Team MedBots

[Eventorizon]

Looks alright over all, you need to radius or chamfer those back corners though. Ditch the HDPE over the hardox, if you have 6mm Hardox you won't need it.
Don't use HDPE for the drum whatever you do, it will turn to a black twisted mess the moment it hits anything. Any of the good Alu grades will to: 7075, 6082, 6061, 2014. Check out 720's battle against NST and look at the hole HST made in its 7075 Alu drum! Now imagine if that was HDPE; it would probably destroy your weapon.
GR02's are no longer in production so you would either need to go Ranglebox or Banebots, either of them will do fine though the Banebots are much lighter but more costly.
All this said, Jamie, Dave and Guilherme are the people to go to for proper drumbot advice, they know their stuff.

[Max]

Looks alright over all, you need to radius or chamfer those back corners though.

Which corners do you mean? You mean the 90 degree foods in the armour at the back?

Don't use HDPE for the drum whatever you do, it will turn to a black twisted mess the moment it hits anything. Any of the good Alu grades will to: 7075, 6082, 6061, 2014. Check out 720's battle against NST and look at the hole HST made in its 7075 Alu drum! Now imagine if that was HDPE; it would probably destroy your weapon.

Hmm, I thought the HDPE drum would attract criticism, in some ways you think if an aluminium drum is going to get destroyed you may as well make it out of something easy/ cheap to replace! But obviously if it falls apart during the actual fight its a probes as then odds are you are not going to win the fight, just needs to be strong enough to survive so maybe aluminium would be the way to go, another option I guess would be nylon for increased rigidity but that may be too brittle and still has a lot of the issues.

At the moment the drum is solid material, there is no shaft going all the way through but a separate, 40mm shaft at each end so the plastic ought to be fairly rigid. This does mean I could use the aluminium and just bore a hole through the centre to save weight but ideally I want the walls to be left as thick as possible to avoid the drum getting crushed/punched through.

Perhaps a composite drum could work, metal centre to give rigidity and plastic outside or visa versa.

GR02's are no longer in production so you would either need to go Ranglebox or Banebots, either of them will do fine though the Banebots are much lighter but more costly.

Yeah I realize the GR02s are out of production so would be a matter of trying to get some second hand ones, depends really on the cost of the RangleBox units which hopefully we will find out soon.

@Jamie: yeah the belt isn't shown but will run directly onto the drum, hadn't thought about the heating issue, didn't realize it would get that hot! And if I were to go HDPE I would have to give some thought to how the teeth where mounted, I was thinking of counterbored bolts in the teeth going all the way through to the other side then into a threaded hole in the tooth on the other side. Alternate bolt direction to keep drum balanced.

[Eventorizon]

Which corners do you mean? You mean the 90 degree folds in the armour at the back?

Yep, they are very vulnerable to horizontal spinners.

In Solidworks you can assign materials to different bodies so you don't have to do your calculations manually.

Asigned Materials C3 01.JPG

If you right click on a body, materials, edit material, then choose one from the list.

Asigned Materials C3 02.JPG

Then you can go to the Evaluate tab and then go to Mass Properties. It will break down all the body masses for you, give you the total and show you the centre of mass.

The reason I said steer away from GR02's is that their will come a point where there are no more left and suddenly your bot wont work. If something breaks you have no way of replacing it. You are best to design around a part you know is still in production and leave what remains of the GR02's to the machines that already rely on them.

[Max]

Ah ok, I've always just gone into mass properties for each part and manually entered the densities but your way is much easier, I knew there must be a way!

As for the folds at the back I will have to see what radius I can bend them, not sure exactly how this hydraulic bending machine works so my plan is to start with the hardox and bend it then adjust the CAD to match whatever radius I get before making the rest of the parts to suit. I will ask if they are able to do a sort of chamfer bend with 2 45 degree bends spaced 10-20 mm apart.

Oh and on the GR02s my main plan is to use the new Ranglebox motors but if they cost an arm and a leg I will have to find an alternative, my hope would be that other people woudo switch to the new motors making some 2nd hand GR02s available. But I was just curious how mario mounted his wheels as I imagine a similar thing could be done with the Ranglebox ones.