Gerald, I have a question that may be obvious but I just want to make sure. Is the spring the only thing that prevents the gantry from "riding" up or down under pressure? I know the gantry rides on the v bearings/rails but there doesnt seem to be anything to keep the entire gantry from lifting up. Does the R and P perform this function as well as drive the gantry??

Thanks!!

Jim

Jim, you haven't considered gravity. The gantry is non-trivial in weight, especially compared to the vertical forces of a cutter that isn't being abused.

In the cases where the spring plus the weight aren't sufficient to overcome the vertical forces, it's a very good thing to have the gantry ride up and relieve the situation. Especially if you have proxy sensors, since one of them will fire (unfire?) and hopefully cause a machine shutdown.

Brad,
I have frequently tried to run the machine feedrate past it's ability to cut and have been happy to see the gantry ride up and shut down the machine. When doing 40+ hours of 3d cutting in a really hard surface it's nice to know the machine is sometimes smarter than the operator trying to make it do more than it should with a dull shaper!

How to join two racks together?
 

Dear All,
Assume, I have rack-A at length = 1500 mm and rack-B at length = 1500 mm. M=1, If I need to use the total length of rack = 3000 mm,
I would like to know how to join rack-A and rack-B at the end rack together.
Pls help advise.

Mongkol

See drawing M2 10 110 W

Preloaded rack question
 

Hi All,
Just about to start my Mechmate build and on the preloaded pinion side is it only the 12Kg preload on the spring that stops the pinion trying to climb out of the rack?

The 12kg spring load gives about 20kg load at the pinion due to the leverage effect. This has been found to be enough force to prevent the pinion gear from climbing out of the rack - the motor will stall first.