Warping on big parts

Hi Guys

I have an oversized mendel max, and my prints are usually pretty big. From 160mmx160mmx150mm to something around 260mm x 260mm x 170mm. Most of the parts are thin walled with wall thickness of 2-3mm.

I am using the printer to make prototypes for my designs, and the prototypes are used in testing before I make injection molds.

Problem I am having is that with ABS they warp, and de-laminate like there is no tomorrow. They will not come off the heated bed, but the walls crack, and even with ribs I still have this problem.
I know that even the slightest wind or difference in temperature can cause this, but what else can I do?

New printer with "heated chamber"
Other printing material (Nylon 618)


Cheers

Wow, those are big parts(for me). I'm guessing you are using a heated build platform, where did you get such a big one? Also, what kind of heated chambre do you have?

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Yvan

Singularity Machine

Could you post pictures of your setup and the print problems?

I made my own heated bed, but I dont have a heated chamber.

Prints de-laminate sometimes from 10cm in the Z direction, sometimes even from 5-6cm.
I dont have any pics, but if you emagine a tube, there would be a gab of sometimes up to 1mm on the wall going around 1/3 of the print

I am just looking for ways to optimize it, perhaps a few different tweaks would go a long way?


Jonas

Have you got the right temp for the hot end? ABS can extrude nice and smooth at a lower temp than it needs to stick properly at.

Also, what is the layer height of the prints and orifice size of the nozzle?

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Yvan

Singularity Machine

Hi Yvan

I am using a makergeat hotend, 0,5mm nozzle.
Layerheight is between 0,25 to 0,3mm
Temp is 235 degrees
Bedtemp is around 110 degrees

My parts have a wall thickness of 2,2mm, so I set my extrusion width to 0,54 in Slic3r so that it does not create any infill on the walls, or it would take 3 times longer to print.

sound about right?


Jonas

I tent my printer with a mylar type blanket, just have to make sure the mechanics can move freely, and that the mylar doesn't come in contact with my motors. They run on the hot side and can melt the mylar. I can print up to my max height of 210mm without warping or de-laminating.

Edited 1 time(s). Last edit at 07/10/2013 10:45AM by Dirty Steve.

As I understand it, the problem with ABS is that hot plastic will not stick to cold plastic. The layer being deposited has to heat up the previous layer before it'll adhere. Airflow from any source is detramental to that. A method I have yet to try is to print a "skirt" around the object that extends in the Z direction throughout the entire object to act as a barrier for airflow. Other than that, make sure your machine is calibrated properly (especially Z and E steps/mm and filament diameter). Print a hollow cube with only 1 perimeter and measure it with your calipers to make sure it is very close to what your Slic3r settings are for trace width.

DS, cool idea with the tent. I guess it doesn't take much to get a greenhouse effect around the heated bed.

Jonas, your numbers are very close to what I use, but I print smaller things. How about pushing bed temp up a bit? You know when it is too high, as the part will start to "cook" and show brown splotches where it touches the bed. May not be visible with very dark colours.

Also, could you reduce layer height a touch and/or increase extrusion width, in an attempt to "push" heat into the previous layer?

Anything to increase the temp in the work area will help, all sources of heat are cumulative. All in an attempt to maintain as much heat in the cooled ABS as Sheck says....

Years ago I think it was Forrest Higgs who started dabbling with ABS and the print that worked in the afternoon didn't stick in the evening. The printer was set up by an open window to help with fumes, and after the sun was down the cool breeze dropped temps below the magic threshold. Didn't take him long to figure out the solution, he put a work light over the bed, iirc!

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Yvan

Singularity Machine

Thanks for the help.

I will try what you guys suggest, and let you know how it goes.
Have any of you tried the Taluman Nylon 618, and have any experience with warping? Looks interesting as well.

Maybe a printer where the Y axis dosent moved would be better, and easier to enclose.
Any recommendations on this? I am going to be printing big parts for the next few years, so building a new printer would not be a problem if it can help to solve some of these problems.



Cheers

Jonas

Professional FDM printers printing with ABS usually run an enclosure temperature of 70 C

I just bought some 618 and 645. I'm waiting for an all metal hot end from Eckertech to show up.

What kind of hot end are planning on using with the nylon?

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Yvan

Singularity Machine

As I understand it, the extrusion temp could be around 245 degrees, so you might not need an all metal hotend at all.

Please let us know how it compares to ABS



Jonas

Okay, I'm going to print up a new Prusa compatible extruder for the all metal Eckertech hot end, and will try this ASAP.

That way, if I burn my PTFE hot end, I could then install the Eckertech stuff and get back to work.

Edited 1 time(s). Last edit at 07/14/2013 02:15PM by Yvan.

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Yvan

Singularity Machine