There are two forms of the extensions Standoff Extender - VEX Robotics - one has a square hole, it’s designed to extend shafts, the other has a round hole and it’s the right size to snap on the end of a standoff or another extension.
To some extent they are interchangeable. Shafts will fit into the standoff extensions, but not the other way around.
When I’m using these, I use the square shaft versions if there is some load on the axle, I think the connector grips it well and cuts down on any wobble. Before the era of the capped axles, I used them all the time to hold axle ends onto beams.
Do you have a guideline how you use these?
And hey VEX engineering, if you are looking for a Christmas gift for your favorite Delaware enthusiast, I would love to have extensions with a double long pin on the end to pin 2 parts together.
TBH, friction isn’t the big deal in VIQ that it is in VRC. Between the smaller fields, lack of a defense, 1 min match times, most things run between 100 and 200 RPM, etc. friction in a well built is not the big deal. Misaligned holes, twisted beams/connectors, using 2 pins when 4 are really needed is a bigger issue.
I have a couple of hours of driving on a demo bot that upper arm hinge is in these extensions and it’s fine.
No this is a wrong take. The motors are not strong at all which makes the friction worse. Using the square one is a bad idea. Kids in a classroom, sure use it to keep a shaft in place so it doesn’t fall out. Kids on a team, absolutely not.
I had actually run some “science” experiments on this awhile ago.
I built a frame with two solid uprights. I put standoffs on either end of an axle and snapped them into the uprights. I then loaded the axle up with weight to see how much it would take to pop it out of the extensions. I got to 10 pounds and I quit since that’s more than the weight of most VIQ robots.
In the same frame I drove two axles on a 12:64 ratio. One set of axles was supported at the far end by a standoff, the other went through the axle. I wrapped a rubber band around both axles to pull them together to simulate a load. I ran the setup at full speed (so 500 RPM) for the life of the battery pack (about 15 minutes). At the end there was no wear / markings on the hole with the standoff or on the standoff. There was white dust in the hole with the bare shaft.
Do you want to reproduce my experiments to see if you get different results?
I, too, am very fond of the Standoff Extender Parts. They’re really useful parts in a few niche areas. Like many of the IQ parts, we (VEX Engineering) affectionately refer to them as their numerical identifiers, “109s”.
We’ll toss this ‘0x2 Standoff Extender pin’ idea idea into the ‘Sandbox’ Folder of IQ Part ideas that have yet to become reality. Maybe one day, it will make it back out of that folder!