Here, I've made an automatic tensioning sanding block suitable for a 457-mm-long sanding belt.
Whether in a carpentry workshop or a metal processing workshop, every craftsman cannot do without such a practical belt sander.
Simply open it gently, remove the old sanding belt, and install the new one, and you can easily start your sanding journey.

My sanding belt products —>https://www.amazon.de/TACKLIFE-Schleifb%C3%A4nder-Schleifband-Bandschleifer-Verbindung/dp/B07LD7DLFY/ref=sr_1_3?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=Tacklife+schleifband+457&qid=1611314534&sr=8-3