Features:

• Dual Izod and Charpy Impact tests
  
• Notchless sample pieces allow for accurate comparison between 3d printed parts, as well as lasercut plastics and woods.
• Replacable Tips 
  
• Space inside hammer for additional weight (76x M5*5 nuts or 114x M5*4 nuts)
  
• Mostly Glueless design: i.e hammer is clamped down around the aluminum rod + press fit rods
  

Hardware:

• 2020 Aluminum Extrusion 400mm x5
• Steel rod 2mm diameter [50mm to 120mm] x1 ≤ longer = better
• M5*12 Hex machine screw x8
• M5*5*7.5 Brass heatset insert x8
• M2.5 Washer x3 [Optional]
• M5 Nuts for weight [Optional] (x144 with M5*4, x76 with M5*5)

How to use:

When in Izod mode, the sample piece should be clamped down with four m5 screws.
In Charpy Impact mode, the sample piece should lay horizontally on the holder.

Energy absorbed by sample = 100 - value on chart

Basically, the more energy the sample absorbs, the lower down the pendulum will end up

Disclaimers

• This is not a scientific test with values, but is a standardized test between multiple
  samples. Designed for comparing multiple samples against eachother. It is best to think of the numbers as arbitrary units (not even %)
• You might want to laser-cut a larger base, or clamp down the tester to keep it stable during operation
• When using "Charpy+Izod" make sure that your pendulum is properly aligned to avoid damage. “Just Izod” can be used if you don't want to accidentaly destroy the clamp
• Pendulum arm may need to be epoxied to the top pivot point. When testing, the arm came out after a few dozen tests.
• If the red arrow does not stay up, add an M2.5 washer as a spacer to increase grip to the
  arrow

Update as of March 2025:

I added a limiter which uses a square m6 square nut, and a hex bolt. it glues on to the tester, and can adjust the release height until the pendulum reaches 100 exactly (with no sample)

release adjuster is provided in the files, along with an m6 allen wrench holder. these can require glue for assembly

I CNCed a metal tip - not strictly necessary, but prevents the tip from absorbing some of the energy