RPM for 1/4 NPT in copper?

[Lewislav]

Hi guys ,
I am new to machining copper and also using tapered taps, I was wondering if anyone could help me with the best RPM to run a 1/4 18tpi NPT tap through copper?
I run a Hurco VM10i , all the data I input is metric and I will be rigid tapping.
Also should I peck or go straight for it?

 

[werkzeug]

Hi guys ,
I am new to machining copper and also using tapered taps, I was wondering if anyone could help me with the best RPM to run a 1/4 18tpi NPT tap through copper?
I run a Hurco VM10i , all the data I input is metric and I will be rigid tapping.
Also should I peck or go straight for it?

i suggest a feed of 8 ipm and 144 rpm spindle speed (with coolant of course)

 

[Richard King]

I know you didn't ask about drilling by hand or in a drill press, but for those reading this and have had issues drilling soft material and the drill grabs or pulls in fast. A old timer showed me this years ago. Dull the sharp or cutting edge by grinding the sharp angle straight on each flute on the side of a grinding wheel aprox 1/32" so it mills more then drills.

 

[doug925]

Copper.... What type? (important)
If 99.9% pure, 30 SFM, drill an Ø11.2mm hole (0.4409") use a bright finish tap, made for aluminum and non-ferrous metals, and standard coolant.
Keep your tap clean, and make sure it is sharp. If not dead sharp, pull it!

If 110 copper, you can get away with 50-75 SFM for tapping. Same applies.

BTW, did I mention I dislike gummy, grabby, sticky, material? No? Well 'Cu' sucks!

 

[Larry Dickman]

I would threadmill it. Cutting taps just gall up in copper. If you need to tap it, I would go with an interrupted cut tap

 

[doug925]

Better still!
As Larry pointed, threadmill that sucker!