Whenever I use lock bars, I get rather old ones from my school. The metal lock plates they had were extremely hard to get on the shaft and usually required a hammer to use.
That being said, one of the plastic lock bars we we’ve been using on our lift for our potentiometer broke at last Saturdays competition, resulting in the loss of just about any autonomous that required advanced lift control.
Long story short:
I’ve only ever gotten used lock plates from the same source and they’ve all been a pain to deal with. Before I purchase anything, I want to know if anyone has bought the metal lock bars recently and if they’ve had any trouble with getting them on to axles.
I got some of the metal ones recently and I’ve never had a problem them. The only time it is hard to get them on is if the axle is brand new the ends can be slightly larger for some reason and make it a huge pain to put it through things (manufacturing method maybe?) or if the axle is cut and not filed. If you use a cut axle and it is filed down then it shouldn’t be too hard to slide it on.
I also got the new 3.25" wheels and I seriously love them. Being able to put metal shaft inserts right into the stock wheel saves an amazing amount of time and headaches dealing with stripped omnis and lock bars. I really hope they release an updated 4" omni this year.
Back when I was on my middle school team in 2008, there were no metal bar locks, just the plastic ones. I remember absolutely hating them. They always broke, even while under very little stress. I remember buying the metal ones for the first time in high school, and thinking they were the greatest thing ever, despite the difficulty sliding them onto axles. My team’s coach asked me why I thought they were so great (well, he really asked why they were worth so much for a small package. FUN FACT: a bag of 8 metal bar locks costs more than a bag of 50 motor screws), if they were that hard to get onto an axle. Of course, the coach never assembled or even touched any of our Vex parts, so the advantage wasn’t that obvious. The advantage (despite the difficulty) of the metal bar locks IS obvious if you use them. They are impressively stronger than the plastic ones (on the plastic ones, it always seemed like the center square hole would come loose from the rest of the bar lock. I don’t know if that’s what happened to yours, but it seems common). The metal bar locks are a single piece of steel, and impressively strong because of it. I use them exclusively, and I think they are well worth the quality time you have to spend with a hammer or filing an axle down.
making sure your axle has a nice rounded edges helps get the metal ones on. Any burrs will make it difficult.
The hammer of persuasion works well too. You really do want a tight fit on the bar locks.
Our team has had a ton of trouble with the metal lock bars. We usually can’t get them on to any shaft smoothly, and usually resort to the hammer method, as said above. Since we don’t use lock bars too often, the plastic ones work for us; they aren’t under high stress, however, so they have a very low chance of breaking. We mostly use the metal ones as a stronger 3 hole bar.
I use the metal ones but only doubled up. if that is not strong enough then I just use a hs gear as a shaft locker. if you put too much touqure on the metal ones they tend to round out the shaft so be careful.