# My First Steel Screw



## ProfessorGuy (Aug 3, 2015)

I was having trouble making a steel screw.  Cutting such small diameter steel (less than 1 mm), it would bend out of the way of the tool.  I had to come up with a way to cut the threads while holding the tiny screw in place.  So I used a tiny center drill to put a divot in the end of the screw, then put a live center on the tailstock:




Of course I didn't need a live center since I thread by hand, with the motor detached from the lathe, so speed is not an issue.  But the center has to be held in the tailstock and I thread with a tool holder on the carriage, so the tailstock has to reach out over it.  The dead center wasn't long enough to reach.  The live center just barely does:




Once I had a screw shape, the threads come next.  You can see how small the shaft is when compared to the 1/4 inch HSS cutting tool.  These threads are at a 0.45 mm pitch.
The threading worked easily because I ground the HSS tool without it getting hotter than say 250 degrees even on my cheapie grinder (how to do that is a neat trick).  So I didn't lose the hardening that HSS has.  And, to cheat further, this is 12L14 LEADED steel.  Cuts like a dream.  I use a 4x jeweler's loupe while cutting.




The final screw is supposed to be less than 4 mm in length.  So why is this screw so long?  This screw is its own tap!

To tap the plate, I filed self-tapping slots into the end of the finished screw and did not cut it from the rod stock.  I held the 'tap' in the mill head with an untightened collet.  The collet holds it perfectly perpendicular to the brass plate and I could turn the entire rod by grasping the rod with pliers.




Believe it or not, this worked.  I was able to almost completely tap the brass hole with decent looking threads that of course perfectly matched the screw.  But just before I completed the entire hole depth, I got lazy and thought, "I bet I could put an entire half turn in at a time!"

No, I couldn't.




It snapped off, then I destroyed it thoroughly by using vice grips to turn the broken tap out.

The threads in the hole looked great and I was able to tap about 7/8 of the way through.  I could have easily finished it if I hadn't gotten impatient.

So close.  Next time for sure!


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## 4GSR (Aug 3, 2015)

That's way too small for me to see!!!! And for me to make!!!!

Kool job!!!


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## brino (Aug 3, 2015)

Jeez I HATE that sound and feeling of the breaking tap.....especially just when you think you're home-free.....

I guess the positive side is that you had some success and learned a lot.

Do you feed the vertical spindle at all, or just rely on the tap to feed itself and the loose collet to let it?

I really appreciate you posting this! 

Thanks
-brino


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## Tony Wells (Aug 3, 2015)

If you turn a 60° point on the RH end, you can use the center hole on a small tap while holding it in a drill chuck. Much more room than a center. It's just the reverse of convention, but it works, nonetheless. After threading, touch it on a grinder to take off the point and no one will think you used any sort of center at all.


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