Box section chassis's

Hi all,

advice needed please, in mid build of my first feather weight. My original idea was to have a complete build from HDPE but having recently met a metal fabricator who has kindly offered to build my chassis for me for near to peanuts..

So to my question, what are peoples thought on a chassis made up in box section? i.e like a car chassis with panels attached after. I was thinking this idea so i could literally plant armour (more than likely ali ) to the outside of it, if it got damaged simply unbolt the the armour and refit a new panel in.

any thoughts and suggestions are welcomed

cheers all

http://teamtarka.co.uk/wp-content/uploa ... C_7348.jpg

Im bad at explaining what i mean sometimes so hopefully this picture helps. haha
Frame would be made like that and armour then planted after. :D

It's a fairly standard way of building a robot. A lot of the newer machines go for monocoques (sp?) however a box section chassis is certainly a standard way to go. Just make sure you don't make it too heavy. 10mm by 10mm box section should be adequate.

My first 2 heavies had a box section chassis. (andProject Onenot much more than that)Box section chassis have advantages, and disadvantages.
Main advantage. Cheap stuff and easely worked. (on the other hand, not many people have acces to cheap ali welding).
Disadvantage. Weight. Even in ali.

Let me ask you a question. What is the purpose of a chassis?

My main purpose for going for a box section chassis is the fact armour can be easy replaced/ Adapted for different battles, it also helps incorporate my self righting/ low powered flipper. I will be posting a build diary soon. Flipper will be front mounted similar to the likes of Firestorm. shape is a low wedge very similar to Rukia (fw) but flipper is obviously hinged differently.

But why would you support the armor with a box-section? The armor should be strong enough without the box section, or not?

Its more to to with the shape and angles i'm planning on doing, and the key factor that i cant weld so say the armour used on its own welded were to get badly damaged i couldn't simply fix it myself, unless it was just dented then a hammer would come in use ha, long story short easier for maintenance from my end, simple unbolt/ unscrew damaged area and plant new piece of armour. I hope this is making sense?

Yep that makes sense.
If you weld your armour into a unibody and the armor gets damaged you are stuffed, especially if its something like Ali or cheap steel that most machines now can cut with relative ease.
With the Box chassis you can bolt on thick layers of light weight material [Wood, HDPE etc] and keep changing it, in the knowledge that its fairly cheap and you are saving your main chassis from getting twisted.
[This is coming from the team with 2 unibody machines :crazy: ]

Eventorizon you hit the nail on the head and have taken the words straight out of my mouth. The main point being is trying to save on cost in the long run, poor wages and rent pretty much dictate this for me :D

Well if its any help, my first machine was effectively a unibody HDPE box, and it did fine until it met NST. The key things I learnt were not to use screws but to use bolts and combine them with brass inserts designed to bite into the material you are using. Try not to leave any 90dgr corners for spinners to latch onto and make sure that you leave some kind of give or flex in the machine so that the force can be dissipated else where, not just at the point of contact.
My machine was so stiff that NST shattered it to the point where it was being held together by a single screw.

Having a box section chassis can be very heavy and easily push you over the limit, however as long as your machine isn't pneumatic you should be alright using it. I would advise thinking carefully about the design of the chassis to keep it minimal and use steel angle or even steel flat section in places which don't need so much strength.