Tapping C110 Copper

[jeff]

Form taps and threadmilling aren't an option at the moment.

I'll start the tap on the cnc and finish by hand because they are blind holes.

The problem I'm having is when I tap by hand and reach depth,it's very hard to reverse the tap to thread it out.

The copper seems to want to grab the tap.

I've tried coolant,wd-40,way oil,tap magic all with the same results.

Using standard Morse plug taps.

Does anyone have suggestions as to make this go smoother for me?

Thanks.

[smokey_44]

Try using the top end of the tap drill size if your not already (leaves you less thread) but should be a little easier , By the way I have always found that copper will always do this , In my experience when drilling copper you always make 1 flute on the drill a bit longer that way the hole comes out oversize and the material doesn't "GRAB" the drill and break it. I found that if you don't do this you will go though alot of drills .....

 

 

Dave

[Guest]

we use anchor lube for exotic metals and i myself prefer 2 flute taps.i would avoid oil based lubes,but thats just me.

[Hardmill]

Id also stay away from the plug taps, get a spiral flute tap.

And yes take the minor dia. as large as possible.

 

 

PEACE

[Tim Johnson]

When you hand tap, make a 1/2 turn with the tap, backout 1/4 turn and then go a 1/2 turn again. Any tapping fluid or oil will work. I don't know how many parts you're finishing but a tapmatic tapping head for a drill press will save a lot of time and energy. Other than that you have my sympathies.

[jeff]

Thanks for all the suggestions.

Tim, I used your suggestion and it seemed to work out pretty good.

[terry5357]

Jeff,

the reason for Tim's method on 1/2 forward and 1/4 back is to break the chip that you are forming. Use this method for any tough to tap metals. A company i used to work for had a Brother CNC tapping machine and there was a "chip break" tapping cycle that was absolutely killer for copper and anything else like that. you could make as little as a quarter turn and back out. I don't know what would happen if you put a "Q" in a tapping cycle. I don't know if it would just ignore it (which is what most canned cycles do with uneeded information).

 

Just food for thought