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Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
Bumping this post/question...
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Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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![]() Sincerely, Andy Baker |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
JVN or Paul, can you explain how the VersaPlanetary motor connectors work? I've looked through the CAD and I see the set screw, the collar type thing with the slit and the place that it goes. My real question, "is the setscrew the only thing keeping the motor engaged?" I do like the access holes for the setscrew, and that you can swap motors with out removing the gearbox from the robot.
I'm excited to get VEXpro parts in. |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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The axle is 5mm #45 steel. If you check out the CAD model, you can see how the axle is supported much further out than you might expect due to some creative design of the cast aluminum roller support; the bending moment on these axles is greatly reduced. We experimented with this geometry when designing the Mecanum Wheels for the VEX Robotics Design System, and liked it so much we carried it forward to the VEXpro line. The rollers will be made from rubber co-molded onto a plastic shell. The shaft is knurled on each end and press-fit into two of these plastic shells. We will offer a replacement roller-assembly pack which includes some TBD quantity of roller-axle-bracket assemblies. Yes, we expect it to handle 3-4 competitions "no problem." Yes, we will provide a mechanism to replace the rollers if you want fresh ones. Does that answer your question somewhat? I will have quantitative load ratings for you sometime in the coming weeks. -John |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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For our gearboxes with aluminum gears, the teflon infused ceramic coating greatly increases the wear resistance of the gears. That said, teams should probably apply a light coating of white lithium grease to ensure longevity. We know many of you will want to be able to use these items for many years, and this will help make that possible. The VersaPlanetary gearboxes use high-strength hardened steel gears. At this time, we are not planning to grease the gears before shipping. -John |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
John,
With the addition of all these great new gearing options, is it possible you might want to make a newer version of your "JVN-DesignCalc.xls" that is defaulted with the "Ball Shifter" specs? I know I can work with the current version by dropping in the numbers, but having the default already have the basics in there would make things even better, IMHO. |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
Hey, I have a quick inquiry about the Mecanum wheels..
I read on the description that they're optimized for the FRC carpet. This is good and all, but how do they fare on other surfaces, like concrete? We like to demo our robots in the courtyard of our school, which is concrete. I'm just concerned that the rubber rollers may not fare too well, and I'd love to know before I put in my order. Thanks! |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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Allen, The motor connection that the VP uses is one of the more counter intuitive engineered items I have come across in my time as an engineer. This technology is used on industrial robotic gear boxes all over the world and is becoming the common adapter for high rigidity, low backlash applications. There are two basic principles at work: (1) The motor pilot is not used, but the shaft is actually used as the pilot. (2) The set screw really isn't used as normal set screw (clamping on a rigid shaft). It is used as a clamping lever to squeeze the C-coupling into an ellipse. The C-coupler (collar type thing with the slit) and the input collar (the thing the C-coupler fits into are precision machined for an exact slight clearance. In addition, you use a specific C-coupler based on the motor shaft diameter. There is a different coupler for 3mm, 1/8", 1/8" with knurl, and 5mm shafts all with the same OD so they fit in the input collar. The clamping screw is tightened (don't really need that much tightening torque) and turns the C-coupler into an ellipse which locks it in place with no backlash. I have accidentally hand tightened a coupler before and it still locks solid. It took me over 9 months of rigorous testing when I was at FANUC to approve this technology for use on our robots, but after the testing I was sold. easy for replacing bad motors, easy for replacing the gear sets, and no more press fitting gears on motor shafts. Now for high end motors like industrial robots use, this next benefit really isn't a benefit, but for some of the less expensive, non-high tolerance motors we use in FRC, I have found that this next benefit is really helpful: Since you do not have to completely clamp the motor face to the VP mounting face, any shaft runnout misalignment between the motor shaft and motor mounting face is completely mitigated by just hand tightening the mounting motor plate mounting screws. Since the screws only act to keep the motor case from spinning, they only need a little loctite and hand tightening. We will have detailed diagrams on how this all works prior to kickoff. Paul |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
Was the question of belt sprockets w/ VersaHubs already addressed? We want to use belts this year, how would this work with VersaHubs?
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Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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With a lathe you could bore out a pulley to fit over one of the versahub bosses and put a bolt pattern in it if you just have access to manual machines. |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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Consider my questions answered! Thanks for all the detailed information. I did pick around the CAD file a little bit, but I wasn't quite sure what all was what. Now I just have to convince the team that mecanums aren't as bad as everyone says they are (you'd think our track record with them would be enough...but no) :D |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
Wheel bearings are not press fits. They are light transition fits, where if the bearing is at its largest and the wheel is at its smallest you may have to press it in by hand.
The tolerances are such that the worst case is a 0.0005" interference. The way the plastic geometry is designed will allow even this interference case to be hand pressed. |
Re: VEX Robotics Relaunches VEXpro Product Line with over 120 New & Improved Products
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(And it works fine without a fancy spherical-race bearing, because the runout is so small?) |
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