Feed rate and Speedle speed for M4-.7 tap

[chakaloso]

I have to mini mill, and I have to make some metric taps. I am not sure how to get the feed rate and speed for taps in metric.

I know in standard taps just multiply the treads per inch by the feed rate. for example. 4-40 tap. feed rate 5.0 speed 200.

Any help thank you

[Webderland]

25.4

[pit202]

just how you described it , a normal M4 has 0.7mm pitch(?) so :

Feed rate = spindle speed * pitch
eg. 1000RPM * 0.7pitch = 700mm/min

[Webderland]

There are 25.4mm to 1 inch, so it's easy to convert any millimeter size to inches by dividing it by 25.4 or multiplying by 0.0394.

[chakaloso]

Ok

for M4-0.7

I can use feed rate:2.756 in/min and speed: 100 rev./min

[Geof]

Originally Posted by chakaloso Ok for M4-0.7 I can use feed rate:2.756 in/min and speed: 100 rev./min

Do not run the spindle this slow; it will not keep the correct synchronization with the feed.

Run at 1000 rpm and use a feed of 27.559 IPM

You could even run at a higher speed if you want to.

[chakaloso]

Thank you for the info.

I will run the part in a few minutes and let you know.

[chakaloso]

It works

Thank You!

[Jason812]

I don't know how many you you are as anal as me with the decimal places in feed rates but if you use a spindle speed with a multiple of 127rpm then the feed rates for all metric taps will come out to a "nice" number.

Pitch in inches = metric pitch/25.4

tpi for M4 x .7 = .7/25.4 == .0275590551 * 127 rpm = 3.5 ipm

multiply by 8 == 1016 rpm and 28.0 ipm

I've made a calculator in Excel to make this quick and easy.

Hope somebody can use this,

Jason

[Geof]

Originally Posted by Jason812 .....if you use a spindle speed with a multiple of 127rpm then the feed rates for all metric taps will come out to a "nice" number.....

But then you get a 'nasty' spindle speed .

It is a neat calculation, however, that harkens back to the manual change gear days with the 127 tooth gear for cutting metric on an imperial lathe.