw_drives#Phillips The truth is that it was already pretty hard to mass produce a phillips recess (vs a slotted one) back then. Once everything transitioned to being stamped, and stamping was easy, phillips became the worst choice for roughly every application.

RobertRoberts 4y ago
I found the original designs that are part of the patent, it was designed to cam out. Edit: I guess the very original patent was edited to _add_ the cam out? I may be wrong on this, but my research showed that the automated screwdrivers on assembly lines did not have good torque controls and therefore were wrecking screws (early 1900s?) and so the cam-out feature was added to help with this problem.
- DannyBee 4y ago
  What you've found in your research is the common story, but there is not a lot of evidence to back it up, AFAIK. Like if you actually go read the references, there isn't a lot of history from the early 1900's that agrees with the narrative. Also, slotted screws (that they were using) actually cam out before phillips (and aren't self-centering). It's more likely the self-centering part was more useful to the automated screwdrivers back then.
  - RobertRoberts 4y ago
    I am really surprised people are calling this a story or narrative. I found factual statement made by the designers in their own patents that "throw-out" (their phrasing similar to cam-out) is intentional to protect against wrecking screws or tooling with use with clutched automatic screw drivers. Sections 7.35 to 7.55 discuss this here: https://pdfpiw.uspto.gov/.piw?PageNum=7&docid=02474994&IDKey=14D96AF311E8&HomeUrl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect2%3DPTO1%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%2Fnetahtml%2FPTO%2Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526d%3DPALL%2526S1%3D2474994.PN.%2526OS%3DPN%2F2474994%2526RS%3DPN%2F2474994 https://pdfpiw.uspto.gov/.piw?PageNum=7&docid=02474994&IDKey... Edit: As a side note, they point out that _all_ screws have throw-out, and the only way to not is to have "zero vertical angle is used on all engaging driving faces or the friction between the driver and the recess walls is greater than the axial component of the driving torque." (Section 7.15 in the link above) They acknowledge that it's possible, but it's not done in their design intentionally.