custom tap

[chucketn]

I am making a custom 1/4" x 40tpi tap for a friend. He had the change gears for his lathe disappear during a move.
I have the threads cut, and a 5 deg taper on the end. I'm getting ready to mill flutes and the square end for the tap wrench. Can I cut the flutes with a regular 1/8 end mill? I don't have a ball end that small. How deep should they be? He'll be cutting threads in cast iron. I have to also make a matching screw, so I will be taping a piece of hex steel stock for a test nut.
I have printed out an article on making custom taps with just a filed obelisk (think Washington Monument) shape for the tapered start and no flutes, but I think flutes would be better.

Chuck

[PixMan]

Why wouldn't you just buy one? They are available for as little as $1.62 (plus shipping.)

http://www.amazon.com/s/?ie=UTF8&keyword...fhq0r3rg_e

[chucketn]

Well, first cause the guy that needs the tap couldn't afford the prices I found on Amazon. I didn't see the $1.62 price, I saw $15 and up...
Second, I've already made and tested the tap. And I didn't have to spend any money other than the electric to run the lathe, already had some 1/4" drill rod...
Why buy when we can make it? Took me all of 2 hours to make, including heat treat! Noe I know I can make just about any tapI need!

Chuck

[f350ca]

Thats the whole point of having machinery, to make things, its a hobby so time shouldn't enter into it.
But curious, if you were tapping the hole and making the bolt why not a standard thread?

[PixMan]

I can't make a tap because I'm way too picky about thread geometry, clearance angles, cutting angles, chip flow geometry, and thread tolerances.

[Mayhem]

picky?

Some would say anal retentive but lets go with picky

Of course, I would never say such a thing - I simply posted in the interest of social commentary!

[PixMan]

Now Darren, to suggest I am anal retentive would mean I'm FOS. I am most definitely FOS, but not about most machining oriented stuff.

I am, however, overly critical of things that really don't matter a bit in a home shop. On that list are time (spending too much of it on simple tasks a primary irritant), not using the right tool for a job, and not using the tool correctly for a job.

Could I make a 1/4"-40 UNS tap? Perhaps. I'd be so concerned it wasn't the correct thread form, that it wouldn't curl a chip correctly, might make an out-of-tolerance thread, could bind in a hole, and so on that I just couldn't make one and accept that "It should work fine for this job."

I guess you're right after all. I'm anal retentive.

[EdK]

I've been thinking about this whole "that's good enough" and would like to bring my skill level up a notch to the point of being able to machine something to a known spec rather than to match one piece to another piece. This is purely a hobby for me so I can afford the time necessary to take the time to do that. Pride in workmanship rather than that's good enough. Sorry for the ramblings.

Ed

[chucketn]

If you build something from a drawing, do you change specs to what ever you want, or do you make the part to plan? My friend is making an engine to the designers plan. That's why a 1/4-40.
I'll be the first to admit I'm still at the "that's good enough" stage. I'm getting better, and my setups and tooling is improving. I made the tap as close to spec as I could get. I made a nut with it to use as a gage for the screw thread I need to make. The screw will mate with the tapped hole made by the tap I made... Whooh, I'm getting dizzy...

Chuck

[Highpower]

(05-29-2014, 07:57 PM)EdK Wrote: This is purely a hobby for me so I can afford the time necessary to take the time to do that.

Ed

I can afford the time as well. My problem (one of many, I know) is I can't afford to buy all of the precision tools that go along with verifying the work that's been done meets those high "standards" in the end.