I live I Cornwall and could go there and bring anything to GSL on Thursday if that's any help to anyoneQuote:
Originally Posted by Eventorizon
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I live I Cornwall and could go there and bring anything to GSL on Thursday if that's any help to anyoneQuote:
Originally Posted by Eventorizon
Can you not do the machine work before you go from the dimensions on the data sheets/ from other roboteers so then its just a relatively simple case of bolting in the motors and soldering the wires when you arrive?Quote:
Originally Posted by Ellis
Would it be possible to pocket out the bulkheads in advance from the drawings? Going with the larger & low RPM motors would be the best remedy if you can fit them.
I had to use rate limiting in the past to stop motors melting - you are probably looking at 20% or less, which will also reduce steering control considerably. Its a good, cheap option to try first.
I know Ellis, sling up a CAD drawing of the bulkhead as it would need to be to take 2 speed 900's. I will try printing a mount for you with 100% fill, and other people can try and work something out as well.
Really, thank you so much everyone for raising your hands and trying to help. Feels good.
I can't really do much of the work before leaving, the closest thing I have to a mill is a £35 pillar drill :). Unless the milling work can be done for sure then buying different motors is academic, there is no way motors larger than about 49.5mm can fit as-is.
Alex, cheers mate, but as before without the milling work too the new mounting plate holes aren't needed.
I'm up for trying dual rates, I just don't know enough about how that works - what exactly is happening there? Does it simply limit travel, so full stick is only partial throttle (or the % of full throttle that you set it)? If so I can't see it helping much, but I can try. Or is it cleverer than that? If it does anything to reduce the amount of power the motor can demand, i.e. changes the pwm shape or something, then I can see how it could get the thing through a few fights.
In the meantime, I'm permanently in the workshop bolting stuff on, all these delays because of issues mean the actual chassis has been left behind. I have now actually properly attached the base and made the drum cutout, the back armour HDPE is also now bolted on, I have done some necessary work on the drum itself, and now I'm about to attempt to make the top cover(s).
After that there's final wiring/cable paths etc, putting the edge on the scoop and making spacers so it fits as it should, making the electronics mounts, and some testing if time allows. Leave early on Tuesday. Oh and I have a lot of work to do on T2 as well.
There are worse kinds of stress, non robot kinds!
I can print what ever shape you need, recessed, new holes, spaces, motor supports, anything :)
You can borrow my mill and tooling if you want to. Snot great but maybe we can ghetto something.
Or could you just file away some of the bulkhead to accodate a wider motor?
How easy is it to fit the bevel gear to a new motor?
If Alex makes you a mount, worse case I'm sure we could mill a pocket into each bulkhead one of the nights to get it running on speed 900's...
That'd be cool. I'll have a look at that possibility later tonight when we do a test on reduced rates. If it functions and doesn't get too hot then then we can run as-is. Also as you suggested on FB, it's easy to lift the back wheels up, that's a pair of button head bolts somewhere near the back.
The good news is, all in sans top covers it comes to 12.1kg, so it should be possible to prevent instant death from above. ;)
I've still got a genuine S900 kicking about that I'll bring with me in case it's needed. But all this talk of different motors and machining is crazy as it's obvious what the most logical and practical remedy is; Ellis, you just need to win all your fights in about 20-30 seconds. Job done ;)
Just called production off, going on 3:30am. Up again to catch a flight in a few hours. Despite several 14-15 hour workshop days neither machine is properly ready. We've had to haphazardly cut out some top protection and make a stab at the wiring for Rango. Comes in at 13.2kg, it works on the bench, had no time to clean anything up or paint anything, let alone do much testing. Seems to failsafe correctly and should otherwise be in the rules, so it can at least enter. It's a bummer, it'll be there, but expect it to go out in the first round in a puff of smoke, lol. I'll get it ready and looking smart for next year. Already got 1-2bajillion ideas.
T2 is still largely in bits and has a partially rebuilt lifter mech, the plan is to occupy ourselves with that once Rango has eaten itself. :P
Thanks again for all the help and support folks, see you all in a couple of days.
Aww, that's a real shame mate! I had you down in the top 18 as well. Whether it works or not, it'll look good in the arena and out of it, can't wait to see it. I'd offer Skyfalls S900s, but they have big pinion gears welded/glued on the shaft.
Aww no, I was hopin that would be a top contender
At least you can try
Still looks great though :)
http://i.imgur.com/n9D4l9K.jpg
3rd place you jammy git
Let me know if you are still interested in those single stage planetary gearboxes - I had a couple of ideas about them overnight that overcome the problems we talked about. Also looking forward to any plans for brushless drive you are investigating.
Lol indeed! It's quite ironic, looking back - and you said you called off the build at 3:30, almost as if it were a sign or something!Quote:
Originally Posted by Ellis
Very solid design, and it's definitely deserving of it's podium finish, because you didn't half work for it throughout... If you can get those flaws sorted for next year, that's going to be a very powerful machine and a tough one to stop! It's a real shame you got caught out a little with the Beauty fight too, it looked like you had him on the ropes at the start...
Still, you got yourself on the podium - congrats on 3rd place, that's a fantastic achievement!
Been a while!
As that super rich Bulgarian guy has yet to transfer his billions into my account (as promised by email), Rango hasn't had any love since the champs. I have various upgrades/changes in mind for next year, but the one thing that remains up in the air is the drive. There's no promise that sensored brushless will work as necessary yet (fingers crossed, Nick!), building a custom planetary extra stage in somewhere is heavy $$$, and there is no drop-in suitable brushed motor that I have found. We're going to be over
to play in September, hopefully taking in MMM, so it needs to be driving. Harry was over earlier in the month and we sort of stumbled across a motor which *might* work in the existing setup.
It's an oldschool RC boat thing, called a Robbe 755/40 (basically a short 775 can). It is rated at 8400rpm @ 18v which is perfect. The downside is that in the kind of boat it would go into they actually want super low power. Robbe say to keep it below 8a. That's 160w on a 5s LiPo, which is less than a pair of 18v 550s (what T2 runs). However the experiment is ten times cheaper than going brushless and fitting in a planetary.
To that end I bought a pair from a German hobby site and they arrived this morning:
http://i1088.photobucket.com/albums/...o/DSC_0003.jpg
As you can see they're smaller (and 150g lighter) than the 885s.
The bolt pattern and front boss are different to the 885's, so I'm modding the existing mount setup to work for these, with making a purpose-built plate in mind should they do well in testing.
The bolt holes had to change from 32mm to 29mm; a really awkward amount. I had to turn and press aluminium plugs for the original holes and re-drill partially across them. The pins and plate aren't the same grade and the holes wandered a little but it's good enough for testing:
http://i1088.photobucket.com/albums/...7072014749.jpg
http://i1088.photobucket.com/albums/...7072014750.jpg
http://i1088.photobucket.com/albums/...7072014757.jpg
Several other bits need making/modding to make these fit but it shouldn't take long. Here's hoping the motors can put out enough power to actually move the robot without melting.
Swiggity motors man. Hope they have enough balls to move the robot.
Why couldn't you have just drilled the mounting holes at 90 degrees to the old mounting holes?
Really cool solution though and good luck with the new motors!
Lemme just get something straight... This is your third featherweight, entering your third UK champs that you called off at 3:30 three days before the first day of the champs... and you came third. That's a bit weird if you ask me!
Looking nice anyway, sure it'll be just as relentless as it was this year.
It could be that the motors are rated very conservatively over a long running time. Most hobby motors are very optimistic with their power ratings, so for the low cost its definitely worth a try!
PS: don't bother with Bulgarians, the Nigerian oil minister will fix you right up with some cash :)
Cheers guys.
@Max: there's too much other stuff in the way!
@Nick: yeah that's the hope. They claim 8-10a for 60sec @12v. Hoping that means it could handle double the draw for half the time. I can sap the heat out really well as they're surrounded by aluminium, so certainly worth experimenting. :)
Also yeah this Bulgarian guy is being slow, what little was in my account has been taken... I assume to make space or something. I'm sure he'll put the billions in soon.
What's the size restriction for motors to fit into the robot and what RPM range do they need to be in?
I might be able to help you out :)
Looking good Ellis mate, I hope those motors work well for you
Look for the dimensions of 885 motors - they are the absolutely largest things that will fit.Quote:
Originally Posted by knightrous
The 885s originally in the robot were 48mm diameter, 83mm length.
Yes please yes please yes please yes ple- :)Quote:
Originally Posted by knightrous
7-10,000rpm on 5s.
The largest cylinder that could fit where the motors go would be 74mm long, 49.9mm diameter. Smaller diameter can be longer, for example a 48mm can could be 78mm long.
This is true, but 83mm is full length minus shaft, the main body is only 68mm long.Quote:
Originally Posted by MicroGravity100
This was the best I could find on a quick break
http://www.ebay.com/itm/New-R775-Ult...item4acd3dbc98
Peak of 240W seems reasonable, so they should have some punch.
Cheers for the link. I've researched far eastern sources in detail. The problem is misinformation. Direct from factory they can give you raw data (I can't afford to buy and ship in bulk), but any level of reseller (aliexpress/hongkong ebay) gives useless or patchy info, often contradicting their own figures or visibly copy-pasting from somewhere else. Western resellers are no better. :P
The ebay link says 240w, but idk what they're calling "max power". If that's max efficiency then it's pretty good.
I found these on ebay, not sure if they're much use to you but they seem to have the specs you're after. ebay item 181451896371
Looks like that seller suffered the same fate I did with the 885s. Pollin sell that motor too: http://www.pollin.de/shop/dt/Mzk0OTg...C785LP_ES.htmlQuote:
Originally Posted by mrsam
Note the RPM/general stats.
Then the datasheet reveals that those stats are in fact at max efficiency: http://www.pollin.de/shop/downloads/D310506D.PDF
Pollin must have indirectly caused so many problems over the years...
I think I have 2 or 3 of those lying about as well