Level the bed, print. Turn off the printer for the night. Try to print. Bed needs to be leveled. Level the bed. Print. Turn off the printer for the night. Repeat. If this is happening to you, your bed may be wobbly because the D rings are loose. A lot of times, the adjustments will be stable until the printer is turned off and turned back on. It will seem like your bed is constantly losing its level. This is because…well…it is. Most beds ride on a series of bearings that ride in a track or v-groove. To adjust the tightness of these bearings to the track many manufacturers use a D ring, which is a ring that fits in the middle of the bearing to hold it in place, but it has a hole that is off-center so that it can be adjusted.

The D rings are usually located on the four corners of the bed, and they have screws that can be tightened or loosened to adjust the tension of the bed. Here are the steps to adjust the D rings on a 3D printer bed that is loose:

1. Turn off the printer and let the bed cool down completely. Do not touch the bed when it is hot, as you may burn yourself or damage the bed surface.
2. Locate the D rings under the surface of the bed. You may need to remove the print surface or the glass plate to access them.
3. Use a screwdriver or an Allen wrench to loosen the screws on the D rings slightly. Do not remove them completely, as you may lose them or damage the bed.
4. Gently lift one corner of the bed and check if it is loose or tight. If needed, rotate the D rings to adjust the tightness against the track.
5. At their proper tightness, the D rings will prevent the bed from wobbling, but will not inhibit the bed from moving back and forth.
6. Replace the print surface or the glass plate and turn on the printer.
7. Perform a bed leveling procedure to ensure that the bed is flat and even. You can use a piece of paper or a feeler gauge to check if there is a consistent gap between the nozzle and the bed on all four corners.
8. Print a test model and check if the print quality has improved. If not, you may need to adjust the D rings again or check for other issues with your printer.

Adjusting the D rings on a 3D printer bed that is loose can help you improve your print quality and prevent your bed from wobbling or shifting during printing. It is a simple and quick fix that you can do yourself with some basic tools. However, if you are not comfortable with tinkering with your printer, you may want to consult a professional or contact your printer manufacturer for assistance.