Has anyone found an effective (legal) way to connect 2 axles to make a longer axle than 12 inches? I seem to recall this question being asked before, but couldn’t find it via the search engine.
How 'bout using two bark locks and spacing them with 1/2" or 1" standoffs? You then have room to put in shaft collars. It might be a little bulky, though.
I often do a similar thing but with two sprockets or gears. The advantage of this is that it looks cooler if you actually do something with the gears/sprockets. Otherwise, using gears and sprockets is bulker and has more slop in it unless you use high strength gears.
You can use a clutch but it isn’t the strongest method especially if it is not supported close by. I really haven’t run into this problem too often i think i have only had to do this once.
~DK
How about a 12-tooth, high-strength (double-wide and metal) gear flanked by a couple of shaft collars. The axles meet in the middle of the gear.
If it is only turning one way, you could get really ambitious and cut threads into the axles and then screw them into the ends of a short stand-off beam.
Blake
Great ideas! The 1/2 standoffs with bar locks work really well, because the shaft collars fit snugly inside so they don’t wobble.
Metal 12-tooth gears would also be a good choice and not as bulky, but ours are in such limited supply that we can’t spare them for this purpose.
We thread the ends of the two axles with a #8 die and the join them with a 1" or larger standoff. A little cutting fluid or 3 in 1 oil makes it easier to cut threads. We add low strength locktite to the joint and can then turn the axle both directions.
Well, if you don’t cut threads (See Jon and my posts) (you can buy what you need at a local Hw store, but it would also be a great excuse to take a field trip to a local machine shop), I’ll bet you could talk some gracious team somewhere into loaning you a gear or two. We aren’t using all of ours…
Blake
Field trip – great idea! We’re still using tin snips and bolt cutters as our “power tools.”
Or dozen? Now I see why people buy the multi-packs of metal gears:o
On the other hand, I haven’t tested how they perform with a load (big consideration with 16" axles). The nice thing about the lock plates and standoffs is that the collars prevent the axles from separating/bowing.
vex should have 18" axles
ill suggest it at the new parts ideas forum
it is crucially important this year because teams will generally want a maxed size dumper/scoop for their robot
i see what you are saying about having 18" axles available for purchase but there are other ways to make a wider scoop or a bigger bucket. It is a design challenge, nothing more. While it would be nice to just buy something to fix the problem. In FRC we ALWAYS need to design new things to fix problems and i have noticed in vex that, myself included, we often find a problem and just ask IFI to fix it for us. With a design system were 90% of the parts you use are out of the box and unmodified i think we should be looking for alternative ways of solving the problem and trying all possible solutions before requesting that a new out of the box part be made.
Just My $0.02
~DK
I would just like to point out this is not a rant directed at you, murdomeek it is just something that i have been seeing for a while now.
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Even if Vex offers a longer shaft, it WILL NOT exceed 17.5 inches. Not a single piece of Vex metal is longer than 17.5". This is done on purpose to allow 1/4" on each side of the robot during sizing.
Teams, I really, really, REALLLLLLLLLLYYYYYYYYiiiiieeeee dont recommend making anything exactly 18", I seriously think teams will be SOL when it comes to sizing if they push those limits and no one wants to see teams that cannot compete. That .5" wont change much of anything.
-Cody
lol my robot is just so close to outside the size limit it scarez me sometimes i neeeeeeeeeeeeeeeeeddddddddddd to make it slightly smaller before mid atlantic
A 24" bar will fit in a 17.5" square,
so 22.5" might be a good size for Vex for a diagonal brace.
Extending to 3 dimensions, a 29" bar will fit in a 17.5" cube.
Triangles are strong, squares are weak.
iv just thought of a “retarded” way last night
if you are really pressed on time and/or space
you can mushroom the ends of the axles (cut but not file), and tap them into a metal 12t gear! =D
just get the “beast” of your team to get them out if you ever need to XD
If you have access to the tools, you could drill and tap a pair of holes in the metal 12t gear for set screws. You might want to grind a flat spot first, but it shouldn’t be too hard. You can even use official Vex set screws from the locking collars.
Seems like this modification should be competition-legal, though I guess it could be considered “attaching in any way that is not provided within the VEX Robotics Design System” (from Rule R15b). The Vex RDS does provide attachment via set screws, just not for gears. I guess it would come down to how pedantic the inspector wanted to be.
Cheers,
- Dean
For the intake roller of the Weaselbot we cut threads on the ends of two shafts and joined them with a standoff. We just redesigned the dumper to use a similarly joined shaft. We aren’t transmitting torque through the standoff, but I see no reason that we couldn’t.
We also cut threads on the end of some shorter shafts and screwed nylocks on in place of shaft collars. They are lighter, smaller, and less prone to failure.
We also did that in our first year
we had to drill out the standoff so it was one size smaller than the axles
but our mentor got mad because we “permanently damaged” a vex part
(we only had one classroom kit at that time)
We found a great way to extend axles, I will have to take a picture and upload it when I get a chance.
How about cutting the ends of two axle pieces at 70-75 degrees, then laying them with the cuts over lapping, and secure them with a Collar or Two. This makes the Axel the thickness of one Collar where joined.