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While I agree with Loren in part, I think she bases her finding predominately on mfg catalog pages behind her desk and without the benefit of field experience
Yes, Connector strength is important…known as “carrying capacity”. The Bosch catalog has an extensive engineering section devoted entirely to deflection, moment of inertia, and carrying capacity of various connectors under various conditions. If the brand you’re thinking about using does not – think again.
Part of my job as a Field structural engineer and P.E. is to evaluate structures based on published data and compare that to real-world environmental conditions. I’m telling you from practical experience with robot design, specifically from last years competition, if you use a t-slot profile smaller than 1.5” or 45mm square – YOU’RE ASKING FOR TROUBLE.
Last year we had 2 robots. 1 was built using BOSCH 45X45 mm & the other using 30x30 mm. Both robots made it to the finals but the robot built with 30x30 suffered some serious structural failures during the end of the 2nd day of competition and required some emergency repairs to the frame. The robot built with 45x45 had a low center of gravity and weighed 20 lbs. (with connectors) It suffered a high speed crash falling from the bridge while it was up, landed and continued play without incident. It was amazing to see how many teams were scrambling in the pits to do damage control in between rounds, while we just sat & waited for the next round.
This year – MORE THAN EVER – there will be high speed impacts, use of bumpers,
pushing, ramming & the like. Take my advice from practical experience and NOT catalog data. Use high strength-weight ratio extrusion like 45x45. If you go smaller this year, you’ll more than likely spend time making repairs in the pit.
If anyone would like to see the cad drawing of our beefy, light weight robot frame which placed 2nd in the LI Regioanals, let me know & I will email it to you in acad R14 format.
Tony G.
Team 569
Lead eng
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Tony Giammarinaro
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