How to prevent breakage in the future

My current set up uses the 25mm kit with a DeWalt 660 with a 24" x 24" work space. I primarily use it for milling wood (pine) and foam. I read the install instructions and reviewed comments in the forum in reference to tightening the screws and bolts that contact the 3D printed parts, as I have never worked with 3D printed parts before.
After about two months of on / off use both tool mounts snapped and I was able to purchase replacements. Today both Z brackets snapped dropping the Z axis right into the project. I was wondering if there was anything I could do to prevent this in the future.

Either those parts were printed poorly or you over tightened them. It is plastic and it does grip metal well, you really do not need much tension I promise.

Ryan, is it possible to purchase these parts? I purchased the entire kit and additional mounting brackets from this site, but there is no option to buy other pieces that I can see.

Sure.

If you want to either PM me or use the contact for to give the email you used I can send you an invoice.