Product Idea's

I was wondering how many of the community members would like to see the following items added to a future vex line up.

Universal Joints. They provide the link when you can’t get the line up that you want. Packs of 8 for $34.99 would be a great bargain. Theres third party items that are roughly $3-5 per coupling. So thats in comarrison price wise. But it requires modifications to work with Vex.

Linear Screw Actuators. Great add on for using items that require linear movement. could be used in conjunction with the linear slides that are already available. Possible 2, 4, 6, inch lengths. Made similar to the pnumatic actuator but instead of air flow have a mount for the shaft to push into. Possible $49.99 a pair.

Shaft Coupling. This a slight chance that this would be a valid product due to the fact you can just cut a longer shaft, they cause weakness in the line. There could be some applications where a longer shaft could be disruptive in the assembly and replacement area and a coupling would ease the difficulty by allowing the longer shaft to be two sections.
pack of 4 for $9.99

Shaft Extenders. Due to lack of knowledge that they are actually called. They have 2 parts that allow for shrinkage and growing of a shaft. Example would be in a suspension system where shock will reduced with springs or other devices. allow the strech or contraction required for fluid motion. They would be best in 1, 2, and 3 inch travel range. Possible $19.99 a pair of 1 inch, $24.99 for 2 inch and $29.99 for 3 inch.

Shocks. Would be a good complement to the universals. They would allow limited travel for better traction and control of componets. These too would be great with the lengths and pricing of the above shaft extenders.

I don’t expect these items to be produced and placed for sale. As well as I’m not an expert in pricing manufactoring conditions. This could be well out of the scope of the abilities of the development team. I’m just tossing in ideas. It’s really hard to find a machinest that can create these items at this smaller size. It’s really a good idea for a person to purchase a hobby mill/lathe machine for $400- $1000 to be able to make these items yourself. Any feed back would be nice. I know John and Ricky will read this, so please post your thoughts on this. I’m not wanting definitive answers but mainly your thoughts and opinions. Thanks alot in advance.

A reasonable alternative to a U-joint is a flex shaft. They are generally cheaper and lighter, though somewhat less accurate than a U joint. They can also be used in many cases instead of what you call a shaft extender below.

I was able to use standard Vex parts to accomplish this, though not as well as purpose-built parts would do. I used a long axle with several worm screws on it. The sliding part of the mechanism had a pair of the worm gears locked in place on either side of the worm screw. As the axle turned, the sliding mechanism would extend or retract.

If they just offered a rack that could mesh with the worm screw, that would provide pretty much everything you need to make a (very strong) screw actuator.

This has been asked for lots of times. Basically, folks just want a double-width locking collar. I’ve been able to use one of the motor clutches for this when I really needed a long shaft, but it isn’t ideal since it requires additional hardware to lock everything in place.

I’ve seen these called telescoping drive shafts. In real machinery, they are often integrated with some other component, such as a U-joint, or some other coupling. They can be a bit tricky, since the power transfer surface needs to slide smoothly with little friction. Another possible use for these is in a gearbox to translate between gears.

As I mentioned above, a flex-shaft is a reasonable alternative for low power/speed applications where absolute phase accuracy isn’t necessary.

The Vex rubber links can be used as short-travel shock absorbers, but it sounds like you are looking for something more like a traditional car (or off-road) suspension.

Most bots don’t want a suspension with a long travel because (1) they tend to operate on flat surfaces, and (2) the suspension can make it hard to precisely position the upper part of the bot, say to score goals or something. It would be interesting to see some competition games that make terrain a larger part of the design challenge.

These are some great ideas, and they all enable mechanisms that are difficult or impossible to create with standard vex parts.


  • Dean

Most of these items i use after market products for cheapish but require additional planning to compensate for the modifications to work with the other vex products. plus it takes time to go out to the shop. set up rigs to hold devices. get measurements find centers cut or drill. which isn’t really a problem a dremmel is a poor mans best friend. i’m not thinking these shocks would be used for “car like suspension” theres many other types of applications that you would like to have a softer landing or start. But your right in so many ways. there is creative alternatives. all you need to do is look at the big picture and take smaller steps. the shaft couplings of what you described is what i was thinking. double shaft collars. Vex just has so much potential it can be more than just learning and competitions. not that is bad. but thank you for your thoughts and added ideas. hopefully this helps everyone advance a little further.

I’d like to see the shocks. One of the problems with the omni wheels is making sure they have good contact with the floor. Slight humps and bumps cause the wheels to slip.

I’d love the flex shaft to make 90 degree turns to be able to drive wheels with the motors mounted above the axle.

The flex shaft would allow the wheels to move with the shocks and have the motor / gear train attached to the frame.

i have used flexible couplings that i got in some old erector sets. i think these would be a better alternative to U joints, because U joints may need lubrication and they lock up at a 90 degree angle. all these things would be great for vex, except maybe the shocks-vex robots are usually on flat ground, and don’t really have a use for shocks. and looking at the price of many other vex products, i don’t think these would be that cheap.

wow, really great ideas and even better descriptions. its nice to see someone make a really detailed poll for once.

No, lub may not be required for all versions of a uvj. I use these. they have great torque so far havn’t had any snap. now the problem is that there is only a 45to 60 degree angle on them. but if you think about your flexable shafts at a 90 degree angle. why wouldn’t you want to use beval gears? understandable that theres friction with the gears theres space issues. what else could there be? i’m not knocking the flexible shaft but i do think i’m missing something about this here.

Those are neat! I might have to get some of those to play with.
What is the bore on the hubs? I assume it is a good fit for a Vex axle?

Both U joints and flex shafts have their place, but flex shafts are generally more, well, flexible! They can be used to transfer power through angles, solve off-axis problems, and can deal situations where length can change (where you would otherwise need a telescoping drive shaft). They can also be a low-mass way to get rotational power out to the end of an arm, etc.

Their one really unique advantage is that they can trivially deal with situations where you need to transfer power between sections that move relative to each other in complex ways. Such as through a wrist or elbow joint of an arm, or between sections of a robot with an articulated body. It is much harder to cope with this type of thing using U-joints and traditional gearing.

Of course, it is usually easier to just put the motor where you want the torque (wires are very flexible :)) but that isn’t always practical. Obviously, flex shafts are not the ultimate solution for all such uses, or cars would use them instead of U-joints.

U-joints have the advantage of being more precise (preserving the rotation phase under load), efficient, and generally handle more torque. For most Vex-sized applications, I think these advantages are not as critical as the weight and complexity reduction that a flex shaft offers.

All that being said, I think it would be great to have both flex shafts and universal joints available as Vex-sanctioned parts.


  • Dean

they are as close as i have been able to find with little modifications. you will need to bore it out roughly 1/32 larger. I forgot what actual size it was. but the down fall is that they use 4-40 set screws yet another allen wrench to the collection… also… just a teaser…%between%

couldn’t help toss thta in there you can get both left and right rotations. and again only need to bore it out just a bit more nothing major. and i’m gonna try and get something going here about the need for a screwactuator. it’s a new approach for a gripper claw.


this is the reason i would like a screw actuator… or maybe even an adaptor for the vex motor to fit an 8-32 piece of all thread. and the adaptor will allow you to make indifenate sizes with out modding a full unit.

this is the reason i would like a screw actuator… or maybe even an adaptor for the vex motor to fit an 8-32 piece of all thread. and the adaptor will allow you to make indifenate sizes with out modding a full unit.

Hey check it out. It looks like Lynxmotion is now selling robot-sized shocks.


  • Dean

You can make a screw actuator by threading a Vex square axle with an 8-32 die. The resulting rod fits into the Vex motor with no adapter required.