Quote Originally Posted by Juranovich View Post
I've planned on using a 250mm span between the outer ends of the square linear rail carriages and as it stands right now the arms would look like the blue lines in your sketch (though if cog is centered with centre of carriages the bit would fall outside or just on the outer edge of the front carriage). For reference the alu extrusions are 45x90.
If it helps I use 300mm wide plates with this design.! Anywhere between 250 and 300 will work ok.
However, keep in mind how you are going to fasten the profile to the plates and fasten the plates to the bearings if going with gantry on rails setup.! It's easy to forget things like access to bolts or one blocking another.!