PROJECT: Half-Life 2 AR2, Update #4 - Receiver & Barrel Test

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Exciting news, I have combined the receiver & barrel assemblies to get a better idea of how things will be functioning together :D

Currently the whole thing is controlled by 3 Arduino Nano's. This may sounds a bit overkill but doing so allows me to run time sensitive modules in parallel, which is a must for the animation sequences

Also, since the previous update the firing/cycling rate has increased to ~5Hz thanks to a stiffer spring. I can push it further but I would need to increase the PWM duty cycle, which would make the coil run hotter (think higher average current). This is something I am a bit cautions about as the body is printed in PLA which has a low glass transition temperature (~65°C)

I guess if I don't manage to reach 9Hz then we can call this the AR1.5 prototype ;^)

Couple of closing notes:

1. I plan to print the final model in PETG which has a higher glass transition temperature (~80°C), so will have the option to push more current through the coil
2. I want to try using a couple of sensors to get the firing pin position, this way I won't be purely reliant on PWM as I could simply switch the coil off once the firing pin has reached the end

PROJECT: Half-Life 2 AR2, Update #3 - The Waiting Game

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Progress has been quite slow thanks to the hectic period we are in (I'm looking at you COVID19). You would think that working from home would give me more time to work on projects, but being stuck inside for a big portion of the day is quite mentally draining....

But getting back to progress, initial tests of the firing pin assembly were quite positive, I could get reliable cycling up to 3Hz (in the game the AR2 cycles at ~9Hz). The big limiter here is the return motion, which can be improved by using a stiffer spring. However if the spring is too stiff then the forward motion will be negatively impacted. So now I am waiting for a bunch of springs to try out

To keep myself occupied I have started working on the magazine assembly. So far I have defined the area that will house all the electronics (batteries, servo, control board...), and am now figuring out the shell movement (from magazine to barrel). Here is how the AR2 is looking so far:

Also, if you have not seen my previous post I have decided to get the multi material upgrade (MMU2S) for my 3D printer (Prusa i3 MK3S). I envision this being crazy useful as it will enable me to print soluble supports, which will make printing awkward shapes (basically everywhere on AR2) much easier

UPDATE: It didn't ;^)

RESEARCH: SolidWorks Topology Optimization

One of the things I have come to realise with my AR2 project is that having a multi-extrusion 3D printer would be crazy useful, as all my prints to date needed support material which unfortunately is a pain to remove. However, with a multi-extrusion printer you can do fancy stuff like print all supports in PVA, which dissolves in water!

UPDATE: Not with a single hotend ;^)

Hence, I finally bit the bullet (bad time to be spending due to COVID19...) and ordered the MMU2S upgrade for my Prusa i3 MK3S. But there is a small hurdle, the MMU2S is designed for large (and preferably flat) working areas, something I do not have. So I decided to modify my current work space with a shelf to hold the 5 rolls of filament, and to spice things up I tried using the Topology Optimization feature in SolidWorks to design the shelf brackets. Overall, this produced quite an organic shape that reduced the bracket weight and gave it the best stiffness to weight ratio

The Steps

NOTE 1: I am running SolidWorks 2018 SP5

NOTE 2: Here is an easy to follow tutorial on Topology Optimization in SolidWorks 

1. Make a 3D model as you normally would
2. Add a SolidWorks simulation (SOLIDWORKS Add-Ins → SOLIDWORKS Simulation)
3. Create a new Topology Study (Simulation → New Study → Topology Study)
4. Select body material (I went with PET as I will be printing in PETG)
5. Define the fixtures (faces where the body will be held in place)
6. Add a force as well as it's direction (I went with 50N as at most the shelf will hold 5 1kg rolls of filament)
7. Add a model goal (I wanted to reduce mass by 40% while having best stiffness to weight ratio)
8. Specify the preserved regions and depth (I selected the bracket mounting faces and went with a depth of 2.5mm)
9. Specify De-mold direction (arrow should be pointing towards flat surface)
10. Create a model mesh (I used a 2mm curvature-based mesh)
11. Run the simulation
12. Finally, adjust the target Material Mass and calculate the Smoothed Mesh

The Results

• Original model: 
• 74.4g
• 210851mm³
• Topology Optimized model: 
• 44.5g
• 84013mm³

UPDATE: Worth The Weight

This one is for all my mates who through the day would never come, and while it's not Half-Life 3, it's certainly a step in the right direction ;^)

WORTH

THE

WEIGHT

PROJECT: Half-Life 2 AR2, Update #2 - Barrel Assembly

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Quick update coming at ya, I have just made the 2nd prototype for the AR2 barrel assembly:

Current variant seems to be working quite well, while still having enough room for electronics. Now I just need to fix a few minor errors and move onto the next moving assembly, the firing pin

UPDATE: Various 3D Printed Projects

Here is another quick update, this time covering some 3D printed projects I recently completed:

1. My wife’s laptop seems to overheat when encoding videos or playing GPU heavy games. So I made a stand to give the laptop intakes/vents more air and move the screen to a more comfortable height. If you want to make one yourself, you can find the model here
   
   
2. Another one for my wife who mainly works from a laptop connected to an external monitor. Recently work threw out a fairly decent PC (i7-3770k CPU, 32GB RAM, GTX 760 GPU), so we decided to refurbish it has her main computer. The problem she soon encountered was that it was a pain having to unplug the monitor/keyboard/mouse from her laptop and plug them into the desktop, so I designed a wee box to house USB & HDMI extension cables. Come to think of it we should have just got a KVM switch…
   
   
   
3. Lastly, I made some 3D printed frames for the postcards & instax/Polaroid pictures we got along our 4 month overseas trip. You can grab the model here
   

PROJECT: Half-Life 2 AR2, Update #1 - Info & Model

Here is a passion project I have been slowly working on since 2012, and only recently has it started to take actual shape. The project is a rifle from my long time favourite video game Half-Life 2 called the Overwatch Standard Issue Pulse Rifle (OSIPR), however in the community it is more commonly referred to as the Pulse Rifle or the AR2

Overwatch Standard Issue Pulse Rifle (OSIPR) aka Pulse Rifle aka AR2

The plan is to make it as functional as possible (sound, lights, and movement wise) with the help of SolidWorks, Altium, and 3D printing. I then want to make a cosplay using the AR2, first as the Resistance/Rebels and finally as the Combine:

Resistance/Rebels from Half-Life 2

Combine from Half-Life 2

Looking back, one of the major reasons this project has only recently started to gain momentum is due to the gradual improvement of my own skillset
For example, when I first started in 2012 I planned to make the rifle completely out of wood and mimic the firing pin movement with a motor, this proved to be quite difficult so I shelved the project. The second attempt (2015) involved me exporting the 3D model from the game files and importing it into SketchUp, I soon found that the model had too many errors to work with plus doing such a complex assembly in SketchUp was never a good idea, so the project was shelved again

With my current attempt I have designed the 3D model completely from scratch in SolidWorks (see pictures below). Next I plan to:

1. Figure out mechanical movement of barrel, reload mechanism, and firing pin
2. Design the circuit (sound, lights, and movement) in Altium
3. Adjust 3D model internals and solve how it all fits together in SolidWorks
4. 3D print rifle on my trusty Prusa i3 MK3S

AR2 game model (exported from w_irifle)

Overlaid AR2 game & SolidWorks models

AR2 SolidWorks model

Simulated AR2 barrel mechanism (gear & rack exported from Gear Template Generator)