bottom layers of print are extremely ugly, rest of the print is fine. printrbot jr

whenever i print something, the bottom few layers that are facing the rear of the machine on the y axis, come out with an ugly finish. it looks all coarse and wiry. is there an easy fix? is my bed not level? is there something wrong with the firmware? also, the build platform is 6,6,6. and whenever i try and put something that is even remotely close to what the printer should be able to handle, it says my part is too big. its set at X:150mm Y:150mm Z:150mm but when i try and print something that is 136mm wide, it says its too big and wont fit on the platform.... any ideas? thank you. heres a picture of the "ugly" side and a picture of the "normal" side

P.S. i also get a very ugly top layer on my products..... is there something im doing wrong???

I would guess it might be that your Z endstop isnt right, That you are starting to print like 0.1mm to high,

Also the 136mm thing, Depends what Slicer you are using, But it could be that you are using a brim or a skirt, wich could be outside your platform.

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Originally Posted by 3DRC

P.S. i also get a very ugly top layer on my products..... is there something im doing wrong???

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Slicer has separate settings for the top and bottom layer. It might make sense to take a look at those and see how much different they are from the middle of the part settings.

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Originally Posted by Roxy

Slicer has separate settings for the top and bottom layer. It might make sense to take a look at those and see how much different they are from the middle of the part settings.

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could you explain hoe to get to those settings?? and its only happening on one side of the object. so im not sure if thats whats happening.

Bring up Slicer...

Do: File / Preferences / Mode / Expert

Probably... These are reasonable settings for you:

Print_Settings / Horizontal_Shells / Solid_Layers Top:3 Bottom:3

Print_Settings / Advanced / Infill : 0

Print_Settings / Advanced / Solid_Infill : 0

Print_Settings / Advanced / Top_Solid_Infill : 0

If it is only happening on one side... The odds are your bed isn't very level. You should check to see if it is level. Use PronterFace to move the nozzle to one corner and then move it down until it just touches. Then move to another corner and see if the spacing changes between the nozzle and the plate. Probably, it would be wise to insert a business card between the nozzle and the plate and make the nozzle just touch that because otherwise, you might dig the nozzle into the bed when you move it.

If you're getting a lumpy top layer you're over-extruding. Calibrate your e-steps per mm. It may also be affecting your bottom layers as they'll be printed solid. The middle layers are likely coming out fine because you're not doing 100% infill.

It's probable your bed isn't level either. Have you run through the calibration guide on the reprap wiki?

Looking at your print and pictures of the printrbot jr, I think your problem is that the Z axis is not perfectly perpendicular to your X/Y axis throughout your print. Possibly the Z axis mounts are a little loose.
As the Printrbot Jr has a cantilever nozzle mount I think your Z axis leans forward or droops a little as the nozzle moves away from the main support tower resulting in excessive Z-lift at the rear of your printed object.

A non-level bed would explain bad results in only the first couple of layers, not bad results through the whole print.