Which die and tap do I need?

[Parson]

My local pen store owner gave me a section/nib/feed from a pen he broke a long time ago. No cap or barrel. He's asked me to tackle making a barrel and a cap for it.

I used my digital calipers on the threads and they're 9.41mm or so. My 10mm die seems to smoothly roll over it, so I think the .75mm size part is correct.

How does one match existing thread size and pitch (or whatever it's called) on a project like this when you're not starting from scratch?

 

[mredburn]

I doubt there is a simple way. I carry 9.4 x .5 but that wont help you if its .75 pitch.
3/8 x 34 would probably work but I doubt you will find one. I think I bought a 3/8 x 36 set from Victor Machinery at one time.
Cutting the threads on a metal Lathe would be easiest if you have access to one or someone who has one.

I just checked and Victor has 3/8 x 32 and 3/8 x 36 taps listed.
.75 pitch is close to 34tpi (33.8) On that short of thread you may be able to get away with one of them

 

[frank123]

It probably isn't some standard off the shelf size so measure the thread exactly, including the form of the thread which may not be a standard v form, and make a tap for it on a metal lathe.

Any idea what brand it is? You may be able to look it up if you know.

 

[Parson]

How does one determine the pitch?

Buy a cheap pitch gauge off amazon.com?

 

[duncsuss]

How does one determine the pitch?

There are tools that look a bit like feeler gauges, instead of being different thicknesses each blade has a saw-tooth edge at a different pitch.

You try each one in turn until you find a match.

If you don't have one of these, a quick test is to take a tap that you think is the same pitch and set it alongside the piece you're trying to match. If the peaks and valleys line up along the entire length of the screwthread your testing, the tap you chose is the same pitch.

 

[mredburn]

Usually with a metric or std inch thread gauge. You can also see if you can match them with a known thread pitch on another part. You could thread a tenon with a die with .75 threads and fit them up together. If its the same they will mesh together easily if not the points of one thread will not fit inbetween the points of the other.

 

[KenV]

Metric measures the distance between peaks (or valleys) for a single thread. Better accuracy is to measure across several and divide to get an average with each end counting as half a thread.

Imperial is number of threads to an inch.

If you happen to have access to a thread gage all the better.

 

[Parson]

OK guys, found out more about this section and nib combo.

It's a Cross Peerless nib/feed/section. I accidentally transposed the width of the threads. It's 9.14mm.

Now does anyone have any idea where I can find a 9.14mm tap? I thought of buying a 9mm tap to see if it will fit it but I'm waiting for my thread gauge to arrive before ordering one to make sure I get that part right.

Thoughts? Suggestions?

I'd really like to make this work because the guy said this is just about the best writing nib he's come across in a long time and he can buy the nib/feed/front sections at wholesale and would like to partner with me on making up a few of them for sale in his store... which has massive sales of Visconti, MontBlanc, David Oscarson, and other high end pen manufacturers.

 

[thewishman]

I hope you can figure it out. It might be worth paying a friend with a metal lathe to make a custom tap and die. That way, you would be set up to go to town on them.

Start a Want post once you find out what the threads are. I'll bet there are a few skilled guys that could make the pieces you need.

 

[Parson]

Quick update... Sent the feed off to a custom tap/die manufacturing company in Illinois for measuring. Price for a custom tap? $130 for one unit!

 

[duncsuss]

Quick update... Sent the feed off to a custom tap/die manufacturing company in Illinois for measuring. Price for a custom tap? $130 for one unit!

That's cheaper than I was quoted for a custom tap two years ago -- back then it was $152 for one.

The price per unit drops rapidly the more you buy -- at quantity 3 pieces they were down to $80.52 each, and by 12 pieces only $34.90 each.

Of course, this doesn't help you since you only want/need a single unit -- but it shows the extent that machine set-up time is a major component of the price.
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[thewishman]

You probably should have them make at least two, in case sales go well, or you drop one.

Congrats on going for it!

 

[ZbR]

What about re-threading? I did it with 6.5 mm Jowo thread: went down to 6 mm and used M6X.5 (the same pitch, it is important) die which is cheap and easily obtainable. I only had to make holder for the feeder (actually a tube) to mount it on a lathe. It worked fine.

 

[Parson]

OK! Got my custom tap and it fits great.

Where can I source a 1.5 inch die holder for the tail stock? An hour on IAP searching hasn't turned up much...

 

[Curly]

http://www.victornet.com/detail/DIE-015.html

The above will work but you'll need to buy a bit more to make the minimum order amount. Need another tap? Put the appropriate transfer punch in a tail stock chuck and slide the die over it. You will be easily able to turn the die holder to cut a thread on any of the plastics we play with. I haven't tried any metals though.

 

[eharri446]

If the company is TapCo, We might be able to add the tap and die to a Group Buy and get a significant discount for multiple people ordering the tap and die set.

 

[mredburn]

Two year old thread, they have a group buy poll going on right now.