Screw thread spec for Bachmann 4-4-0 bottom plate?

[Maletrain]

A club member has an old Bachmann 4-4-0 with the screw that holds the bottom plate under the drivers missing.  So the bottom plate drops into the track and the loco spins its wheels without moving.

Does anybody know the spec for the threads on that screw?  The version has "Bachmann" and "China" molded on the bottom plate, and is the "American" type.

http://spookshow.net/loco/bach440a.html

[Lemosteam]

Bachmann Parts store for $3.11 + shipping:

https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=70_79&products_id=5334

[Maletrain]

Yes, we had found the Bachmann screw set, but its $3 for the set and $9 for the shipping, plus there is the statement in Spookshow's review that some of the screws were changed between the versions.

That is why I was hoping somebody knows the actual thread specs for that screw in that version.  I may very well have a suitable replacement in a drawer.

I may just bring the member's loco home with me and carefully see what fits.

Calling Bachmann parts didn't help, because they have no dimensional info on their stock.

[Lemosteam]

@Maletrain I can look at my old white box model.  I have a metric thread gage. and I can measure the length.  I'll get back to you.

[Ed Kapuscinski]

I'd bet it's an M2 or M3. The big question would be length, but you might be able to figure that out with some creative measuring.

[kiwi_al]

Diameter 1.62mm
length 7 mm
So you need a M1.6 or an imperial equivalent.

Actually, you probably could just use an M2

[Maletrain]

That diameter seems like an M1.6 screw.  I would not want to try to force an M2 into an M1.6 threaded hole, because, besides the shaft diameter difference, the threads have different pitches (0.35 vs 0.40 mm).

I can measure the depth of the hole without much trouble.  I have M1.6 x 3mm screw, so I could check fit of the threads with that. 

But, another possibility for that diameter is a 0-80 Imperial screw, which has a slightly finer thread pitch (~0.32 mm).  I have more lengths of those, so I'll see what fits best.

[Maletrain]

@kiwi_al , I am assuming that the screw you measured looks like the one in Lemosteam's picture that is just a silver panhead machine screw that is sitting among several brass-looking machine screws with squared edge truss type heads?  And that the 7 mm length does not include the head?

[kiwi_al]

It's the silver panhead and you are correct, the 7mm length is the shaft only not including the head

Edit: see pictures:

[peteski]

Yes, it is a plain Phillips pan head screw with 7mm long threaded part. Just like the  one in the Bachmann screw assortment photo or in kiwi_al's photo.