Quote Originally Posted by Gustave View Post
I am also thinking on making the two side plate of the gantry in steel instead of 20mm aluminium to limit the cost. Have you an opinion on that ? What the minimal thickness to be equivalent to 20mm alu ?

Best regards
I wouldn't go less than 10mm in steel thou in theory 6mm would do the job as it's only for the cross brace but it's the resonance why I would use 10mm, unless you braced it up with a few Vertical strips.
To be honest I would use 15mm aluminum plate not 20mm for that part. Again could even get away with a 10mm aluminum plate but I wouldn't for resonance reasons.