Rough estimate on number of holes for small drills

T

turnworks

Cast Iron

Joined

Dec 12, 2018

• May 30, 2021

• #1

Currently drilling some smaller holes in 6061 aluminum and trying to determine how many holes before swapping it out. I'm guessing trail and error but figured I'd ask in case there is a good rule of thumb.

#66 drill (.033") HSS bright finish 118 degree point jobber length.

Blind hole .350" deep .030" peck 2.5ipm 2.1k rpms full coolant.

Also using a spot drill.

The parts are around 10 dollars a piece at this stage so just go until one breaks then back off 100 holes?

So far I'm at 810 holes and counting.

 

gbent

Diamond

Joined

Mar 14, 2005

Location

Kansas

• May 30, 2021

• #2

Impossible to answer as chaos theory will govern when the drill breaks. Chances are at that slow surface speed the drill can last about as long as the spindle bearings.

 

G

gustafson

Diamond

Joined

Sep 4, 2002

Location

People's Republic

• May 30, 2021

• #3

That small a drill you want more rpm

Good coolant correct feeds you can get many thousands of holes out of a drill
We get tens of thousands of holes out of HSS ~.12 drills in 6061/6063

 

crossthread

Titanium

Joined

Aug 5, 2004

Location

Richmond,VA,USA

• May 30, 2021

• #4

If it was me I would drill 1000 holes and then feel the edge of the drill. If it still drags on you fingertip then drill another 1000 and so on. As said, there are so many variables involved that I don't think it is possible to predict when your drill is going to crap out.

 

T

turnworks

Cast Iron

Joined

Dec 12, 2018

• May 30, 2021

• #5

Thank you for the replies. I'm rpm limited at the moment. I checked after I went over 1000 holes and heck if I could tell if it was still sharp or not. Too dang small for my fingers so I looked at it under a stereo scope and looked ok to me so I'm just going to keep running it for now.

Thanks again.

 

T

tdmidget

Diamond

Joined

Aug 13, 2005

Location

Tucson AZ

• May 30, 2021

• #6

Drill till it won't then you will know.

 

B

boslab

Titanium

Joined

Jan 6, 2007

Location

wales.uk

• May 30, 2021

• #7

The titex carbide drills were stated at several thousand cycles before bin, they didn’t recommend resharpening without a small drill grinding set up
As you say microscopic set up, they didn’t think it was cost effective even then, can’t argue!
Mark

 

W

Winterfalke

Stainless

Joined

Mar 26, 2011

Location

Huron

• May 31, 2021

• #8

I ran screw length drills whenever possible, in almost exclusively 6061. I don't think I ever changed out a small drill because it wore out, they only broke due to loss of coolant, swarf building up, bad workholding, or flat out losing the drill somewhere. In ti or stainless you could hear a change when it started to go dull, in al they pretty much lasted until you dropped or lost them.

 

C

CalG

Diamond

Joined

Dec 30, 2008

Location

Vt USA

• May 31, 2021

• #9

What is your consideration for chip load?

Might play the productivity game, while watching the micro amps.

Twisting off a $2 drill costs a $10 part, once every ?? thousand holes. What is your shop rate?

 

tnmgcarbide

Diamond

Joined

Jul 6, 2004

Location

N. GA- 33.992N , -83.72W usa

• May 31, 2021

• #10

you will know. your sfm is fractional , and we don't know your feeds and
coolant...

if you get 1000 holes, don't change a thing .!! sometimes the odds are
with us.

i have experienced a large endmill that literally shattered, and hummed
along , once 1/3 of it was history. it should have not worked ..

machining is an artisan ability... not a science

if it ain't broke........

 

Mike1974

Diamond

Joined

Nov 5, 2014

Location

Tampa area

• May 31, 2021

• #11

By your limited RPM, that thing should last *forever* unless you lose coolant, or have an "oh shit" as others said. If you ever get a faster spindle go with a carbide circuit board drill. We use small drills (and smaller) all day everyday. Almost anything under 1/16" is a carbide circuit board drill. We run those small guys close to max 10-12k rpm.

 

EPAIII

Diamond

Joined

Nov 23, 2003

Location

Beaumont, TX, USA

• May 31, 2021

• #12

A high quality, 10X magnifier is a tool that every machinist should have in his pocket 24-7-365.2425. I have carried one in my pocket since my late teens, about 60 years now.

The Hastings triplet is one of the best.

 

T

turnworks

Cast Iron

Joined

Dec 12, 2018

• May 31, 2021

• #13

Just under 1800 holes and it snapped off.

I mainly do welding and fabrication along with cnc lathe work and a few things on the knee mill.

I have had a product I've been wanting to make for awhile now and the parts have a good amount of smaller holes on them. Not sure if they will sell well or not and no other work that I can't get done on the knee mill to justify a VMC. I didn't fancy sitting on a stool at the mill to drill all the holes so I impulsed bought a pair of older teach cnc mills.

I was changing the drills out after ever 400 holes at first without issues then I figured I might as well have some fun and a chance to learn something.

If these take off I'll do it proper but for now they just hum away in the corner while I get other things done.

Thanks again.