Bop! - Beetleweight Build Diary

Pretty excited to be posting about my current project, bop!, a beetleweight hammer based on my love of Beta.

This is one of the more recent cad versions, showing the 4wd 22mm drive.

I plan to print the wedge in TPU, cast the wheels in either 30 or 40a PU (dyed pink of course!), and use 5 and 10mm HDPE everywhere else.

Felix has been a wonderful help already on this, putting together the aluminium hammer head (with steel insert) and a gearbox for a 2836.

Very excited to bring this build to Rapture this year!!


That hammerhead is stunning :heart_eyes: Whole bot looks like a great design - can’t wait to see this fighting

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Very excited for this build, the hammerhead is a lovely piece of work and should fit the theme of the bot perfectly. :star_struck:
Will there be a boat mode, however? :thinking:

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Lovely looking design, can’t wait to see it develop!

Keep us updated pls :grin:

No boat mode planned! Have been iterating further on the design today, had to strip out a few of the details for ease of work…
20mm wider to accommodate this new gearbox, but also 20mm shorter! It’s starting to feel distinctly robot shaped

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That gearbox :heart_eyes:
Can’t wait to see this in an arena!

What a perfect name for the robot

Love it! Very excited to see this in action!

I want to see this so bad! I’m also curious of the gear ratio in the weapon motor?

Love the Beta-esque shape of it, this could be a sure…


been cooking up more bits n bobs for it.
pretty much just the belts and pulleys to sort :slight_smile:



Looking cute mate, robot isn’t bad either.

Are you planning any sort of slip/clutch system? Probably something you can avoid at beetle levels but it does look like you’re going to be packing a tidy punch for the weightclass.

This looks amazing, really looking forward to seeing this progress :+1:

little iterative updates here and there.

progressing towards being done, still.

poly done-ish and ready to cut, stacks quite nicely into smol space. all this cnc and potentially laser is very new ground for me.

wheel hubs, being printed and tyres cast by mr tweedy himself

new lipo and esc have been acquired too, so all go!

It’s really starting to happen!

Lots of parts laid out including the new printed gearbox casing and pulley, as well as the beautiful cast wheels. Thanks Filo and Tweedy for all your work!

An actual thought out locking bar ahead of time

This project is a big learning curve for me, CNCing the body being one of the biggest hurdles. Thanks for your patience Joe!

The first test fit of chassis parts. It’s so small! Also one or 2 parts you might notice are not the size they should be. No worries, will recut those another day.

And a Mouse House for scale. This thing is gonna look tiny until the wedge is on it!

I’m very excited. Can you tell?


Absolute hype!

Seeing how lovely and compact it is in reality I’m wondering if you’re going to need a little springy tail to stop the bucking while it’s bopping. Or are magnets on the table (stuck to the table also)?

Thanks Harry! I’m looking at hopefully adding some lil neodymiums on the bottom to aid with traction as well as downforce but we’ll see if clearance allows! Tail is a great shout otherwise though

Just come from your team page, Craig. I thought for a minute you were doing Lockjaw-style stanced drive, but looking at the CAD, a Beta style beetle is a very exciting prospect, and I’m not disappointed to be wrong!

This will be the first of a few posts over the coming days, just reviewing a few bits and bobs from the last month or so of bop! building and competing.
I’m hoping to put a lil video together soon of the development of the bot start to finish as well as a few fight videos, and also a bop!topsy (haha get it, I’m gonna take it apart and see what’s wrong).

But, for today… let’s carry on from where we got to. I decided to try and give less updates over this part of the build on my page/forum thread to try and keep it interesting when the big rollout came.

There were a lot of cnc antics, to say the least. The version of cambam we were using updated and broke a whole bunch of stuff, hence some of my panels coming out wrong as seen above. Eventually got this fixed up and started to combine bits, including the new wedges from JoeM.

Decorating the wedges was another adventure, I hadn’t thought of how sharpie would run through the print lines, as seen here.

The solution was paint pens, which were super crisp and vivid even when correcting previous mistakes… This wedge remained the spare as the other wouldn’t have the sharpie correcting white pen!

I started having ‘fun’ with belts, something I’ve never dealt with before. In one of these photos, you can see the pulley I cut down, drilled and tapped to fit in the small space.

At this point, I passed proof of mobility (thanks for saving me that day Gaz)

Later, took some deliveries and cut some polycarb…

Some paint and wiring later, we were aesthetically done.

Some fun lil comparisons. I especially enjoy seeing it with my first build, and the photo completing the holy trinity of my beetles inspired by my 3 favourite robots.

After adding a tensioner to get the hammer running (would come back to haunt me in my first comp match!) and finishing some extras here and there (including cutting actual white polycarb extra top plates), we were good to go!

The best place to go for my thoughts on the next bit, and more images of the competed bot at the event, is my fb page.

To kind of re-iterate what I said there, I’ve never been this proud of a build. It really was such a level up for me in my knowledge of different processes and design methods, and I can’t believe how well it came together.

During the tournament, I did try running the snoot (too low) and magnets (made me nervous) but the standard setup seemed pretty fun and great.

I like bop!. I hope you like bop! too. Thank you for reading. Let’s bop! together soon.
For tonight at least, Craig out. :slight_smile:


Super cool!

bip! bap! bop! cluster wen?

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you should give him a snickers man, he be looking mad

neat build tho, chibi beta ftw, next time hopefully i can pose a bit more of a challenge to it and not have to dance around the pit for half a minute lol

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