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I'm contemplating a CNC Router build soon, but have not settled on a design.
If I was to build a Moving Table design, pssibly using steel, if seems to me that the weak link would be the single stepper on the Table?
Is is optimal to use dual steppers,as well as 2 linear rails on a moving Table? Not sure 'optimal' is the right word, but anyway.....or is it a waste of time and money with no real gain?
If so, what would be the best layout?
This is one of the designs I am looking at:
At that rail spacing dual motors would be a waste imo, At least if the concern is racking.
Thanks...so preventing Racking is the only time dual steppers would be used?Quote:
Originally Posted by cyclestart
Hi Sterob - Its not the job of the drive to prevent racking., That's the job of the bearing system. Dual drive is only used if more torque is needed rather than using a bigger motor for some reason eg keeping the profile lower. But a single drive is always preferable over a dual drive. Why would the single drive be the weak link? Peter
For a moving table design, single vs dual isn't much of an issue. But for a moving gantry, I see an awful lot of dual motor designs. I'm no expert but it sure seems like a single motor moving gantry could rack pretty easily without some way of driving each side. Then that becomes a question of complexity, I think.
Hi Phil et al - Moving gantries do not have enough bearing spacing to be stable. The moving table in Sterob's image has a square bearing pattern which is geometrically stable. Gantries are so wide that we can't have the bearings spaced that far apart otherwise the machine would be huge. I have had motor pulley slips on one side of the gantry and they rack really bad even when the gantry is very stiff. So a moving gantry machine is a compromise in the area of bearing stability that has to be countered with dual drives, a countershaft or a single under or over drive. The price you pay for a bigger envelope, moving gantry. Peter
It all makes sense...thanks guys.
I never thought about the lack of spacing between the rails and the ball screws on Moving gantry designs....I do now...lol
So a Moving Table design, as well as easeir to make ridgid, can be simpler, ie single Y axis ballscrew.