Micro Trains - February 2025 announcements

[bigdawgks]

Yes, it seems that is technically correct, but in some parts of the world flathead just means the type of slot and driver used.

[peteski]

Yes, it seems that is technically correct, but in some parts of the world flathead just means the type of slot and driver used.

That's ok I guess, but the screws currently included with the couplers are slotted pan head. 

[OldEastRR]

It's confusing because "flat-head" can also refer to a slotted screw/driver, of which the current screws are.

MTL current screws are pan head. They don't make flat heads.

[Lemosteam]

MT 90x Z scale couplers come with 00-90 Flat head screws, but the coupler box has a countersink for it.  1015/6, N scale couplers do not have a countersink and therefore need a pan head screw.

I have countersunk my own 1015/6 with a couple twists of a 1/8" drill bit and used some Phillips head flat head screws in them for clearance to wheelset axles.

Pete's screw head chart above is the industry standard for screw head naming conventions.  Anything else is colloquialism.  And now we all have learned something new, right?

[thomasjmdavis]

Too bad this thread got so jumbled. I was looking forward to my next purchase of MTL couplers coming with flathead screws

As to screws, yes, a flathead is a flathead.  And when we are talking about screws, Peteski's chart is correct.

As to screwdrivers... well, what I've always called a slotted screwdriver, as it turns out.... a US "slotted" screwdriver is indeed an English "flathead" screwdriver.  And, some major US companies use either/or. As I just discovered, when looking for a chart of specific screwdriver types assuming that a "slotted" was a "slotted"-
England:
https://www.redboxtools.com/news/screwdriver-types-uses/

US:
https://www.lowes.com/n/buying-guide/types-of-screwdriver-heads

Still, obviously, a screw and a screwdriver are not the same thing- not all screws driven by a "flathead" (ie  slotted) screwdriver are flathead.  And that appears to have been the original source of confusion.  The vast majority of flathead screws I've used over the past 60 years are phillips (almost universally available), followed by robertson (the standard for my company in the 1980s), torx (what I've used in the 2000s when I could get them) .  I've only rarely used a slotted flathead screw since the early 1970s, because the others are all so much easier to drive. If you want to drive a 3 1/2" slotted screw (flathead or otherwise) through a couple 2x4s, you would need to drill a pilot hole almost bigger than the screw, whereas a 3 1/2" torx will zip right in as long as you have enough horsepower behind it.

[reinhardtjh]

I've only rarely used a slotted flathead screw since the early 1970s, because the others are all so much easier to drive. If you want to drive a 3 1/2" slotted screw (flathead or otherwise) through a couple 2x4s, you would need to drill a pilot hole almost bigger than the screw, whereas a 3 1/2" torx will zip right in as long as you have enough horsepower behind it.

I've often wondered why - especially while trying to keep a "slotted" screw driver in the slotted flathead screw when driving with one hand hold things together - why does any new item ever use anything other than a phillips or allen or torx head?  Anything that keeps the screwdriver centered unlike a slotted one.

[Lemosteam]

It’s because slotted screw (with the correct screwdriver blade in it) can withstand much more torque than other screws with less material at the root of the drive socket due to the recess. Referring to steel of course. With internal drives, the torque load is at a much smaller radius where the drive contacts the screw.

Each design has its flaws, it’s the mousetrap syndrome. A Torx head is the best and can handle the largest load before stripping.
 

[GaryHinshaw]

Since this is now a thread about screws, I'll add a few more thoughts/questions:

1) Is the standard nomenclature "botton" head?  I always thought it was button head.

2) I imagine the main reason single slot screw heads are still around is because they are cheaper to manufacture. 

3) (Sorry, a bit of physics.)  As lemosteam notes, torque is force times distance.  When you want to transmit torque from a screwdriver to a screw, its best to apply the rotational force as far from the rotation axis as possible.  In a slotted screw, the main contact points between the driver and the screw are at the outer edge of the head, so a smaller force can deliver the same torque as a larger force applied closer to the centre.  This puts less stress on the metal.  A Torx head beats a slotted head because it effectively has 6 slots (but they don't reach quite to the edge of the head).  The driver force is transmitted equally in each of the slots, so you get a multiplicative advantage, which outweighs the slightly smaller slot diameter.

4) The same principle applies to the handle of the screwdriver: it is much easier to drive a screw with a fat screwdriver handle than a skinny one because you can get away with applying a smaller force to the fat handle for a given torque.

5) (Slightly back on topic.) These new MTL flats would be good candidates for bolster screws.

[OldEastRR]

Ahh .. it's the ZEE SCALE MTL couplers that have flatheads. That was not noted in the original post I saw about them. So can we use Z screws on N coupler boxes?

[peteski]

Ahh .. it's the ZEE SCALE MTL couplers that have flatheads. That was not noted in the original post I saw about them. So can we use Z screws on N coupler boxes?

Well, flat head screws should be used in countersunk hole. The Z screws are also not a typical flathead you expect. They have very compact heads and they are slightly domed.  It is not like any shown in the screw heads chart I posted earlier.

[Maletrain]

Despite Gary's theoretical analysis, I find that I usually can put more torque on screws with self-centering drive indentations (phillips, torx, etc) than I can with flat heads.  The reason is that it is hard (for me, at least) to prevent the flat blade from tipping up a bit in one side of the slot, and riding over the edge as I try to twist the screw driver.

It does work best with a tightly fitting blade in the slot, which is why they sell "gun smith" flat blade sets that have a variety of blade thicknesses as well as widths, a large variety.  I do have and use a couple of those sets, but they don't come in the "n scale" sizes.  Perhaps watch makers have similar sets in smaller sizes. Whatever, the typical flat blades have flat faces that are not parallel, which hurts in keeping them in the slots.  The "gun smith" variety have flat surfaces that are parallel, and they obviously stick in the slots, better.

[GaryHinshaw]

Hopefully I did not send the wrong message: a torx head can outperform a slot head of comparable size because it has more slots, each of which can deliver torque.  The stability is an additional advantage.

Another style we have here in Canada is a Robertson head, which has a square "slot."  They come in a small number of standard sizes.  I like them because the driver can capture the screw pretty reliably.  Here is a bit of interesting history RE Phillips vs Robertson.

[Dwight in Toronto]

Another style we have here in Canada is a Robertson head, which has a square "slot."  They come in a small number of standard sizes.  I like them because the driver can capture the screw pretty reliably.  Here is a bit of interesting history RE Phillips vs Robertson.

The good ‘ol Robertson is pretty hard to beat, alright!

[Englewood]

I always figured all the different shaped screw heads was a plot by the large multinational tool making conglomerates to make more money by requiring us to buy many different screwdrivers.
Or aliens. Space aliens.  🤔

[basementcalling]

This is a flathead. They are a catfish. Often caught by hand "noddling" for them by reaching into the cracks in the rocks where they live when not feeding.

As for the type of screw, well, you wish you could get that lucky.

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