Luthier CNC

[Voicecoil]

If I were you I'd stick with 15mm (or even 12mm) on the gantry sides and add some reinforcement ribs (say 40mm tall) all the way up along the edges (40x15mm flat bar for instance) - if you do the sums it works out much stronger than thicker flat plate. Aluminium Warehouse are not bad for plate, even if not the cheapest and having had a slightly checkered history with some of us on here, at the moment they are giving good service, cutting plate VERY square and generally 1...2mm oversize: to select the cast stuff click on "grade" and select the bottom item from the drop down box.
If it were me I'd also be adding some plates top and bottom of your bed frame members to form like a "sandwich" structure and tie it all together in X and Y - though I can see that might have some weight problems for you.

[bluesking]

If I were you I'd stick with 15mm (or even 12mm) on the gantry sides and add some reinforcement ribs (say 40mm tall) all the way up along the edges (40x15mm flat bar for instance) - if you do the sums it works out much stronger than thicker flat plate.

That was my feeling too - If I can spread the cross sectional area of those gantry sides that would be better than basically just adding more mass. I was just going to bolt some 45x45 extrusions to the outside of the plates. Easy to align and not a lot of extra weight.

Aluminium Warehouse are not bad for plate, even if not the cheapest and having had a slightly checkered history with some of us on here, at the moment they are giving good service, cutting plate VERY square and generally 1...2mm oversize: to select the cast stuff click on "grade" and select the bottom item from the drop down box.

Very useful information - I didn't expect the cuts to be oversize - hell, when I have bought pre-cut sheet wood/mdf I expect much better than that! May not prove to be that critical though if I can at least drill all the holes accurately relative to each other. Even if the measurements are out, maybe they will be consistently so, such that two pieces of the same spec are the same size, even if its not the right size!

I do have a table saw and maybe if I buy the right blade I may have to take the plate cutting into my own hands - but I'm a little concerned about cutting it square enough - its not a precision table saw by any means! I'm scared enough of the table saw when cutting hardwood - don't know what to expect with aluminium!

If it were me I'd also be adding some plates top and bottom of your bed frame members to form like a "sandwich" structure and tie it all together in X and Y - though I can see that might have some weight problems for you.

Yes, I may just plonk a single plate on top. I was going to use a couple of layers of 18mm MDF here but might make the lower one of them aluminium. Putting one below the frame will mean some redesign and yet more gantry height plus hinder what little access I have to the drive mechanism - I'm already worried about how I'm going to retension the pulley belt under there.

[Voicecoil]

I do have a table saw and maybe if I buy the right blade I may have to take the plate cutting into my own hands - but I'm a little concerned about cutting it square enough - its not a precision table saw by any means! I'm scared enough of the table saw when cutting hardwood - don't know what to expect with aluminium!

Cast plate cuts quite nicely with the appropriate blade if you keep it lubricated (WD40 works OK) - just take it steady. Provided your saw is rigid enough you can do quite good work if you spend the time to get it set up square.

[bluesking]

Cast plate cuts quite nicely with the appropriate blade if you keep it lubricated (WD40 works OK) - just take it steady. Provided your saw is rigid enough you can do quite good work if you spend the time to get it set up square.

I've gone through the design with a fine tooth comb and it seems there is only one plate where the dimensions are critical. If any of the other plates are cut a mil or two oversize it won't make any difference.

Also, costings show that I would pay more for uncut plate of adequate size than I would pay getting aluminium warehouse to cut everything for me.

I'll probably just go with the precut cast plate.

I've given up on a plate for the tabletop - aside from the weight - it'll cost rather a lot. A piece of well attached MDF will suffice I think.

[A_Camera]

I do have a table saw and maybe if I buy the right blade I may have to take the plate cutting into my own hands - but I'm a little concerned about cutting it square enough - its not a precision table saw by any means! I'm scared enough of the table saw when cutting hardwood - don't know what to expect with aluminium!

Cutting aluminium on a table saw is no big deal. I have a Bosch GTS 10 J and with the Bosch blade made for cutting aluminium, it cuts aluminium like butter. Squaring the saw took some effort, but now it is square enough for this type of work. It is though messy to cut aluminium, so a shop vac is a must.