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

 

[MachineTom]

With a 40 tpi you might get away without any relief in the threads, but i'm doubtful.

 

[MachineTom]

If you end up with negative. Rake as well, could be much work for naught.

 

[chucketn]

Well, as responses were slow, I went ahead and completed the tap. I used a 1/8" end mill to mill 2 each 90 deg. flutes. I hardened the tap with a maps gas torch and a dunk in old motor oil. I made a nut out of 1/2" hex steel and it cut fine! I'm so tickled! I messed up the nicely made screw body, so my buddy is making another.

Chuck

 

[mcostello]

Nothing like the smell of success!

 

[barnesrickw]

Been trying to make one for a while. Ended up buying a 1/4 - 40 tap.


Sent from my iPad using Model Engines

 

[chucketn]

Well, though the tap was a sucess, all my effort was for naught. I got my hands on the plans my friend is using (long story) and the screw is actually 3/8 x 40. So, it looks like I get to extend my tap making experience! Unless he made the part the screw goes into to the same scale... He's away for the weekend so I can't ask...

Chuck

 

[OrangeAlpine]

Chuck - time to fess up. You needed the practice anyway.

I made a 1/2-20 left hand tap in High School. As that was over 50 years ago, I think I should shut up and sit down.

Bill

 

[chucketn]

No problem, Bill. Cost me a pleasant afternoon or two in the shop, works as to function. What else would we ask?
The satisfaction and confidence boost I got from it was well worth it!
I recently bought a box of 5 NOS 1/2 x 13 LH taps for a project on Evil-Bay, for a project. I paid less than $2 each, so I saved a bit, but , now I know I could have made them!

Chuck

 

[gus]

Been trying to make one for a while. Ended up buying a 1/4 - 40 tap.


Sent from my iPad using Model Engines

he d

Same with me. Tried making my own counterbore and it just won't bore.:wall:
End up modifying a DIY flycutter and it did the counterbore with good finishing. CounterBore hole for the 10mm CM6 Spark Plug.

It was so easy in the ''Taig'' forum.:rant:

 

[gus]

Chuck - time to fess up. You needed the practice anyway.

I made a 1/2-20 left hand tap in High School. As that was over 50 years ago, I think I should shut up and sit down.

Bill

Hi Bill,

Practice makes Perfection. Failure is the mother of success.

I have two mini IC engines that just won't start and run. Will try again.

Just been informed two stroke aeromodel engines have very unforgiving fits and the inlet and exhaust port holes height must be precised and marked with digital height gauge and cut to these measurements.

Fortunately my luck with my limited tooling and limited skill been good with Webster and Rupnow 4 stroke engines. Will redo ''Firefly'' 2 stroke engine and ''Bolero''.

 

[chucketn]

I made a counterbore for the heads of M6 SHCS by grinfing a drill bit to a square end like a mill cutter. Makes a nice flat bottom hole if I drill to desired depth with the next smaller drill before the flat ended drill. The flat end drill takes the < at the bottom of the larger hole.
Chuck