Testing Ideas

[MY63]

I make custom leather cases for fountain pens I have shared pictures before of finished cases but have not shared their construction. Well not here, I have often been asked how strong they are I would like a simple way to test them without special equipment. Better still if someone knows anyone with testing equipment.
The final test will be driving my car over it but I think that might be final.

This is the formed Kydex a thermo plastic used in the aviation industry, It is very popular in the USA for tactical gun holsters. I heat it with a hot air gun and form it over wooden molds.

2021-05-03_09-23-42 by my0771, on Flickr

After trimming I wrap them in suede.

2021-05-03_09-24-22 by my0771, on Flickr

I then mold a leather outer cover

2021-05-03_09-24-57 by my0771, on Flickr

This is the finished set which unfortunately have been lost by UPS

2021-05-15_07-16-40 by my0771, on Flickr

These are the single cases which I want to test.

2021-07-19_09-34-38 by my0771, on Flickr.

I have made a few for testing which I am happy to destroy.

 

[Robert]

If you want to know how much weight to crush one my first thought is some kind of strong frame with bathroom scales for load measurement...a bottle jack for force...and suitable pads to do the crushing.

Or just stack measured weights on top of it until something happens. Guess you'd need point load and even crush load figures.

Have fun - and take pictures

 

[novocaine]

it depends what you want to test, but everything comes back to a load cell of some sort if it's compression strength.
impact tests will need high resolution to capture the impact force where as static load is a much lower resolution (as suggested, bathroom scales would do to an extend)
point load or piercing resistance and crushing are both static loads, so a frame with a load cell and something to apply force (a bottle jack would do it, but so would a threaded shaft and a big handle) will be sufficient.

dynamic load AKA impact is a harder thing to measure, I'd be tempted not to go down that route at all.

as it's kadex, I think there will be a few existing studies on it's ability to withstand load, most likely against ASTM standards. saves you having to do the tests (which I'm afraid are meaningless if not done in a real lab and you don't want to see the price for that).

 

[AndyP]

In normal use Michael what is the worst that could happen to these cases?
Dropping on to a solid floor from a table? Dropping from a greater height, an upstairs balcony perhaps?

Perhaps your tests should be done with the pen inside as the purpose of the case is to protect the pen and not necessarily to remain undamaged in the process.

Real world testing rather than knowing how many pounds per square inch they would survive would be of greater interest to me as a purchaser.

 

[sunnybob]

Put a pen inside, use a video camera, smash the case with a hammer. See how many hammer blows it takes to break the pen. :eusa-doh:

Or..... using my preferred method, take it to the range and have at it with a 12 gauge shotgun. :eusa-dance: :eusa-dance:

Video evidence will always top graphs and charts, and the more spectacular the video, the more impact (hah) it has.

 

[sunnybob]

Looking at your last picture, you should also be marketing them as cigar cases.
People who buy big cigars love to spend money on showy extras :eusa-whistle: :eusa-whistle:

 

[novocaine]

People who buy big cigars love to spend money on showy extras :eusa-whistle: :eusa-whistle:

I a similar vein, people who buy high end pens for themselves like to look at facts and figure. :lol:

I have to say I'm rather tempted by Bobs preferred method of testing but with a minor alteration to the tool of choice.

as to worst case, I'd have thought crushed under the large bottom of a London banker. :lol:

 

[sunnybob]

as to worst case, I'd have thought crushed under the large bottom of a London banker.

C'mon man, nothing could survive that test :eusa-hand:

I'm not much use as a guinea pig here because I have never smoked any form of anything, and I dont even carry keys around, let alone a pen :lol:
But if you want I still have good friends at a gun club in the UK..... :eusa-dance: :eusa-dance:

 

[droogs]

for testing it would be more useful I think for a buyer if you were to film a drop test from 2nd floor onto paving with a test weight inside and showed the results and if it is meant to be sold on the old Samsonite idea show it being driven over or having something dropped on it and show the results.

 

[Pete Maddex]

My wife could test them, she has the knack of destroying things just by using them.

:shock:

Pete

 

[MY63]

In normal use Michael what is the worst that could happen to these cases?
Dropping on to a solid floor from a table? Dropping from a greater height, an upstairs balcony perhaps?

Perhaps your tests should be done with the pen inside as the purpose of the case is to protect the pen and not necessarily to remain undamaged in the process.

Real world testing rather than knowing how many pounds per square inch they would survive would be of greater interest to me as a purchaser.

I have made a fountain pen case for a Master Sargent in the US Army to protect his pens on deployment, but have to agree most of them are used to transport pens to and from the office or maybe a pen show.

The pen I make most cases for is a handmade Japanese fountain pen, made by the Namiki pen company and called the Emperor. They cost between $5000 and $15,000 dollars.
https://www.gouletpens.com/collections/ ... ntain-pens
I just think it would be interesting to know how strong they are.

 

[MY63]

I dont know if the links will work my son weighs 100kg and he was able to stand on the case while I videoed. We then moved onto the hammer which I dropped repeatedily onto the case I did eventually manage to damage the Kydex lined but it took quite a lot of force

https://youtu.be/NlPbsrbUfag

https://youtu.be/JydDO8qg3_U

The leather outer cover only creased slightly, as you can see the kydex liner deformed but still maintained most of its shape.

2021-07-20_06-57-04 by my0771, on Flickr

 

[AndyP]

Fair enough Michael, at those prices they sure need protection. I have no idea who would spend that sort of money on a pen nor what they would expect from it’s case.

I have no idea on the force exerted on a case if dropped from 12 feet on to a hard floor. Equally I have no idea what (say for example) 50lbs per square inch is. A fall from 20 feet, 40 feet, 100 feet? Just my way of looking at things I guess.

 

[novocaine]

I reckon you could find yourself a friendly final year engineering student who needs a project.

 

[sunnybob]

Fair enough Michael, at those prices they sure need protection. I have no idea who would spend that sort of money on a pen nor what they would expect from it’s case.

I have no idea on the force exerted on a case if dropped from 12 feet on to a hard floor. Equally I have no idea what (say for example) 50lbs per square inch is. A fall from 20 feet, 40 feet, 100 feet? Just my way of looking at things I guess.

Imagine a design board laid out in squares, that are one inch long on each side. Then Imagine a tall 1 inch square rod of lead that is 50 pounds in weight. Stand it on end on one of the squares. that is 50lbs per square inch

But what most people dont get, is that measurement applies to every single square inch of the surface being measured.
If the pen case is (for example) 8" long and 2" wide, to put that under 50lbs /sq" pressure you would have to load (16 x 50) eight hundred pounds onto it. :shock:

Whats even more startling, is that air pressure at sea level is 14.7 lbs /sq". Which means while youre paddling your feet there is 14.7 lbs pressing against every single square inch of your skin. The only reason you can survive that is that the same pressure is also inside you pushing out to equalise.

Thats why veneering is done inside a plastic bag and the air is removed, resulting in 14.7 lbs (6.6kg) pushing down on every square inch (25mm x 25 mm) of the wood.
Here endeth todays science lesson :lol:

 

[AndyP]

Imagine an egg, uncooked, placed inside a wooden box. Hit the box with a hammer and egg is undamaged. Knock the box off a table and the egg will break.

Testing Michael's cases with a pen inside to prove it (the pen) remains undamaged, to me, seems more important than a point load test on an empty case. Or am I being too naive?

 

[MY63]

Imagine an egg, uncooked, placed inside a wooden box. Hit the box with a hammer and egg is undamaged. Knock the box off a table and the egg will break.

Testing Michael's cases with a pen inside to prove it (the pen) remains undamaged, to me, seems more important than a point load test on an empty case. Or am I being too naive?

I did ask my friends and customersif anyone was willing to provide a pen for testing purposes, unfortunately no one offered. As some of the single cases are going on sale with a large pen dealer who wanted an easy way to show potential customers.
I shall be returning to this with twin pen cases which I think will be much stronger.
Thanks for all of the input.