AndyUK's Build - 1.2x1.0m Gantry

[routercnc]

Hi Andy,

I think bolting the gantry beams to the platform will be a bit awkward from underneath and will make it difficult to align everything.
Better to bolt from the top side - you will also get a better joint because the bolt will pass through the thin gantry section and tap into the thick platform. These can be cap head bolts, but if tool access it tricky then hex head will be better.

I didn't quite follow your 'square-ish steel plate idea' but if you want to bolt the gantry in place (i.e. without any welding) then better to use a solid block at the top and bolt it to the gantry, and bolt the side plates to that. Will get a nice support from the top of the gantry down to the platforms. The small L corner brackets are not really up to the job.



I think you said as much but make sure the gantry pieces are connected to each other otherwise you don't get the benefits of the much larger overall shape. Either bolt the inner faces together, using a clearance hole in the rear face of the small square to pass the bolt through, or weld them.

p.s. aluminium is 1/3 the Young's modulus of steel, not 1/4. So in like-for-like sizes steel is stiffer. But as aluminium is less dense (therefore lighter in a like-for-like size) you can increase the aluminium size or wall thickness and recover the stiffness and be no heavier than the steel version. Aluminium profile is easier to bolt together, so good if you don't have a welder. But then aluminium is expensive. In short, use what you feel comfortable working with - either can work well.