Drill bit size for portholes

QUOTE: Originally posted by mfsob And speaking of scale ... what is the formula for figuring scale? I'm trying to get some things down to 1/700 size. I know I saw that formula in here somewhere, but now, naturally, can't find it!

Assuming the scale really is 1/700, just convert your desired size into inches and divide by 700.

And speaking of scale ... what is the formula for figuring scale? I'm trying to get some things down to 1/700 size. I know I saw that formula in here somewhere, but now, naturally, can't find it!

You can get drill bits from # 81 to # 97 (.0059) from this supplier

http://www.drilltechnology.com/drill/dt2.html

I have not dealt with them, but the prices are what I have seen before for these sizes - the smaller you go, the more expensive, with # 97 going for # 12.90 each. Hate to break those! Even scratchbuilding a lot, I have yet to see a need for a drill much smaller than .0010.

Kurt

Try Model Expo, that's where I bought mine. They have small sets to large sets, but more importantly, 10 packs of each individual size. Hope this helps

www.modelexpo-online.com

John

I did get a set from MicroMark, one each from 61-80, so I see what you mean about the #80 being really, really small! The smallest in the unlabeled set from the jobby shop appears to be at least a 60, possibly a 58, so now I know why it was way too big to bore out the portholes in my 1/700 model/ Onward through the fog!

Here's a set of micro drill bits... you get 50 bits,


Qty. - Size - Dia. Inch
-----------------------------
5 - 80 - 0.0135
5 - 78 - 0.0160
5 - 75 - 0.0210
5 - 74 - 0.0225
5 - 73 - 0.0240
5 - 71 - 0.0260
5 - 0.75mm - 0.0295
5 - 67 - 0.0320
5 - 65 - 0.0350
5 - 1.15mm - 0.0453

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=34087&item=4376555473&rd=1

He is a reliable seller... have purchased these sets, and they've REALLY come in handy on many modeling areas!

Take care,
Frank

They make them smaller than #80 all right; I've heard stories of high-tech industrial drill bits that can only be seen under major magnification. I remember when I was working at a hobby shop in Columbus, Ohio, a customer came in one day with a #80 bit that he'd turned into a tube. He worked for - as it was called in those days - North American Rockwell Aviation, and had gotten a technician to hollow out that drill bit as a gag. But I question how useful such tools would be for model building - and I suspect I wouldn't be able to afford them.

My suggestion is for any serious modeler to pick up a good set of bits ranging from #60 to #80, stored in an index that identifies them individually. That range will cover just about anything that comes up in ship modeling.

Thanks for all the input. It is a Loose Cannon resin Victory ship, and the smallest drill that came with the set from the hobby shop was too big to deepen the portholes, so I'm guessing it wasn't a #80. But I did do a little looking, and they do apparently make drill bits that are much smaller, all the way into the #90s.

I have the impression that the #80 bit is the smallest commonly available. Years and years ago I did find a set of smaller bits at a jewelry supply company. They had fat shanks; the drilling part was only about 1/8" long. For model building, frankly, they were virtually useless: they were made of high-carbon steel, and snapped under the slightest side pressure. They also, simply because they were so small, got dull quickly - and were, if I remember correctly, quite expensive.

I'm sure modern industry produces bits smaller than #80, but I question how practical they'd be for model building - in terms of handling, breakability, and money.

I wonder if, in fact, the unmarked set mfsob bought actually goes all the way down to #80. A #80 bit is mighty small. In 49 years of model building I can't think of an occasion when I've really needed anything smaller. A #80 bit certainly would be small enough for 1/700 portholes; in fact it might be a little too small for that purpose. A hole drilled in plastic with a #80 bit can, if you're careless, be filled up accidentally with paint.

Unfortunately the drill set I got at the hobby shop did not list the sizes on them, but I need an even smaller one. Where would you get bits smaller than #80?

In 1/700 scale, a 12 inch porthole would be .017, or take a about a # 77 drill.

A 16 inch portohole would be about a number 74.

You can get these sizes at hobby shops or most hardward stores, as they are standard wire guage bits. You might find that a common set of # 61 to # 80 comes in pretty handy, at at $ 20 or so, might be worthwhile.


Cordially,

Kurt

i have the tamiya hand drill..i used the # 80 for my 1/720 graf zeppelin port holes..it came out perfectly..if you have alot of different size bits, than i would try to match it up to your port hole size..like i said, the # 80 was fine for my 1/720 scale ship