v-varella

helper

13/12/2018 at 13:13

Test: Trying to screw in PP sheets

Objective: Find how the material behaves when screw in.

Material: PP

Tools: measuring tape, hammer, marker, screwdriver + drilling tool

Process

In order to attach two plates I wanted to test the crews as it is a basic joinery technique. I tried three different distances from the edge (12mm, 8mm and 5mm). Just by screwing directly into the material, the 8mm and the 5mm test are not recomendable. But for the 12mm worked well. In order to avoid cracks I did a second test with preholes on it. This time it worked much better. 12mm – ok, 8mm – ok, 5mm – cracked a bit.

Conclusions

– Screwing on PP (which is kinda soft) is relatively easy.
– And then you have the marks in the inside hole.
– Screwing directly near the corners is not recommended.
– Prehole first is recommended.
– The union is really strong.

v-varella

helper

13/12/2018 at 13:22

Test: Trying to use an HDPE joinery from the bazar

Objective: Learn how strong is the HDPE joinery from the bazar.

Material: PP & HDPE

Tools: Drill, HDPE joinery, marker, clamps.

Process

Found this Joinery on the bazar and I wanted to give it a try. I predrilled a hole and then just used the joinery to attach them together. Unfortunately I broke the joinery while tighten up the parts. Still really strong since it has a big contact surface.

Conclusions

– PP is kinda Soft and makes it perfect to work with bolts because it keeps the pressure really well.
– The HDPE union can brake if not used properly.
– The HDPE union works really well keeping both parts tighten because of his big contact surface.

v-varella

helper

13/12/2018 at 13:24

Test: Trying to hammer an HDPE beam inside PP plates.

Objective: Test how strong is to join two parts joined by pression.

Material: PP & HDPE

Tools: vertical Drill, HDPE beam, hammer, clamps.

Process

I tried to smash a piece of HDPE into two plates of PP in order to tight them together. The hole is slightly smaller than the piece so I made a cone out of the beam by polishing it carefully. Then I found a stable surface where I could start hammering it in. It worked out but I accidentally broke the second plate.

Conclusions

– HDPE is strong enough to resist the hits and fit inside the soft PP.
– Good base is required to hammer it.
– Having this type of union opens the possibility to melt the HDPE since it has a lower melting temperature than PP and therefore weld it into the surface.
– Kinda time consuming but the results can be interesting.

v-varella

helper

13/12/2018 at 13:29

Test: Trying to make a T (90º) union

Objective: Test how to make a T union.

Material: PP

Tools: Caliper, clamps, jigsaw, chisel, hammer, drill, small circular saw, sander.

Process

To make the T joint first I had to draw the desired shape. I had to invest a reasonable amount of time to have both parts properly done. The same problem happen again with the Jigsaw, the sides melted because of the friction. The ended result is really strong and could work very well to attach pieces in 90º.

Conclusions

– The amount of tools needed to make this type of union is high and the result is strong but not very good looking. Making the process slow. A CNC milling machine would solve this problem since it would be more precise and fast.
– The snapping is a really good technique since plastic works well with tolerances and keeps good pressure. Very tight.

s2019

warrior

21/04/2019 at 21:21

Thanks for the Techspan link. What I found interesting was the mention of the plastic test kit https://www.plasticweldingtools.com.au/product/rod-test-kit-rtk/. While not useful for regular sorting, if you have a large piece or many of the same but unmarked parts this technique may be useful. I would guess you don’t need the kit but just make some material reference standards.

I wonder how accurate it is