1. ## Tool Tip Length

Hello,

Is there a nifty formula or simple constant I can use to calculate the length of a standard twist drill tip? Just thinking about Z depths in canned cycles.

We work in English units (anything Metric gets converted to English).

Thanks

2. ## Drill tip length

I encountered the same problem when I was first introduced to cnc. A really fast rule of thumb that works every time is to multiply the drill diameter (English or metric, doesn't matter) by .3. Here's how it works. 118 degree standard tip angle/2=59 degs. 90-59=31. Tan 31=.6009. .6009/2=.3004 or .3. Drill diameter x .3= tip length. EX.: .250 drill diameter x .3=.075 tip length. Hope this helps.

3. Hey thanks a million. I do remember someone in the shop throwing out something about adding .3, but it was a while back, and I had no idea at the time where that number came from. Thanks for the details.

4. ## Cnc quick formulas

Eliot, I have many more quick tips and formulas for calculating feed rates, spindle speeds, drilling feed rates and milling feeds for most materials. If you are interested, contact me at cedarcreek@comcast.net and I'll be glad to share. I'm now retired, and they are yours for the asking.

• Thanks much for the offer, George. I'm pretty well covered on speeds and feeds, and I found some neat trig for chamfer depths and diameters. I'm sure there are plenty more useful formulas out there; it just hasn't even occurred to me to know what to ask for yet. I've been at this for about 5 months.

I'll hold on to your e-mail though, and you'll probably here from me sooner than later.

Hope you're lovin' the retired life...

Thanks again