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Topic: Bottom of print curve

[Hi
The bottom of my prints is curving, any ideas ?
Is the bed to hot (85dg)

Thx!
Kim

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Re: Bottom of print curve

Put a skirt on them

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Re: Bottom of print curve

more like the bed isn't hot enough.

make an enclosure for your machine to keep heat in, and get the bed up to 100 C for printing bigger pieces.

4

Re: Bottom of print curve

more like the bed isn't hot enough.
make an enclosure for your machine to keep heat in, and get the bed up to 100 C for printing bigger pieces.

Actually, the bed can be too hot in some cases.  For example, my prints begin to curl more if I go above about 85 C.  Like pcporier said, a brim is important for holding the piece down. 

An enclosure does help, though, by raising the ambient.

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Re: Bottom of print curve

I just use a glass mirror and aquanet. My bed gets to 80-85c. I use no enclosure. The prints stick like glue. I think a wide brim is essential too.

6 (edited by 2n2r5 2013-05-18 23:31:35)

Re: Bottom of print curve

Ghostling wrote:

more like the bed isn't hot enough.

make an enclosure for your machine to keep heat in, and get the bed up to 100 C for printing bigger pieces.

^
Ditto.
The enclosure isn't just for keeping the first layer down , which it does indeed help. It really helps keep your layers from separating on big prints. Curling happens you have the colder shrinking plastic of the top layers pulling on the warmer pliable plastic of the bottom layers.

I run multiple borosilicate glass surfaces. Some of them have Polyester Masking Tape (Green Masking Tape) and some have Kapton Tape. The green masking tape works the best but can be difficult to remove the part.

Most prints work fine on just glass with hairspray. For prints that have large flat surfaces which have a tendency to curl at the edges, I use hair spray on a 100c green masking tape surface. I usually have to wait until the plate completely cools before I can even think of prying the parts off. Even then it can be tricky.


I think the biggest problem that I had was finding out how to get my bed temperature to get past 77-82c. I took a bunch cotton rags and cut them into strips. Then I took Kapton tape and added them as insulation (about 1/2 inch worth) to the bottom of the bed. That brought my temps up to 85-90c. Then I added the glass which helped trap the heat and that got me to 95. The addition of an enclosure made it so I could get 100C.

Cotton facts:
Glow temperature: 205 °C (401 °F)
Fire point: 210 °C (410 °F)

SD3 w/ mods:
Glass bed with QU-BD heat pad upgrade, threadless ballscrew w/ 8mm smooth rod, spectra line belt replacement, lawsy MK5 extruder, Lawsy replacement carriage, E3D hotend, Ramps 1.4 w/ reprap discount controller, DRV8825 drivers, 12v 30A PS, Acrylic case, Overkill Y-idlers, Filament alarm, Extruder fan + more.

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Re: Bottom of print curve

Hi
Thx. for your ideas, I will try them out.

8 (edited by DePartedPrinter 2013-05-21 20:12:50)

Re: Bottom of print curve

op7ical wrote:

Actually, the bed can be too hot in some cases.  For example, my prints begin to curl more if I go above about 85 C.

I have also found this to be true in certain instances.

I think the plastic near the bed gets too soft which makes it susceptible to layers cooling above it.

SD2 with E3D, SD Press, Form 1+
Filastruder
NYLON (taulman): http://www.soliforum.com/topic/466/nylon/