A few weeks ago, my mentor, @Emerson1706, and I set out to create a drop in NEO gearbox replacement for the Armabot Turret240. We had a concern that the absolute encoder would come unplugged or skip teeth. We also wanted the rotation speed to be faster than it was, as this was sometimes a limiting factor of our move and shoot. Using a full size neo would get rid of this issue and allow for increased performance at a similar current draw. The design I eventually came up with is nearly identical in weight to the current gearbox. It uses a 15 tooth, 32 DP pinion gear on the neo with a 3/8 hex 80 tooth, 32 DP gear connected to the pulley with an overall gear-ratio of 58.2:1. In the linked Onshape document I have separated out a majority of the parts for easy access and modification. Keep a look out for footage from a recent practice match as well as some possible test footage on our team’s YouTube channel. Onshape
nearly identical in weight
Just to clarify, we took the 775pro setup off the robot fully assembled and weighed it vs our new NEO gearbox fully assembled and our scale registered the exact same weight down to the tenth of an ounce. And our version is using .125" plate instead of .080 because that’s what we had in the shop.
Also @Bigathedestroyer did not mention it but I think it’s worth mentioning that this gearbox setup would work just fine with a Falcon with the 15T pinion from Andymark
I also had him add those NEO 550 mounting holes which allow use of a NEO 550 with a 9T pinion (we did testing with a steel pinion off Amazon for RC Cars) for extra weight savings when performance/speed is less of a worry (acceleration and holding torque is reduced vs full size NEO)
That looks amazing? A quick question as to how one would get / manufacture one of those plates that spins with the pulley ( sorry if i am describing it weird)
Are you referring to the washer/spacer under the pulley?
That looks awesome! We’ve been making parts for our updated version that supports the 775pro/Redline and Neo550. Should still be compatible with what you’re designing.
-Andrew
Those are actually what came with the turret: Turret240 – ARMABOT
I believe the plate you are speaking of is the turret bearing which has 10-32 clearance holes drilled on regular intervals to mount the pulley sections.
Excited to see what the update version has in store! This turret has served us well for the past 3 years. After Houston we wanted a little more speed and being able to adapt the gearbox, and belt tensioning system based on your original design made it much easier!
@Emerson1706 Can you post a link to the “Amazon for RC Cars” steel pinion?
Yes I believe it was
Tighten set screw and recommend using “Green” Loctite on shaft interface as well.
Awesome, thanks!
Unless I’m missing something, there is no absolute encoder, just relying on the brushless motor encoder in this design. Does this become a pre-match checklist item to align turret before robot init? Or some other alignment procedure?
I forgot to mention the one slight downside to this design. Yes it lacks an absolute encoder which brings some added bonuses, but you do have to line it up before the robot is switched on. For my team the only thing that would be affected by a misalignment would be the location of the dead zone area. We tend to just eyeball our alignment to where it is close to straight, but some teams I believe like 254 have a timing mark that they line up.
What material is your bearing made of?
The body of the main bearing comes with the turret. If you buy the original turret240 that is part of it. The only thing new that we designed is the gearbox.
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