[MOC] Ripsaw Tank

[JLiu15]

Simple model of a ripsaw controlled by BuWizz. Features drive with 2 RC motors, suspension, and a dual-missile turret that can be elevated and lowered.

Functions/features:

• Drive (2x RC motors, 1 per track)
• Suspension
• Dual-missile turret
• Turret elevation

It's been several months without publishing any new MOCs, and this is largely due to me working on my huge New Flyer XD60 articulated bus model. I placed two major orders of pieces directly from LEGO back in August, and as their parts take several weeks to ship I decided to work on a smaller project in the meantime. Since my Azure Racer XL I wanted to create another MOC using RC motors and BuWizz, so I decided to go with a tracked vehicle this time. However, I did not want it to be just another boring tracked vehicle with drive only (like my Lime Tracker from 2017), and I realized a ripsaw would be just big enough to house a turret that can be elevated and lowered.

The building process actually started out with the body instead of the tracks. The model has a rather modular build, with individual parts (tracks, chassis, body) built separately and joined together. The turret mechanism was built in the rear of the body, and it is elevated by two small LAs. To reduce complexity, the turret motor is attached directly to the turret and moves with it when elevating. This however required more space in the chassis to allow it room to move. Both the turret elevation and missile firing are driven by PF M motors, and the turret consists of the new spring-loaded turret in a brick housing from the 51515 set. The missile firing motor has a 2L liftarm attached to it that hits the release button on the left/right missiles depending on the direction it turns. Overall, both turret functions worked well.

As for the tracks, they have a suspension system with bogies attached to arms with shock absorbers. This part was a challenge, as the tracks needed to sit high but also be reinforced enough to resist the forces from turning. After several attempts with the tracks falling off, I was able to create a setup with the optimal tension in the tracks to prevent them from falling off during serious driving but also not too tight as to add excessive friction. I was initially worried that driving the tracks straight from the RC motors' outer outputs wouldn't be enough torque, but it looks like the finished model performed fine.

In the end, the model performed well other than being a little bit top-heavy, but I feel like I could've modeled the shape better to make it resemble a real ripsaw more. I tried to be loose with the design, using curved panels over flat panels and stacked liftarms wherever possible, but still I feel like it can be improved. And as for the color, I think DBG would work best for a ripsaw like this (a Google search for "ripsaw" would show several dark gray ripsaws), but given all the pieces I'm ordering for my New Flyer XD60 model I didn't want to spend anymore on pieces for a side project, so I went with white for the model.

Photos:

 

 

 

 

 

 

 

Video:

 

[jorgeopesi]

Interesting features and enough functions for its size.

[JLiu15]

10 hours ago, jorgeopesi said:

Interesting features and enough functions for its size.

Thanks! It might not be big, but I still managed to fit plenty of mechanisms in there.