Starting Point

[zoll]

Re: Starting Point

Weapon wise, I like the sound of an axe but im not sure on the particalities of this? Also I have fairly limited equipments so if anyone could suggest a good material to build from it would be a great help

[RogueTwoRobots]

Re: Starting Point

I'd say HDPE or Nylon. HDPE is relatively low-cost and easy to work with as you can use basic hand tools to cut/drill it etc. It's also a great form of armour against spinning weapons as it absorbs some of the energy from the impact and, depending on the weapon type and speed, all you will be left with is a gouge in the armour. HDPE can also be used for bulkheads/structural supports but I wouldn't recommend it as it's quite a soft material so can deform under some of the stresses exerted.

Nylon is more expensive and stronger than HDPE but you can still work on it with hand tools. It can be used for armour but I'd recommend it more for structural components. It's heavier than HDPE too, but use it in something like a bolted bulkhead structure and you've got an incredibly strong chassis.

I've used both materials in two different robots and while the Nylon one cost more and took more effort to make, it's still going after two years. The HDPE had to be scrapped after two events. In its defence it took more of a beating from spinners and the Nylon one has steel armouring the back, but in general terms of internal strength, the HDPE one was not as good.

I'd have worded this more clearly but I'm off to a lecture shortly, so in summary I'd recommend Nylon for a chassis with HDPE for armour. If your budget is tighter go for HDPE for it all, but expect it to need more maintenance.

There are of course different options such as steel, aluminium etc but I've suggested the plastics as they are generally cheaper yet still endure the rigours of combat well.

http://www.directplasticsonline.co.uk is where you can find prices of Nylon (it's Nylon 6 you'd be after) and HDPE as well as other engineering plastics

[craig_colliass]

Re: Starting Point

Hi I have a Heavy weight robot The Saint that has used 12mm UHMWPE (similar to HDPE) for the wheels it has been axed by THZ and Thor with no problems at all and I now use 20mm UHMWPE for the top cover as it has proved to be more durable than 5mm steel armour and half the weight!
I love the stuff for making robots, if you look on the builders diaries for The Seraphim this robot is made entirely of HDPE and the stuff I quite often use is called RG1000 from direct plastics they are very good.
It is easy to cut (sharp wood saw) drill and with some heat you can bend it!
Have fun

[banana_man]

Re: Starting Point

My featherweight, Blitz, is made entirely out of 10mm HDPE. It has no additional structural components, but can take
all the beatings you like from any type of weapon I have encountered. It's cheap, easy to use,and if you use it well it
is super strong. You can also weld HDPE using a special nozzle for any heat gun and some HDPE filler rod.

[zoll]

Re: Starting Point

Cool, HDPE seems the way to go then, apart from welding how easy is it to make good joints?

On the weapon front so i can start making a final design does anyone know of basic weapon guides? (Axe or flipper are probably my prefered choice but may be too complicated)

[muchalucha]

Re: Starting Point

If you dont have access to a welder , which i doubt you do :shock: . I have never had problems with wood screws, never had one rip out of hdpe yet. For something a little stronger , cant go wrong with bolts and washers. Unfortunately hdpe cant be tapped so you will need to use nuts. To join 2 pieces togethor at a right angle use a bigger block of hdpe or use some andgle iron or box section as mounting blocks . Its really lovely stuff to work with . Sounding good so far !

[zoll]

Re: Starting Point

Got a message from Rick Mass back saying he can make the XXL for me but has never run 4 drill motors off it so not 100% sure it will be ok. He says:

I€™m not 100% sure that 1 XXL can power up 4 drill motors, because drill motors can draw high currents.

The biggest motor that we use in combination with an XXL in our robots are speed900 motors, they got the following specs:



Nominal voltage 12 V
Operating voltage range 6 ... 40 V
No-load rpm 6500 min-1
No-load current drain 1,1 A
Current drain at max. efficiency 8 A
Current drain when stalled 54 A
Max. efficiency without gearbox 71 %
Length of case, excl. shaft 85 mm
Diameter 51,5 mm
Free shaft length 15 mm
Shaft diameter 6 mm
Weight 645 g



Do you know what the drill motors are drawing at current in stall?

If you know that then we can see if 1 XXL is enough.

Anyone have any opinions of this for me?

[banana_man]

Re: Starting Point

If you do not need to undo the screws, HDPE can be tapped, but the thread may give way under a very heavy load.
As such, it is fine to tap and bolt hdpe as long as it is not holding on something like an overhanging panel that could be ripped off.

[zoll]

Re: Starting Point

Thanks for all the help on that, whats the standard thickness to buy 10mm? and can anyone give me any advice on that speed controller so I can order it if its any good. Again many thanks

[muchalucha]

Re: Starting Point

Looks like your only real option for an esc is 2 sabertooth 40 A. I hate them , but many people have used them for years with no problems. You will need 2 as they are only signle channel , but these will drive 2 drill motors each and should do what you need done .

As for the hdpe , for structural parts id use very thick hdpe , or 10 mm nylon or similar , for the armour , unless you plan to put this up against a lot of spinners , 6 mm hdpe will be fine.

[typhoon_driver]

Re: Starting Point

I think you mean electronize 40A and yes they last forever, still got a pair that are around 5 years old that work fine.

Nylon for bulkheads (10 or 12mm) and hdpe for armour, 8mm will stand up to most spinners but 6mm will do you fine

[RogueTwoRobots]

Re: Starting Point

As mentioned, the best bet that can at least guarantee successful running of four drill motors is the Electronize range. Specifically you'd be wanting two of the 30A units that can be modified by having their internal relays replaced with some bigger external relays rated at 40A which helps ensure that your controllers are less likely to be damaged from being over-stressed.

Technobots used to offer this product (the speed controller with a pair of external relays and any modifications necessary) but due to lack of demand they do not stock them anymore. You would have to contact Electronize directly (http://www.electronize.com) and ask if they could supply you with modified controllers. They don't provide the larger 40A relays though, you would have to buy them yourself. You can get them from Maplin or Technobots:

http://www.technobots.co.uk/acatalog/On ... s_360.html

(the 12V ones, and you would need two per controller, so four in total for full robot drive)

I will admit though, depending on how tight your budget is, that this option isn't necessarily cheap. I believe you'd be looking in the region of £100 for both controllers and relays. But Christmas is coming up, so let Santa know what you're after :wink:

[zoll]

Re: Starting Point

If I stretched to say £150 would there be anything good that I could use straight out the box and would last?

[psycho_fling]

Re: Starting Point

i'd go for the controller i suggested early i think the controller will be able to deal with 4 drills

[psycho_fling]

Re: Starting Point

pm sent