Empirically testing Young’s modulus of stainless and carbon rods.
A 400mm rigidly supported length of D8mm stainless rod deflects .07mm with a 482g wades extruder hanging from it.
I was thinking “man, that’s pretty cool!” Then I realized I have the ability to do all that in the garage.
Why not just cantilever from one end? More response gives you better signal/noise in your measurement, and it’s a simpler formula.
@Dale_Lombardo the main point of this exercise is to test the real world deflection of commonly used 8mm steel rod in the way that they are commonly used in cnc gantries.
Even if I thought I knew how the math worked inside and out, this is a valuable exercise to check the math. In this case the real world test has shown me that my math is completely wrong.
Oh. I thought guy was doing an experiment to measure the Young’s modulus of the steel rod.
I love that the math was wrong, but since it was impeccably understood it couldn’t be a bad choice of boundary conditions.
Maybe you’ve discovered a steel with properties not seen before. That’s another possible cause that had not yet been dismissed.
For machine center accuracy assessment… ASME B5.54
You can map roll/pitch/yaw errors on your servo axes. There’s also techniques to apply ‘volumetric error compensation’ if you have enough DOF… See API Sensors or Etalon and literature…
Here’s an intro to the asme std.
@Dale_Lombardo Thanks Dale! I’m very far from an ‘impeccable’ understanding of the math so it is almost certain that I’ve made an error.
I really appreciate the help.
I’d be very curious to learn what the Young’s Modulus is for the carbon fiber rods (say, 8mm?) that Igus has. I’m sure they’d give you a sample so you can do the testing and share with the community!