There are a number of reasons to consider a ShopSabre CNC system driven by Ball Screw over a system using a less sufficient drive system like Rack and Pinion. The first reason is the improved wear and tear levels. The Ball Screws on our Router tables are a sealed bearing with many ball bearings evenly spaced and constantly lubricated as it moves through a channel design which is cleared by wipers a head of time to prevent any debris or dust from penetrating the inner bearing. Rack and Pinion has none of this technology and is simply a gear and track that mesh together with no lubrication (Metal on Metal contact). You must apply grease manually to the track which will become contaminated by dust, dirt, and other debris from cutting which reduces the lubricating and increases the wearing of the gear and its track. Over time this begins to wear down the gear/track which means the teeth now become further apart eventually changing the overall accuracy of your table. This is caused by the fact that a Rack and Pinion system must stop on the same points over and over. Our ball screw design does not have this issue because the ball screw again has many ball bearings which have an unlimited amount of contact surfaces the ball bearings can stop on so it wears this system much less and allows your system to hold a tighter accuracy for much longer.
The second reason to consider is the overall accuracy of the machine can be at risk with a Rack and Pinion design. ShopSabre CNC mounts it’s ball screws directly in the center of EVERY axis which allows the cut forces to be evenly distributed throughout the bearings, guide rails, and the frame design which allows you to eliminate the wobble, dog walking, and inaccuracy that many top mounted ball screws and Rack and Pinion drives have. With Rack and Pinion you have 2 motors on the Y axis(long axis) with independent gears and rack which allows for your machine to eventually wear unevenly if you have more work done on 1 side of the machine. As you use your machine the gear on one side may become smaller then the gear on the other side of the machine which can result in a dog walk, wobble, or inaccuracy. The reason you will not have this with a ShopSabre Ball Screw machine again is because everything is mounted on center to improve the results.
The third thing to consider is overall cut forces and machine movements. Center Ball Screw drives allow the machine to apply maximum cut forces to the head and allow your bit to cut more materials at higher speeds without bending, breaking, or twisting your machine like many of the competitors systems. Again Rack and Pinion will not allow for even cut forces because the router head will apply additional cut forces to the motor it is closest to meaning the other motor must adapt its speeds to keep the gantry straight. Many competitors do not have a intelligent enough machine control system to perform this task which means in the end you will be finding yourself slowing your cuts down or re-cutting inaccurate parts. The Rack and Pinion design requires both motors on each side to run the exact same start and stops with cut forces applied against it otherwise any delay in motor reaction could turn into a difference in accuracy between the left and right side. Again ShopSabre CNC uses Center Ball Screws meaning there is only 1 motor driving the center of the gantry giving you better cut forces, better accuracy, and fewer headaches. We are so confident in our Ball Screw Design we have actually had a full grown man pull against our gantry as the machine moved from 1 end of the table to the other and then went back and hit the same cut after the person let go. The machine is built with many of the largest components in this machine class so accuracy is no issue for a ShopSabre.
Choose a design that has been proven by high end CNC systems in the $100,000 price range. Anyone can build a CNC system that cuts the first day but ShopSabre CNC designs a machine that will continue to hold tolerance and perform essential cuts 2-5 even 10+ years down the road.
