Keying question

Hi,
I need to make a gear carrier for keying two gears together to make new cluster and I will need to fit the 1/8 inch sq key to the 1/8 inch
x 1/16 inch slot in the carrier. I'm interested to know what is the best way to go about this ? The key has nowhere to go when the gears are fitted so it would seem that a press fit should be enough (no locktite or soldering required) but can anyone tell me how much smaller the slot should be than the key so as to get an appropriate press fit ?
Also, as an aside, can anyone tell me what is special about key steel cf ordinary ms square section ? The stuff I have is quite bright compared to bms but I'm interested to know what its mechanical properties are ?
Thanks,
Mike
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On Fri, 24 Oct 2008 14:30:10 -0700 (PDT), Mike

As no one seems to have responded I chuck in my 2d's worth. As regards fit, if you have as much as 001" interference you won't get the key in the slot. If you have the machine to do it, an end mill or woodruff key cutter is the ideal choice. An end mill can make slots full depth, but blind which keeps the key captive, an woodruff cutter will result in a ramp at one end at least.
Key steel is somewhat harder, a fair bit tougher and somewhat stronger than 'mild' steel. I have seen En6a quoted as key steel, but I can't find that listed in my 1980 copy of BS970. A couple of other sources quote keysteel as variously '0.4% carbon steel' and En8, both of which are broadly consistent with my initial comment.
Richard
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