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I think I need to work on my section turning...

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RobR

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Joined
Feb 2, 2022
Posts
111
Location
The wilds of Norfolk
First Name
Robert
20240209_082352.jpg

From left to right.

  1. Ebonite. Really happy with the shape. Thread broke off while drilling hole. Lost thread.
  2. Ebonite. Not such a great shape. Thread broke off while drilling hole.
  3. Ebonite. Didn't even start to shape. You guessed it, thread broke off while drilling hole.
  4. Kirinite. Using threaded sleeve. Hole was off centre for some reason, and I hit the sleeve while shaping. Also melted a bit while I was sanding.

I know exactly where I went wrong with the ebonite ones. Drilled too large a hole too deep. Onwards and upwards.
 
D

DuncSuss

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Mar 27, 2023
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48
Location
Wilmington, MA
First Name
Duncan
Can we talk about this "thread broke off while drilling hole"?

First, which hole? (I'm guessing the one through the threaded tenon where the ink cartridge/converter goes, but you might mean the one through the grip section where the nib unit will go.) What diameter are you drilling out?

What diameter do you make the tenon ready for threading? And what thread specs?

Not that there is only one right sequence for the steps to make a section, but it looks like you're leaving the risky operation till last, when you've done a lot of work and therefore have a lot invested in the part.

I do things in a sequence that (after the blank is a straight-sided cylinder) puts the tenon threading first, then drilling through the tenon, then parting it off the ebonite rod, flipping it around and drilling the steps for the housing and threading for the housing. It gets the risky stuff out of the way before I spend any time shaping and polishing the section, so I don't feel quite so bad when the tenon snaps off. (Notice I say "when" not "if" - I've made a lot of sections and it still happens to me from time to time.)

FYI - typically I make the tenon 8.9mm diameter with a small chamfer on the end, and thread it M9 x 0.75. I do not cut away threads at the base where the tenon meets the body of the section, it is safer to remove the first couple of threads from inside the barrel. Then I fit a threaded collar (helps keep it from exploding) and drill it 0.25" or slightly larger for the ink cartridge/converter.

Hope this helps -

Duncan
 
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RobR

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Feb 2, 2022
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Location
The wilds of Norfolk
First Name
Robert
Hi Duncan,

Thank you so much for taking the time. I was venting as much as anything, but your comments are really helpful. I've answered below.

DuncSuss said:
First, which hole? (I'm guessing the one through the threaded tenon where the ink cartridge/converter goes, but you might mean the one through the grip section where the nib unit will go.) What diameter are you drilling out?
Click to expand...

The one through the grip section. I'm drilling 7mm all the way through (on an M10x1 threaded tenon) from the tenon end which goes just fine. Then I'm drilling 8mm from the other end (I don't have a tap for the nib yet, so I'm push fitting it as an experiment until I get one). This is where I've been going just too far and weakening the tenon.

DuncSuss said:
What diameter do you make the tenon ready for threading? And what thread specs?
Click to expand...
10mm and M10x1

DuncSuss said:
Not that there is only one right sequence for the steps to make a section, but it looks like you're leaving the risky operation till last, when you've done a lot of work and therefore have a lot invested in the part.
Click to expand...
Great point, and one which I realised on attempt 3.

DuncSuss said:
I do things in a sequence that (after the blank is a straight-sided cylinder) puts the tenon threading first, then drilling through the tenon, then parting it off the ebonite rod, flipping it around and drilling the steps for the housing and threading for the housing. It gets the risky stuff out of the way before I spend any time shaping and polishing the section, so I don't feel quite so bad when the tenon snaps off. (Notice I say "when" not "if" - I've made a lot of sections and it still happens to me from time to time.)
Click to expand...
Good to know it's not just me!

DuncSuss said:
FYI - typically I make the tenon 8.9mm diameter with a small chamfer on the end, and thread it M9 x 0.75. I do not cut away threads at the base where the tenon meets the body of the section, it is safer to remove the first couple of threads from inside the barrel. Then I fit a threaded collar (helps keep it from exploding) and drill it 0.25" or slightly larger for the ink cartridge/converter.
Click to expand...
The threaded collar is a great tip and makes lots of sense.

DuncSuss said:
Hope this helps -
Click to expand...
It does, enormously. Thank you again.
 
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