Need some advice

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justaccord

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Nov 14, 2007
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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.
 
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justaccord

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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

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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?

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
 

duncsuss

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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

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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

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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
 

justaccord

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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

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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!
 
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