Endmills for dealing with broken taps where to buy.

[cmccull166]

I had a rush D-2 part and used my stock of 1/8 ,4 flute throw away endmills to
remove a broken 1/4-28 tap...

I found some 1/8 4 flute coated made in the US for 4.00 ea..
But
Started thinking I need some 2mm made in the US for smaller taps..
As I don't think I have the spindle speed for thread milling smaller sizes.
Anyone have a source?

 

[eKretz]

I always suggest using a carbide spade instead of an endmill. They are easy to regrind even by hand if they get damaged and are much more durable than an endmill.

 

[cmccull166]

Interesting...I will put some in stock.
What speed would you use for small diameters.
Thanks

 

[eKretz]

Interesting...I will put some in stock.
What speed would you use for small diameters.
Thanks

I generally try to stick to around 100ish SFM when cutting HSS with uncoated carbide. Sometimes that's possible, sometimes not. Also keep a good air blast going so that any chunks of tap that come loose get blown out of the hole immediately. Those are what do most of the damage to the cutting tool when they get caught and wedged, chipping or breaking the tool as well as damaging the part.

 

[MrWhoopee]

I recently had to remove a broken 10-32 tap. Snag ground a "spade drill" from a broken 1/4" carbide end mill shank. It wasn't pretty and required several trips to the grinder, but it got the job done.