Threads for Jowo and Bock Nibs

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keithy

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I am working on my designs for a series of kitless pens. The body and cap are working well but the sections are driving me crazy.

For both Jowo and Bock nibs the threads on the nib fit the threads cut by the taps when I drill and tap holes in scrap material but the same size holes in the section will not grip the nib at all.

I'm working in ebonite and M3 and don't want to waste too much material.

I even set everything up in my metal lathe with collet holders for the section and used end mills to size the tapping holes but no improvement.

Do I need to use reamers to get the size right or will I have to make test sections in decreasing drill sizes to find the working drill

Any advise appreciated

Keith
 
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I would:
-Re-run the taps a few times.
-Re-run the taps with the body connected

Some materials I will actually use a slightly wider bit. Also, if the material get a bit hot during drilling, it will shrink by the time you tap it and make the fit too tight.

Not sure if any of this helps, but its my 2cents
 
keithy said:
... the same size holes in the section will not grip the nib at all.
Click to expand...
So, are you saying that the nib housing goes all the way into the section and just spins?

If so, this would suggest that either you are drilling to large a hole resulting in shallow threads or that the threads are stripped. What size drill bit are you using before you tap the threads?
 
Last edited:
d_bondi said:
So, are you saying that the nib housing goes all the way into the section and just spins?

If so, this would suggest that either you are drilling to large a hole resulting in shallow threads or that the threads are stripped. What size drill bit are you using before you tap the threads?
Click to expand...
I am drilling 6.9mm for the 7.4mm x 0.5 jowo tap. what puzzles me is that this size drilled in a flat off cut is a perfect fit
 
keithy said:
I am drilling 6.9mm for the 7.4mm x 0.5 jowo tap. what puzzles me is that this size drilled in a flat off cut is a perfect fit
Click to expand...

Sorry, still need clarification, when you say "...will not grip the nib at all" are you saying it is too loose and spins or it is too tight and won't start into the threads you tapped?
 
When you get a perfect fit in scrap - are you drilling on the lathe or some other way (such as using a drill press)?

If it's a perfect fit using a drill press but too loose when you drill on the lathe - I'd say your problem is the drill bit is not perfectly aligned on axis.

That could be because the drill bit isn't properly centered in the Jacobs chuck, or the Jacobs chuck is not properly centered in the Morse Taper, or the tailstock is out of alignment. All of these things could result in a drilled hole that is larger than the drill bit.
 
duncsuss said:
When you get a perfect fit in scrap - are you drilling on the lathe or some other way (such as using a drill press)?

If it's a perfect fit using a drill press but too loose when you drill on the lathe - I'd say your problem is the drill bit is not perfectly aligned on axis.

That could be because the drill bit isn't properly centered in the Jacobs chuck, or the Jacobs chuck is not properly centered in the Morse Taper, or the tailstock is out of alignment. All of these things could result in a drilled hole that is larger than the drill bit.
Click to expand...
This is possible. I drill the scrap on my mill and the section on the metal lathe with the Jacobs chuck in the tailstock. I'll test with the drill in a collet rather than in the chuck and check the runout
 
Are you using me 7.5 or m7.4 for the Jowo #6? DId you check the center alignment of your lathe? If it's off, the hole will be too big and the threads won't fit.
 
@keithy it could also be compression. I have found that if I really tighten my collet chuck, on softer materials, it will compress the material. When I drill the hole out, especially if the drill I'd run multiple times, the hole is the right size until I release the chuck and the material expands back to normal. This, in conjunction with other tolerances, can easily leave you with a to large hole. Remember, you are talking about a thread that is only .25mm deep.
 
keithy said:
I am working on my designs for a series of kitless pens. The body and cap are working well but the sections are driving me crazy.

For both Jowo and Bock nibs the threads on the nib fit the threads cut by the taps when I drill and tap holes in scrap material but the same size holes in the section will not grip the nib at all.

I'm working in ebonite and M3 and don't want to waste too much material.

I even set everything up in my metal lathe with collet holders for the section and used end mills to size the tapping holes but no improvement.

Do I need to use reamers to get the size right or will I have to make test sections in decreasing drill sizes to find the working drill

Any advise appreciated

Keith
Click to expand...
 
duncsuss said:
When you get a perfect fit in scrap - are you drilling on the lathe or some other way (such as using a drill press)?

If it's a perfect fit using a drill press but too loose when you drill on the lathe - I'd say your problem is the drill bit is not perfectly aligned on axis.

That could be because the drill bit isn't properly centered in the Jacobs chuck, or the Jacobs chuck is not properly centered in the Morse Taper, or the tailstock is out of alignment. All of these things could result in a drilled hole that is larger than the drill bit.
Click to expand...
Hi,
I am new at kitless pens, but using Bock now. My complaint is thev Bock nib units are bigger at the nib end. If I drill a hole and tap the threads, the nib unit won't fit and I have to drill another very slightly larger hole so the nib unit will fit flush with the section. I'm thinking of getting a slightly larger tap and die that will fit the bottom of the flare up from the tenon where the threads are now.

Am I not seeing an easy solution to this issue? I ordered a few Jowo nibs to see if they have the same size difference from threads to nib end. There might be a reason for the threads to be on a smaller tenon, (its 7.9 x 0.8 I think). Maybe I'm using the wrong size bit. I'm using either a 6mm or 7mm for the threads. I'm not home and so new I'm not sure of the size.

Quick rant. Why are there four methods of sizing bits? I get metric and imperial, maybe one tweener method, but why numbers and letters?

Anyway, do you have any ideas on what I am doing incorrectly or why tapping the nib unit on the thicker section is not a good idea?
 
The hole for either Bock or JoWo nib units needs to be stepped. The smallest step that runs the deepest is the tap drill. The next is the clearance for the shank of the housing which should be a close fit and the last is the clearance for the rim to sink it into the section. If you don't want to futz with multiple drills, get a step drill from Rick Herrell (he's a user here, search for him) and do it in one shot.

As for why there are multiple standards for twist drills, most of that is simply legacy. While there are close metric equivalents for gauge sizes, they've never taken hold in some countries, particularly America. We also haven't fully embraced the metric system even though we use straight conversions for most measurements. There's a reason an inch is 25.4mm exactly and it's not a coincidence.
 
HugeElvis said:
Anyway, do you have any ideas on what I am doing incorrectly or why tapping the nib unit on the thicker section is not a good idea?
Click to expand...

If you want to see the recommended dimensions to drill out a section to receive a Bock #6 nib unit (or any other, for that matter) the vendor who sold them to you should be able to provide technical drawings that give you the exact diameter and depths.

Or do as Oliver suggested - contact Rick Herrell and get a step drill which saves the hassle of changing bits and measuring the depth to drill with each bit. It will not only make it easier to get the steps correct, but all the steps will be perfectly concentric and on-axis (which can be a challenge using a normal Jacobs drill chuck.)
 
Oliver X said:
The hole for either Bock or JoWo nib units needs to be stepped. The smallest step that runs the deepest is the tap drill. The next is the clearance for the shank of the housing which should be a close fit and the last is the clearance for the rim to sink it into the section. If you don't want to futz with multiple drills, get a step drill from Rick Herrell (he's a user here, search for him) and do it in one shot.

As for why there are multiple standards for twist drills, most of that is simply legacy. While there are close metric equivalents for gauge sizes, they've never taken hold in some countries, particularly America. We also haven't fully embraced the metric system even though we use straight conversions for most measurements. There's a reason an inch is 25.4mm exactly and it's not a coincidence.
Click to expand...
It takes me 4 different bits to drill out for my Jowo #6

Drilling
  1. Center drill
  2. Drill - 7mm (for #6 Jowo) works fine for me for the threads.
  3. Drill N (7.67mm) to 12.7mm (ref full Dia)
  4. Drill R (8.61mm) to 3.0mm (ref full Dia)
  5. Drill 9mm (.354") to 0.5mm (ref full Dia)
 
darrin1200 said:
It takes me 4 different bits to drill out for my Jowo #6
Click to expand...

You're absolutely correct. I fitted my first just last week so I should have remembered that extra step. To be completely honest, I'm not especially prolific, and I use many different kinds of nibs and housings, so I pretty much just bore everything to fit and single point the threads.
 
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