Interesting AM14U2 and AM14U3 upgrades

[Billfred]

As I began preparing my powerpoint slide deck a question occurred to me: How far back does the KoP chassis go, and what did it look like in the early years? The earliest mention I can find of it on CD is 2005, but it is just a couple of mentions. I know that the 2012 and 2013 KoP chassis were essentially the c-frame chassis that AndyMark still has for sale. What happened from 2005 to 2011 (and before that if my search missed something)?

Also, what other “kit chassis” are currently available that are likely to work at an FRC scale? I just want to hit these quickly and move on, but be complete as I can as I do so. I know that the AM14U3, AM C-channel, AM Nano Tube, Vex VersaChassis, and WCD chassis are out there.

I started in 2004. That year, the messaging was “It’s easy to build a drivetrain out of the kit of parts!”–if you had a welder and could manage to figure out this funky and questionably-documented helical gear setup and drill motors whose gearboxes liked to puke their guts. (True story, our driver that year had a gearbox and said “I think this’ll work!” all optimistically…and then the gearbox dumped a bunch of planet gears on the floor.)

In 2005, the original IFI Kitbot came out. John V-Neun and Paul Copioli were the driving forces behind this, JVN on the sheetmetal frame and Copioli on the first widely available gearbox that was actually meant to take two CIMs (which was itself a novelty, we had two CIMs total the year prior). The result wasn’t quite perfect (Copioli was working for Fanuc at the time, which was all metric, so the output shaft was metric which made it trickier to find other keyed sprockets for a then-very-US-heavy crowd), but it was such a tremendous upgrade over the year before it was hard to give him too much crap over it. (Legend has it that the gears inside the gearbox were the first big order for a little no-name garage startup in Indiana.)

2006 was a total carryover.

2007 saw the original gearboxes banned by rule (there was a different philosophy about the kit then), and replaced with the then-new BaneBots planetary gearboxes. They were ill-prepared for the abuse of a defense-heavy game, and many teams had catastrophic failures. (I’m pleased that they got it together since then.) On the plus side, 6" AndyMark FIRST Wheels made their debut.

2008 saw the drive gearbox switched again, to the original square-case AndyMark Toughbox. Cheaper to produce than the cast aluminum housing of the Copioli design, and a 1/2" output shaft. For FRC purposes, this was just about perfect.

2009 was the changeover from the IFI control system to the cRIO, and I don’t know if the changeover to the AndyMark C-Base was driven by that too or what. But that’s what we got, still with Toughboxes. And, of course, rover wheels.

2010 had these funky stilts added onto the C-Base to clear the bumps. They were…okay. Also, 8" FIRST Wheels in both the gray rubber and the white rover wheel material, so you had hope for turning in a 4WD.

2011-2012 were, as I remember carryovers from 2009, but with HiGrip wheels instead of the slick Rover wheels. Edit: Also, they used CIMple Boxes.

2013 saw the addition of belts in the drivetrain, replacing chain. Big improvement!

2014 was the AM14U, and you know the saga from there.

[BumblingBuilder]

And if you want to see the stuff Billfred was talking about for yourself, FIRST has an archive of old game documents, which includes a KoP checklist for most years you are curious about.

[GeeTwo]

In 2005, the original IFI Kitbot came out…

And if you want to see the stuff Billfred was talking about for yourself, FIRST has an archive of old game documents, which includes a KoP checklist for most years you are curious about.

Thanks, both of you! Last time I checked the firstinspires archive (a year ago?) it only ween back a few years. I have game rules I scrounged from somewhere, but not a lot of the other docs. Good to know they’re back.

[GeeTwo]

It might be worthwhile trying these. The setback on them appears to be 3/16". The top flange of the end sheet is twice as deep as this, so no go here without cutting the flange. The top flange of the outisde sheet is only 5/32", and looks like there is enough room for it to fit underneath. If they’re thin enough, they may solve the “removing the outside sheet” issue. I’ve placed an order (slow shipping); will follow up in a week or so.

Confirmed! These came in today. They fit fine in the holes of the top and bottom flanges of the inside and outside sheets. They are thin enough that with a tiny bit of convincing (just the heel of my hand) these can then fit inside the end sheet. They are not deep enough to mount on the end sheet, except at the left and right ends, but that’s not going to help mount bumpers on most kit chassis.

Curiously, they also fit the 1/4" holes at the end of the inside sheet, and those below and forward/aft of the TB Mini. Edit: The two used to mount the EVO Slim 4 Red Line in Richard’s post below.

To help you make your decision, we can give you some general information about the 2019 Drive Base Kit.

It’s similar to the AM14U3 from 2018, and includes a bumper and battery mounting kit.
Features are such that they enable a team to execute basic elements of game play.
Design is such that the drive base can be assembled and driving by a small team with limited resource within two days.

Whew! It may not be exactly like the U3, but at least I don’t need to start over on this!

[Nate_Laverdure]

During the day, away from my computer, an interesting thought occurred to me.

Many maintain that they can drill out a rivet faster than remove a bolt and nut. Has anyone ever riveted bumpers onto the robot, knowing they would have to drill them out and replace every time they change colors? If so, kitbot or not, how’d that work out?

See 148 in 2009, and many others who have followed in their footsteps. Discussion.

[Richard_Wallace]

^ Thanks for the trip down memory lane, Nate.

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Back to the OP topic: the thumbnail below shows my latest favorite KoP chassis upgrade.

[Donut]

You discussed attaching versaframe via small tubes mounted to the top of the chassis, with gussets off those. Another option we have used is to have vertical pieces of versaframe bolted directly to the inner rails of the AM14U3. You can see this on the back of our robot from this year, there are parallel 2x1 versaframe tubes that bolt to the inside of AM14U3 and rest on the flange of the inner rail on each side. We’ve done this the last two years and it has made mounting a super structure really easy for us. The bonus is that you can typically remove the entire upper structure by removing 6 - 10 bolts for the handful of places those tubes attach to the KOP chassis.

My number one improvement to the KOP chassis each year is to modify the wheel size/type and gear ratio. The wheels and gears included in the KOP work, but are not very well optimized. We’ve either gone larger (2016, 2018) or smaller (2017) most years and changed the gearing to achieve a faster speed. We still use the Toughboxes just swap out the gear sets with others from AM. The wheel changes can get a little time consuming, if you can stick with the HiGrips then it is just a case of getting different belts but if you have to go to 8" wheels the HiGrips are out. That forces you to change spacers for the Plaction or VEX Traction wheels or go all out with a wider wheel channel for the pneumatic tires, and we had to notch the end plates on the KOP chassis to fit the wheels some years (take a look at the end wheels on the picture I linked to). It’s not difficult but for teams with very limited capabilities it can be issues they overlook until they run into them. The chassis notching delayed us getting the chassis put together by a week since we don’t meet often.

[GeeTwo]

You discussed attaching versaframe via small tubes mounted to the top of the chassis, with gussets off those. Another option we have used is to have vertical pieces of versaframe bolted directly to the inner rails of the AM14U3. You can see this on the back of our robot from this year, there are parallel 2x1 versaframe tubes that bolt to the inside of AM14U3 and rest on the flange of the inner rail on each side. We’ve done this the last two years and it has made mounting a super structure really easy for us. The bonus is that you can typically remove the entire upper structure by removing 6 - 10 bolts for the handful of places those tubes attach to the KOP chassis.

3946 did something quite similar this year on our Bayou bot, using 3x1x1/8" channel (super easy to mount TB micros to and run chain inside). We had a heck of a time getting everything square or even consistent from side to side and robot to robot. It also interfered with the wheel mounts on those corners, and (in our design) was NOT easy to remove with wheels on one side and control systems on the other. Would not likely do again for a light-duty elevator; would have redesigned the climber to only need to be so sturdy in tension.

Edit:

It may be possible to add one piece of material on each side to solve the access/maintenance issue.

Understood that it is something which can be designed to be easier to access; 2662 managed it. Given the issues the team had in uniform fabrication of the simple version, I would not want to make it more complex without a compelling reason (or an improvement in capabilities).

[philso]

…It also interfered with the wheel mounts on those corners, and (in our design) was NOT easy to remove with wheels on one side and control systems on the other. Would not likely do again for a light-duty elevator; would have redesigned the climber to only need to be so sturdy in tension.

It may be possible to add one piece of material on each side to solve the access/maintenance issue.

[risho900]

I definitely recommend this. It is much easier and more repeatable to mount the brackets to the bumpers and secure these to the robot than to use the tee-nut solution. It’s too easy to push a tee nut out, especially after repeated removals and replacements, and repair means taking the bumper apart.

If you really want the threads in the bumpers, I’d recommend threaded inserts that have female machine threads and male wood screw threads and mount on the frame perimeter face of the bumper lumber rather than from the noodle side. You can get these at a hardware store in several sizes; #10 is most common for bumper mounts.

Instead of having threads in the wood like you described, would it be ok if we used self tapping/drilling screws to attach the bumper?

[Akash_Rastogi]

Instead of having threads in the wood like you described, would it be ok if we used self tapping/drilling screws to attach the bumper?

I don’t recommend this if I understand your question. You want to drill into the bumper backing each time?

If you don’t want to insert threads into the bumpers, use L brackets that are attached to the bumper and then the L brackets are bolted to your chassis.

[Type]

I don’t recommend this if I understand your question. You want to drill into the bumper backing each time?

If you don’t want to insert threads into the bumpers, use L brackets that are attached to the bumper and then the L brackets are bolted to your chassis.

+1
We’ve been doing that for years and I cant imagine having to reattach through the wood each time we wanted to mount our bumpers.

[Richard_Wallace]

+1
We’ve been doing that for years and I cant imagine having to reattach through the wood each time we wanted to mount our bumpers.

+2.

Please don’t attach your bumpers using only wood screws. They will come off.

I have sometimes been one of those grey-haired inspectors informing a team that their bumper attachment method is not secure enough. The most recent incarnation of the robot rule I have in mind is R30-G (2018):

G. must attach to the FRAME PERIMETER of the ROBOT with a rigid fastening system to form a tight, robust connection to the main structure/frame (e.g. not attached with hook-and-loop, tape, or tie-wraps). The attachment system must be designed to withstand vigorous game play

Generally, my spiel goes like this: “I could pass your bumpers now, but if they come off during a match, which is likely if your robot takes a modest hit, then two things bad things might happen. The first is that your robot will be disabled per G07 (2018), causing your alliance to become weaker and perhaps lose the match. The second is that a referee will order a re-inspection before your robot is allowed to compete again, and in that case your inspector will require more robust bumper attachment. My advice is to get it done now.”

[GeeTwo]

Instead of having threads in the wood like you described, would it be ok if we used self tapping/drilling screws to attach the bumper?

I can’t imagine any circumstance I’d be sanguine with self-tapping screws being removed and replaced to mount bumpers. You don’t want each removal/replacement of the bumper to actively threaten your fastening system.

[risho900]

Sorry sorry, I meant use self tapping screws to attach the bracket to the bumper and then when we take off or remove bumpers, its the bracket that gets unscrewed from drive base, not the tapping screws.

[Type]

Sorry sorry, I meant use self tapping screws to attach the bracket to the bumper and then when we take off or remove bumpers, its the bracket that gets unscrewed from drive base, not the tapping screws.

My team always uses t-nuts and typically flathead screws to attach our brackets to the wood. Since we are never removing the brackets from the bumper, we dont have any issues with the t nuts getting messed up.

[GeeTwo]

Sorry sorry, I meant use self tapping screws to attach the bracket to the bumper and then when we take off or remove bumpers, its the bracket that gets unscrewed from drive base, not the tapping screws.

Some self-tapping screws are really designed for metal and some will damage wood more than is necessary to enter the screw. Also, there are no threads on about 1/4" of their length; I wouldn’t recommend these for either of these reasons. Drywall/deck thread screws work pretty well, though I’d try to find some which present a flat face (rather than a fluted face) against the bracket. And whatever screws you use, don’t overtighten.

Single-use T-nuts should work OK. I seem to recall a team which used 1/4" carriage bolts (head on the noodle side) to good effect.

[Richard_Wallace]

We’ve been using these wood screws for attaching angle to bumper backing.

We have also used them to attach brackets that reinforce the corners of our wrap-around one-piece bumpers.

[Bill_Klein]

We’ve been using these wood screws for attaching angle to bumper backing.

We have also used them to attach brackets that reinforce the corners of our wrap-around one-piece bumpers.

I was under the understanding that you could only use aluminum to reinforce the bumper corners. Did I interpret the rule incorrectly?

[Richard_Wallace]

I was under the understanding that you could only use aluminum to reinforce the bumper corners. Did I interpret the rule incorrectly?

Good catch, you’re right. R30-F requires those brackets to be aluminum. R30-B also requires that they not extend more than 1" beyond the frame perimeter. I don’t think we found a COTS aluminum part to match the common steel one that I linked earlier, so IIRC we had to make them.