You're right. Also the fact that their drums had lightening holes beside the teeth could also be one of the reasons. However, I didn't remember any of the drums crack right beside the holes but I could be wrong.
Sun Oct 29, 2017 8:40 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
got bored revising for exams;
drew a drum according to my sketch on paper; (about 15 cm radius and 32 wide)
the drum turned out to be like 13kg;
gave up;
Wed Nov 01, 2017 10:44 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
After a few hours of experimenting this design has been the only one that can be about the same weight as the weapon on Abomination and have only 5% less MOI, but I do worry a lot about the structrual strength of this weapon.
Wed Nov 01, 2017 11:34 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
I don't believe anyone has gotten a design like that to work at high RPM - the screwed together connections just don't have the strength. The vertical parts are aluminium to keep the weight down? Its also going to have even more aerodynamic problems than my beater. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Wed Nov 01, 2017 11:40 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
i agree... guess ill just scrap this one.
will probably try a classic egg beater next...
Wed Nov 01, 2017 11:48 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
I think I need some ballpark numbers on this one... how thick is Mr. Mangle's egg beater and how thick is each horizontal bar? For some reason the weight is getting out of hand quickly...
Also the design is getting closer and closer to an overweight Shiny...
Thu Nov 02, 2017 12:28 am
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
If I recall correctly, 30mm Hardox 500 for the monoblock beater waterjetted in Belgium.
Thu Nov 02, 2017 1:20 am
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
The cross section is 30 x 19mm and the weight is a fraction over 3Kg _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Thu Nov 02, 2017 6:44 am
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Thx for the info. Just drew one with a similar cross section.
Which turns out to be around 5.5kg. Maybe my initial design was too wide...
Thu Nov 02, 2017 8:31 am
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Changed the layout of my sketch and made the bot more compact, the width of the eggbeater is now around 22cm.
This allows me to have a larger diameter (18cm) and a somewhat acceptable MOI finally. (just a bit lower than the hollow drum for Contraption) Also beefed the bars up over the ballpark numbers just a bit for safety since this one has way more mass (5.1kg) to stop when it hits something.
Thu Nov 02, 2017 12:54 pm
maddox
Joined: 21 Dec 2006
Posts: 786
Location: Belgium
You want bigger radiï on the corners everywere.
Thu Nov 02, 2017 3:30 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Hmmm... What radius does the egg beater on Mr Mangle have? First time designing such a bot and I don't know a thing lol
Thu Nov 02, 2017 7:43 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
I used a 5mm radius and the beater hasn't broken yet _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Thu Nov 02, 2017 8:21 pm
pilleya
Joined: 31 Mar 2016
Posts: 91
Location: Sydney
Try and make the axle/shaft as large as possible. It looks like it is smaller than the beater thickness at the moment, 30mm bearings are common so that won't be a problem.
Thu Nov 02, 2017 8:38 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
I am only using 20mm bearings to reduce weight & size and the shafts are still like new. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
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