i need some advice

Re: i need some advice

vinmicgra — Mon, 30 Dec 2013 20:13:50 -0500

If your print sticks well to the heated bed:

Every extruded layer shrinks during the difference in temp from being extruded to room temp.
If you always put a small (hot) layer on a big (cold) layer the model begins to warp.

So you have to lower the difference in temperature from extruding to room temp:
A too high extruder temp could cause that too. Higher the Bedtemp in upper layers could solve the problem too. (Avoid cold air around the bed - heatchamber)

vincent.

Re: i need some advice

uncle_bob — Mon, 30 Dec 2013 19:51:55 -0500

I sure thought I posted a reply to this already .....

Stick to the bed:

1) Bed is not level
2) Bed zero is wrong
3) Bed temp is wrong (if abs)
4) Printing speed on first layer is to fast

Upper layers:

1) Extruder temp is to low
2) Print speed is to low
3) Extrusion flow is to low

Either one:

1) Z axis is not calibrated
2) Extruder is not calibrated

Re: i need some advice

A2 — Mon, 30 Dec 2013 18:01:34 -0500

@makovai ,

What kind of hot end are you using, looks like a custom thermal break, can you provide some details of it?

Notes:

ABS, (Acrylonitrile butadiene styrene, Type: extruded):

Drying Temperature:
Range: 70°C to 93.3°C, (158ºF to 200ºF)
Average: 80.9°C, (178ºF ).

Dry time:
Range: 2 to 4 hours.
Average: 3.2 hours.

Glass-transition temp:
Range: 108°C to 109°C.
Average: 108°C, (226.4ºF ).
Wikipedia: 105°C, (221ºF ).

Begin testing around this temp:
Substrate/bed temperature: <105°C, (221ºF ).
Enclosure temperature: <105°C, (221ºF ).

Material properties are generally stable between:
−20 and 80 °C (−4 and 176 °F).

Linear Mold Shrinkage (extruded):
0.002 – 0.008 cm/cm.
Average value: 0.00532 cm/cm.

Machine parameters:
Extrude temp (RepRap): 210 C ~ 240 C

Re: i need some advice

sheck626 — Mon, 30 Dec 2013 12:24:12 -0500

It looks to me like it's an ambient temperature issue. During the winter months, I'd expect this kind of thing with ABS.

i need some advice

makovai — Mon, 30 Dec 2013 09:56:03 -0500

I have been printing for a while now and all of a sudden I have a situation i just cant seem to figure out.
Curling, or massive strees in my parts.
I have two scenerio's of which neither are acceptable.
I get solid tight layers on the part, but cant get it to stick to the table, or I use ABS glue and it nice adheasion to the table but the stress breaks my layers apart.

I know this is a temperature issue. I have experimented with every combination of temperature, nozzle dia, and layer thickness i can think of. I print in a office room in my house. The temperature is a very comfortable 70° F.
Any suggestions would be appriciated.