You can measurebate all you want but you won't use much more than the capacity from a 3Ah pack. I've run a few high powered discs and never used much more than 2 to 2.5Ah from a pack and that's running it non stop for an entire 3 minutes
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You can measurebate all you want but you won't use much more than the capacity from a 3Ah pack. I've run a few high powered discs and never used much more than 2 to 2.5Ah from a pack and that's running it non stop for an entire 3 minutes
Ewan, you mentioned using Nylon as a chassis material. Where would you advise getting it from an do you know what the density is. Solidworks is giving me 2 options, one with a density of 1400kg/m^3 called Nylon 6/10 and another at 1150kg/m^3 called Nylon 101?
At 10mm thick for all parts the chassis weighs 2Kg in 6/10... which given as I have cut the back off seems a little strange...?
Here you can buy sheets of Nylon 6. http://www.directplasticsonline.co.uk/N ... Sheet.html
I believe many people use that site for HDPE and such as well.
I found this site...
http://www.nyltek.com/pdf/SAFETY.pdf
in an attempt to find the density of Nylon 6 and it has given me...
Specific Gravity / Density: 1.0840g/cm3
and this one for Nylon 66
http://www.theplasticshop.co.uk/plastic ... _sheet.pdf
which says 1.14 g/cm3
Does anyone think that these are wrong or unreliable?
The link that Ellis gave (http://www.directplasticsonline.co.uk/N ... Sheet.html) is a good source and where I get mine. Here's the datasheet for the natural (white) Nylon 6 they stock http://www.directplasticsonline.co.uk/p ... t_Cast.pdf with a density of 1.15g/cm^3
A 2kg chassis seems reasonable for a feather- where's the remainder of your weight going if it's still too much?
I will have 2 GR-1 motors (Got them today :) ), 2x 30A electronize ESC's, 1x 40A Electronize ESC, 1x Speed 900, 2x Technobots Blue wheels, then probably a linear actuator to act as a shrimech and flipper, and I am looking into getting lipols onsteda of my NiMH's so combine that with loosing 2 motors and 10cm of body work it should all fit in :)
Quote:
Originally Posted by Eventorizon
If the 40a speedo was for the speed 900 I would get a bigger speedo to be on the safe side e.g victor 883
Quote:
Originally Posted by Eventorizon
What are they? Do you mean robo challenge or banebots?
Done it again, the Robochallenge blue wheels and yeah the 40A ESC was for the Speed 900BB, will it definately blow cos I have already ordered it!
well most people who use speed 900's use victors.
as its a spinner your motor will stall if you have a low ratio and hit another robot, so its just to be on the safe side soo you dont blow the speedo.
another way to get round this is to put a fuse in so you dont blow the speedo, and blow the fuse instead
I was going to go for a 4:1 ratio with speed 900 so the disc will spin at about 1400RPM, is that enough of a drop?
I was also going to fit a massive heat sink if that will make a difference...
I have no experience with spinners but that sounds a good ratio.
What voltage will you run the speed 900 at?
I'd say the Electronize will be fine if you're careful not to stall the motor too much. 40A is the /continuous/ current rating and a speed 900 at 12V has a stall current of 54A, obviously more at 14.4 or 18.5V but should still be within the controller's peak ability. And 4:1 is actually rather a high reduction
Its currently 14.4V with my 2 NiHM packs but If i get a LiPol it will be slightly higher than that, the motor is rated up to 24V so I should be ok, fingers crossed, and could I get away with 3:1?
I believe Drumroll uses a 3:1 ratio on his drum.
3:1 should be fine. I'd recommend a 18.5V Li-Po
Also remembered what the first CAD reminded me of, an American machine called Manta: http://www.youtube.com/watch?v=a1mr7fpxqt0
the electronixe will probably be fine, if it blows just replace it with a battleswitch and 100 amp solid relay. i run 2 speed 900s of one of them
If I were you I would run the speed 900 at around 24v and use either a 4:1 or 3:1 ratio on the disc and either use the solid state or Automotive relays (70A ones work well).
How do you go about boosting the power up from 18V to 24V. I know its somem kind of transformer (A couple of my flat mates had to get a mains Cree LED running of 2 AA batteries :crazy: )
Generally, that would just be buying a 6-7 cell pack instead of a 5 cell pack depending on the exact voltage you wanted.Quote:
Originally Posted by Eventorizon
1400 rpm on the disc? That should be doubled at least to make anything effective (if I read that right).
Do the sums regarding the disc. I assume your design software will give you the rotational moment of inertia of the disc. With that work out the rotational kinetic energy. You should be aiming for something of the order of 800 joules or greater. For comparison, boner/old drumroll gets around the 800 joules mark, 360 I believe is approaching or around 4kJ and my old robot hornet 2 was around the 1.5 to 2KJ mark (depending on the variant). Videos of each can be found on Jamies youtube feed.
One thing I don't like about the design is the fact that the front panels are sloped inwards towards the disc \,/ (comma being the disc), I think they should either be flat or slope the other way. Problem with how it is setup just now is that you are shielding the disc from your opponents. Get a wide flat edge facing the disc and the disc may not be able to make contact and you won't be able to turn into an opponent (one of the best methods I found for making good contact with a vertical disc)
Plus the front looks like satans mutt (as seen on gadgetshow) which looks good... But is a nasty grab point for horizontals... Satans mutt is 4mm titanium on the front... And I've put a big slot in either side with 360 :) one on tv... The other at gadgetshow live doing a demo.
Another downfall in your design could be your self righter... With a mechanical disadvantage like that you'd need alot of force at the actuator... Check out my build diary for the lengths I had to go to, just to make 360s work.
All in all if I were you I'd go for 2wd run of a small lipo, make the robot invertable... Then make your disc around 3kg @ 3000 rpm of speed 900s and a seperate lipo at a higher voltage.
That setup should give you a reliable competitive first robot.... But the choice is totally upto you.
The \I/ a the front was a concept I wanted to try. After years of watching Robotwars and then all the featherweight fights on Youtube It crossed my mind that unless you can protect your disc until it gets up to speed then it is close to useless in a fight. Take Tornado VS Hypnodisc. I was convinced that Hypnodisc was going to win but Tornado never let it get up to speed. The same held true for a couple of Supernovas final fights and S3 if I recall correctly. The \I/ also has the purpose of holding an opponent against the disc and it prevents them from turning away.
The dsign was also linked to a build someone had done in the states where they had put the disc in the middle of the robot's 4 wheels [1 in each corner] with ramps at either end. He has said this was to reduce the gyroscopic effect against turning and apparently it worked wonders, he just could not hit anyone with the disc... not so good.
And the Shrimech was a head ache but it should work. The actuator on its own will lift 750N then that drops to 160N with mechanical disadvantage but thats still more than the robot so... I don't know!
Though of course this is just a load of theory but I thought I could at least put it into practice :)
And I have been lucky enough to see the damage 360 did for myself! Robochallenge came to our local design event at Elvington and (I cant remember the guys name (feel Bad)) one of the team walked me through the build and the design features... was amazing! And they had Venom there to! :D
Extra...
I have just had a chat with the guy from Electronize and he reckons that the FX40HX will be fine for the job despite the stalling as it has inbuilt current and temperature cutoffs that self reset when it gets much for the ESC. He reckons I should be more worried about the motor now cooking itself when stalled... I guess the only way to find out is to try it!
You just gotta be a good driver to get a disc up to speed ;)
Fair enough, it's your machine at the end of the day and you will learn more by doing than us telling you.
So this is a complete rework...
4WD, Disc, runs on 2 wheels when inverted and can still attack. Nylon Base and vertical supports (Black) with 20mm sides and 10mm top HDPE (translucent).
I look to have enough weight left over for a second Speed 900 but I wont be able to run both off 1 40A Electronize so might switch to a solid relay...
Comments?
And I know its not as interesting but I think I will go simple for the first one, cutting the prototype armour for the other one was really difficult!
I would advise going for a soilid state relay anyway. Speed control on a disc sounds wonderful but in the few minutes of a battle, throttling it back is generally never on my mind.
New design is less fancy but looks more solid
Edit - just to add, I would see if you can run the disc lower to the ground so it's only a few mm off glancing it. I did this with boners drum and flippers couldn't get under me. Sure you may have a glancing blow with the floor but the robochallenge arena has a hardox floor so it's not an issue.
Or you could add ramps/wedges to the front bits on both sides of the disk. Then the other robot rides up onto the ramp and you get a solid impact from below the other robot. With a heavy enough weapon you could get some serious flipping action going! Also the flat front edge would be other spinner food, in that sense angled front edges would be advantageous.
Like this from above:
|______________|¦|______________|
|__|_______|__|
¦ being the weapon.
(sorry, can't represent it much better on this keyboard)
I'd agree with the sloped backwards from vertical front, otherwise all looks good
Looks awesome
with a spinner you don't want to over complicate it and have other robots running over ramps or up slopes etc. As far as weapons go, spinning a piece of metal up to high speed is pretty agricultural engineering wise and you want the collision to be the same, as simple as possible.
Yeah I can get the disc closer to the ground, 5mm off the ground should be enough. A ramp at the front would not be to difficult either and I can make it removable so I have a choice over it. What disc materials do people use, that model is currently set for carbon AISI 304 Steel (Its the most dense of the preset steels in solidworks)
omen's disc is hardox, not sure what grade though (can anyone enlighten?). to expand on my previous comment i like the looks of your design i'll be interested to see how well it works.
Here it is, current weight is 12.5Kg thats with no wiring, relay for the speed 900's and the receiver, as well as all the nuts and bolts... I think this is now design 5 version 8 or something stupid...
Well its looking great,
as for disk materials people use Hardox 450, titanium and steel
Looks like a nice design modification. As Gary said, less fancy but much more robust and tried/tested. You've also negated the components, material and electronics for a srimech which is guaranteed to make your life easier as it's one less thing to go wrong.
For cost-to-strength, I think Hardox 450 is the first choice. It's hard by general standards, but as a spinning implement it's not the hardest material around. So if you put a nice sharp tooth/teeth on the disc, it'll have blunted after a few fights. But blunt teeth aren't bad. Boner's teeth have long lost any form of sharpness but can still rip things to shreds. Plus you can always reshape and resharpen your teeth before an event.
Harder materials tend to come from the realm of tool steels. P20, S7 and D2 are the few I've seen used or talked about in combat (although I have no experience of using them myself) but they also cost a lot more to buy and then have machined. If you've got the money though, may as well go for it.
Drumroll's current teeth are a material called Supralsim 690, where 690 relates to the hardness of the material. Compared to the 450 value of Hardox, it's a tougher material, but they've not yet been subjected to enough fight-time and impacts for me to tell how well they last.
P.S. If you're still struggling for weight at any point, the Nylon base is probably a little overkill. Can't remember what you said the thickness was, but I use 3mm aluminium and it seems to be more than capable.
if you can manage to get your hands on some higher grade hardox like 600 or 650 you could make a nice disk from it. a job lot of disks were made from hardox 650 a while ago, i think inertia xl runs one.
by the way, seeing as you've come up with a nice viable design:
http://www.youtube.com/watch?v=RYU8g8FBXCM
tried to embed but the mysterious art still eludes me..
Apparently 650 grade isn't available in thin-ish form and that those discs were made as part of an experimental batch or something (or so the guy from SSAB told us a few years ago on here). So if you want a hardox 650 disc, you'll have to wait for one of the batch to come up for sale, assuming its dimensions fit your needs, or spend a tonne of money on a huge big thick bit of 650 and machine the hell out of it :PQuote:
if you can manage to get your hands on some higher grade hardox like 600 or 650 you could make a nice disk from it. a job lot of disks were made from hardox 650 a while ago, i think inertia xl runs one.
Don't know why embedding is causing a problem for folk. Just click the 'youtube' button below the bold and italic buttons in the posting section and then paste the link between the brackets. So in text form, it should look like this:
[url]http://www.youtube.com/watch?v=RYU8g8FBXCM[url]
I'll just leave this here
http://i0.kym-cdn.com/photos/images/...jpg?1306120444
hmm, it appears i forgot the / in the last set of brackets. you might want to look into other types of wearplate then. i know dillidur goes up to 500.
also give these people a call first, they have loads of hardox/weldox and on site waterjet.
http://www.steelpro.co.uk
thanks gary, that illustrates my point rather well.