Getting a smooth bottom layer of PLA

[Oliveros 11]

Hey Guys,

 

I'm trying to get a smooth layer of bottom of the attached part, for some reason when I print it won't get smooth. I'm using blue tape, bed is 45*C and glue stick. Nozzle is 0.4 MM, printing at 0.1 MM layer height, temp is 230*C I believe.

 

 

In interview frame 20 MM Insert.obj

[Job_van_gennip 23]

I would say start by cleaning the bed and apply a thin layer of gluestick that you spread with a little bit of water. I would also lower the printing temperature to around 205 215 max. 230 sounds way too much for pla.

[Oliveros 11]

Thanks, I'll give it a go, I'm also printing it face down on the bed since it's the strongest when oriented that way.

Edited November 8, 2019 by Oliveros

[Oliveros 11]

turned out it was 210*C.

 

I tried pulling the tape off my bed and just bare glass, turned the bed temp up to 70*C and redid the Z offset so it makes a drag mark on a piece of paper or -0.55 Offset so the nozzle is very close to the bed.

 

Sticks to the bed OK without anything but I can still see the layer lines on the bottom, I need it to be completely smooth.

[gr5 2,224]

I don't think you can get it so the lines are invisible.  You can get it so smooth you can't feel the lines but because a tiny variation in angle can be a large change in reflectivity, our eyes can see amazingly subtle things.

 

Please provide a photo.  Maybe we are talking about 2 different things.

 

You can certainly get the bottom better than the top if you print on glass.  Shiny, glossy smooth.  But you will see very thin lines.

 

[gr5 2,224]

Note that non-glossy filaments (which are uncommon) hide layers and such better than glossy.  The absolute worst is going to be shiny black filament which highlights the tiniest changes in angle.

[Oliveros 11]

Good to know, I tried taking a picture but it's hard to see. 

 

I gave one to the guy who needs them to test it out and see if it's good enough as is.

 

 

[gr5 2,224]

Okay so if it looks perfect in the camera, how bad can it be?  🙂

 

Try using white filament and/or matte filament (usually achieved with a wood fill or other non abrasive fill) and it should look even better.  🙂

 

[Oliveros 11]

The problem is i'm trying to get it perfectly smooth or not noticeable to the eye unless you get close to it. 

 

I'm using Monoprice white PLA filament, it's not very shiny.

[gr5 2,224]

Well let me provide a photo if you can't.

 

This is a print with a typical bottom.  Looking at it I realize that most of the visible imperfections are caused by the glue on my glass bed.  I can get it much better if I clean the glass, then I heat the bed and with a paint brush I apply a coat of 10 parts water mixed with 1 part wood glue (or 20 parts water - it doesn't have to be exact - the water all evaporates anyway).  Typically when the glass hits 60C the last of the water evaporates.

 

This gives you a very clean, very flat layer of glue between glass and print and makes for a nice smooth bottom.

 

The bottoms of my parts are usually the best side.  I can get the bottoms much better than the tops.

[gr5 2,224]

Don't look at the sides (embarassed), lol.  I have printed hundreds of these but the filament was tangling on this print which gives it some underextruded layers so I gave the good prints to customers and kept this bad one for myself.  It's a tool I use quite often.

[Oliveros 11]

Very interesting, thank you for sharing.

 

I've tried printing PLA directly on the glass bad that was cleaned with alcohol with no glue and the layers still don't come out very clean.

 

I don't have the part anymore since I gave it away so I'll have to print another one, perhaps I can get a good shot of it somehow, showing what I mean.

[RobinsSon 0]

I print on glass bed and i clean it often and use hairspray, my first layer is always smooth as glass. i think the extrusion needs to be set perfectly and also the first thing to check is the distance from glass bed to nozzle. I had an issue, i was printing on the middle always and the middle was to close to the nozzle. You can actually see it. do auto home and than move axis to the middle using commands. you should be able to see a small gap between the nozzle and the glass bed. sometimes bed can be higher in the middle from factory. and also you should heat up your bed good before calibrating.

[geert_2 558]

This is what I standardly get by printing on bare glass (0.4mm nozzle). The lines are visible, just like they are visible in injection moulded parts where material flows meet, but the indents are very small. The overall appearance is high-gloss (see the lower half of the first photo: here I focused on the fan cover mesh reflected in the bottom).

 

 

 

[Oliveros 11]

Wow, that's really good.