# Tap drill chart



## hopeless (Dec 9, 2011)

Hi fellas I need a bit of help in finding a chart that lists the required drill size for a particular tap. I have the engineers black book but it lists them in metric sizes which is of no use as I have imperial number & letter drills and too broke to buy a new set 
I use mainly BA and imperial bolts when I do modelling work. I have google etc but not found what I need as yet so hoping someone here has some idea that could help me.
Pete


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## rake60 (Dec 9, 2011)

Would _*THIS*_ help?

Rick


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## lampy (Dec 10, 2011)

This is the one I use....http://www.google.com/url?sa=t&rct=...65GNBg&usg=AFQjCNEDZNCsEcHl40ESLcLrzeurgpaQCw


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## Lew Hartswick (Dec 10, 2011)

Not to belabor a point BUT the statement on the chart that Rick posted:

<For Metric sizes only. Diameter of thread minus the pitch equals the tap drill size.
eg. M6 x 1
6 - 1 = 5mm
and you thought metric was difficult ;-) >

is NOT "JUST FOR METRIC" it works for any screw thread. If you can't determine the 
pitch for a thread in "thread per inch" you need to re-take your 4th or 5th grade 
arithmetic.  
 ( for those who failed that course: 1 divided by the tpi = inches per thread or pitch)

  ...Lew...


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## bezalel2000 (Dec 10, 2011)

Hi Pete

BA  tap drill
0   #12
1   #19
2   #26
3   #30
4   #35
5   #40
6   #44
7   #48
8   #51
9   #53
10  #55

Cheers
Bez

Edit: for clearance sizes use the tap drill from 2 sizes bigger e.g. #51 Drill is Tapping size for 8 BA & clearance for 10 BA  ;D


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## Blogwitch (Dec 10, 2011)

Try this chart

John


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## krv3000 (Dec 10, 2011)

HI all just a bit of info int the USA staret was giving thees out free to anyone that applied for one on their web page i applied for one of their UK web page and i was told you had to by them when i told them that their where free in the USA it was not long before i had a new wall chart


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## ShedBoy (Dec 10, 2011)

For those of you in Oz Sutton do a wall chart which you can usually get fro free if you can corner a rep. I harassed one off a bloke as he was trying to leave the local bolt store. Doesn't have BA though.
Brock


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## hopeless (Dec 10, 2011)

Thanks to all those who answered. I now have a heap of sites to help out when I get stuck.
Thanks Bogs just the ticket, much appreciated and to Lew for a trick I didn't know. 
This is a great site and I tend to recomend it to friends and others that are looking for this type of forum. I don't come from an engineering background so I find you guys very helpful and love the tips that I get here :bow:

Pete


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## gunboatbay (Dec 11, 2011)

I made up the attached chart years ago when I first started into hobby machining. It's an all-in-one chart that provides what you wanted, plus a visual metric/imperial cross-reference. If you don't have a set of metric drills for example the chart will show you a very close imperial size. The chart was originally made in MS Excel, but the attachment below is pdf for ease of downloading. It prints out in 8x10 size.  

View attachment Drill chart.pdf


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## hopeless (Dec 11, 2011)

well what a hopeless case I am  I was tidying up some old model engineer books and I find a chart that lists the lot : Now laminated and on the wall. I have severely chastised myself over wasting the forums time.The others are also laminated and can be taken with me when helping out friends etc. Thanks again for all the help.
Pete


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## Hilmar (Dec 11, 2011)

Pet
take a look at this chart it may help You  http://www.gewinde-normen.de/en/index.html
Hilmar


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## arnoldb (Dec 12, 2011)

> <For Metric sizes only. Diameter of thread minus the pitch equals the tap drill size.
> eg. M6 x 1
> 6 - 1 = 5mm
> and you thought metric was difficult ;-) >
> ...



The above is only valid for 60 degree thread forms... (Metric, UNC, UNF)

For others such as Whitworth, ME and BA , some calculation is needed - or look it up on a handy-dandy chart.

Regards, Arnold


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## Chazz (Dec 12, 2011)

A lot of tooling supply catalogues will have tapping\conversion charts at the back, as well, a lot of suppliers will have handy 'pocket size' plastic threading or conversion cards for free, all ya gotta do is ask.

Cheers,
Chazz


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