Best Replacement for AndyMark 72" C-Channel frame?

Our team has been using the AndyMark 72" C-channel with 1" hole spacing as our drive base for what seems like forever (after some bad experiences with KOP frames maybe 15 years ago). Anyway, I apparently bought the very last 2 pieces yesterday and it’s been discontinued. We have a couple pieces in stock already, so we should have enough to do this year’s frame. Beyond that, we’re probably going to have to switch to something else.
I know they still sell the 30" pieces (with the pre-drilled bolt pattern for through shafts), but I’d like to know what other framing options are out there and people’s experiences with them since our team hasn’t re-evaluated frame options for years.
Alternatively, if someone knows where AM bought their channel pre-drilled (or did they do it in-house?), we still have a lot of corner brackets, spacers, etc. that would make good use of the same type of framing.


If you don’t need the c-channel part of c-channel and are looking just for pre-drilled holes, MAXTube from rev could be a good option: MAXTube - REV Robotics


That is a very old way of doing things (probably why Andymark doesn’t make it anymore).

If you are looking for a more modern building system, the Rev ION system is pretty great. We’ve been playing with it this off season, and I really like it. I’d argue its the best “erector set” style building system in the FRC market right now.

If you have more tools, many teams are using just regular 2x1 tubing, and machine it as needed.

Oh yeah - the KOP chassis gets yearly updates. I think far more teams doing custom chassis should be using the KOP chassis instead. What’s on top of the drivetrain is far more important generally.

I hope you dont mind me asking, but what happened to have you swear off the KOP chassis for so long?

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15 years ago, the KOP drivetrain WAS this frame. The AM14U didn’t come out until the 2014 season (and had since been iterated on several times!).


I would highly encourage you to take a seriously hard look at the am kitbot chassis. It has tons of mounting options, its very simple, very sturdy, quite customizable for being a bought solution, and if you opted in, you already have one.

There are tons of example of teams using this successfully (see 133 from NE district) because like what’s be said above its really what mounts to it that matters. In all honesty if we didn’t have the manufacturing resources we do to make the parts for a drive base in a few days we’d be building a kop chassis and probably wouldn’t have performed any different.

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hey there - I was on 451 my senior year in '05. Happy to help y’all make a switch to a different set up (zoom call, design reviews, phone calls whatever) because I’d have a vested interest also in seeing my old team be successful.

I obviously don’t know 451s current shop availability - but there’s a lot that can be done with some COTs options.

EDIT: The obvious answer is the KOP drivetrain. It is a good drivetrain, and I’d have no problem doing that as it’s got plenty of documentation and lots of people familiar with it. However, if the team does not want to do the KOP drivetrain and go with a custom base, the below I think is the direction I would go.

If we were doing a WCD this year we’d probably be looking at the rev 2x1 grid pattern whenever it becomes available (ie not the light 2x1 - I don’t think that’ll be suitable for the rigors of a season in a base) MAXTube - REV Robotics. I’d also be looking at potentially using the through-bore gearbox: 2 Motor Drivetrain Gearbox - Through Bore - REV Robotics . Basically their WCD example that has a full onshape model here: High Complexity - ION BUILD SYSTEM


I may have misspoke when I said 15 years ago, this was while I was off at grad school so I don’t have all the details. I might also be counting the last 2 years as like 8 in my head lol.

So far all the options mentioned seem pretty nice, we will probably make a summer project out of trying a few builds with each one.

As far as shop tooling we have standard machine shop tools (including a mill and lathe) and access to some Markforged printers via our sponsor. However with such a young team (student-wise) the more modular the frame the better.

We transitioned from C-Channel construction to the AM14U kitbot chassis in 2017 and haven’t looked back. As long as the builders pay attention to details when using the assembly instructions (gear bosses matter!), it’s smooth sailing, robust, and easy to build upon.

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