Shaft coupler

How about metal shaft couplers as a new product idea? I’ve ran into a lot of problems where my motor shafts aren’t long enough or that i ran out of the 4" ones.
An idea:
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I’ve tried using the clutches as a coupler, but they’re always too fat.](“”)

this has already been posted before,
at here
but yes, I would.

Another suggestion would be to use a clutch from a motor.

Another Extremely easy solution is to go on Google look up some sort of hobby supplier and order 1/8in square steel rods, I bet for $5 you could get a 1 meter long rod Just get 5 of those and you could cut any axle length that you need.

Also shaft couplers are a bad idea it becomes a weak point between the two rods that would be prone to breaking under any sort of torque or speed, just stick with a single beam because it will be stronger.

Yes, I tried using the clutches, but they seem “too fat” (too wide) for use in my robots.

I think I’ll try that…

yes, i see what you mean. but having a shaft coupler is a quick way to have the exact length you need.

Yes it is a quick way but most of the time the quick fix gives out. It would work but for how long?

Personally I am perfectly fine with the size of the current bars. If you arrange your metal pieces close enough and don’t leave extra space on the shafts open then you should have long enough shafts. You could also cut up the long bars if you need other sizes. The shaft couplers would be a a bad idea. They take up space and they might btrsk when a lot of torque is exerted on the bar


Several people seem to think the shaft couplers would be a weak point, but I’m curious where this notion is coming from. I could imagine the couplers slipping or possibly loosening, but if they were made out of metal then they would almost certainly be stronger than the axles.

Most rigid shaft couplers are built like a double-wide Vex locking collar. I’m not sure how you would break something like that without having also destroyed the axles going into it. ServoCity sells some, but not for square shafts. I suspect you could use a 3/16" round-shaft coupler, though the fit wouldn’t be ideal…

From reading this forum for a while now, I think shaft couplers are close to the #1 most commonly requested item - right up there with more powerful motors and metal gears. So, clearly there is some demand for them.


  • Dean

OnlineMetals sells 1/8" mild-steel square bar for about a dollar a foot in lengths up to eight feet. It isn’t zinc-plated like the Vex axles are, but it should fit Vex parts OK. They also offer it in other materials like stainless and tool steel. Sadly, they don’t carry titanium square-bar :wink:

I think that long runs (> 12 inches) are more likely to twist under load, and will need support to prevent sagging. I don’t know enough about the properties of different metals to know which would be best for this application. I suspect, for instance, that tool steel would be less prone to twisting since it is very hard, but it might shatter under enough load.


  • Dean

Shaft couplers would work better than the motor clutches. I’ve actually had one or two of my motor clutches fall off of the motors.

just so you all know, people have tried this before and it DOES NOT WORK. now, i dont know if they used the same thing, but if you look closely at vex axles, you will notice that the edges are rounded. this very small change will make a difference. non-rounded axels do not fit into the vex axle holes on wheels/gears…

We had a short rush before a competition and had to use non-vex axles. All you have to do is sand/ grind off a little of the corners. The ones we found fit into the gears and wheels, but not into the collars.

i guess that is because the collars are steel and unforgiving, whereas other vex parts are plastic and will give a little.

I’ve used 1/8" “key stock” from my local hardware store, and it fits all the Vex parts exactly like a Vex axle. I didn’t need to file anything down and other than not being quite as shiny as a Vex part, it works identically.

I’m not sure if the square bar from OnlineMetals is square-edged or not, so YMMV.


  • Dean

Rounded edges are not a big deal, just use a dremel to sand the edges and even some fine sand paper but that would take longer.

speaking of dremels… you know any cheap ones? (under $40) home depots cheapest is 50, radio shack carries none.

I got mine at home depot for about $45 I think. It’s not the best dremel out there but it works.

Look on amazon, I think this is what I have

I also have the xpr dremel and I can say that that thing packs a punch, the dremel above gets the job done but it gets hot and the motor is a bit weaker but the xpr is unstoppable.

I recommend saving up and buying the $120 xpr 400 kit because it includes the xpr dremel, the snake attachment, all sorts of bits and a router attachment.

If you have to buy a dremel on the cheap stay away from the cordless ones your battery will run out very fast at high rpm, stick with the corded multi speed ones that go up to at least 25,000 to 35,000 rpm so that you can cut metal easily. 35,000 rpm literally cuts metal like butter but sparks fly everywhere so where eye protection and long sleeves.