I modified a 38xx I-refill cartridge ...

Started Apr 4, 2013 | Discussions thread
OP JJ Winkel Senior Member • Posts: 1,387
Additional testing ....

Bob's hint about gluing plexiglas to the cartridge plastic got me wondering.

So far I only tested the robustness of the joint by trying to rip the two parts apart by hand, and though I am not a famous bodybuilder I did apply some force without breaking the joint. But decided to do another more scientific rupture test, if only to put my mind at rest.

Details :

Cartridge body seems to be made of some white hard plastic pvc that can be cut, drilled, sanded, glued, etc ...

Back plate is made of transparent hard PMMA (Altuglas / Plexiglas), 2 mm thick, it's 2nd prefered glue is cyanoacrylate glue better known as SuperGlue both in liquid or gel form (1st prefered being Chloroform ...... excellent if you want to make very neat and invisible joints, but that's another story).

So far I used two scrap off cuts glued together with gel superglue like that and left to dry minimum 24 hours :

For the scientific test I modified the jig like that :

I started with lighter weights and ended here :

2920g = 6.44 pounds

I stopped there as it was the scale's max, I didn't really want to break the jigĀ and the axle began to bend

So now some maths :

The test jig's glued surface (colored light blue) is about 1.6 cm²,  actual full size it will be 4.90 cm² thus the equivalent test weight would have been  2.92 kg x 4.9 / 1.6 = 8.94 kg / 19.7 pounds

And it still didn't break yet .....

Now about pressure :

The internal area of the backplate is : 63 x 25 = 1575 mm² = 15.75 cm² =  2.44 in²

The equivalent test pressure would be :  8.94 kg / 15.75 cm² = 0.568 kg/cm² = 8 psi

Would you think that's enough ?  Can that poor rubber accordion pump of the 3880 exceed that pressure ?

Before that I did use some other glues like silicone and MS Polymer (supposed to be the strongest of all ... :-O) none resisted very long.

One more detail : inkjet inks are water based, so no solvent to attack the joint in the long run.

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C&C welcome if ever there's a pic of mine posted above !

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