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Unread 13-12-2013, 01:45
Travis Schuh Travis Schuh is offline
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Re: Back for more..VEXpro 2014 Product Unveiling

Quote:
Originally Posted by JVN View Post
Hi Sean,
Unfortunately, I don't have a data sheet to back this up. We spoke directly with a few belt manufacturers, off the record on this topic.

Of course those users who would prefer GT2 belts can purchase them from any number of suppliers. VEXpro has chosen HTD based on the feedback we received, and some simple preliminary testing.

If you have any concerns, feel free to email prosupport@vex.com to discuss further.

-John
Quote:
Originally Posted by Jared341 View Post
Given that HTD is at this point a de-facto standard while GT2 is a proprietary profile*, I don't think a lot of belt manufacturers would want to go on the record with an unbiased recommendation. Gates is going to say that GT2 is the way to go, while everyone else will say HTD.

In reality, a wise designer would probably want to have enough of a safety margin that either profile would not ratchet.

* A brief Google search couldn't confirm or deny this, but it is my recollection. I'm sure that CD will correct my statement if it is incorrect
Everything I have seen in the Gates literature showes the GT2 profile ahead of HTD. Check out page 10 of the Gates Light Power and Precision manual. This shows the ratcheting torque of 5mm GT2 and HTD being evenly matched across a range of tensions tested at 2300 RPM (roughly 3X FRC drive train speeds), with GT2 being slightly better than HTD (<5% and decreases as tension increases).

The main advantage as I see it of GT2 over HTD is reduced backlash. In a light load test condition (as defined by Gates), the backlash on 3mm GT2 is 1/3 that of 3mm HTD (.012" vs .030"). This is because the GT2 profile is designed to have less clearance than the HTD profile.

Given the small performance difference as reported by Gates at the 5mm size, the FRC application, and the vendor feedback that Vex Pro got, HTD seems a reasonable choice. I look forward to having more timing belt and pulley sources. We will have to look into it more, but it looks like this offering may enable us to make our wheel modules using all Vex Pro products.

-Travis
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