So with Bugglebots coming back and after the disappointing performance of Léim last time round, I've began a new spring flipper build with the intention of fixing all of the mistakes the old model had. I'm calling the new build Léim Thart, and the goal of the build is to make a viable spring BW flipper, same as last time but hopefully without the same failings (pronounced "lame heart", and means "jump around" in Irish. Also now you can listen to this while reading and suffer as I did as a kid:




An overview of the CAD. As you can see the design has gone through a complete overhaul.

the previous design unfortunately didn't live up to my expectations, and for this machine I had two goals driving the entire project: to have a stronger, more reliable, four-wheeled drive, and to optimize the flipping mechanism to get as much energy as possible from the springs into the flipper. As such, I've forgone the old DÃ*otóir-inspired design for a design inspired by US Beetleweight Butterfly Effect's winding mechanism, and American flippers such as Bronco or Sub-Zero, which aim to reduce the distance between the rams and the flipping blade. I've scrapped the choo-choo mechanism for a more traditional snail cam mechanism, and have swapped over to using two compression springs mounted on shock absorbers to allow them to hinge. The trick for me here was to design the flipper in a way where a) the springs were as far forward as possible to the start of the flipper for maximum energy output and b) the cam was as far forward as possible so that I could get as much useable torque out of the motor as possible after all other losses (size of the cam, increased forces by being behind the springs etc.).





Shots of the flipper mechanism in the wound and fired position.

The motor I'm currently using is a Servocity 34RPM Econ Gear Motor (https://www.servocity.com/34-rpm-econ-gear-motor), which has an output of 110.20 kgf/cm, though I may upgrade to the 19RPM model in the future for an absurd +180 kgf/cm. For the mechanism I'm currently using two Flexo Springs 133414 (http://www.flexosprings.com/stock-sp...springs/133414), with a rate of 10.51 N/mm, compressed down to 15mm. I've taken most of my parts for the motor mech from Brandon Zalinsky's US Beetle Butterfly Effect, with the exception of using a snail cam winding method instead of his choo-choo inspired method.

For the drive, I was impressed by how much power WeeWoo had at Bugglebots, and after getting some brushless ESC's from Alex Mordue there, I decided to go brushless for Léim Thart. The drive will use 3D printed wheels with hydraulic hosing for rubber grip, and I will be replacing the Banebots hubs with press-fit wheels instead protected by 5mm HDPE. I'm using DYS BE1806 2300KV motors (https://www.banggood.com/DYS-BE1806-...r_warehouse=CN), combined with the Rotalin Planetary Gear Motor's gearbox (https://www.ebay.com/itm/Rotalin-Pla...1-87ca813ef861), with belt drive to drive the front wheels. As well as all of this, the new design will use interchangeable titanium flipper blades, as well as a D2 inspired hinged wedge for the rear for horizontals, though the thickness is entirely down to what I can source.

Given how irritated I was at the performance of the bot last year, I decided to segment the build to get all of the new parts of the build working before combining. As such, I set myself the challenge to not apply for Bugglebots S2 until I had a) a driveable base for the 4WD brushless drive, and b) a working spring mech that could send the old Léim chassis airborne. The next few posts here will be my build logs for how I got both working, to be written in the coming days. Know now though that I have accomplished both, and have now submitted in my application for Bugglebots 2019. I look forward to publishing all I've done so far.


The old Léim chassis along with my flipper and drive base, to be explained in the upcoming posts.