poor 1st layer, can anyone suggest what is wrong?

Hi All,
Could some kind soul please take a look at the attachment and offer some advice as to what is going wrong?
The photo is taken from underneath and shows the 1st layer having "holes".

I am printing using White PLA and I have found having the bed set to 90 for the 1st layer it sticks really well to the glass.
The hot end is set to 190 for the 1st layer.

Thanks
Phil

Try using Blue Painters Tape. The reason that is happening is not from the temp of the glass but rather the ambient air temp. Make sure that there is no drafts (even if you cant feel one). To test the draft theory drape a towel over your printer and check the results. When printing ABS I have a clamping desk lamp with a 90 watt light bulb shining right on the print bed to keep the top layers warm. This might work for your PLA issue as well but I think the blue painters tape will suffice. ALSO drop your bed temp back down to 60°c PLA can be a challenge to get off the print bed with the tape method as it is. It probably won't need another 30° of sticking attitude. My issue has never been getting things to stick to glass with ABS juice (ABS/PLA), Kapton tape (ABS), or Blue painters tape (PLA). My issue has always been getting them off the surface when done! LOL I have heard of using hairspray as an adhesion aid but I have not tried that one yet. I am hoping that it will allow me to not use kapton tape as I am trying to get away from it ($$).

What is happening there is the top surface is cooling quickly and in spots not sticking to the glass well. When the top layer cools it lifts the layer ever so slightly and as the print head goes back and forth it causes the layer to buckle. Due to the heat of the print head the buckle lays back onto itself.

Hope this helps! Let me know...

Mike

Hi Mike,
Thanks for the info.
I don't think there are any drafts but I will try using tape to see if it improves things :-). Thank you.


Could I be cheeky and ask for your advice (or anyone else who may be reading) on another matter (if I can describe it correctly, I should have taken a photo) ...

Prints start out OK but after they get higher than say 5mm the layers start to lose definition, the plastic seems to be creeping to the edge and the whole thing starts to look "fluffy".
I have tried using a directional fan to cool down the plastic after the first layer but that hasn't made any difference.

Could it be the Z steps which are wrong? I have tried updating the firmware and changing the values ( default is 2560 I think) but going 500 either way seems not to make any difference.

My hotend is 0.4 and the slic3r software will not let me choose layer height greater than my nozzle size (so I set it to 0.4). It does look like the hotend is disturbing the previous layer, but the first lot of layers look good.

Any ideas?

Thanks
Phil

Hey,

I have the same machine as you and dont need to use any tape on my bed to get a good stick.

Just make sure the bed is level (to the print head) ... really level ... and start with a small first layer, I use 0.15mm first layer and 0.2mm other layers. Once the bed is set up I never have issues with first layer sticking. I use bed temp of 75 and head temp of 185 for my PLA. I also have the extrusion width set high for my first layer ... something like 200%. Bottoms of my prints are solid and glass smooth like this.

For the failures as you rise through the layers. I had this also and I found it to be a cooling issue so I added a fan. Which for me causes WAY more curling and lifting from the bed but might be worth a try. I got round the upper layers being crap by using slicer's "slow down if layer is below X seconds" and set it to about 30 ... seems to work fine. Larger items are better.

Clem

Thanks Clem,
I'll try those settings :-)

Phil

I'll second Clem's suggestion. If you have a HPB there is no need to use tape for PLA.

Just keep the first layer low and slow.

Depending on the PLA I use, my HPB is between 60 and 90 degrees and gets a good stick.

Also, If you have a fan (recommended) blowing on the printed piece to minimize curl-up, don't turn it on until after the second or third layer.

-Rob A>

Where exactly is slicer's "slow down if layer is below X seconds" setting?
I cannot see it anywhere (running Slic3r on OSX if that makes a difference).

Thanks
Phil

Its under the "cooling" options on the filament settings tab.

You need cooling turned on for it to work. I turn max and min fan speed to 0 to stop the fan thereafter.

Thanks Clem,
I couldn't see it for looking, must have been getting late!

I have hooked up a 12v fan to the fan control but it never comes on under software control, so I need to play with the settings.
Manually turning it on after the first layer at the moment.

The single walled cube and circle test objects print out mostly ok (still goes a bit wonky if there is any height involved), but struggling to get out anything a bit more complex :-( Maybe I need to add a second fan at the opposite corner?

I think I need to strip down the HPB and come up with a better way of levelling. Will try the 3 point method.

Do people usually slice manually and then load the G-code into Pronterface, or slice within Pronterface?
I take it that if you load G-code, the slic3r settings are "baked in" at that point and the Pronterface settings are not used at all?

Looking at the G-code, the settings at the beginning are all commented out, so are these just given as a convenience to show what settings have been applied?

Sorry for all the questions.

Phil