I am new to CNC and I recently purchased a used Shapeoko 3xxl. The gentleman that I purchased it from fired it up and went through the operations before I bought it. I now have it set up and loaded the correct parameters (I think!). When I initiate the machine, it sends the spindle to the back right position and runs through the motions as it is supposed to, however it then brings the spindle to the front of the machine and about 7 inches to the left of the right corner on the x-axis. I’m very confused and can’t seem to figure out why it doesn’t stay in the back right corner. Any information would be greatly appreciated! Thank you!
Sounds like a configuration issue. Try running the configuration again. Make sure you pick the XXL and the Z axis you have. You have a choice of Belt Z, Z-Plus or an HDZ. On the SO3 the Belt Drive Z and the HDZ run in the same direction and the Z-Plus runs in the opposite direction. So if you have an BeltZ or the HDZ the initialization will start with the Z going up to the homing switch and then proceeding to the right rear corner. Then depending on which CM you have and if you have a BitSetter the router will come to the right front corner and wait. If using the current CM you can then set your X Y and Z origins that match your CC file. Then the router will move to the BitSetter and plunge twice and then come to rest just to the left of the BitSetter.
So re run the configuration with the correct configuration.
If your configuration is correct you could be losing steps due to belt tension. Get the gantry all the way back or all the way forward and put your finger under the two y belts. They should feel like about the same tension. Then with the Z at one end or the other do the same to the X belt. All should feel about the same tension.
If the belts seem tight then power off the SO3 and slowly move the gantry all the way back and all the way forward and it should move smoothly. If you move too quickly it will sound like the belts are slipping because the stepper motors create back emf so move slowly. If you find any tight spots find out why.
The v-wheels at the bottom of both sides of the gantry should move the gantry slightly without the v-wheel slipping. If it does not move the gantry then tighten the v-wheels by putting a wrench on the hex head eccentric and slightly loosen the metric bolt and move the wrench to get the v-wheel tight and hold the hex head while tightening the bolt. Not holding the hex head will cause the eccentric bolt to move and over tighten the v-wheel. There are also two v-wheels under the z and test them the same way. The v-wheels should feel snug but not distorted. Also the v shaped piece of the rail the v-wheels ride on can become dirty and a white 3m finishing pad will clean them. You can use a stiff nylon brush to clean the v-wheels if they appear to have a lot of debris attached to them. Clean the rails and v-wheels before trying to adjust them. Only the 4 v-wheels on both sides of the gantry at the bottom are adjustable as well as the Z. The top v-wheels are fixed and are not adjustable. ’
Sometimes things like the router cord or a dust collection host can cause the gantry to not move smoothly.