[Momentz]

HI
I am going to be starting a new 4x8 build soon, and i will be doing a welded steel base, what i am wanting to know is how far can i span the steel.

Here is a picture of the machine that i like the look of and that i will be making the base similar to, its a camaster stinger, if you look at the picture you can see that it only has 4 legs and so it has a span of roughly 3m from front to back, i am making my machine out of 100x100x6mm (4x4x1/4in) so i am wondering, would i get any flex in the middle or sagging? from having a gantry that will weigh in the ballpark of 120kg?

Attachment 199896

The reason i would like to do a similar design is so that i can put my motors and gearboxes underneath the machine instead of hanging off the side, so if i put legs half way down i wont be able to do that.

Thanks
Chris

[arizonavideo]

How large is more about what you plan on cutting and how hard you'r going to push things.


I did find a nice video of a bunch of the Cammaster routers and some of the work done. They look fine with many using a single R&P in the middle of the underside of the table. You could copy any and they would work.

camaster machines - YouTube

[Danny1978]

Hi Momentz if you are using dual rack and pinion you could stagger some middle legs to the inside of the tube to stabilise the centre of the 3 metre lengths and attach the rack to the underside of the 3 metre tube that way you can still run the motors underneath and gain stability in your frame,I'm in the process of building a heavy duty moving gantry machine using 125*125*6mm tube my frame is just over 2 metres long and I have used a middle leg,but saying that my gantry is around the 200kg mark. If your anything like me the look of it also matters but sometimes you have to put the good looks behind and go with what will work the best.

[pippin88]

Having built a router with a middle drive for the x, I wouldn't do it again. Much better to spend the little extra on driving both sides off the gantry and have a must more solid machine without racking.