Knocking/Clicking sound when Y-Carriage passas trough the middle of rods
I don't think the sound is coming from nuts and springs.

I can think of 3 possible sources.

Y axis rod bearings

Those four bearings that are mounted onto your bed frame may be binding through rough spots on the smooth rods. Usually printer kits don't give you the best quality stuff and those rods may not be perfectly the same diameter throughout its length or may be bent so slightly. Your best bet to test if this is the problem is to remove the belt from your bed and slide the bed back and forth and see if you can recreate the sound trying different speeds and pressure while doing so.

Y axis pulley/idler

I think it's probably this because I have heard a similar noise and this part has failed on me. Usually these are either a plastic pulley, two bearings, two bearings inserted into a plastic pulley, or one larger bearing inserted into a plastic pulley. If your printer uses a bearing here, I recommend taking that part off and inspecting that bearing. I've had mine destroyed and the little balls went everywhere. You can test this by just trying to hear for it. Turn off the printer motors and move the bed manually, see if it sounds like it is coming from the idler.

Nozzle hitting print

I doubt this but sometimes when prints are over extruded or curl up, the nozzle hits the print as it passes over so maybe your hearing individual collisions clicking. Again I really doubt this.



Will this break your heated bed? Probably not. Will it cause problems in the future? If it is a fault with the bearings, most likely they will fail eventually but nothing else should get damaged in the process. But no worries, parts are cheap and readily available online or even at some hardware stores.



Note : My mechanic taught me this when trying to figure out which bearing was making noise in a car. Take a long screw driver, preferably with a wooden handle, and place the tip on the part you think is making noise and place the handle to your ear. Usually this amplifies the noise when your making contact with the faulty part. Using this I was able to figure out which bearing was squeaking among the half dozen points where the belt would spin. Not sure how well this works for a printer and be careful not to have the mechanical moving parts(such as your printer bed) hit the screwdriver into your face.