Starting on a Robot

[dan500]

Didn't think so - thanks Jamie.
Will most likely be saving up a bit more money then.

I have done a very quick chassis design - I think I'm probably going to go with the box shape with a wedge on the front, nice and simple for a first robot. Should also be able to add a few other features I plan on having quite easily then.
I expect I will have the wheels on the inside and currently the pieces are set to 16mm, but I expect this to change when I see your comments on what material and thickness to use

[typhoon_driver]

Put a weapon on there!!!

An electric lifter is relatively easy to implement and makes battling with your machine so much more intense!!!

[dan500]

Put a weapon on there!!!

An electric lifter is relatively easy to implement and makes battling with your machine so much more intense!!!

I can't put a weapon on at the moment, if you read my first post you'll see why.
But I will probably modify it in the future to add a weapon.

I'd like to get some recommendations on material and thickness for the chassis from a few people before I order.
Will HDPE do, or, as I want it to be quite strong and be able to hold weight, go with something like nylon from the start?
And then what thickness? 16mm?

Thanks a lot,

-Dan

[RogueTwoRobots]

I knew I'd forgotten something! Meant to reply to your last post with regard to material choice but that got lost among the Christmas festivities.
Based on the design you've posted above, I would go for either Nylon 6 or UHMWPE (or the slightly cheaper, but essentially the same, RG1000) and for a thickness, I'd say 15mm should do the job. I'd normally suggest HDPE as well but I'm conscious of the fact you want it to support quite a lot of weight, and I feel HDPE wouldn't be the best option in this instance.

You could also go for a thickness up to 20mm if you wish/can afford it. A 20mm thick chassis of Nylon would be incredibly tough; the first chassis I built from it back in 2007 was still going as recently as September, and although a few threads are stripping here and there and there have been several weight-reducing chunks taken out of it, it could still go for a little while yet (although its current owner does have plans to replace some parts of it).
I only started using UHMWPE/RG1000 in my most recent build and compared to Nylon, it's not quite as strong or as heavy and it wears down faster but it is still a good plastic and a better choice for your purpose than HDPE. Again 15-20mm for a chassis would give a solid structure, so it really just comes down to your budget.

So; Nylon 6 > UHMWPE/RG1000 > HDPE
and anywhere in the region of 15mm - 20mm thickness.

Just my opinion though.
And you seem to have done your research so I'm guessing you know this, but just in case you don't, Direct Plastics is probably your best bet when it comes to buying the stuff.

[dan500]

Thanks Jamie - will more than likely be ordering some 16mm Nylon soon then!
What do you think about me using 2mm aluminium for the top and possibly also the front though? I already have some and saves on getting too much Nylon.

Oh, and how do most people mount their motors? I haven't looked into this yet properly, but thought I'd stick the question on here anyway.

Thanks a lot
-Dan

[team_orr]

2mm ali is too thin, i would get somthing thicker, 6-7mm would be better but again you could be better off getting somthing a bit thicker
also on the motor mounting front, most people use the robochallenge ones (if your using drill motors)

Jack

[gizz]

Hijacking a fewllow roboteer photo: http://i31.photobucket.com/albums/c367/ ... uild22.jpg
If you get 16mm nylon you can make an additional spacer out of plastic or something (the white ring by the motor) and just mount it in the bulkhead as shown.

[RogueTwoRobots]

Yeah, that's 15mm UHMWPE/RG1000 in that photo, and the depth of the drill motor collar bit is usually just over 20mm. The white plastic spacer is HDPE of 8mm thickness (so 23mm total) and the black metal plate on the end with the two screws in it is from the drill. It is usually the piece you have to remove after you have unscrewed the chuck and before you can remove the plastic torque limiter. The hole in the chassis (and white spacer) is a rectangle of size 25mm x 30mm. This allows the collar of the drill motor to just slide through and once the black front plate is screwed on, it holds the drill motor in place very securely. It essentially holds the drill motor in the same way as the Robo Challenge motor mounts but requires a little extra work on the builder's part to cut/drill/file the hole etc...

As for the ali, I agree 2mm is a little thin. I used 2mm chequer plate for a whole chassis once and it just couldn't withstand the constant ramming from other robots. That won't be much of an issue if you're using Nylon for the chassis, but for top armour I'd go a little thicker. I'd say 5mm would be thick enough, but I'm currently using 3.5mm chequer plate as top armour on Drumroll II and it does a good job. Having said that, it hasn't suffered any axe attacks yet but a little bit of good driving can go a long way to avoid being hit with an axe.

For the front wedge plate, I'd say 5mm should be your minimum. Again, I've used thinner stuff on front panels and it just isn't up to the job. The bottom corners in particular can be susceptible to being bashed and bent and that can mean your robot getting grounded if it is bent below the level of your wheels. Thicker material will be less likely to bend, but make sure the way it is mounted is nice and sturdy too; I've seen many front armour panels flying off my robots due to me mounting them insufficiently.