Print bed temperature and warping??

Hi,

I am getting some warping when printing a larger object and was wondering what the correct print bed temp should be?

I have been running it at 55 dec C (as measured by an IR temp gun) all the way through the build. Do you guys run it at the same temp? Or do you decrease or increase it after the 1st layer?
Or should I increase or decrease the bed temperature for the entire build?

What is weird is it only warped on the X axis, the Y side came out fine. Any suggestions, ideas or why??

Thank you for your time and help,

PS - The part is upside down in Photos 1-3 from how it was printed.

Print Settings

Layer thickness .2mm
Fill density .2 
Perimeters 3
Solid Layers 3

Speeds
Perimeters 30
Small Perimeters 30
Infill 60 
Solid Infil 60 
Bridges 60

Temp
First layer Temp 185
Bed Temp - 60 (This comes out to 55 when measured) 
First layer bed temp - 60 (This is 55 when measured)

Cooling
Fan always ON
Slow down if layer print time is below - 45
Minimum Print Speed 15

Edited 2 time(s). Last edit at 06/05/2012 07:42AM by tjhj2.

I'm assuming you're printing on a glass plate? Try taking it off and clean it thoroughly using dish washing soap (I like to rinse it off with vinegar as well). I do so when the adhesion starts to deteriorate due to fingerprints and PLA buildup.

Also, an IR temp gauge is not a very accurate method to measure a glass plate, as the IR rays bounce off the reflective surface.

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-Nudel
Blog with RepRap Comic

For PLA:

55C for first layer or two
35C for rest of print

Edited 1 time(s). Last edit at 06/05/2012 03:41PM by akhlut.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

You could try adding a "brim" to your prints to stop curling too

[forums.reprap.org]

Those bed temps sound low to me. I have glass over a MK2 bed with a thermistor in the hole and lately I start off at 80C for the first layer and 70C for the rest of the print.

I think if your printing directly on glass you'll need more temperature, I gave up since my bed won't get much above 70 degrees surface temperature.
On Kapton on glass I can print large PLA pieces at about 55 degree surface temperature.
I can go a little cooler than that ~50 degrees with blue painters tape on glass.

What is a better way to measure the tempature? A temp probe doesn't seem accurate. Because of hard to contact. Is there as much inaccuracy with the krypton tape?

I'm not printing direct to glass, currently it goes PCB (layer of kapton) glass covered with kaypton.

Thank you for the help and suggestions.

Edited 1 time(s). Last edit at 06/05/2012 01:56PM by tjhj2.

Depends on the level of accuracy. I measure the temp at the edge of the heated bed, knowing that the center is invariably hotter. How much hotter? For me about 15C at full blast.

Why the kapton between the PCB and glass?

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

Just saw these for measuring temperature... what does everyone think? Good idea? Bad idea?

[www.mcmaster.com]
(Scroll down to the non-one time use labels)

Akhlut,

The extra layer is because I was printing directly on the tape then added the glass. It seemed easier not to remove it since it was hell to get it on to start with and if I need to go back.
Do you think it's affecting it?

Thank you

Those labels (the reusable ones) seem like they might work - not too expensive either. Only problem is range - no single sticker will work for PLA and ABS - the sticker ranges are too narrow. And it's a bit expensive...

I just ask about the kapton because unless it is perfect it may be interfering with heat transfer. Since heat transfer is a function of surface contact any imperfection in the kapton layer decreases contact and heat transfer. Alot? No, but every little bit helps. That said, if you're only printing PLA I wouldn't worry about it. If you keep the bed temp too high (above the glass temp of the material) it might warp - besides it's like printing on jelly.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

To get an accurate measurement I tape a thermocouple on the top with Kapton and cover it with a small piece of ceramic cloth insulation. If you don't cover it convection cools one side of the thermocouple and it reads low. Of course the insulation may create a local hot spot, which is why I keep it small.

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[www.hydraraptor.blogspot.com]

Nophead,
What do you run for PLA temp settings?

Thank you,

90C on the first layer and 55C after that.

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[www.hydraraptor.blogspot.com]

Really? That seems very hot. Anything above 50C for me results in PLA warping.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

That is measured on the top of the PCB. The top of the glass may be a bit cooler. The Tg of PLA is around 55C so I aim to be just below it.

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[www.hydraraptor.blogspot.com]

Did you try with ABS juice (ABS dissolved in acetone) on glass ?

The part is printed in clear PLA
left : without ABS juice
right : with ABS juice

Check my post on defeating curling!

Cure For The Common Curling

[forums.reprap.org]

I know this topic is old, but a hint to all that may come across it. Use a thinned mixture of Elmers glue to keep PLA down. 5 parts water to 1 part glue. Mix it in a jar and put on a new coat when ever you print. Works wonders! It is similar to ABS juice for ABS printing. Hint: use a sponge brush to apply it in a thin coat with the bed at print temp (~60c). The first time you apply it, put on three coats. Watch the YouTube video by Maker Tool Works