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@Brandon - Yep, scoop on the front will be on its way soon!
@Overkill - Egg beater it is then!
More cad work today!
Figuring out the drive system. Pretty happy with it so far.
http://www.fightingrobots.co.uk/atta...tid=5520&stc=1http://www.fightingrobots.co.uk/atta...tid=5521&stc=1http://www.fightingrobots.co.uk/atta...tid=5522&stc=1
The blue parts are spacers to help add support to the framework without the need for more threaded rod/bolts.
All of the wheels will be 3D printed to include the pulleys in one single piece. I will be insetting bearings into these by pausing the print half way, inserting the bearings and then resuming the print.
The idler pulleys will be 3D printed also. Because I have complete control over their diameter with 3D printing, I will be able to adjust them to give the perfect amount of belt tension (hopefully!).
The motors are counter sunk into the alu frame and will be held in place with a 1mm or 2mm front plate.
I've changed the material of the outer wall to use HDPE and I have also cut out the majority of the material from the inner piece, making them 86 grams instead of 200!
THINGS TO DO:
Firm up the weapon bulkheads - I'll probably add a set of bolts either side of the shaft and another plastic spacer between the two walls either side.
Add scoop - Design and integrate some form of scoop. Probably a similar idea to the mini flip out ones I printed out as a test. This will help to push opponents up into the spinning weapon.
Add weapon motor mountings and belts - Need to think about how this will work. Thinking of using two o-ring style belts for it.
Housings/shock absorbers for electronics - Thinking of putting these inside a little box which is shock mounted onto the frame. Hopefully this will take some of the stress away from the electronics.
Design an egg beater style weapon - Replacing the drum design with an egg beater.
For all of the 3D printing I will be using two types of filament.
The first one is Taulman 910 Alloy. This stuff is STRONG. I'll be posting some strength tests of the stuff when the new spool arrives next week. They have some stats on the website for it here: http://www.taulman3d.com/910-features.html I'm hoping it will be a nice light yet strong alternative.
The second filament I will be using is called Ninjaflex. Its a rubbery filament that can stretch and bend. With a durometer of 85A it seems perfect for tires and shock mounting things. I'll be playing around with different uses for this stuff a lot. One idea is to make little pouches to put the ETC's/receiver inside of.
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You're so legit it hurts slightly. Great work fam.
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I don't think the 3D printed wheels will last long - all the 3D printed antweights that I have seen broke after a few fights, including nylon ones printed on pro machines by Shapeways. Give it a go, but also think of a plan B just in case.
Making printed carriers for electronics works very well, I haven't had anything die from shock damage in several years.
I'm guessing that the blue spacers are plastic. Would it be possible to replace them with a custom sized aluminium nutstrip? That would save space internally and provide a much stronger attachment between the outside bulkheads and the rest of the frame.
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I don't know how they've been 3D printing antweights Nick but all I can say is that it's wrong if they are dying in a few hits. If you do it right they can be EXTREMELY strong. Nylon prints being some of the strongest of the lot.
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The ability of a 3D printed part to survive in a robot is down to a number of factors. Material, printing technology, the way in which the model was printed, layer thickness etc and the design of the part in the first place.
For your wheels are you making the tyres and hubs separate or in the same build? Which printer do you use btw?
Great designs :)
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The 3d printed ones were almost universally ruined after a fight with a spinner, I can't recall any being made from it in the last event we had, but then again its an enclosed arena so the robots don't shoot out after the first hit :P
Thats a sweet design too, Looking foward to seeing it running. The forks are especially cool!
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Taulman may be ok but you need to watch what the orientation of the weak bonded layers is in relation to the most likely stress.
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Thanks for the replies all! My shipment of filaments arrived today, so I'll be testing out the feasibility of it all over the next few days. In my experience with 3D printing, this stuff should be up to the job, but we'll see!
I just realised that since swapping the side panels from being aluminium to HDPE, I can no longer get them laser cut. Does anybody know of a good CNC service that can work with HDPE? Or perhaps another option?
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HDPE cuts nicely with standard woodworking tools - just have a steady hand
I use either a chop saw or a circular saw and fence
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A jigsaw with a woodcutting blade works great for HDPE, especially in the smaller thicknesses. It will go through thinner stuff like a hot knife through butter though, which makes it quite easy to end up with wavy lines as opposed to nice clean straight ones, so if you do opt for that method, a steady hand as Chris mentioned, or even just taking it slowly, will prevent that.
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Have just been speaking to Ellis about this and it definitely seems cutting it myself is the best option. I've got a table scroll saw which is great for cutting thin materials precisely (if a little slow). Going to print out some templates and simply cut around them!
Good to know that wood working blades work well!
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This Taulman 910 is strong stuff! Just printed out a few bits to test.
The first thing I printed was a 20 x 20 x 5 box with 20 percent infill. This was extremely light and only had 0.8mm wall thickness. Despite its flimsy looks, it was very strong. The part couldn't be bent or squashed by hand, so I moved to the vice. The vice was able to squash the part with a lot of force, but upon removing the part, it just sprang back into (almost) its original strength.
After giving it a good squashing, I decided to test its impact resistance. I was expecting one hit with a hammer to destroy it, given the low infill of the part - this was not the case! I was smashing the heck out of that thing for multiple hits with the hammer until it eventually gave in and the top layers begun to give way.
I then printed out a longer 5mm thick strip with 100% infill. This was quite flexible, definitely don't want to use this stuff for a frame! But still very strong. The vice did nothing to it along the same axis as the print was made and the hammer didn't do anything, the part just flung itself around the garage. It cuts reasonably easy with a pair of wire cutters, but requires a lot more force than a beetle could deliver.
I also printed a part with some test holes, keeps its dimensions very well, with a 12mm hole fitting a 12mm bearing perfectly with a tight grip.
Impressed with this stuff for sure, I think it'll fit the bill nicely! I'll try to post a stress test video once I have some wheels printed out.
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HDPE does cut very nicely with a waterjet so that could be an option of the hand tools don't work out, from quotes I have got it can be relatively affordable
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Printed out some idler wheels. The filament wasn't quite flowing correctly at the start, so the bottoms of them are a bit messy. Will reprint these once I've got more parts to work with. Bearings fit nicely though and they roll great :) Are the flanges required? Or would the belt run on them ok without?
http://www.fightingrobots.co.uk/atta...tid=5523&stc=1http://www.fightingrobots.co.uk/atta...tid=5524&stc=1
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If it all tracks right and the idler is slightly wider than belt width + the maximum side-side movement of the belt then it shouldn't need them.
Looking good. :)
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Is that the new Mars rover? :) Its looking great but I think you should either use longer nutstrips or split the existing lengths in two and move them closer to the wheels. Also, are you planning to use cap head screws as shown or countersunk screws on the outside panels? Raised screw heads are magnets for other spinners.
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man i wish i was that good at 3d modeling
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Thanks guys. Going to add more support to the front area soon. Probably a mixture of nutstrips and 3D printed supports again.
Here's the wedge design. They are flush with the frame when not in use and will slide along the ground when they are.
http://www.fightingrobots.co.uk/atta...tid=5531&stc=1
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2 problems with the prongs that I can see.
1: The angle of the upper prong will prevent movement of the lower prong, locking them up. Increasing the length will help here.
2: They feel thin, and will easily be swept sideways and bent. Bring spares for they will work against many a machine.
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Could you elaborate on what you mean with the arms preventing each other from moving? Each arm can rotate freely regardless of the position of the other arms. Unless I've overseen something?
You are completely right about the bending though. Unfortunately I think I'm just going to have to live with it and bring plenty of spares as you said!
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The arms look like they touch each other at a 90 degree angle, which can lock up due to gravity.
When tilted slowly this might pose little problem, yet when flung due to an opponent this could do you in.
I might be wrong and your cad design is sound. but I can't help guestimating how it would react to the effects within the arena.
Anyone else willing to weigh in on this one?
Edit, try animating it when flung sideways...
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I think the GIF makes it look like the prongs have the same horizontal position on shaft, where as in actual fact i think they're just next to one another- you can see this if you slow the GIF down. That probably doesn't make much sense but I think Giles can probably explain further.
In short, it looks fine from where I'm sitting :)
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That's absolutely correct, yes. They sit side-by-side, using the axle of the neighbouring arm as a stopper, preventing it from going too far into the wheel housings when not in use. (I've yet to model the axles in here):
http://www.fightingrobots.co.uk/atta...tid=5532&stc=1
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Brb whilst I just whip up a sweet 3D gif of my robot for the hell of it.
Awesome stuff man!
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CAD files sent off to LaserMaster for cutting! Look forward to putting some bits together at last!
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Laser cut stuff arrived today. Its starting to shape up nicely! The side armor is a little on the heavy side, might have to do some weight reduction on those or replace them with HDPE if that fails. I've gotta drill out all of the 5mm holes as for some reason they are way off and do not fit the 5mm bolts. 4mm ones are fine though. Can't wait to get this all assembled now. Need to file off all the burrs first ;)
http://www.fightingrobots.co.uk/atta...tid=5547&stc=1http://www.fightingrobots.co.uk/atta...tid=5548&stc=1
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thats looking awesome...heavy......but awesome
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No update in a while! Been busy working on my feather. I finally printed some nylon spaces for the chassis and cut some threaded bars to size. I also had to redrill some holes as they needed to be slightly wider. Heres a chassis semi assembled:
http://www.fightingrobots.co.uk/atta...tid=5593&stc=1
http://www.fightingrobots.co.uk/atta...tid=5594&stc=1
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looks awsome whats it weighing in at
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A thought about those front forks. When the bot is upside down the weapon will, in effect, be spinning downwards, so if it hits something it will end up trapping whatever it hits between the forks and the weapon will stop. While this probably not going to break the weapon, it may well bend the forks and it will give the weapon motor and belt a massive shock. Given my new version of Conker is very similar I have been thinking about this a lot, and I believe you only need forks on one side so you can use the weapon to self right on the arena wall/opponent when the wrong way up.
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Wouldn't the articulated forks just move out of the way as the bot flips itself over? And does this mean that Conker now has articulated forks?
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If he can't hit anything because the forks are sticking out, he cant turn himself back over. Also, if they can swing out the way then there is the potential to get beached on your own forks.
And no, Conker doesn't have forks.
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Sounds like Alasdair is completely forked...
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Weight wise the frame is a lot heavier than I'd like :P Its 900g or so. I need to replace the outter side panels with HDPE instead of alu, as those are currently weighing a lot, and it'll probably play nicer with other spinners then too. Gotta print out all of the nylon parts this week, mainly motor mounts and pulleys/wheels. Going to be experimenting with 3D printed rubber tires too.
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Getting that in weight is probably going to be tricky with a 900g frame, Hyperion's was only around 450 and it is only 25g under the limit now it's finished. It looks fantastic though, looking forward to seeing it in combat.
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I'm still alive!! I moved jobs, so low on free time recently, but starting to settle down again. Here is a belt drive test, its way too slack at the moment, gotta either get small belts or increase the diameter of the idlers.
Please excuse my TX screaming at me in the background, the battery was very low but I didn't want to swap it out before capturing a video quickly tonight :p
https://www.youtube.com/watch?v=DsDz...ature=youtu.be
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Belts need to be much tighter, so there is no slack at all, but aside from that... this is an amazing first build! Dat CNC!
