DRILL SIZES

[Anonymous]

Hi Everyone

I am a british modeller that is learning about model railways the American way. I am a regular reader of Garden Railways and Model Railroader.

I have a done a deal with a friend in return for him painting the front of my bungalow. I will put the hadrails and lighting units in his HO Super Chief coaches from Walthers. In the instructions it talks about a No 80 drill bit. Can anyone please tell me what size in mm or imperial it is. I know it must be small but I do not want to guess a ruin a great coach.

[Anonymous]

I don't know the exact size, but this is a TINY drill bit, a fraction of a millimeter. Most hobby shops carry them...

[Anonymous]

My drill index shows it as .0135".

Bob Boudreau

[chutton01]

Here's a drill chart: http://bobmay.astronomy.net/misc/drillchart.htm

#80 = .3429mm; other common drill sizes requested in US kits are 76 and 72s

80 is very tiny, and likely to break if you stress it too much - usually I have several on hand, plus lubricant like beeswax or soap or such, and take my time drilling. So far, I haven't had a drill break off IN a project piece in over 10 years. (there are several ways to deal with this, none of them easy or good; usually the most efficent is declaring the piece a total loss [:(!] )

[tatans]

AHHH, the English (American now) and the metric system, aren't they great. 80=.3429(watch the decimal point) 80=.0135 inches. the only thing missing would be 80= 27/64 of an inch. Who said there is no need for a standard measuring system.

[Anonymous]

I would like to suggest using watchmakers pivot drills. They are available in Metric sizes and they have a very short flute length about .062" and a .039"D.(1MM) X .500"L. shank. Also you should specify that you want the twist drill type as these work best on plastic.These drills are a little pricey but they do work very well when used in a hand pin vise. All these items are available from a watchmakers supply house. Good luck.

[Anonymous]

You are right tatans. But there is a standard measuring system. It is the metric system and almost everyone in the world uses it except the slow, dull minded americans who insist on using their obsolete measuring system. The ameircans are slowly catching up with the rest of the world but at the rate they are going it will still take a long time.

[tstage]

QUOTE: Originally posted by tatans

AHHH, the English (American now) and the metric system, aren't they great. 80=.3429(watch the decimal point) 80=.0135 inches. the only thing missing would be 80= 27/64 of an inch. Who said there is no need for a standard measuring system.

tatans,

Careful! 0.0135" is actually smaller than a 1/64th, not a 27/64th. (27/64 is equal to 0.422".)


Englishsteam,

I double-checked my machining book and the closest metric equivalent for a #80 drill bit would be 0.35 mm drill bit. (Only about 0.0003 difference between the two.)

You should be able to pick something like that up at a tooling supply store in your area. If you don't want to run around then you can pick up one online somewhere. It's a VERY tiny and fragile bit so be careful. You may also want to consider getting 2 or 3 of them. (1, plus 2 backups.)

Hope that helps...

Tom

[novacoach]

Agree with the 0.35mm conversion. Unless you are really keen I'd go with 0.4mm as I find that the 0.35 is too small for my pinvices and the drills are far less robust. I actually use a .45mm most of the time for freight cargrabs etc but I tend to do resin kits or kit bashes and then paint so with CA gel as the adhesive it makes no difference
0.35 = 80
0.4 = 78
0.45 = 77

Chris
Modelling New England in the old one

[bogp40]

Agree with novacoach,
Many times a kit will call for #80, I find that a#76 or #78 works much better. The bit needed for the coaches is to apply the grabs. A slightly larger hole allows for any minor adjustments and for CA glue. Experiment on some scrap to check wire fit.
Bob K.