Size drill bit for 8X1.25 tap??!?

[SUPERJET-113]

Can anybody tell me what size drill bit i need for a 8X1.25mm tap?
Is it 17/64? or mm?

TIA

 

[blaster800]

Can anybody tell me what size drill bit i need for a 8X1.25mm tap?
Is it 17/64? or mm?

TIA

http://www3.telus.net/public/aschoepp/tapdrill.html it also said 6.80 mm on another chart

 

[SUPERJET-113]

I cant get that link to work.. what does it say?

 

[IceRocket1286]

it should say right on the tap.

 

[blaster800]

I cant get that link to work.. what does it say?

another site said 6.80 mm

 

[blaster800]

http://www.efunda.com/DesignStandards/screws/screwm_coarse.cfm try this link

 

[SUPERJET-113]

Doesnt say on the tap, but i think i found tap drill chart online im checking out now..

http://www.newyorktwistdrill.com/taps_technical_data_02.html

What i dont understand is the:BASED ON APPROX. 60° THREAD or
BASED ON APPROX. 75° THREAD

Guess I'll go with the 6.80mm on your site

Thanks man!

 

[tomski]

17/64 is fine. the 60 or 75 is percent

 

[SUPERJET-113]

Cool, gonna use a 17/64, cause thats what i have.
Tomski, I got the bosses welded onto the pump nozzle for $30 at JD machine. They also cutback my Skat swirl -5mm for $30 also. Not bad prices!

Thanks guys!

 

[SJet]

To figure out the tap size for any metric tap, all you do is subtract the pitch from the size of the tap and that is your drill size.

So for, M8x1.25

1.25mm - 8mm = 6.75mm

So, 6.75mm is the drill size. To convert that to inches, 6.75/25.4= .265

.265 is 17/64ths

Confused yet? :smile: