Thx paulus.v

I've seen this web page but they don't have any equations or information on timing belt stretch, load capability etc.


Yes I did consider aluminium but only briefly as 1. it doesn't make sens too use it 2. it's too expensive .

ad. 1. If I use aluminium as a material for this gantry I end up with 60% more deflection then with steel, so to make it up I'd have to use 50%-100% more material and I would end up saving 30%-50% of a gantry mass and thus reducing:
gantry weight from 70 kg to 40-50 kg
total X axis moving mass from 150 kg to 120 kg - 20% reduction
total equivalent moving mass from 250 to 220 kg (that is including inertia of motors and gears) 12% of weight reduction for $$$ - see below...
And I would get into aluminum welding that is more expensive and problematic, although I probably wouldn't have to pay for stress relieving.

ad. 2. Prices in Poland are 7$ per 1 kg of Alu and 0,9$ for 1 kg of Steel.
I would save 30 kg so instead of paying 63$ for steel I'd pay 300$ for aluminium. For this 250$ I could buy motors and get much more acceleration or buy Leadshine digital drivers and get much more speed and solve inevitable resonance problems.

As you see although it's very tempting and everyone is using it, it doesn't make sens to use it. I think that aluminium is so popular because most people don't take under consideration Inertia of motors and screws that are much "heavier" then bare gantry.

Thx for the link but since there was no good calculator online I've created my own. It's free for non commercial use :) hehehe
Attachment 11085

According to it I should get good acc and Vmax but I'll see soon how does it work in real life :)

Please keep pointing out better solutions - if I can't defend mine it means that I can make it better.

Best reagards