Partial Answer Layer lines on my prints are not even

It might be loose belts, but it might simply be over-extrusion -- have you calibrated the extruder?

 

Heh, not really a way to be specific via typing.
The best way to describe it is imperfect, but if you pluck it like a guitar string it should make a low thrum. Not a thud

 

Referring to the visual guides:

https://www.simplify3d.com/support/print-quality-troubleshooting/#lines-on-the-side-of-print

mechanical issues would still be my guess, but there are a couple of others mentioned

 

Exactly which printer are you using here?
R1 beta? R1? R1+?

The last two are similar, but the first one is totally different with respect to how the bed is assembled

 

OK, so that has the linear rails under the bed and the bed is attached to them with magnets (the rails have plastic cross-bars that the plate is magnetically attached to). Then the rails pass through two bearing blocks (one on each side for that rail). Inside those are some LM8UU bearings that the rods run inside of.

I would make sure the bed is not loose on the mounts (magnets still holding well) and that the bases the rods run through are not loose/cracked/missing screws to bolt them down to the frame.

Assuming all that is good you may simply have bearings that a going out. They can be replaced if you need (and are not too expensive).
If you can (with the bed off) wiggle the rods side-to-side (i.e. the bearings are letting them wiggle that way) then you probably need new bearings.

Check it out and see where you think the issue is.

 

If any of the plastic parts are damaged they can be reprinted (if you can't print them yourself one of us can print it for you)

I would not use the bushing, but sure they will work if you would rather go that route. The IGUS teflon/glide bushings that those are modeled on is fine, but I would not used printed ones and the bearings are not expensive. Here is an example: https://www.amazon.com/gp/product/B00ED150S4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 that is a set of 12 (you don't need 12) but you can see they are rather inexpensive.

I think some folks on here HAVE used printed ones maybe @WheresWaldo can speak to that or perhaps he remembers who might have done that.

 

The reason I would not use printed ones is that I am lazy and having to take it apart to replace them is a pain. The Igus teflon ones will last well, but nylon would be the closest filament approach and again they are cheap enough so....

 

I am not 100% certain. You may need to use a wrench on the nuts under there. Sorry been a while since I took them off. Let's go with the assumption that you will have to get at some of it from under the bed. You probably have the screws on the top and the nuts underneath.

 

I have tried the printed bushings and while they work, there is more "stiction" in the bearings than a ball bearing model. it makes it quieter but they wear too fast to be really useful. If you don't want to just replace the ball bearings then an oil impregnated bronze bearing can be used, just note that you will need to print a new holder for them as none are direct replacements for LM8UU bearings Robo and others typically use.

 

To answer the other question, you will need to pull off the bottom of the printer. The nuts used are nylon insert lock nuts and they will just spin if you only try to remove them from the top.

 

No, only if you are using oil impregnated bronze bushings. LM8UU are drop in replacements for the existing bearings, if you are getting some like @mark tomlinson linked to above.

Examine the brackets closely after removal, when I finally replaced my bearings I found 3 of the four pieces (they are all identical) had developed cracks. So I had to print new ones anyway.