Unclear Materials on VEX's Product Information

When I am using CAD software to design a robot, I like to include every detail I possibly can (screws, spacers, nuts, axles) in what I am making, not only to properly communicate any particular point of a mechanism to my teammates but also to take accurate weight and center of gravity measurements using the iProperties feature in Autodesk Inventor. Because mass, center of gravity, and weight are all determined by the material of the objects you are importing, one thing that makes it somewhat more difficult to undergo analysis of the various materials within the VEX ecosystem is the fact that some materials on the website are left ambiguous.

For example:

HS Insert - Powdered Metal

What kind of powdered metal?

vs.

Cold Rolled Steel per ASTM A-1008 CS Type B (approx 40ksi tensile strength)

This is VERY detailed material information! (Admittedly more detailed than it needs to be)

There are also many instances where materials are not included for some parts that are actually pretty commonly used in VRC. Usually, we really only know the weight of them (and sometimes not even that). A few examples include:

  • Omnidirectional wheels of all sizes
  • Traction wheels of all sizes
  • VRC Spin Up discs
  • Drive shafts
  • V5 Battery Clip
  • Claw Kit v2
  • Standoff Retainers
  • Click-On Spacers (it’s assumed by the color to be nylon…?)
  • Bearing Flats
  • Pillow Block Bearings
  • Shaft Collars
  • Set Screws
  • Hex Nut Retainers
  • Keps Nut, Nylock Nut, Hex Nut (although at this point, for seasoned competitors, the material is pretty common knowledge)
  • VRC License Plates

Additionally, we have no clue what material the casing of V5 electronics and Cortex sensors are. I do think this would be another useful thing to know along with the weight of the object.

If I’m being honest, I have not tried to look into the materials of each part myself, nor am I going to sit here and pretend this is a major issue within each product’s documentation, but if you’re already listing the materials for parts like C-channels and gussets, you may as well also disclose the material type of parts that currently do not have specified materials or weights. But also, that’s just the opinion of a CAD-crazed competitor who wants to be able to estimate the physical properties of his robot in the very software he designed it in.

10 Likes

As the famous philosophers Richards/Jagger mused “you can’t always get what you want…”

No, you can’t always get what you want
You can’t always get what you want
You can’t always get what you want
But if you try sometime you’ll find
You get what you need

That said - you can quantify a lot of these values by measuring and sharing results in terms of mass / density that might help in your quest in precision.

10 Likes

be that as it may, if im buying construction materials i expect to be told what they’re made of.

12 Likes

Ok, here you go:

for 2x2x2x20 U-channel - it is made of 5052-H32 Aluminum

Here is the data sheet:
https://asm.matweb.com/search/SpecificMaterial.asp?bassnum=ma5052h32

A lot of material data sheet is available for items that vex sells. Now little fasteners on the list, like set screws, that you can evaluate on your own if it is really that critical to your design.

So let’s be clear - the post had a whole list of material that they wanted the weight of, for example first on the list Omnidirectional wheels of all sizes… well, my first go to would be to check the product page and see what they had:
Omni-Directional Wheels

  • 2.75" Double-Roller Omni-Directional Wheels: 0.154 lbs (70 grams)
  • 3.25" Omni-Directional Wheels: 0.132 lbs (60 grams)
  • 4" Omni-Directional Wheels: 0.232 lbs (105 grams)

Traction Wheels

  • 2.75" Wheels: 0.110 lbs (50 grams)
  • 3.25" Traction Wheels: 0.110 lbs (50 grams)
  • 4" Wheels: 0.198 lbs (90 grams)
  • 5" Wheels: 0.352 lbs (160 grams)

Traction Tires

  • 4" High Traction Tires: 0.077 lbs (35 grams)

Mecanum Wheels

  • 2" Mecanum Wheels: 0.122lbs (55.34 grams)
  • 4" Mecanum Wheels: 0.41 lbs (186 grams)

Wheel Legs

  • 6" Wheel Leg: 0.074 lbs (34 grams)

All listed weights are actual weights of one item (no packaging)

I think a little more research/fact checking or measurements can work in this situation can get what you need.

I think common sense is needed here - what do VRC teams really need in terms of details for designing their robots? and follow up, how much as they willing to pay for level of precision they are asking for? Sure VEX can cater to deep details, but that documentation and verification/certification comes will an additional cost. also, what if the mass is slightly off?

But back to my remark - you can’t always get what you want.

11 Likes

but, didn’t you give them, what… they wanted?

1 Like

What @lacsap did was by his own research and estimation… and not from the specs sheet.

But his point is - even if it is not provided, there are still ways to get the info that you might need.
Don’t expect spoon feeding.

3 Likes

I know this, a lot of people know this, but homie still caved in and gave them what they wanted. just thought it was funny