screw type on30 rail bus.

[dutchbuilder]

I have a lot of screws left over from my box full of dead railbus chassis.
What is the type?
I measure 1.33 mm or 0.052 inch.
I have a metric/Whitworth feeler gauge but because of the size of the screws in can't see what i am doing.
I'm only familiar with metric.
Does anybody know what type of screw i am looking at?

Ton

[James in FL]

A 00-90 screw measures 0.0440 in.
The next size up is a 0-80 which measures 0.0600 in.

Not sure what you have.
What are you measuring with?
Calipers?

[dutchbuilder]

A 00-90 screw measures 0.0440 in.
The next size up is a 0-80 which measures 0.0600 in.

Not sure what you have.
What are you measuring with?
Calipers?

Yep, a digital one.
Millimetres as is usual in Europe and inches.
The inches scale is devided in tenth of an inch and not 1/16 th
I'm asking because i want to buy a thread tap and drill.

Ton

[James in FL]

Well you're between sizes in SAE, and between sizes in metric.
Somewhere between an M 1.6 (1.25mm) and an M 1.8 (1.45mm).
So either you have something not either SAE or Metric, or it may be possible your calipers are out of calibration.
Assuming you are using/reading them properly.

[Len]

You need to get yourself one of these, or something similar:



Len

[dutchbuilder]

Well you're between sizes in SAE, and between sizes in metric.
Somewhere between an M 1.6 (1.25mm) and an M 1.8 (1.45mm).
So either you have something not either SAE or Metric, or it may be possible your calipers are out of calibration.
Assuming you are using/reading them properly.

Sorry James but M x.x is what is means , x.x mm diameter.
The (x.x mm) must be for the drill to make the hole.
That is compensating for two times the thread height.
I'm inclined to think that these tiny screws must be non Metric because of the 0.052 Inch diameter measurement.

I used to earn a living as a machinist, so i think i know my calipers.

Maybe our friends at Bachmann can have a look at it or ask around in China.
There must be production drawings floating around somewhere.
Ton

[Len]

Don't have any railbus chassis to check, but all my other Bachmann locos have metric screws. Checking the sizes on the 'thread cutting' screws, that go in plastic mounting posts, with calipers gets a bit off because of the distance between thread peaks. But they check out using the metric scew size gauge.

Len

[James in FL]

Ton,
Are the screws "thread cutting" as Len suggests aka self-tapping?
Or are they screws that would fit a nut?
Have you anyway to measure or count TPI, or I guess in metric, it would be TPMM?

[dutchbuilder]

Ton,
Are the screws "thread cutting" as Len suggests aka self-tapping?
Or are they screws that would fit a nut?
Have you anyway to measure or count TPI, or I guess in metric, it would be TPMM?

Screws that would fit a nut , yes.
I made a grip to hold the screw so i could measure the thread under magnification (reading glasses strength 3).
I used my thread feelers and had a best fit on thread pitch 0.3.
It's soooooo very small i need a microscope
According to the tables M1.3 doesn't exist.
M1.4 has a thread pitch of 0.3.
so, i think it's M1.4

Ton

[James in FL]

I used my thread feelers and had a best fit on thread pitch 0.3.
It's soooooo very small i need a microscope Grin
According to the tables M1.3 doesn't exist.
M1.4 has a thread pitch of 0.3.
so, i think it's M1.4

That's exactly where I was going with my question.
Trying to get an idea of diameter according to thread pitch.
You beat me to it, and I think your guess is correct.
Glad you figured it out.
And I know what you mean by "so very small" ...
I model N scale, I don't have a microscope, but I do use a 5x loupe.  

I used to earn a living as a machinist,

Me too.

[dutchbuilder]

I tried to use a loupe but i miss the depth.
I don't need reading glasses but for this type of work i use reading strong glasses nr. 3.
Gives good magnification and what is important, depth.

Anyway, thanks for thinking along.

Ton
BTW, I switched to 0n30 in 2006.
I had Grafar N but it doesn't agree with cat hairs.