I’m interested in hearing from other teams about their experience so far using REV ION to build a robot. How has it held up? Have you encountered any surprising instances of failure? This year, 695’s overall experience in fabrication is pretty green, and ION has proven itself to be very easy to build with. However, with a healthy amount of drive practice and two regionals under our belt, it’s safe to say our robot has been pushing the limits of the ION tube extrusion.
For those of you who were watching Miami Valley this past weekend, you might have been wondering why we were out entirely for one of our qualification matches. (We also had to sit out our first round playoff match, but for a different reason. Our roboRIO conveniently decided to quit altogether). Allow these pictures to explain why:
Realizing that playing another match in this condition could cause even more severe damage to the robot, we made the decision to try and make the repair. Unfortunately, we ended up running out of time, as other parts of the frame no longer lined up with our replacement extrusion. To be clear, the choice of extrusion profile was an error on our part. It is an area of the frame that takes some pretty heavy impact from both defense and totally sick jumps off the charge station. What’s important is that this became a learning experience for us and we are looking into other, stronger options.
This happened once more during Finals 2, but thankfully it ended up being an all-or-nothing scenario:
I’d like to briefly explain how and why these failures occurred. Notice the extrusion has a scribe line manufactured into it. While this is very useful for accurate marking and cutting, it creates a loss in strength and reduces fatigue life of the part. (I would suggest reading the Wikipedia about it!) It’s worth noting this extrusion is the thicker-walled ION tube REV offers. This does not make much of a difference, however, as both versions have the same wall thickness on the top and bottom:
222 suffered a similar failure at Mt. Olive. Our failure was due to a high speed collision with the corner of another robot. The collision and point load was enough to break our bumper plywood as well.
While we should have used heavier material for our front drive rail, I’m not certain the material choice is to blame. I believe, with swerve drive being more prevalent and driving corner first, there will be more damage suffered due to similar collisions.
Our Rev Ion experience has been positive overall. Most failures we’ve seen were caused by our own mistakes
We also used the REV Ion tubing and had bending and cracks form under load, I’m sure it would be solved if they offered an option where it was thicker on all sides but until then in the future it will be used for light and medium duty only. Another thing to note I don’t know if it was just our batch but the predrilled number 10 holes had quite a bit of wiggle room with a #10 screw in them, this led our team to have some problems with play in your wrist mechanism, again could just have been our batch
Our team had some similar issues with very slight bending (mostly from sending it off of the charge station frequently), but other than that can’t say enough good things about REV ION. Last year, we perpetually struggled with drivetrain reliability, but switching over to it this year and having the drivetrain run quickly and consistently through our entire first event (knock on wood) was amazing.
Wow. FRCFIRST Robotics Competition would be even wilder if bumper collisions were elastic.
I’m pretty sure that inelasticity was one of the key attributes of pool noodles that made them a component of FRCFIRST Robotics Competition bumpers.
Yeah, we could do a lot worse than pool noodles. They are a great combination of damping and distribution. If you neglect that we build robots in winter.
My team has not played an event yet, but we’ve already seen a similar failure of our REV ION thick wall box tubing on our chassis from drive practice. The replacement was relatively quick all things considered, but we didn’t have to do it in the pit between matches. We’ll likely not use this again on the chassis, though the 3/16” hole pattern is such a nice feature. We are bringing spare drive rails to our event for a quick switch out if needed.
At our first event we experienced splitting down the 1" side and swapped to VEX thick wall 2x1 for our second event and had no problems. I tagged @Greg_Needel about it and never got a response. There were other teams that had posted issues too. I agree a big problem is the score line reducing that very thin 0.04" thickness down to aprox. 0.02" creating a failure point. Also the spec on the #10 hole is 0.201 which is quite large for precise fitment considering a #10 fastener and a 3/16" rivet is 0.1875". A 0.19x would’ve given clearance for a bolt or rivet to fit without as much slop.
Team 6045 wouldn’t have been able to build the robot we built without the REV ION build system. It’s a game changer and made building competitive robots so much easier. We’re looking forward to utilizing more REV ION products in the future!
Favorite products for us have been the MAX Planetary Gearbox, MAX 90 Gearbox, and Through Bore Encoder. The combination of those products makes powering/controling our robot possible.
3357 is very happy with the rev Ion tubing. I don’t think we have any of the thick wall on our robot though. We were already using thin wall tubing, and it requires a slightly different design philosophy, we use many lighter weaker tubes to do a job that may once have been done with a few thick walls, and build robust full coverage bumpers to distribute loads. For example we have 2 1x1s and a 2x1 running from front to back on each side of the robot, and an additional tube running across middle from side to side. This year we opted for a single 1x4x1/8 tube for our front and rear as these can take the hardest hits and it had some other packaging advantages. If you are using a single tube for a high load application I would go custom machined thick wall every time.
This might be my least favorite rule. It sets up unrealistic expectations about what FRCFIRST Robotics Competition really is. Teams need to understand this is a contact sport, and to design their robots to be thrice as robust as they think they should be.
There were a couple of extremely questionable red cards at our first event that called G205 because a robot (kitbot drive base, really) that didn’t have its battery well connected had the battery pop out on a hit in two different matches. And these were extremely normal hits that got called “combat robotics.”
As far as the Ion, it’s been really good and saved us a lot of time. The only failure point was when someone mounted a motor with a bracket off the thin-walled side, and since it was a high-torque application it just ripped the motor and mount right off when they ran it (but that was a matter of not-listening-to-mentors since it was the expected result, hah).
The only issue we are having with it is lack of stock for the 90 degree gearboxes. I really hope nothing fails because we’ve got no spares and there are no spares in stock and no clear idea of when they may be back.
The industry standard for a close fit #10 thru hole is .196. For a free fit #10 thru hole the standard is .201. Unless you can hold tight tolerances on drilling, or your design demands the close fit tolerance you want to use a free fit hole. A free fit hole will be more forgiving when assembling, especially when assembled by students learning to assemble mechanisms.
Definitely keeping an eye on this topic, especially regarding the MAXtube feedback! Historically, one of 573’s sponsors has provided us with aluminum tube but did not do so this year for whatever reason. This, combined with the observation that even top tier teams have adopted pre-drilled extrusion indicates that we’re just making build a bit harder on ourselves at this point and that it might be time to make the switch.
Additionally, I’m interested in any feedback anybody may have regarding MAXswerve. Aside from the stock wheels de-laminating, I have not seen much in terms of the rest of the module. We’re currently running SDS MK4i modules and they’re fantastic, but the lower weight and smaller form factor found on the MAXswerve are pretty tantalizing!
As for our own experiences with REV ION, we were able to use gears and sprockets in our shoulder. We knew that these components would be subject to fairly high loads, but we’re surprised at just how much the loading from our arm is causing our gearbox to flex. Despite this, the gears and sprockets are holding up well and don’t have any visible signs of wear.
I try to be as active as I can be on CD, but unfortunately can’t reply to all the tags/DMs I get. If you need support please email as we have a whole team of people who respond quickly.
In regards to the tube, The score line does impact where it breaks, and creates situations where the rip continues instead of isolated deformation, but when you use thin wall tubing in general you need to ensure that it is the right part for the right application. Putting plugs inside the tubing makes a huge impact and we will be making plastic ones available as part of Phase 4 of ION. We will also be revisiting the score lines on all our tube with potentially removing them on pre-punched tubes. In regards to the tolerances, these tubes are punched, while .196 is the right size hole for #10 clearance, we needed to be on the larger size of things to ensure that everything always fits for everyone, If tighter tolerances are required for your team it might be better to machine or drill holes in blank tube.
We are planning on sending out surveys to teams to collect some additional feedback as we are going to continue to improve the product line in the future.
The original parts were designed and the drawings effectively show a 5mm (~0.197) hole. Did this end up being changed on the actual production?
We made a printed jig with 5mm dowel pins installed to easily make miter saw cuts at 1/2in off the center of a hole, and I did find that the 5mm dowels were much closer in the holes then I would have expected. Originally I was worried it wouldn’t be a slip fit or would just barely be, but it ended up being loose enough that I started to suspect that the holes were now larger. In addition, we have been having issues with the 3/16 clecos we bought being able to hold in the holes of the tubes/gussets, which I also did not expect.
Can you confirm what the actual size of the holes on the tubes/gussets are being manufactured to?
Edit: for further context, below is a pic of one of the extrusion drawings. It is a bit flawed because it shows 0.20in diameter, but the dual dimension shows 5.0mm. If the 0.20in is correct, the millimeter dimension should have rounded to 5.1mm. conversely, if the 5mm is correct, then the 0.20in would be correct.
In any case, it would be good to know what the actual intended manufactured size is.
The maxspline, as a shaft greater than 1/2 inch hex, is a huge boon. Teams seem overly reliant on 1/2" hex and use it in all sorts of undesirable ways (axles for arms anyone?).
When max spline gets all the encoder, bearing/bushing and collar/spacer/clamping options we are in a great place.
One thing I would love to see for shafts (max spline included) is a “torsion spring in a module”. Mounts similar to a rev through bore, stackable, fails safe within its housing, available in a few different strengths and or degrees of rotation.
We are looking in the future for this material. The system, on paper, looks great! We are hoping to get some to develop our swerve drive system for R&D…go see what we can do with it. Coming from KoP drive…it should be interesting for us.
As for the “combat robotics”, there is always an inherent risk for full contact…hence the pool noodle bumpers. IF the issue is prevalent in certain extrusions, which are they? The failures are concerning if they are on the scribe line…and the load issues…maybe a thicker extrusion for the base and load bearing areas are needed. I am not sure. IF frames are being bent…aside from the obvious of having additional replacements…a standoff for impacts for all sides. I am just learning about swerve right now…possibly speaking out of turn or ignorance on this.
