Quote:
Originally Posted by RRLedford
We haven't tried the 15mm REV frame yet and even though it is 7000 series much better aircraft strength aluminum, the 3mm fasteners are IMO just too weak of a size fastener for stiff joints that will not shift or loosen with cyclic loading. We use both 10-32 and 4mm hardware with the 20mm and the 1" framing too. If loading is high, we try to use 10-32 as much as we can.
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You are right 7000 series is a stronger series for aluminum but unfortunately it comes with a much higher price. We chose 6063, because it is cost effective to product and is strong enough for the application. We take the price vs performance evaluation very seriously and try to make the best decisions which will work for widest group of teams. If there is interest in a High strength version of our profile, we can always make one out of 7075
The other note is about our choice for 3mm screws. When I was working on the profile design more than a year ago, we discovered the really great relationship between a 15mm profile and how well it works with the size of the 3mm nut (5.5mm). In my experience building sample robots and testing we have never had a problem with 3mm screws, but I do understand your concern. We do use rated steel screws in all of our kits and recommend the same on all of our product pages. Again this one came down to trying to make the best decision for the mass number of teams where 3mm will be good enough.
I do appreciate the feedback and we are always open to discuss our decisions and listen to new ideas. We do our best, but can always improve.