Nib Taps ?

[southernclay]

A few questions with nibs and taps from my reading.

It appears the Schmidt uses a M6.4 x .5 tap but I've also seen M6.5 x .5 referenced which is also the Jowo #5 tap correct?



So the Jowo #6 is M7.4 x .5 does that mean a M7.5 x .5 would work for it?



And finally the Bock #5 is M6.4 x .6 I assume the M6.5 x .5 won't work for it?


Seems so close....yet so far away? :biggrin: I may be missing something but appear they are all single start as well. I'm not to the point where I want to order any of these but curious for when I may. Thanks for the advice!

 

[edstreet]

7.4 and 7.5 is interchangeable as is 6.5 and 6.4. The only difference is the larger diameter male threads will have a more snug fit, which is not always a bad thing.

 

[southernclay]

Thanks Ed so with these being larger female threads any major concern with loosening over the long haul? I would assume it depends on how much use, heavy handedness and fiddling one does with the pen...

 

[edstreet]

The backstop will fix that.

 

[frank123]

.1mm difference between .4 and .5 is approx .004 inches (actually 0.003937).

Not enough to cause problems for most uses, but the difference of .1mm in pitch (.5 and .6) will limit the amount of thread engagement before it binds significantly and may not be usable (don't have both pitches of taps to try it to find out).

Wouldn't mind finding out about the pitch engagement if anyone has tried it or has the taps to test it.

 

[edstreet]

N X .5 pitch is 50.8 threads per inch
N X .6 pitch is 42.33 threads per inch

That's 8.47 threads per inch different. That's equal to going from a 24 TPI to a 33 TPI. Huge difference in coverage.

 

[mredburn]

I have both taps and you wont get much more than a turn and a half before it binds.
I went with the 6.5 over the 6.4 because it allows a better fit, the feed housings are rarely truly round they can be quite a bit oval. They are injection molded not machined and you can feel them tighten and loosen as you turn them at times as they rub the sides of the walls in your front section.
I also recomend that you run a die over the threads of the feed housing. I have had feed housings that had fins or debri in the threads.
If you use a 6.4 tap and Die you wont have the issues that just tapping the hole can give you. Since most people dont want to spend $60.00 + for the die a 6.5 tap works better.