More buffalo horn

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jalbert

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May 17, 2015
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586
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Louisville, KY
In continuing my playing with natural materials, as well as improving my method for making silver parts, specifically tricky ones like caps, here is another buffalo horn/silver pen. This time I used a cream/black pattern blank, with black acrylic for the threaded parts. The cap is improved, as the clip is removable rather than soldered on, and has a screw-on finial to hold the entire cap together without adhesive. The cap was cast from wax sheet, which I wrapped around an aluminum mandrel I made, which essentially mirrored the curvature I wanted the cap to have. This helped me keep the weight and waste to a minimum. The cap has an acrylic liner in it, in which the cap threads are cut into. The barrel is built around an acrylic liner. The threads are 12.5x3mm triple start.
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jalbert

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Joined
May 17, 2015
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Location
Louisville, KY
Always enjoy looking at you pens. 12.5? You threading on a lathe or did you get a special tap and die set made?

Pete
Thanks! Threads are single-point cut. I recently switched over to metric threads, as that’s technically what my lathe is set up for leadscrew-wise, so it’s much easier to do a triple start at 3mm pitch because I just have to move the compound 1mm for each lead. Much better than the guesstimating I was doing with my prior imperial threads.
 

BigShed

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Joined
Feb 14, 2008
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1,067
Location
Adelaide, SA, Australia.
First of all, great looking pen and very nice work.

When you say 12.5x3mm triple start thread, doesn't that really equate to 12.5x1mm thread? Only asking as the threads in the photos don't look anything like a 3mm pitch. My wood lathe spindle is M30x3.5mm and my metal lathe spindle is M39x4mm and both look way coarser than the threads in the photos.

I have, among others, a M12x0.8mm tap and die set and the threads look a bit finer than yours but not that much.

Edit:

Just asked Dr Google and found this explanation for multiple start threads and it appears that the pitch of the finished thread, as opposed to the lead, is the measurement between each thread in the completed thread.

 
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jalbert

Member
Joined
May 17, 2015
Messages
586
Location
Louisville, KY
First of all, great looking pen and very nice work.

When you say 12.5x3mm triple start thread, doesn't that really equate to 12.5x1mm thread? Only asking as the threads in the photos don't look anything like a 3mm pitch. My wood lathe spindle is M30x3.5mm and my metal lathe spindle is M39x4mm and both look way coarser than the threads in the photos.

I have, among others, a M12x0.8mm tap and die set and the threads look a bit finer than yours but not that much.

Edit:

Just asked Dr Google and found this explanation for multiple start threads and it appears that the pitch of the finished thread, as opposed to the lead, is the measurement between each thread in the completed thread.

Dunno what the correct nomenclature is. I set the lathe gears to a 3mm pitch, so that’s what I refer to. Regardless of how many leads there are, the pitch still remains a constant.
 
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