Quote Originally Posted by peteeng View Post
Hi MR - Are you going to make moulds for these parts? Aluminium or steel is the stiffest and cheapest source of stiffness you will get. If you use fibreglass for instance it will be difficult to get to half the stiffness of aluminium. I'm involved with a project at the moment and we made FG parts in an autoclave and got to 30GPa which is less then half the stiffness of Al. These were for a structure that requires high voltage insulation so FG is the go. If you infuse FG you will get to 20-30Gpa. You can infuse in your garage. If you use carbon fibre and infuse or use autoclave you'll get to 60 or 70GPa which is same as AL. My point is that if you can machine the part out of Al or Steel there is no reason to go to a composite. If the shape is complex, difficult to machine then there are reasons to go to composites. By the shape of the original model is it going to be cast? Cheers Peter S

When you compare stiffness there are many aspects that have to be considered. In every case sandwiched construction is lighter and stiffer than uncored structures. The final product is going to be as follows.

The bed will be Advantech Flooring which is dense, stiff, and dimensionally stable. More mass in the base is desirable as it absorbs vibrations.

The bridge will be cored aluminum skinned structures with a total of 1/2' of aluminum skins and 1.5 inches of end grain western red cedar. Some people have expressed concerns about thermal expansion differentials but this machine will be in a controlled environment.
The YZ plate is 1/2 aluminum, and the Z Plate is 1/2 aluminum.

The construction is coming along well. Using aluminum plating for the skins is good, as you all know it utilizes the natural flatness of aluminum extrusions.

We have a lathe, a mill and a shop full of industrial tools. I really have to give credit to people that build theses things in a home garages. You can see why so many of them are built using T Slot extrusions.



I will be posting some pics soon.