Thoughts on VEXPro Drive in a Day

Hey all!

Just wanted to get your thoughts on using the VEX Pro Drive in a Day chassis nearly 10 years after its initial release. We are looking to move to using everything Versa since our program currently doesn’t have precision machining tools (and I’m not entirely sure when we’ll be able to get them yet) and having a pre-drilled system seems to be the best way to go for us currently. Thank you in advance for your responses!

Wait a week or two before making a decision on purchasing this. Champs is coming up, and there may be new products that meet your needs


I don’t think there’s anything inherently wrong about the Drive in a Day chassis, but I don’t think I’d opt out of a hypothetical AM14U chassis next year in favor of it. (Hypothetical because we don’t know next year’s kit.) Sometimes 4" wheels are a bit on the small side for field elements, you’ll still need to shell out for a gearbox, etc etc etc.

I also don’t think I’d lock myself into the VEX ecosystem right now. They have some great things, AndyMark has some great things (I prefer their gussets), REV has some great things (MAX Planetary is a delight), Thrifty Bot has some great things (the Megaplate offers stuff even the gearbox vendors aren’t selling), and that’s just what’s out now.

AndyMark sent an email blast today saying they’ll be showing off new and in-development products at their Championship booth, REV was on Facebook teasing an April reveal (and really, when else in April would you choose?), CTRE showed off a prototype of the Talon FX controller the year before the Falcon 500 came out, so on so forth. And between AM/REV/VEX, all of them can be useful in a build technique where you match-drill with a hand drill. We did most of our Championship rebuild that way.

If you have money that must be spent before the end of the fiscal year, that’s one thing–but I’d still wait for May to make an informed decision.

Full disclosure: I used to work for AndyMark, and The Thrifty Bot has sponsored parts for my team this year.


2x1 box tubing and Vex clamping bearing blocks are the correct choice if you want to do anything other than the AM kit at the moment and don’t have a mill or related. Especially if you plan to have one in the next year or so, as the transition is fairly easy from that to a traditional WCD.

IIRC the Vex drive in a day chassis gives you…ballshifters (which take about 10 minutes with a cordless drill to make function in the AM kit chassis). And they’re frankly obsolete, as well as that entire chassis.

There isn’t really a “being locked into one ecosystem” in FRC, at least at the moment. Everything runs on 1.125" hex bearings, 0.5" hex, two 6 hole patterns, and CIM, 550, and 775 series motor mounting holes. I’d advise against standardizing on one manufacturer’s system, though the desire is understandable, especially given the annoyances of your location.


558 used the Drive in a Day chassis several times, the most success being in 2014. It’s a great alternative to the AndyMark kit chassis. Is there a specific reason to move to the DIAD sheet metal chassis vs the AndyMark kitbot.

Perhaps you mean the VersaChassis? These are two different products.


We’ve been looking at both, but the Drive in the Day seems like a great option for how we build. However, I am going to follow everyone else’s advice in this thread and wait until after champs before any decisions are made.

1923 and 1914 both used the VP Drive in a Day this year after our CNC Router died in the middle of cutting drive-rails for a Custom WCD. We debated many options including manually milling the rails, shopping it out to local machine shops, doing a laser cut delrin parallel plate drive, and finally settled on just buying and overnighting 3x of the Drive in a Day to cut our losses. We avoided the AM kit chassis because we felt the design of the Drive in a Day allowed us to more closely replicate our then current WCD as well as offer more standardized mounting patterns. We did do things a bit differently and use the DIAD rails to build a pseudo-WCD, and used custom delrin and Markforged flipped gearboxes. All together we went from no drivetrains and a broken router to 3 finished drivetrains in about 3 or 4 days. If it suited our needs, we would not hesitate to do this again.


So, uh, how are you backing your bumpers on the corners?

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Following. The corners look fine since they’re supported by the front and back rail, but I’m curious about the sides since after the lexan plate and cf springs those side rails aren’t the outermost perimeter of the “robot”.

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That picture was from mid build season. Our bumper supports consist of a piece of 1/4” delrin that rigidly backs the bumper down the entire length of the side except for a small gap where the backing material transitions over to the actual corner of the front and back drivetrain cross-rails.

More than 1/2” support on either corner and no gap in support greater than 8”


That’s really clever, I like it a lot.


Thanks for showing this. As someone who inspected both 1914/23 I was a little nervous that I missed this :relaxed:


Photo lovingly-stolen from the FMA flickr that might help contextualize where our bumpers actually end up height-wise.

Keep in mind the Drive in a Day rails normally have an outer rail as well! We just opted out of them, which made our bumper backing a different design challenge. To Sarath’s point, though - we loved this kit and would use again if it suited our needs.


Thanks for sharing this! The standardized mounting is exactly why we are strongly considering the VEXpro drive in a day. Waiting to see what the other companies release within the month!

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Is it possible to use 6 inch wheels with this kit? It is tempting, but 4 inch wheels are a bit small.

Also, people who have used these before, do you brace inside (like the KOP chassis with churros), and do you use bolts rather than rivets (for accessibility to fix a problem)?

As someone who’s already had to make a disclosure statement in this thread about other suppliers and whose team is also thin on precision machining, I have to ask: What standardized mounting does a DiaD offer that the AM14U series doesn’t? The latter has #10 holes every inch (closer on the ends), 1/4” holes every two inches on the inside plate, and plenty of configurations for drivetrain itself.

I’d ask the same question if the Drive in a Day was in the kit and the AM14U wasn’t—the thrust is that I don’t get the appeal of flipping from the KoP drive base kit to another drive base kit that doesn’t bring a massive obvious benefit on the field. Doubly so for a team with limited fabrication ability.


We used it in 2018 and I wasn’t impressed. We had to make custom billet extension pieces to get the chassis length we needed and mounting things generally to the chassis was a pain. I’m fully willing to admit that was because we had 0 experience mounting anything to a not 2x1 tube chassis, but the experience left a bad taste in my mouth.

More things need to be 2x1 tube.


We used 5" wheels this year, I’m not sure 6" would fit in our specific implementation, but I could be wrong.

We felt that by building the DiaD in a non-standard psuedo-WCD configuration, it suited our needs well. I have nothing against the AM14U and think its a great starting point. This just fit our needs a little more closely and also at the time we ordered, we had the ability to get VP orders processed faster than AM order due to the school purchasing system. We also liked that we could tap many of the holes in the DiaD to 10-32 or drill out to .201 to have a clearance fit. In the end it was a spur of the moment decision, driven by unforeseen router breakdown, but it did work out quite well for us. I don’t think the DiaD is a no-brainer answer for teams with limited manufacturing capability as we still had to cut a lot of custom parts to interface with it, including custom gearboxes.

We chose the DiaD because we knew it was large enough to accommodate everything we needed. In fact at 27" long its 3" longer than what we were originally planning for. I’m still sad we didn’t fully realize the tiny 24" x 24" robot we were originally planning for. I fully agree that if you need something longer, it’s not a good option and should be passed over.

Top 10 FRC Betrayals (though it’s usually the other way around)

What if you wanted to build a cool robot, but the school purchasing system said “best I can do is 3 weeks from now and we didn’t think you actually needed bearings so we didn’t get them”.