Brittle failure - Top choice make Kitless pen blanks

[Sri Pens]

I bought these blanks from Turners warehouse( Top choice ) few months ago and happened to turn them yesterday . Both of them failed in identical ways , a brittle failure . Out of curiosity, I investigated in depth and found the following . Don't know whether there is any special care for handling these shining and shimmering blanks which have gold and silver or probably mica particles suspended in the epoxy matrix .

1. During drilling operations , I did not get any curly flakes but was almost powdery always .
2. Dusing tenon cutting , it was curly material all over .
3. Cracks appeared after the banks were turned and set aside .
4. The centre part of the round blank had segregation which meant the suspended shiny particles were floating while the centre was mostly resin.
5. Cracks appeared on the threaded area wherever there were minimum particles from where the fault-lines appeared .

Are there any special instructions to be followed for turning or this is a case of avoiding such blanks completely .After blowing up 30bucks , I have decided not to turn these blanks anymore . If there are any individuals who interact with Chad , please do take it up with them else very this should serve as a caution .

mohan

 

[its_virgil]

Not all resin material is conducive to threading. It would be nice if you knew what resin was used. Contact Chad and discuss this. He needs to know that material is not good for making (kitless, bespoke, artisan, etc) fountain pens.
Do a good turn daily!
Don

 

[Hippie3180]

I can't be sure but that material looks like it has flake in it (silver and gold.) Generally, this kind of blank will need some gluing and sanding along the way to fill voids from where turning will disturb the flake. Glue fills in and voids or holes, sanding will create an even surface once again to allow for a few more coats of glue as your finish before polishing. The nature of flake is that it can create big enough voids that it's easy to get a catch or for your blank to fail as well if not given attention with glue along the way.

I can't be sure what the resin/epoxy material is,so can comment there. I know some materials are more brittle challenging to turn and coupled with flake could be a potential issue.

I should also add that additives like flake, glitter, flowers etc in the area of your threads will almost always lead to thread failure.

 

[hooked]

I use top choice blanks quite a bit and like working with them. I have used the blank you have, but I have never tried to thread it. I use those for accents/rings on pens. Most of the other blanks use dyes and micas, but these flake blanks use giant flakes of glitter in the blank. The blanks are made from alumilite.

As said above, that blank will not thread well due to the flakes.

 

[its_virgil]

The blanks are made from alumilite.

Alumilite is a brand and not a specific product. Alumilite sells several types of resins. I would assume the resin used is either Alumilite Clear or Alumilite Clear Slow which are their urethane resins. Both take threads well. Alumilite Amazing Clear Cast is their Epoxy resin which also threads well. I agree the threading problem is the flake material cast in the resin. AS you mentioned, material cast in the resin can cause several issues while turning or trying to thread.
Do a good turn daily!
Don

 

[Paul-H]

With this sort of blank I would suspect using a threaded (in a more thread friendly material) insert might be the way to go. And a way to salvage the two blanks you had fail.

 

[d_bondi]

With this sort of blank I would suspect using a threaded (in a more thread friendly material) insert might be the way to go. And a way to salvage the two blanks you had fail.

I agree with @Paul-H , you should find an alumilite clear/clear slow blank that is a complementing material like gold or silver. Part off the failed threaded tenon, drill a mortice in its place. Then with the new/complementing material, turn a tenon down to fit in the mortice you just drilled in the piece you showed a photo of. Epoxy the two together and let it cure. Now you can cut your new tenon, thread it and then drill and tap for the section.

Please show us how you make the save!

 

[Sri Pens]

I can't be sure but that material looks like it has flake in it (silver and gold.) Generally, this kind of blank will need some gluing and sanding along the way to fill voids from where turning will disturb the flake. Glue fills in and voids or holes, sanding will create an even surface once again to allow for a few more coats of glue as your finish before polishing. The nature of flake is that it can create big enough voids that it's easy to get a catch or for your blank to fail as well if not given attention with glue along the way.

I can't be sure what the resin/epoxy material is,so can comment there. I know some materials are more brittle challenging to turn and coupled with flake could be a potential issue.

I should also add that additives like flake, glitter, flowers etc in the area of your threads will almost always lead to thread failure.

I did not see any voids or unevenness. Simply it cracked after threading .Did not commence any turning with the pieces . Probably if I turned would have experienced the problems you cited

 

[Sri Pens]

I use top choice blanks quite a bit and like working with them. I have used the blank you have, but I have never tried to thread it. I use those for accents/rings on pens. Most of the other blanks use dyes and micas, but these flake blanks use giant flakes of glitter in the blank. The blanks are made from alumilite.

As said above, that blank will not thread well due to the flakes.

View attachment 375559

Turners ware house or Top choice should leave instructions and not sell them under Kitless pen category. Beginners like me get ambitious with such blanks And end up wasting resources .

 

[Sri Pens]

With this sort of blank I would suspect using a threaded (in a more thread friendly material) insert might be the way to go. And a way to salvage the two blanks you had fail.

Sure will try . Thanks for your advice . I am checking the possibility of using them in one of my kits

 

[Sri Pens]

I agree with @Paul-H , you should find an alumilite clear/clear slow blank that is a complementing material like gold or silver. Part off the failed threaded tenon, drill a mortice in its place. Then with the new/complementing material, turn a tenon down to fit in the mortice you just drilled in the piece you showed a photo of. Epoxy the two together and let it cure. Now you can cut your new tenon, thread it and then drill and tap for the section.

Please show us how you make the save!

It's going to take some time since these blanks are not available in India . Need to import . Meanwhile contemplating to utilise in Kit pen varieties. Definitely will save and share the salvaging .

 

[hokie]

It's going to take some time since these blanks are not available in India . Need to import . Meanwhile contemplating to utilise in Kit pen varieties. Definitely will save and share the salvaging .

What you might have an easier time finding is cast acrylic rod (as opposed to extruded) as a replacement for currently cracked threaded tenon. I believe it's machinable/polishable and doesn't have the internal stresses that extruded acrylic rod can exhibit (resulting in cracking).

I am curious about your order of operations... do you drill out the center hole before threading? I tend to avoid that unless I know I will have beefy wall thickness. The threading operation can put a lot of stress on walls that thin.

It looks like you may be working on the section? I gave up using resin/plastic threads on my sections a long time ago. They were definitely the weak point in the pens. I switched to brass threads. Aluminum might be an easier option and look good with the gold/silver flake as well.

 

[Sri Pens]

What you might have an easier time finding is cast acrylic rod (as opposed to extruded) as a replacement for currently cracked threaded tenon. I believe it's machinable/polishable and doesn't have the internal stresses that extruded acrylic rod can exhibit (resulting in cracking).

I am curious about your order of operations... do you drill out the center hole before threading? I tend to avoid that unless I know I will have beefy wall thickness. The threading operation can put a lot of stress on walls that thin.

It looks like you may be working on the section? I gave up using resin/plastic threads on my sections a long time ago. They were definitely the weak point in the pens. I switched to brass threads. Aluminum might be an easier option and look good with the gold/silver flake as well.

I am not sure about the availability of cast rods but will surely check this option.

On the barrel threads ,i cut the tenon using a Jim Hinze style tool which requires a 6 mm hole, followed by threading . Then 9 Mm hole to cut the internal threads for section. While internal threading , the wall is hardly 12.8-9 /2 = 1.9 mm which is challenging but never had a failure like this in the past ( hardly 7 pens young ) . I have a sleeve of 13x0.8 over the tenon while threading the 10x1 for section .

I am exploring the brass option . Got few sections , made but the challenge has been to get a smooth fit of brass and acrylic/ resin/ ebonite .Tried a combo of 9.1 MM holw for 10x1 tap and the brass tenon at 9.8 instead of 10 . It's some what better but not 100% . The fear of breakage remains . Do you use a combination or a complete metallic system which obviates the need for any of the tensions ? Saw a metallic sleeve with beaufort which can be embedded into the barrel thread to solve this , but the hole in the tenon in that case is even bigger ( 11 MM ) in a tenon of 13 Mm .

sorry it was rather a long message

 

[Sri Pens]

With this sort of blank I would suspect using a threaded (in a more thread friendly material) insert might be the way to go. And a way to salvage the two blanks you had fail.

understood it the hard way .

 

[PatrickR]

I never cut the cap threads after drilling for the section. It puts a lot of torque on a thin piece. I would suspect that as the main issue. Try one without drilling first.

 

[Sri Pens]

I never cut the cap threads after drilling for the section. It puts a lot of torque on a thin piece. I would suspect that as the main issue. Try one without drilling first.

 

[Sri Pens]

My sequence is as follows
1. on the 18/19 mm blank I drill a 6.1 mm to make way for the tenon cutting tool Supporting pin.
2. Cut tenon of 13 MM , which leaves a wall thickness of 13-6.1 /2 = 3.45 mm per side to thread.
3. Thread on the tenon for the cap.
4. Drill 9 MM in the tenon and thread internally for the section .

The threads cracked not immediately but after few hours of the operation. Many people in other fora also complained about this cracking . They suggested to take the insert route rather than threading the shimmering blank directly . I respect your view and will certainly try out .

 

[PatrickR]

I've never used those blanks so I could be wrong but it's worth a try. It's odd that they cracked later, not during the treading.