# Need some advice



## justaccord (Jul 3, 2015)

Trying to make a barrel to thread onto a Lamy joy calligraphy pen section.  Section measures 3/8 across top of threads.

Used 11/32 drill and 3/8-24 tap with proper holder.  Hand tapped 3-4 times using entire tap.  Section starts to thread well and then seizes.

What am I doing wrong?

Thanks.


----------



## KenV (Jul 3, 2015)

Are you using a lubricant -- like pam

Are you clearing the threads about every 1/4 revolution?


----------



## justaccord (Jul 3, 2015)

Yes, clearing threads.  I didnt have any Pam; used wd40.  Threads look ok but very shallow.


----------



## Penultimate (Jul 4, 2015)

Greetings
I think you drilled the hole too large. Tap drill charts for 75% thread specify a letter Q (0.332) bit. The closest fraction is 21/64. 

Tap Drill Chart


----------



## Penultimate (Jul 4, 2015)

Greetings again
24 TPI is 1.05 metric pitch. I wonder if it is a metric thread.


----------



## justaccord (Jul 4, 2015)

Thanks Mike.  i will try again (obviously brand new at this threading business).

What explains why the section threads on part way then binds? 



Does anyone know what the section-barrel thread size/pitch is for Lamy?


----------



## Ed McDonnell (Jul 4, 2015)

justaccord said:


> Thanks Mike.  i will try again (obviously brand new at this threading business).
> 
> What explains why the section threads on part way then binds?
> 
> ...



If the Lamy section goes part way into the threads you cut and then binds, here are a couple things I would look at as possible problems:

1) maybe you didn't cut the threads deep enough.  Especially if you are using a tapered tap.

2) maybe you got close on the pitch / count, but not close enough. Getting an imperial and metric thread gauge won't cost a lot and can save you a lot of headaches in figuring out what thread you are trying to duplicate.  Eyeballing the threads against a ruler can get you close, but not always close enough.

I don't know what the thread on the Lamy is.  Sorry.

Ed


----------



## farmer (Jul 4, 2015)

*Threading*



justaccord said:


> Yes, clearing threads.  I didnt have any Pam; used wd40.  Threads look ok but very shallow.


 
http://www.amazon.com/Cutting-Fluid...&qid=1436031508&sr=8-4&keywords=tapping+fluid

https://www.youtube.com/watch?v=KVnN4jiB7Gk


----------



## duncsuss (Jul 4, 2015)

justaccord said:


> Used 11/32 drill and 3/8-24 tap with proper holder.  Hand tapped 3-4 times using entire tap.  Section starts to thread well and then seizes.
> 
> What am I doing wrong?



Did you turn down the outside of the barrel before you tapped the hole?

If so, maybe there was enough flex in the material to let it stretch a little as you tapped it. This has happened to me, I found the best approach was either to put the barrel into a collet chuck and tighten it up, or to drill and tap while there was still a lot of material around the hole.


----------



## 79spitfire (Jul 5, 2015)

Lamy is a German company, I am 99% sure the threads are of a metric size, likely something like 9.8X1.0 or so. It is also a multi start, with 2 thread "tracks". I don't have a thread pitch gauge handy to check, it's at work. The joy uses the same size section as the Safari or Al-star.


----------



## justaccord (Jul 6, 2015)

Thanks to all of you.  Very helpful responses.

79spitfire, I checked and indeed it is a double start.  Will a single start tap work with that thread, or do I need a double tap for the inside (barrel) threads as well?

I do not yet have a gauge (one is coming shortly), so if you can measure the thread pitch and let me know I would greatly appreciate it.

Thanks again.  The first thing I want to try is kitkess pens which use manufactred sections and nibs.  I really like the way the lamy stub writes, and want to make a custom barrel for my first kitless pen.  Since the cap snaps onto the section, it will be an easy project once the threadi g is straightened out.


Dave


----------



## 79spitfire (Jul 6, 2015)

You would need a tap that is also double start.


----------



## justaccord (Jul 11, 2015)

*Update*

Just returned from a business trip-- my thread pitch gauge was delivered and best I can measure the thread is 9mm-0.75.  (My thresd gauge (little machine shop) has .75 and 1.0 with nothing in between-- is that accurate enough?)

Anyone know where I can find a double tap in that size?


----------



## 79spitfire (Jul 11, 2015)

9X.75mm is common enough, but double start isn't. If you really want to do a lot of these you might have to have a tap custom made. Tapco does it, but it isn't cheap!


----------

