Tapping in copper

M

M2I

Plastic

Joined

May 16, 2011

Location

FRESNO, CA

• Aug 25, 2011

• #1

I was having trouble with 4-40 cut taps breaking in copper i am a size up #42 to try and help but when it gets to the bottom it breaks, any advice would be helpful sfm is 30. I am running it in a hass vf2 with coolant

 

Porschefix

Hot Rolled

Joined

Dec 3, 2009

Location

Bluff Dale

• Aug 25, 2011

• #2

Im no expert with CNC apps but this sounds like a perfect application for a forming tap. Drill with #39 for a 70% thread. http://www.kar.ca/pdf/catalog/H4.pdf
When tapping copper I have found it useful to use just oil and with a small tap, to peck it so as not to built too big a chip in front of the cutting surface to break on retract. I am sure the experts will reply with the right solution, lets see what they say/

 

I

IronReb

Stainless

Joined

May 26, 2011

Location

Shreveport/Louisiana USA

• Aug 25, 2011

• #3

You are sure you have a good hold on the tap so that it isn't slipping?If the tap slips just even a little bit it is enough to lose the lead on the thread.

The right tapping fluid can make a world of difference also.Was years ago,but if memory serves we used a flavor of Tap Magic.

Also,COPPER FREAKING BLOWS to machine,I hate that gummy crap.
Went to work in a tool and die shop that machined a lot of copper,my first project with it was some sort of copper welding electrode.I went at it with an end mill like I would have in aluminum....part flew out the vise with chunks of my end mill across the shop

 

KIMFAB

Stainless

Joined

Jun 21, 2008

Location

Logandale,Nv

• Aug 25, 2011

• #4

I use a good form tap with a tapmatic and keep it cold. (3/8" bus bar)
I run a spray mist on it and peck all the way out about every 2 diameters.
Use a slightly larger hole if possible.

This takes longer but is easier on taps.

 

kwmachine

Aluminum

Joined

Apr 29, 2011

Location

Duvall, WA, USA

• Aug 25, 2011

• #5

+1 on use the form tap. We use those or thread mill in copper.

Mark

 

rklopp

Diamond

Joined

Feb 27, 2001

Location

Redwood City, CA USA

• Aug 25, 2011

• #6

If customer will allow it, go with a form tap. It's the only way to fly in copper. You might have to up coolant concentration or hit each hole with some strai

 

J

jmcvo

Cast Iron

Joined

Jul 25, 2007

Location

Willamette Valley, Oregon, USA

• Aug 25, 2011

• #7

Welcome to PM.

We machined a lot of copper for EDM electrodes (for KRUX EDM's) where I served my Moldmaking apprenticeship. Plain ol' cutting oil worked best for milling, drilling, tapping, and turning and when forced to surface grind copper on the dry grinders we sprayed it with silicone. The worst part of making intricate copper electrodes was definitely deburring them.

-jmcvo

 

J

Jmorgan

Plastic

Joined

Aug 12, 2011

Location

Liberty Hill, Texas

• Aug 25, 2011

• #8

Schaeffer's 412 Tap Sheild will eliminate the binding and stop breaking your tools. Works on copper without staining.

 

M

M2I

Plastic

Joined

May 16, 2011

Location

FRESNO, CA

• Aug 26, 2011

• #9

thanks guys i will try form taps next time. i ended up tapping it in the tap matic out of the machine manually with oil and it worked. you guys are right though copper is NOT fun material to work with

 

M

metalboy

Aluminum

Joined

Oct 15, 2010

Location

Houston, USA

• Aug 26, 2011

• #10

There's nothing more evil than turning three-nines copper... you get to the last finishing / cleanup pass and BOOM it just wraps itself up into a ball of junk with no warning.

 

I

ian3846

Aluminum

Joined

Apr 6, 2009

Location

Australia, Gladstone

• Aug 26, 2011

• #11

I use to work with a lot of cooper mainly 110 grade. I found a tin coated aluminum tap worked best. But always used a floating tapping head even with rigged tapping cycles. But beware as soon as the tap shows any sings of wear change it. If i remeber right i use to get 300 or so holes per tap.

I also drilled .2mm over size and still had a good thread.

 

M

M2I

Plastic

Joined

May 16, 2011

Location

FRESNO, CA

• Aug 29, 2011

• #12

thanks ian did you also use a form tap like everyone else is suggesting?

 

J

Jpm7871

Plastic

Joined

Feb 16, 2020

• Jun 3, 2020

• #13

M2I said:

I was having trouble with 4-40 cut taps breaking in copper i am a size up #42 to try and help but when it gets to the bottom it breaks, any advice would be helpful sfm is 30. I am running it in a hass vf2 with coolant

Click to expand...

we tap in copper a lot
for 4-40 we use a YG1 4-40 ROLL FORM #THR02163 Coolant flood and works great

 

B

Bluechipx

Hot Rolled

Joined

Dec 29, 2008

Location

W. Mich

• Jun 3, 2020

• #14

I made some small 1/4" dia x 3/4" long pins out of an Inconel based alloy ( a superalloy aircraft blade material actually ) that needed a 4-40 thread in one end. The pins were tested in a solution that simulated body fluids and a electrical charge was used to speed up the process. I started out with standard tap drill, no go, I gradually went bigger on the tap drill with the customers permission until I was able to tap the material. If I recall a 4-40 tap measures .114" and a tap drill is .089", I kept going bigger with the tap drill until I could thread it---at .113"! .0005" per side thread. Looking at a part you couldn't tell if it was threaded or not unless you tried a 4-40 bolt in the hole. I have no idea why this is relevant here, maybe cabin fever.