Are 3d Printed Machine Keys Acceptable for Practice bots?

We have determined that we want a test drivebase running for our programmers to really get the controls theory down for this years’ game. We are having the same issues as some other people with the typical Cim Keys not working in the neos we put on the test base.

We are running the Vex drive in a day drivebase with four 4" mecanum wheels (for now).
http://link.vex.com/vexpro/pdf/217-8000-VersaChassis-MD

So, my question is, if we 3d print some keys for the Neos out of PLA+, do you think they will hold?

Our main goal with the base is to combine Mecanum Drive Kinematics with the new vision systems opened up by the limelight.

No. They will not hold. They will shear right at the connection point, probably melt due to friction and create a horrible mess.

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Keys are pretty common at most hardware stores for pennies. At least the common sizes, 2mm for the NEO seems common to me at least.

Maybe I am missing something and the keyways are different sizes in your application or something.

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Are the keys you have too big? If so, you can usually get pretty good results by hand filing them to fit. We have had to do that on a few NEOs for our swerves.

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Thank you all. This is incredibly helpful. That would have been a disaster :slight_smile:
Do the Neos use the 2x2x10 keys that the Cims do? The keys we tried are too large (Width)for the keyway. They look like they will fit, but you cannot actually put them in the slot.

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Yes, but sometimes you may have to file down the key a tiny bit. It usually doesn’t take more than a couple minutes.

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Just order some key stock from McMaster and then make your own keys to the length you want. I always ordered undersized since the keyways from the FRC manufacturers always seems tight. Order some 2mmx2mm and some 1/8"x1/8" and that will take care of pretty much all your key needs for a while.

Example: https://www.mcmaster.com/92288A710/

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I went to my local hardware store today, and though they had keys, they had no metric. Then in a, well it couldn’t hurt effort, I checked Lowes. They had no keys at all (well short of the locks obviously). So I went to McMaster. I also added a few to my last Andymark Order. I think they are a bit cheaper through them.

Yes, the CIM and the NEO use the same key, we have seen NEOs with a burr on the keyway that prevents the key from fitting, try scraping the edges of the keyway with the tip of a file. It is very rarely the key itself that is the issue. Once you get the key started you may need pliers to squeeze it the rest of the way in.

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We ran into this just tonight - burr in the keyway. Lightly filed & key fit great.

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One year we somehow lost a CIM key and didn’t have a spare… but a usefully sized piece of scrap steel, a hacksaw, a file and about 30 minutes of elbow grease got us a replacement. Maybe not quite as perfectly machined as a COTs version, but if memory serves me… it lasted through two regionals and many off-season demos!

Jason

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