Well, all I'm asking is a test measurement, some engineering data! Why not?
Zat German wrote:This is called "camber" , not pre-stressed. You see this in the beds of those open bed shipping/transport trucks that if you look at will curve up slightly when unloaded.
Camber it might be, it's the tension at the ends that improves the beam's properties. The method of creating the tension is what is known as "pre-stressing" in concrete.
http://en.wikipedia.org/wiki/Camber,
http://en.wikipedia.org/wiki/Prestressed_concreteTLHarrell wrote:This would be a perfect solution for suspending a static load. Since you are probably thinking of a CNC type machine, the stresses involved are not static, therefore this solution would not solve it. Makerslide is a lightweight structural member, with the intent of lightweight machine design. Anything larger than 18-24" unsupported, and with larger stresses (milling and cutting, carrying more than 10 lbs) is outside of the original design intent.
Is there something wrong with getting the test done? I would have done it before posting but the longest makerslide I have in my possession is 420mm long from a Hadron ORDbot and I find it ridiculous to order a 2m extrusion just to perform a test. Even with that I would have done the test, were it not for my fear that if I break or scratch something, a replacement is not likely to be here within the foreseeable future.
I cannot see how a static or dynamic load would change something to the worse, with regard to pre-stressing. At least not before I or others can perform some calculations and see that come out. Engineering is all about measuring and nothing about believing, so 10lbs and 18-24" might be a good general rule of thumb but not proper data for engineering design.
Filling the voids with (polymer) concrete would probably make the extrusion stiffer and improve other mechanical properties too. It would also make it heavier. This is another "good to have" test, if test data can be obtained and published.
EDIT: I'm not claiming that makerslide will become ideal for CNC milling or anything else but, because it is an open source/hardware design, it would be so useful to have some data published. You never know by whom and how it can be used.
EDIT2: The reason I'm talking about pre-stressing is because it might prove to be a cheap and non destructive method of re-enforcing makerslide in applications that might need it. The same extrusion can be later used in other applications by just releasing the end nuts.