# drill bit/tap and die chart??



## RAdams

Is there a chart or something that tells a big dummy like me what size drill bit to use for what size tap? and what diameter material for the matching die? thanks for any help!!


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## ldb2000

Here ya go Ron , http://www.victornet.com/reference/Tap_Drill.html . I covers SAE and Metric .


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## Paul in OKC

That looks pretty complete. Should be able to google a chart and find one as well, but why now! (see above =8^)   ). As for material diameter for the die, your thread diameter is what the od should be, maybe a couple of thou under if anything. IE a 3/8-16 thread for example, 5/16 drill for the tap. 3/8 diameter for the die.


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## randyrls

RAdams said:


> Is there a chart or something that tells a big dummy like me what size drill bit to use for what size tap? and what diameter material for the matching die? thanks for any help!!



Hi Ron;  Try this chart.  Includes both Imperial and metric in all standard threads.

Take a gander around this site.  LittleMachineShop has just about everything for the hobbyist metalworker.  Very good information there!
http://www.littlemachineshop.com/Reference/TapDrillSizes.pdf


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## RAdams

Paul in OKC said:


> That looks pretty complete. Should be able to google a chart and find one as well, but why now! (see above =8^) ). As for material diameter for the die, your thread diameter is what the od should be, maybe a couple of thou under if anything. IE a 3/8-16 thread for example, 5/16 drill for the tap. 3/8 diameter for the die.


 



 good grief... I am doing something WAAAY wrong. Itried to use the 3/8 die on a piece of PR that was just barely under 3/8. It wouldnt even think about starting. I chamfered the end and still nothing. I need lots of practice or better tools or something...


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## ldb2000

Ron , PR is a bear to thread without breaking . The softer acrylics like madreperlato from Ed and Dawn at exoticblanks.com are much better because they are not quite as brittle . To thread PR you are better off making a longer tenon and tapering it to help start the die then take very small cuts (1/4 turn or less) then turn the extra length off . Tapping isn't as bad but you should get all your threads cut while the blank is still full diameter then turn to the correct size .


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## skiprat

You don't need a chart ( though it is a nice quick reference )

*Metric*; simply subtract the small number from the big number = drill size

*Standard*; Use the magic number 0.9742

0.9742 divide Pitch = 'x'

Decimal Tap size subtract 'x' = drill size ( in decimal )


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## RAdams

skiprat said:


> You don't need a chart ( though it is a nice quick reference )
> 
> *Metric*; simply subtract the small number from the big number = drill size
> 
> *Standard*; Use the magic number 0.9742
> 
> 0.9742 divide Pitch = 'x'
> 
> Decimal Tap size subtract 'x' = drill size ( in decimal )


 


TOTALLY makes sense!

I could always subdivide the co-radient by the infractional quadrant, and then account for drag and wind resistance. 

I gradieated from the tenf grade boss. I am lucky to be able to read the chart.


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