Sledge Hammer Model

Construction Timeline

January 2022 - Design Begins

I thought about what my next major project would be for a while and eventually landed on trying my hand at another HUSS Jump2 model, even though that went against how I was feeling after moderate to no success in functional models in recent past. The scale of the project was quite daunting but I tried my best to take my time and not skimp on components. This included doubling (or tripling) motors and having alternate designs in mind to fall back on in case the first (or following) attempts did not work.

March 2022 - Printing and Vertical Construction Begins

After a couple months of designing the model, it was time to start printing. Daily prints accumulated hundreds of printing hours!

As the parts started coming into physical reality, the scale of the project was even more terrifying. Feeling the weight of some of the pieces in my hand had me revisiting the design and doubling (or tripling!) motors, just to be safe.

I don't have the steady hands or the eye for really small miniature details but I'm very happy with the way that these gondolas came out.

July 2022 - First Lift and Rotation Tests

The first electrical things to go in were the main rotation motors that rotate the hub and the vertical lifting motors.

Rotating the hub wasn't as much of a concern because I was fairly confident that the two motors would be good enough. What I was worried about up to now was whether or not my gambling with the vertical lifting motors would work out.

The first test was exciting because it worked perfectly! It had just the speed and power that I needed for the jumps.

Originally in the design, there were only two lifting motors. Soon after, before even printing anything, I decided to double them up just to be safe. The jumps were fine but it was struggling to get a comfortable drop so I added another couple motors on the empty level below.

Unfortunately one of the motors stopped working so the final project ended up with five lifting motors.

For height feedback, the black and white strip on the rack was going to be an encoder strip to use with a QRE1113 IR line sensor but I couldn't get that to work reliably so I swapped it out for a couple A3144 hall effect sensors and a magnet attached to the rack.

Another last minute addition was a little stopper arm that slides under the rack during the cycle. This established the operating height so that the rack can't crash into the very bottom during the cycle and that the lifting motors wouldn't have to be stalled all the time to keep it at the operating height during the cycle.

February 2023 - Gondolas Connected

Lots of procrastinating later, the gondolas were wired up!

Power to the rotating hub is passed through a homemade slip ring to power the gondolas and its controller. The slip ring has three rails: 5v for controls, 5v for motor power, and ground. Wire brushes made from 12AWG stranded wire make contact with the rotating rings. (The slip ring went through three revisions before even bothering to test any of them.)

There is an Atmega2560 Pro Embed in the hub that communicates with the base controller. Communication is wireless using HC-05 Bluetooth modules. (Originally, wireless communication was going to use NRF24L01 wireless transceivers but I couldn't get bi-directional communication to work.)

Each arm has a magnetic cover so that I can easily access the wiring. Every gondolas has two servo motors and a A3144 hall effect sensor. One of the arms also hides the HC-05 Bluetooth module that communicates with the base controller.

February 2023 - First Real Test Cycle

After getting the gondolas wired up and some basic programming done, I threw it all together.

It was time to see if my homemade slip ring would be reliable enough during the rotations as it hadn't been tested up to this point. I'm not even exaggerating when I say I sat for a moment in disbelief after seeing the first successful test. I was fully prepared to watch the slip ring and wiring get ripped apart.

As you can tell from the video, the programming was still in its early stages with nothing finding home positions yet and the tilt motors staying stationary the entire time. Just like with the hardware, it's also fun to look back at the programming and see how far it has come.

February 2023 - Completing the Panel

I was really happy with how the Soaring Timbers panel came out with the logo and vinyl covering so I tried to keep that going with the Sledge Hammer panel.

There was still some empty space after adding in the Sledge logo so I added the PCW one above it.

The LCD is four rows with 20 characters each so it was a lot more real estate to work with compared to the 2x16 displays I've used in the past. The usual start and stop buttons are there, along with three additional buttons for extra menu selections when they may be needed.

Under the hood, the panel is using an Atmega328p on a custom PCB (basically a bare bones Arduino Uno). It uses a wired serial connection to the base controller for communication.

Note, April 2023: The plan is to redo the entire front of the panel to swap the buttons out because they're very springy and I suspect they're causing too much bouncing which is making programming more difficult than it should be.

February 2023 - Painting the Tower

Taking my time with masking and using thicker acrylic paints really helped making the tower turn out way cleaner than I thought it would.

The tower shell is cut into four vertical sections. They use magnets to attach to the tower.

March 2023 - Platform... Check

The platform was a bit of an afterthought as it wasn't designed until this point. The support arms hook into the tower's lowest level flange. They're not that strong as they cantilever out with no direct support underneath them but they do the job.

With all of the variations after the rest of the model was put together, the platform height did not work out quite like the CAD model had it. If I went with the original dimensions, the actual model's gondolas would have ended up sitting directly on the platform. Some adjustment to how the platform pieces connect to the support arms got it down to a level that makes more sense.

With the success of using a vinyl covering on the Soaring Timbers model, I got one with a concrete texture for the Sledge model.

The platform also includes gondola numbers, two loose article bins, and a garbage can for a few finer details.

April 2023 - First Riders!

I thought it would be fun to print some people to load up the ride.

The original restraint design did not have people in mind so I had to redesign them. I ended up reprinting all of the restraints even though the model wouldn't have people loaded on for most of the time. I think they look more realistic than the original restraints anyway.

I didn't think the total weight of the little people would be enough to affect how the model operates but it did cause some jumps to get stuck and made the final landing back to the platform a bit more abrupt.

April 2023 - Another Snag but a new Panel!

The model suffered another incident where one of the gondola motors shorted out. The replacement motor (and some spares) came in very quickly so this fix was completed in good time.

While the model was down, I took the opportunity to change the panel buttons. The original springy buttons were annoying because they either didn't register presses or they were providing very noisy/bouncy signals. I redid the top of the panel to get the new tactile buttons in. It's a little more plain without the logos but it's clean and straightforward which I like. I stole the button labels from the old panel top.

February 2024 - Custom PCBs and a New Panel!

Wow. I hadn't realized it was so long since the last update!

In the time since the April update, there have been a few updates to the Sledge Hammer model that have been very slow to come into reality. As it usually goes, I find myself with more time for my projects once Wonderland winds down and closes for the season so here I am with a pretty decent update on this project in February.

The main focus has been to reorganize the wiring to the arms. Each arm now has a custom circuit board that better organizes the wires to and from the controller in the rotating hub. When the original wires were put in, I learned as I went on so some arms' wiring didn't look like the others. Now they all look the same and are much neater!

The hub controller now has a custom companion circuit board that, again, focuses on sorting out the wires and makes it better at distributing power to all of the arms.

If you go back to the update last February (2023), you'll see a picture of what it originally looked like. It doesn't look as neat as I thought it would but it's a challenge to work in such a small space.

I decided to make a new panel with all new buttons with lights. The original panel had its own controller so that I would only need to send a few wires from the panel to the main controller. (Serial communication between the panel and the main controller.) However, I found it very difficult to manage the programming between three different controllers so now there are wires from every component on the panel to the main controller. It's a lot of wiring but it has resulted in a much more responsive panel!

In addition to having the model wait for the Bluetooth modules to connect up before being able to do anything, I have added a few more startup checks, including a button check because one time a wire came loose and the model started doing things on its own. (An unconnected pin/floating connection on the controller registered as a button press.)

What's next?

There are many areas of the code to cleanup to make it more efficient and robust. A manual operation mode is planned.