Axle to wheel

How do you attach a threaded axle to a wheel that doesn’t have a threaded bore? Minus the fact that you can thread the inside of the bore. Also how would one keep the rod from shifting when it’s in the wheel?

Perhaps if you tell us more about the “Threaded axle” you are referring to, and the wheel you want to attach to it, we could offer more helpful suggestions.

But usually the axle is not threaded, it has a shape such as a hex, or perhaps it’s round and has a groove for a key.

Pictures are very helpful for you to get useful answers. Or maybe part numbers of the stuff you intend to use. And a sketch of how you intend to use it.

It’s for a project I have separate from FRC. The threaded axle is just a regular threaded rod and the wheel I don’t know. So perhaps would you recommend any wheels for a threaded axle. Also the wheel should be less than 4 inches in diameter.

Would a vex traction wheel work for this ?

It’s not easy to transmit torque from a threaded rod, to a wheel…it will always try to “unscrew”. And again, without knowing more about what you’re trying to do with this stuff, it’s impossible to say whether, or how, a Vex traction wheel might work.

What would happen if you nut it from both sides and leave enough space so that it doesn’t stop the motion.
Also I will send a pic to clarify what I am referring to

Although this wheels isn’t a traction- how is it attached and if one wants to use some other wheel how would they use the threaded axle

you can put one nut on each side of the wheel, and tighten them. If there is any load on the wheel (like you are trying to use it to move something), then the nuts will get loose, and the wheel will not be turned by the threaded rod. How much torque it takes to move the “thing” that you are using the wheel for, will determine how tight the nuts have to be to hold. I can only guess, because you still haven’t told me what it is you’re trying to do with the wheel. If it just has to turn around and not support or move any weight, it will probably work. if it has to move something heavy, it won’t work.

Are you attempting to transmit torque to the wheel through the threaded rod, or is the threaded rod just supporting the wheel and you wish for the wheel to spin freely?

To me, the more immediate question is why you’re using a threaded rod as an axle.


If you MUST use nuts on either side, then use locknuts. With locktite. Bonus for adding an extra jamnut on each side, also with locktite and being a locknut. Then weld the whole thing to the threaded rod.

But the fact you’re trying to use a threaded rod as an axle is… uh… let’s go with disconcerting.

Let’s go back to the beginning for a moment.

  1. Are you trying to use the threaded rod as a live axle, or as a dead axle? If you’re going for a dead axle, you should be OK. Live axle, you REALLY want to rethink what you’re doing–threads in that application are best described as stress risers.
  2. Is the reason for the threaded rod one of attachment, budget, or “it’s handy”? I can answer all three options with a better solution, but that’s going to depend on what you’re trying to do.
  3. And, uh… you still haven’t said what your general overall “I’m doing this because” is. Answers you get will be different depending on if you’re trying to use this for a drivetrain or a flywheel shooter…

so I am building a small sized vehicle and the threaded rod is part of the braking mechanism. All the vehicle has to do is go down a ramp Straight and stop at a certain spot.

That’s why I am looking for a set of wheels that are compatible with a threaded rod axle

Can you explain this?

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I’m going to double down on this. The more you can provide us with your constraints (including rules) and goals, the better we can help. Normal screw threads are designed to allow easy rotation (the exact opposite of torque transfer) until the threads are stretched under tension. The information you have provided so far appears to be mutually contradictory. In the more colorful words of one of my retired Navy Senior Chief co-workers, it’s a soup sandwich.

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So I am using a wing nut on a threaded axle and one of the wings is against a wooden dowel. So once the wing nut spins, part of the “wing” gets caught on the dowel. As the vehicle is moving, the wing nut is progressing towards the wheel. Once the wing nut hits the side wood piece of the vehicle, the threaded axle stops and therefore the vehicle stops. Hope this helps

There are two ways I can think of getting the wheel mechanically linked to the threaded rod. Option A, put a set screw into the wheel allowing you to clamp/tighten the wheel to the shaft. You could also put a flat on the threaded rod to make this connection much more solid. Option B, depends on how much torque is in the system. With a low enough load, I could see tightening a nut on either side of the wheel being enough to have your threaded rod spin with the wheel.

I’ll make it 3.

Option C requires some decent drilling ability–think a drill press with a vice, bare minimum, with a mill preferred–and a reamer and appropriate pilot bit. Drill a precise hole (no larger than 1/2 shaft diameter) through the center of the axle where you want the wheel. Drill a matching hole in one side of the wheel’s hub, align with the axle, drill the other side, drive a pin into the hole.

But the thread will make this one tricky–drill bits are going to try to walk.

Nylock locknuts and washers should work if it’s a small load, which is what this sounds like. Just tighten it down well with wrenches.

Is this what you want to happen, or is it the problem?
Is this shaft powered, or is the car coasting down a ramp, or what?

If the goal is to have the wing nut serve as a brake, and the vehicle is gravity powered, it would make more sense to use a hex head bolt than a threaded rod, and use the hex head to keep the axle and wheel keyed to each other. Some 1/4" bolts have 3/8" heads, and most 5/16" bolts have 1/2" heads which will interface with FRC hardware. Of course, you also have to keep the wheel from falling off the end of the axle. How about this:

Get a 5/16" tap bolt (threads all the way up), a narrow wheel with a 1/2" hex bore, and two 1/2" hex bore shaft collars. Then, get enough 5/16" coupling nuts to equal the width of the wheel and shaft collars.
Thread the coupling nuts up to the end of the bolt, stopping so that they are clocked (aligned) with the hex head and each other. Mount the shaft collars and wheel on this hex, so that the end shaft collar engages both the hex head and the first coupling nut, keeping it from rotating, and any other discontinuities inside the wheel. This will keep the wheel in place on the axle, and keep it coupled to the shaft for modest torque transfer from wheel to axle.