drilling a tap

[farley]

don't know if that's the right word.

I need to tap an allen screw hole.

It doesn't matter what size, so I figure I would use the same as the SS allen wrench, so I can also use the little allen screws I have.

What size do I drill and tap?

never done this before, but I have a bunch of taps, if that is the thing that makes the threads. I can read the sides of some, 1/4 x 18, etc etc.

TIA

[SDSSmith]

don't know if that's the right word.

I need to tap an allen screw hole.

It doesn't matter what size, so I figure I would use the same as the SS allen wrench, so I can also use the little allen screws I have.

What size do I drill and tap?

never done this before, but I have a bunch of taps, if that is the thing that makes the threads. I can read the sides of some, 1/4 x 18, etc etc.

TIA

That would be a 5/16"-18 tap size and according to this chart would be an F drill.

[JPG]

don't know if that's the right word.

I need to tap an allen screw hole.

It doesn't matter what size, so I figure I would use the same as the SS allen wrench, so I can also use the little allen screws I have.

What size do I drill and tap?

never done this before, but I have a bunch of taps, if that is the thing that makes the threads. I can read the sides of some, 1/4 x 18, etc etc.

TIA

Tis the thread size/pitch that determines proper tap drill size. Drill indexes(boxes) created for the machinist trade and most others as well, gave a body/tap drill guide built in.

You will likely need to use 5/16-18 screws to have a 5/32 hex socket.

IIRC a 1/4" tap drill size is appropriate. If not, I will correct this after verifying. I like robb's chart(what is 0.007 amongst friends?)

If you have not 'tapped' before, keep in mind: start the tap as near as possible in a line parallel to the bore; do not allow the tap to get 'cocked' off that line; feed the tap a partial turn and back it out until it turns freely(that breaks off the burr being created by the tap); DO NOT force(it will require considerable torque to cut the threads, but if you are rotating the handle and the tap is not turning. the tap is twisting and will break if over stressed).

Lubrication helps, and if no 'cutting' oil is available #10 machine oil will be better than 'dry'.

Do be attentive so as to not break off the tap in the hole. Getting the tap shard out is a thread of its own!;)

The 'tactile feedback' from the tap handle is different between cutting and twisting. The quicker you learn to tell the difference, the less likely breakage will occur.

[farley]

HEY
it works, thanks