Help choosing some steel?

[helihurley]

I need to get some steel tubing to start building chassis for robot and can't decide what to go for. I know I need it strong but the lighter the better.

My initial thought would be 25x25 steel tube, not sure weather to get 2mm,3mm or 4mm wall thickness though.

Any one with experience building heavies got any suggestions what to go with?

I tend to cover the chassis in as heavy a steel/hardox plating I can fit on without going over weight.

[psycho_fling]

tbh a lot of heavies just use the armour as the main structure well designed armour means no need for an internal structure

but if your design requires it then id say 25 x 25 2 mm is good maybe even a thinner wall....presume by your dimensions u mean square box section ?

hope this helps

[helihurley]

Yeah I meant square box. I don't think I could make it using just armour.

So do you reckon 25x25x1.5 would be strong enough then if it were well designed.

[psycho_fling]

yeh id say so but thats just my opinion ....if u weld the joints properly as in 45 angles to make a corner should be ok but obviously the thinner you go the hard to weld

[helihurley]

Does anyone know if it would be better to go thicker wall and maybe 20x20 box.

[blazerbotics]

I Use 20x20 2mm wall in Merlin, all depends on the armour that you put around it.

[typhoon_driver]

either 20 by 20 or 25 by 25 with a 2mm wall thickness will do you fine. I have used 3mm 25 by 25 and it was just too heavy.

[maddox10]

2mm wall is fine to be welded. Of course, MIG or TIG is easier than stick.

Project One andProject II: Hexemhad a frame of 40*40*2 box section, with -if possible- the cross section so the most impact forces were handled with the 40mm side in the same line. In Project One I made the mistake to weld the frame, and then getting the fun job to drill holes in a completed frame because it was overweight.

In Project II we predrilled the box section with 22mm holes with 32mm between centers .
33 holes the meter , giving us 400 grams gain on 1.7 kg. A lot easier working then drilling the frame after welding.

[helihurley]

Any recomendations on where to buy from. I have searched the interweb and found plenty of places I could get it from but the price varies by so much I was just curious as to what I should be paying.

Going to go for 20x20x2.

[typhoon_driver]

Look for a local stockist in the yellow pages. I have bought box section and tubing off these guys before. Wasn't so fussed about price, more about delivery as I didn't have an easy way of transporting full lengths which I needed.