High Strength Shafts Different Sizes


Our team found something interesting when changing regular shafts out for high strength ones. Our 3.9" HS Shafts can’t fit into the V5 Motors, but the 12-inch ones can. It seems like the shorter shafts have a larger diameter. The short ones don’t spin very well in the bearings, but the long ones are just fine. Is this a thing? Are the shafts 2 different sizes?


I mean, if you notice their sizes being different I guess they are. I never had anything but the 12" ones, so I can say myself, but this might be caused by just wear and tear on your 3.9" shafts, are they new or have they been scuffed up a bit?


All the shafts are BRAND NEW. Like, never been used before.


hmm that’s odd. try using a dial caliper or some other measuring tool to see how different their thicknesses are. and of course, you could always sand down your 3.9" shafts to give them a smooth fit.


I was gonna try a caliper yesterday to prove it to my coach, but the only calipers on campus were in another teacher’s room near to our VEX room, and they weren’t there, so I need to wait till Tuesday to measure them.


Probably just go along the shaft with sandpaper lightly. Its probably a tiny difference and is just manufacturing defect. I have bought short shafts and they worked fine, as did long ones.


It’s not a small difference. The small ones will not fit into the HS shaft collars at all.


Post a picture of your shafts next to each other?


Not gonna be back at school till Tuesday


I think the manufacturing process changed at some point for the high strength shafts. Some of our shafts are a square with a concentric OD to fit into the vexpro bearings and others are a square with fillets that are not concentric (presumably) to work better in the EDR plastic bearings. Some shafts fit into the vexpro bearings and some are a tight press fit or don’t fit at all. We’ve measured some at 0.299" “OD” and others at 0.302".