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**Anttazz** · 9 January 2012, 17:52

Re: Design Dilemma

To save weight, would it be possible to run it from 4WD by using 2 motors and running belts between the other 2 wheels?
Then using something like an XL which hardly weighs anything and save yourself the weight of another ESC too. Also, if you're not using LiPo's you could change over to them and save yourself a load of weight.

**Max** · 9 January 2012, 17:59

Re: Design Dilemma

You could stick with your first design and add hoops (like on the first drumroll) to make it self right. This would be much lighter than your self righter and cheaper! You could also just use 2 wheel drive rather than 4 wheel drive. I also think I remember reading that you are using 2 speed 900s for the weapon you could reduce this to just one or use a brushless setup.

**PJ-27** · 9 January 2012, 18:00

Re: Design Dilemma

I think I speak for a lot of people when I say this but...

GET OFF CAD AND START BUILDING!

Seriously, you will learn so much more and actually experiencing the problems and working with them, fighting with your robot and meeting others cannot be simulated.

There are so many little things you'll run into when building that you just can foresee that'll mess up even the best laid plans.

It's good to have an idea of when you want to make, and a plan to get it in weight, but the knowledge to get that right in theory takes years to accumulate so pick a design and get building.

If you know for a fact that your first design will be over weight then make some tweaks like what Tony suggests.

I like the articulating disk idea though. I suggest you have a maximum of 2 teeth of the disk though, otherwise it'll end up 'grinding' against other bots and never get a good bite. You'll also probably want some more weight in it, although Inertia XL's disk is 2kgs (I believe) and that's very effective.

**Laser** · 9 January 2012, 18:05

Re: Design Dilemma

As Pj said get to an event and look around.

my first robot was useless and I learnt sooo much by going to an event.

as for weight try only 2wd, use just HDPE/ nylon 6, Lipo's

**graeme** · 9 January 2012, 18:06

Re: Design Dilemma

There are prob only 2 full combat events for feathers this year in the uk and they are going to be in april so i would build it for then and then improve it for 2013.

**Anttazz** · 9 January 2012, 18:08

Re: Design Dilemma

Originally posted by Max

You could stick with your first design and add hoops (like on the first drumroll) to make it self right.

I wouldn't, they didn't work and have probably shortened Jamie's life considerably with stress. I remember at RL Edinburgh last year he was having flashbacks when there was a Design your own Hoola-hoop desk

**psycho_fling** · 9 January 2012, 18:16

Re: Design Dilemma

tbf cad is a great tool and if you want to go down the route of machining etc it makes sense, working out the problems etc will be harder but will make things cheaper by using cad

**Eventorizon** · 9 January 2012, 18:50

Re: Design Dilemma

Originally posted by Anttazz

To save weight, would it be possible to run it from 4WD by using 2 motors and running belts between the other 2 wheels?

I have tried belts in the design and I just canâ‚¬â„¢t seem to make it light enough, but I know it works so I am probably doing something fundamentally wrong.

Originally posted by PJ-27

It's good to have an idea of when you want to make, and a plan to get it in weight, but the knowledge to get that right in theory takes years to accumulate so pick a design and get building.

And its not all CAD I have made 4 prototypes, 2 from card and 2 from laser cut wood, the final one is a functioning robot. The reason it got redesigned, again, was that the motors I chose just were not up to battle. Check this link for a video

http://www.youtube.com/watch?v=ISM3dgcBCyw

Originally posted by Anttazz

Also, if you're not using LiPo's you could change over to them and save yourself a load of weight.

I have steered away from LiPols because of the cost and the possibility of explosions, and the fact I cant have them in my rented flat or in uni (stupid health and safety)

When are the 2 full combat events this year? I cant find them on the siteâ‚¬Â¦ only the heavyweight ones.

**Gabe01** · 9 January 2012, 19:16

Re: Design Dilemma

Simple, to make your Robot lighter you need to make it smaller, two motors are sufficient, and then you can almost half the width of your Bot. I am designing my feather at the moment and playing around with the bits. I have built three heavies and you must think compact and small. I remember Ian Lewis shoving his arm and hand into our first Robot, a good lesson learnt

**MikeNCR** · 9 January 2012, 19:18

Re: Design Dilemma

Originally posted by Eventorizon

Originally posted by Anttazz

Also, if you're not using LiPo's you could change over to them and save yourself a load of weight.

I have steered away from LiPols because of the cost and the possibility of explosions, and the fact I cant have them in my rented flat or in uni (stupid health and safety)

If that's the issue, you may want to look into LiFe/A123 systems batteries if they specifically ban LiPo, they're much more stable and still have decent energy density.

**typhoon_driver** · 9 January 2012, 19:25

Re: Design Dilemma

1) have it run on 2 wheel drive. Scrap the 4 wheel drive option, it will drive better with 2 driven wheels on the same axis as the disc. Gyro forces and all that. Skid plate at the back, job done, around a kilo saved.

2) Use lipo. Don't worry about explosions etc, you seem to have your head relatively screwed on so you should be fine. Regarding the rented accomodation.....don't tell them? Keep them hidden, job done.

**psycho_fling** · 9 January 2012, 19:31

Re: Design Dilemma

i like the video

i noticed in its description it says your a product design student just curious as to where you are studying? as i am doing the same course at de mont fort

alex

**PJ-27** · 9 January 2012, 19:38

Re: Design Dilemma

I don't think I've ever seen a short hold tenancy agreement that mentions Li-Po's before!

**RogueTwoRobots** · 9 January 2012, 19:45

Re: Design Dilemma

Lots of good suggestions here. Can't really suggest anything on top of them, but the 2WD suggestion is the best by far. Ewan (Gimson Robotics) built a 4WD vertical spinner years ago but I remember reading on his website/through event reports that he then changed down to two wheels as it made driving easier when competing against the gyroscopic forces generated by the disc. Most of the notable vertical spinners, from Robot Wars through to today, all use 2WD, and for good reason. Also, if you can, keep the wheels as close as possible to the disc's line of rotation. Again this helps to decrease the gyroscopic effects.

Regarding lipos, I was hesitant at first as well, partly due to loads of videos of plebs on the web blowing packs up (as well as numerous vids of them going up in flames in American robot fights) but I've heard the following from several experienced people now: lipos are a perfectly safe and usable power source as long as you respect them, their limits and take the appropriate safety precautions with regards to installation and charging/discharging etc.
They're also not too expensive these days either (just avoid the extremely cheap crappy packs). Like Gary said, just don't tell the uni/landlords. Much worse stuff goes on in these places. Our halls had a zero tolerance policy towards drugs but I can guarantee you they were kicking about in one room or another.

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