Kitless El Grande, for starters

[magpens]

Could someone (or more than one) verify my measured thread sizes for the El Grande rollerball/fountain pen kit, please:

Metric threads

Finial end: 10 x .75 single thread
Feed: 10 x 1 single thread
Cap/Body: 12 x 0.8 triple start thread
Cap/Cap: 8 x 0.8 single thread (this is the black cap on the closed end of cap)

I am pretty sure of the thread pitch, but not so sure of the diameter.

I am getting set up to do kitless and thought I would start by copying the El Grande.

The reasons I made this choice are: I already have the Cap/Body tap&die (albeit, in double start thread); the Feed tap&die is readily available at HF and Princess Auto; if I start with a closed-end design that's all I need for starters.

Also, what size holes do I drill, and what size tenons do I cut, please, for the various tap&die requirements ?

Thanks !

 

[Dalecamino]

You subtract the thread pitch from the diameter to get the size you need to drill. (10-.75=9.25)

Here is a chart from Littlemachineshop.com for tap & drill clearance


Tap & Clearance Drill Sizes - LittleMachineShop.com

Have fun!:biggrin:

 

[magpens]

Thank you, Chuck. . Is there a similar rule for calculating the size of the tenon for threading ?

 

[Dalecamino]

Thank you, Chuck. . Is there a similar rule for calculating the size of the tenon for threading ?

I'm afraid I'm no help there. I only use two sizes. It seems I have a chart for that out there. Not sure. Hopefully Redburn or someone can help with the tenon size for you.

 

[skiprat]

The tenon will be the same size as the required thread.......theoretically.
In reality, and with a little experience, you will make it a shade under the thread size. So, a 10mm male thread will need a 10mm tenon. (9.95 to 9.97mm)
This simply stops the die from trying to cut threads with sharp peaks, which invariably chip off while threading. :wink:

 

[Dalecamino]

The tenon will be the same size as the required thread.......theoretically.
In reality, and with a little experience, you will make it a shade under the thread size. So, a 10mm male thread will need a 10mm tenon. (9.95 to 9.97mm)
This simply stops the die from trying to cut threads with sharp peaks, which invariably chip off while threading. :wink:

That's it!!! Yeah, what he just said :biggrin:

 

[magpens]

OK, thanks, guys !!! . I am starting to get the the idea I think .

When I say the cap-to-body thread is 12 x 0.8, it is actually 11.86 outer diameter, so that is quite a bit smaller than the minus 0.5% of nominal (as in Skiprat's example above). So if I were to make the body tenon in this case ~11.90 I'd probably be OK.

As for the cap, drilling to 12 - 0.8 = 11.2mm seems to be the thing to do, per Chuck's example above. . 11.2 mm = 0.441" so close enough to use 7/16" = 0.438".

And for the feed ... 10 x 1 ... I'll drill a hole of 9 mm.

Woohoo ! . I'm off to make my first closed-end kitless ! . Think I'll try an Alumilite blank.

But don't expect to see the results for a few days ... I've got a customer order to finish !

 

[Dalecamino]

Map, may I suggest you practice on a sacrificial piece? Make sure everything is inline before you actually make your pen.