Flipping a few measurements?
 

I will first start off saying I'm not one to reinvent the wheel. I like the way the plans are its just the amount of space that I have is limited and the fit would be better if I can.

So I was wondering what you guys thing of switching the measurements round of the y and x axis. So make the Y axis 8ft long and the X 4ft long. This will allow me to load full sheets from the side. If you guys think that it would be bad the other alternative for my situation is adding another garage door to the side of my shop. Just trying to figure what the easiest choice would be. Thanks

I think the problem would be way too much flex in an 8 ft gantry if I understand what you are saying correctly.

I think you got it. That is what I was worried about. 8ft pretty long to be unsupported no matter what the material is. Adding a new door isnt to hard just figured I shoot this ideal out and see what everyone thought.

there are pleanty of machines that have a looong Y axis, so it is completely possible, however......

you would need to strengten the axis to make it work.

maybe make the machine a bit longer so the ganry is out of the way and you can load it from the front with ease ? The design really lends itself to making it longer without too much concern.

Dave

An 8' gantry is quite feasible within the original design. On drawing 10 20 440 S, increase the tube wall thickness to 3mm [1/8"]

I'm going that route too, however the gantry will have to be a little longer than 8' to be able to cut a 8' sheet to the edges. But I'd like a cutting length of 9'6"-10', so the gantry would be ~10'(3048mm) + 500mm. I guess 3500mm will be good. 4mm thickness or will 3mm do?

I have not built a MechMate, but in mechanics, when you lengthen a span, you need to increase it's strength. As I under stand, doubling the length requires the strength to increase 5 times.

I do not know the modulus of elasticity of the metal beams being used, but I would think that when one increases the size of a part there should be a corresponding increase in strength.

I come back to the origional design, but making it longer where the base is suported every few feet.

Since loading is the issue, maybe drop the rails below the cutting surface ? That adds height, or another can of worm !

Dave

Håvard, I think you will need 120x60 beams, which are going to need some other very small changes. Should make some sketches for you . . . . .

Dave, that 5 times "strength" for doubling in length is a new one to me - normally these things work in 2times, 4times or 8times, a factor 5 is very odd???

Hi Gerald,

no hurry. Just got the laser cut parts from Kim(Thanks Kim!), need to get the cart/trolley finished first before I go ahead with the gantry. Also thinking about major modifications of the table for my use. Will post some sketches soon.

How about long X - axis, with loading from under the rails (no middle supports) ? Same setup as Art from Texas . He was complaining about the rail sag. His x-axis was 12' long made out of 4" square.

Darek

If you use 120x60x2 tubes instead of the 100x50x2 tubes the gantry can be 40% longer and still have the same deflection under the same load. If you reduce just the ends to fit the end-plates, then you do not loose any strength/stiffness: