Thread: Why not use unsupported rails?
Enjoying your stress analysis so far - good work there. I think people are finding the pretty colours more interesting than my old spreadsheet of numbers.
You mention the bed analysis - any plans for stress analysis on other areas of a cnc machine such as gantry sides?
think i missed all the fun here-!
on my build i'm looking to mount the profiled rails to some 120 x 80 x 6 RHS, one side of the frame fixed, the other will be adjustable, and the frame will bolt together to allow for some tweaking and to shoehorn it into where i plan to install it.
will that give me enough adjustment do you think?
also Jonathan, what program do you use for your FEA simulations could be useful for my actual work
I was only thinking of various thickness plates vs RHS. Both cantilevered with one end grounded over an area representing a typical gantry end section (e.g 80x80 extrusion). For RHS the inside gap at the grounded end would also be filled in over the same area as the end of a typical gantry (e.g a spacer) since this represents the best bolted joint.
You are quite right that this is available in the original spreadsheet its just that your pictures are easier for most people to follow, and it is another question that gets asked on this forum. Just a thought since as this is now a sticky it might help newcomers to see the relative performance of common CNC machine designs if the analysis results are all grouped here.
Sounds like a promising start based on the concept so far.
The Following User Says Thank You to ecat For This Useful Post:
Thanks ecat i was just about to go and find those links!
Just to let you know i have moved both those threads (and this one) to the FAQ's, Problems & Solutions forum as that seems the most appropriate place to have them at the momment.
Keep up the good work guys, without letting to much out of the bag, all of this kind of information is going to be grouped and made more readily available in the not too distant future. So thanks, as every little (or greater) helps towards what I am trying to do here for the site.
EDIT: Forgot to say i have also made them "Sticky" should you need to reference them at any time.
Last edited by Lee Roberts; 05-04-2012 at 10:57 PM. Reason: added edit
My little Roland uses unsupported rails, the Z axis rods are only fixed at the bottom end.
Perhaps it is a question of size, quite okay if you don't go wild on the length?
I got one of them somewhere ? Came from a school with dead controller, can jog but not run a program.John S -
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