[TowerTalk] Tapping or cutting copper

Its from Onion aredandgold at msn.com
Wed Aug 19 04:59:25 PDT 2009

Bacon fat or lard is best. If you use milk then clean everything 
nearby as soon as you have finished, milk splashes stain and rust steel 
very quickly. 

Use a very sharp (or roll-form) tap, and some arrangement to keep the 
tap vertical is almost essential - a drill press or the like will do at 
a pinch. Without some such arrangement it is very difficult to tap 
copper, even a slight misalignment from vertical will cause the tap to 

When (dry-) turning or drilling copper I find high speed helps, but 
that's a bit impractical when tapping. 

As with all tapping, a slightly oversize hole will make life much easier. 

As to taps, carbon taps are plenty sharp and hard-wearing enough, but 
HSS taps are tougher and break less easily - and toughness counts, 
especially if you are hand tapping and aren't using a tapping machine or 
drill stand etc. to keep the tap absolutely vertical. 


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