How to measure the screw of THK ball screw purchased from the merchant： To measure the size of a ball screw, the following steps are usually required: 1. Prepare measuring tools: You need to use some measuring tools, such as micrometers, calipers, external diameter micrometers, etc. Make sure these measuring tools are accurate and reliable, and calibrate them before use. 2. Choose an appropriate measuring position: According to the size you are concerned about, choose an appropriate position to measure. Generally, measuring the diameter and pitch of the ball screw is the most common. 3. Measure the diameter of the ball screw: Use a micrometer or external diameter micrometer to measure its diameter along the axis of the ball screw. Make sure the ruler is perpendicular to the surface of the ball screw and gently rotate the ruler to obtain accurate measurement results. 4. Measure the pitch of the ball screw: The pitch refers to the distance between adjacent threads on the helix of the ball screw. The pitch of the ball screw can be measured using a caliper or a dedicated pitch measuring tool. Place the caliper between two adjacent threads and make sure that the contact points of the two legs of the caliper are on the high points of the adjacent threads. Then, read the measurement result on the caliper to get the pitch value. 5. Record and verify the measurement results: Record the measurement results and compare them with the specifications of the ball screw. If necessary, you can make multiple measurements to ensure the accuracy of the results. It is important to note that when measuring the ball screw size, you should try to avoid applying excessive force to it to avoid damaging the ball screw. If you are unsure or have difficulty with the measurement method, it is recommended to consult a professional mechanical engineer or use specialized measuring equipment to ensure accuracy.