Tool to pull the "C" ring out of the filling knob on Modern MB149/146

[fountainbel]

 

Hi all,

As you surely heard - or experienced yourself - the “C" ring which holds the lead spindle in the filling knob is extremely difficult to remove.

I've designed and made an alternative approach to get the C ring out, using  a tool which uses the screw effect of the broken piston lead screw in the tool's integrated piston rod.

Below the drawing of a tool that allows to pull the "C” Ring and the broken/short lead screw out of the filling knob

There is however a limitation : one needs a minimal  remaining thread length of 8mm inside the filling button..

As far as I’ve experienced  a remaining threaded  length of 8mm or longer is luckily rather common

So this would allow the pull approximately 90% of the “C” rings..

Note the tool will not work when the remaining thread length is shorter as 8mm !

The tool consists of 2 parts :

1- The" screw-in knob 1" with screws deeply in the filling knob and axially backs-up against the front of the MB filling knob.

I’ve cut a filling knob to use the maximum penetration depth available for the screw in knob 

The end of the inner bore fits just around the back diameter of the MB piston rod, avoiding the rod would expand/crack when applying torque

Note the top of the  MB  piston rod axially backs-up against the end collar inside the screw-in knob bore

2-The  "actuating knob 2” is permanently  glued with epoxy on the shortened MB piston rod 

The Montblanc piston rod threads will engage with the remaining end of the threaded rod.

On the first picture you can see a threaded rod with a remaining thread length of 8mm, before I've installed it back into a perfect filling knob and secured it with the "C "ring.

On the second picture I still have to  slide the actuating knob fully into the screw-in knob, finally screw it over the broken lead spindle 

By turning the knob  slightly further in clockwise direction, the "C" clip will easily jump-out of its seat groove.

This is shown on the third picture

I tested the tool several times on different MB146/149 filling knobs with the short 8mm thread ,and the short lead screw always came out together with the “C” ring

As always your questions / thoughts are most welcome.

Sincerely,

Francis

 

 

 

 

[Dione]

Excellent fountainbel.  However, this assumes you have a broken thread. Once upon a time I was trying to flush out my 146 and the piston spindle came completely out with the C ring on there. I rather crudely pushed it back in and uses a very thin screwdriver to push the C ring as far down as I could see. It's worked ever since so it must have just been loose somehow.

[fountainbel]

1 hour ago, Dione said:

Excellent fountainbel.  However, this assumes you have a broken thread. Once upon a time I was trying to flush out my 146 and the piston spindle came completely out with the C ring on there. I rather crudely pushed it back in and uses a very thin screwdriver to push the C ring as far down as I could see. It's worked ever since so it must have just been loose somehow.

Hi Dione

The tool works logically also to pull an intact rod and "C"ring.

But mostly one wants to remove "C" ring when the spindle is broken and one needs to install a replacement !

Francis

 

[siamackz]

Genius, as always! 

[fountainbel]

On 9/19/2021 at 4:44 AM, siamackz said:

Genius, as always! 

Thanks my friend !

However not genius, simply applying farmers logic !

[PENRob]

Yes it's a good idea, it seem like "controlled forcing", you just have think about it !

Indeed as Dione says, the C-rings aren not extremely gripped, so it creates opportunity to disassemble this way...

The different types of existing C-hooks make serious some damage and scrathes also, so you cannot say this is not a good way

Definately when you only have a short end of spindle left !

Thans Francis for sharing, I 'll make one...

[fountainbel]

15 hours ago, PENRob said:

Yes it's a good idea, it seem like "controlled forcing", you just have think about it !

Indeed as Dione says, the C-rings aren not extremely gripped, so it creates opportunity to disassemble this way...

The different types of existing C-hooks make serious some damage and scrathes also, so you cannot say this is not a good way

Definately when you only have a short end of spindle left !

Thans Francis for sharing, I 'll make one...

Thanks Rob, look forward reading on your  experiences using the tool!

Initially I was afraid the contacting radial anchor notches in the filling knob or the one on the spindle would shear off when applying the extraction torque.

Intensive tests assured me however the torque to extract the  "C" Ring out is not as high as I've had expected. No damage to either of the anchor notches occurred !

Francis

[Ron Z]

Getting these the C ring out is THE problem with replacing the spindles on Montblancs.  You can't simply flick it out with a hook because anything that is thin enough to reach in is thin enough to bend.  I like the design - a piece to reinforce the cap and keep the puller from pressing directly against the cap, and that applies the force to the already broken spindle.

 

When can  I get mine?

[Dione]

9 minutes ago, Ron Z said:

Getting these the C ring out is THE problem with replacing the spindles on Montblancs.  You can't simply flick it out with a hook because anything that is thin enough to reach in is thin enough to bend.  I like the design - a piece to reinforce the cap and keep the puller from pressing directly against the cap, and that applies the force to the already broken spindle.

 

When can  I get mine?

I believe there is a line already.....

[fountainbel]

6 hours ago, Ron Z said:

Getting these the C ring out is THE problem with replacing the spindles on Montblancs.  You can't simply flick it out with a hook because anything that is thin enough to reach in is thin enough to bend.  I like the design - a piece to reinforce the cap and keep the puller from pressing directly against the cap, and that applies the force to the already broken spindle.

 

When can  I get mine?

Thanks for your comments & interest in my new tool Ron !

I'll let you - and other interested members - know how things evolve.

Best,

Francis 

[Ron Z]

You've saved a lot of pens, and made a pen mechanics life a heck of a lot easier with the tools you've come up with.   They might be "small", but they allow us to make repairs for people all over the world...

[eckiethump]

Fountaibels engineering mindset is unsurpassed in pen repair tools and design, as is his generosity in sharing his designs with full detail . Yes Francis, I'll also be in the market for this tool when you make it available, PEEK, who I discovered through you is a wonderful material.

Eric

[hari317]

Francis, I will buy one set too if you can make it available. Thanks!

[fountainbel]

Thanks for your kind reactions Ron & Eckiethump, much appreciated.

Hari, I'll keep you posted!

Francis

[gyasko]

I’d love to have one of these tools too

[fountainbel]

Hi all,

And the story of the extractor tool continuous...

I've had a rightful remark that the “C” Ring was only used on the later "precious resin” MB pens.

On the earlier ones the lead spindle was secured with press fitted "cup ring', which is even more difficult to remove!

See my post on a combined "C ring" and "Cup ring" extrator tool in the MB forum:

https://www.fountainpennetwork.com/forum/topic/343398-mb149-piston-spindle-replacement/page/3/?tab=comments#comment-4475166

Best regards,

Francis