Ok, So I've built the heavy, and now I am programing the control board. I noticed after doing the settings in the article that in the CNCjs software when I move 1000MM it is more like 500mm....I am using everything that was listed in the heavy build guide.

You probably not set the same microstepping. (a microstepping of "2" means you double the number of steps of your motor to do the same movement} 

Thus in Grbl you have to multiply the resolution (steps/mm) by 2... Or you can choose the previous value of microstepping on your step-drivers. 

Hoping this was useful for you

Fred 

So the build is 1000x1000x1000, but when I move my Y from "home" to the furthest the CNCjs software says it's 3150mm total on the Y axis...how do I configure the device to be true to its size?

i think you also need to check the dimension details of your used leadscrew.... if it is 5mm per round or 8mm.... and  how many steps per full turn you set in hardware for the stepper motor... 800per full turn or 1600... i also have done one time wrong settings on z axis and had double the distance travelled as wanted. I do not know the control software used but there must be some fields to enter these details i assume.

I'm using Nema 17 1.8° 200mm rotation motors and T8 Tr8x2 leads 3 x 1000mm(dual y single x)1x 200mm(z), I set what was given to set in the instructional video on setting up the electronics. 🤷‍♂️

hmm... i think it comes down to checking the microsteps... the screws etc... so if i am right you should have 8mm movement per full turn... now... question is your microsteps... if you have 1/4 and 200 steps per full turn then 800 steps per full turn should be right... that is also what you have to set in hardware with the jumpers on the shield of the motor drivers.... i assume you have checked all this.... if so... then it is the software... i use estlcam...