printed part does not stick to green base

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cambazz
Posts: 28
Joined: Fri Mar 18, 2011 1:58 pm

printed part does not stick to green base

Post by cambazz » Wed Mar 30, 2011 4:13 pm

Hello,

For the past couple of prints - (generally large complicated objects) the base does not stick to the bottom part. it starts from the corners and goes kinda up on the corners, distorting the part shape?

Why does this happen? the glue? the seperation between the printing tip and the base? I have made the tip closer to the base, and although it seemed ok at the beginning the print, it then starts to unstick.

best regards,
c.b.

William
Posts: 340
Joined: Tue Sep 21, 2010 12:02 am

Re: printed part does not stick to green base

Post by William » Wed Mar 30, 2011 7:01 pm

there are many topics here related to 'warping'. You should search on that term and read some of those threads.

Essentially, you need to get better adhesion for the bottom most layers of the raft.

The first way to do that is the ensure your heated platform is at temperature for a while. Heat up your bed and let it sit at 105C for about 15 minutes. Some even put a little 'blanket' on their bed to make it even better.

Then, use something other than that green paint. The most typical choice has been 'blue painter's masking tape'. Some here have used the green paint that comes with the printer, to good effect. Most have used blue painter's tape. A few have used Kapton. I've used acrylic conformal coating, but the blue painter's tape is the most efficient and inexpensive solution for me to date.

Lastly, you want to ensure you're printing in a fairly decently heated room without any draft. The curling comes from the top layers of plastic cooling faster than the lower layers, and thus pulling up on the lower layers. That's the nature of thermal plastics. So, whatever you can do to even out that temperature gradient (warm room) will help the situation.

Large objects with big flat areas that are flat against the build platform will tend to warm more than others. Smaller objects won't see it as much, simply because they have less mass to pull up on the corners. If you're doing objects of your own design, you'll want to think about reducing the amount of surface area that comes in direct contact with the platform.

And lastly, you can always rotate your object (either x or y axis) to get surface area off the platform. It will likely still print fine, and reduce the amount of warpage in the process.

Just some quick tips.

cambazz
Posts: 28
Joined: Fri Mar 18, 2011 1:58 pm

Re: printed part does not stick to green base

Post by cambazz » Wed Mar 30, 2011 11:33 pm

hello,

this did not used to happen because I was not printing big enough parts.

I am indeed printing large parts, namely the reprap. So all my parts are rafted, and it it does not look like adhesion problem but rather thermal.

what else can I do?

best regards.

trebuchet03
Posts: 467
Joined: Sun Sep 12, 2010 6:52 am

Re: printed part does not stick to green base

Post by trebuchet03 » Thu Mar 31, 2011 12:09 am

cambazz - if your parts are not sticking to the green paint, that is an adhesion issue. The material is warps enough such that the sticking force of the platform is overcome by the material.

You can resolve this by increasing the holding power of the platform. Blue tape can work but I personally use perfboard because its not an interface bond as much as it is a mechanical bond. I have not had any issues printing big things (including Reprap parts).

(http://en.wikipedia.org/wiki/Perfboard)


-----
Just FYI - if you're printing with the Up!, your parts will always be rafted ;)
Engineer - Mechanical, Mechatronic, Reliability, Etcetera
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cambazz
Posts: 28
Joined: Fri Mar 18, 2011 1:58 pm

Re: printed part does not stick to green base

Post by cambazz » Thu Mar 31, 2011 1:44 pm

well, i printed many parts with up, big but planar ones, and they were never rafted.

this happened after calibrating my printer. Could I have made a mistake on the Z calibration part, which can cause this.

for example right now, i am printing the footed vertex of the reprap, just to try, and there is noticable rafting in the foots.

I will try the perfboard method.

William
Posts: 340
Joined: Tue Sep 21, 2010 12:02 am

Re: printed part does not stick to green base

Post by William » Thu Mar 31, 2011 10:09 pm

I'm not sure we're using the same language here.

What do you mean by "rafting"?

Do you mean "warping", that is the curling up of the ends of a part.

The "raft" is that wasted plastic that you typically snap off from the bottom of the print.

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