Our linear carriages are an accurate, effective, and low-cost linear motion system, especially when adjusted properly. Below are step by step instructions for adjusting your carriages for accurate travel and long life. When adjusted properly, these carriages can provide motion that as is accurate as the cold rolled steel rails they ride on (often +/-0.002" or better), and should last for miles of travel before bearing replacement is required.
The first step in assembling the carriages is to insure you have the proper tools and components available. For each carriage, you will need 4 M8 x 30 hex bolts, 4 lock washers, and 2 M8 hex nuts (provided with each carriage sold). A 1/2" wrench and set of SAE allen wrenches is also required to make the proper adjustments. Lastly, the rail that you intend to install the carriage on should be available. It is easiest to adjust the carriages to the rail prior to installation on your machine.
Next, install the fixed bearings in the tapped holes on the wide face of the carriage, with a lock washer in between the bearings and the carriage. Tighten these down completely.
Back out the set screws on the adjustable bearings -- we will tighten these up later as we fit the carriages to the rail. For now, it's easiest to have them out of the way.
Flip the carriage over and put a hex nut in each of the retaining slots for the adjustable bearings.
Install the bolt, bearing, and lock washer from underneath, but do not tighten all the way. You want just enough engaged to keep the hex nut from falling out.
Now place the carriage on the rail (or the rail in the carriage if it is not on the machine) and tighten down the bolts on the adjustable bearings.
Now is when the set screws come in to play. If the bearing does not turn when the rail is moved, it is not tight enough against the rail. If it takes much effort, or if you feel bumps or difficult spots while moving it, it is too tight. To make adjustments, loosen the bearing bolt and loosen or tighten the set screw as appropriate, 1/16 (or less) of a rotation at a time, then re-tighten the bearing bolt. Check fit again. Once motion feels smooth, tighten the set screw against the bearing bolt "finger tight" -- there is no need to apply excessive torque.
When you have completed adjustments, the motion should be easy to accomplish (the system should glide with very little force applied), and all rollers should be engaged, as seen in the video below:
Your carriage is now ready for use. It can be removed from the rail if neccessary, and then installed as part of machine construction when you are ready -- just ease it back onto the rail, and pair it with a piece of extrusion (or plate) and another carriage to fully constrain the rail. To square up the two carriages, it is recommended to clamp a square to the rail, and then clamp both carriages to the rail and square before tightening their connections to the extrusion running between them.