W.I.P Portal sentry turret - fully working replica

Yes it was my lock down project and what I was supposed to be doing after my initial ZF1. I decided instead to see how far I could go with the ZF1 kits, and I will return to this project as soon as the first and second batch of ZF1's are out in the wild.

I will wire it up and get it shooting some BB's in my new workshop at some point soon!
 
Just a couple of images of where the model is right now. Obviously it’s really easy to create things on the screen, but if you know at some point you’re going to have to fabricate that part, you generally take a bit more time working out what goes where, why and will it get in the way later?

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The lower image shows the design so far off the main carcass and legs. The real concern is how the body will hold up on those spindly legs and how much twisting movement there will be when the guns pan and tilt.

The thin leg spindles will be fabricated from bent steel rod, with the pointy leg bits probably moulded and cast out in resin. The upper legs will also be fabricated steel sheet I think, to add a bit of weight to the construction.

The main body will be made from different hollow ‘boxes’ of folded sheet aluminium, as these will need to hold electronics, batteries and remain as light as possible, with most weight being situated in the arms and gunpods, and the large hopper of BBs in the ‘head’ of the turret.

Thanks for looking!
 
This is an excellent project, can't wait to see it finished. Those legs present an interesting engineering problem.
 
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Yes I was thinking I could do something with counter rotating weights to try to offset the torque from the rotating tilt/pan mechanisms, but this only increases the overall weight of the main body.

I think I will have to compromise on the original design of the turret, and increase the diameter of the leg rods significantly, to mitigate any wobble when the whole thing is moving about. I think bending pipe instead of rod might increase the rigidity too.
 
This is fantastic!

I bring a Weighted Companion Cube to Burning Man, and of course have thought about a few sentry turrets too. However, in my case, the most they would do is shoot water, or blow bubbles, which would make the overall mechanism a lot lighter.

Oh - also, my cube is a steampunkified, so I could probably make my legs out of regular table legs in my version of this, but given how much machining you're doing, it's making me think there's no way; I don't have access full time to that kind of equipment.

What size of mill / lathe would be required? I'm really tempted to get a Harbor Freight mini mill.
 
It all depends on what you want to make I guess. You don't need a large pillar mill, a standard desktop one would be fine. Lathes are a bit different as the pipe I am turning in this project needs a slightly larger chuck then most of your standard 'hobby' lathes have.

The Harbor Freight mill you specified would be a good start. The big cost is always the tooling, as you'll always need the one tool that you do not already own!

If you're going to be shooting bubbles or water, the main weight will be in carrying the water, and not the mechanism. If you're planning on storing it somewhere else, and pumping it to the mechanism, then it's not a problem.
 
Amazing. Do your motor controllers support changing the PWM frequency? At least for me one a project I had to push the PWM frequency to 18 KHz to make it higher than I could hear. (It probably still bothers the dog and younger folks)
 
Hi yes I will probably use an Arduino library to change the frequency to get rid of the PWM whine. It's on the to do list, I was just happy the whole thing was moving nicely.
 
Amazing work! I'm excited to see how it comes along! I can hear Cave Johnson in my head "How do we put so many bullets in um? Like this!"
 
Thanks for the interest everyone.

Before I can make the arms pivot left and right, I need to build out the body, which is what I have been up to.

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Space for the eye (tracking camera) is included at the front..

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...along with a large hopper on top for the thousands of BB's this thing will churn through.

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I'm hoping to get it pivoting in 2 axis in the coming days, and firing some BB's too!

A lot of the printed plastic will be swapped out with folded aluminium, resin printed and machined parts in the coming months. I just like to get things together and working first before going back and refining everything.
 
Movement looks really smooth, really well done...

Thanks! It still needs improving but I got rid of the high-pitched PWM noises from the previous video, and there are a few improvements to the code I can do like introducing S-curves to the movements.

Lots of other improvements too:
  • New barrel extension mechanisms
  • Extension mech latch to stop it pushing back out when retracted
  • Central eye (and maybe laser if I can get it all to fit)
  • Legs
  • Polished white shell
  • Lots of machined aluminium and most visible parts replaced with SLA printed or cast parts.
 
This is awesome. I started doing pretty much the same project a couple of years ago, even bought exactly the same BB guns, but eventually I gave up because I realised it was going to be too hard/expensive for me to do.
So happy to see someone with the skills to pull this off. Keep up the good work! (y)
 

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