10-20-2015, 06:06 AM
Over here in the US there's a company who sells a series of "tap extensions", the Walton Tool Company.
http://www.waltontools.com/products/extensn.htm
It's a simple design and often copied for exactly those situations where you need that elusive "in between" length. Many times there's simply no other way to get the job done, so it's nice to be able to make what we need. I've been lucky so far. The only time I needed an odd length I found the one 5/16-18 pulley tap I had was the perfect length. It was to re-tap a hole in an in-situ engine block, a water pump mounting hole. Bolt had broken off and I got it drilled out, probably the first time I ever actually got one drilled on center!
http://www.waltontools.com/products/extensn.htm
It's a simple design and often copied for exactly those situations where you need that elusive "in between" length. Many times there's simply no other way to get the job done, so it's nice to be able to make what we need. I've been lucky so far. The only time I needed an odd length I found the one 5/16-18 pulley tap I had was the perfect length. It was to re-tap a hole in an in-situ engine block, a water pump mounting hole. Bolt had broken off and I got it drilled out, probably the first time I ever actually got one drilled on center!