Wednesday, August 7, 2013

Heated Printbed "Part 2"

I have had the heated printbed now for 2 month, printing ABS and PLA parts.
No more part warping. It is working great.
Since there are more and more CubeX users installing the heated printbed, I thought I post my experiences and what I have learned.

Here is some of my standard equipment:

Acetone slurry (Acetone with some small pieces of ABS dissolved in it)
Exactor knife

I use kapton tape on the print platform. I use a 5" wide 1mil thick kapton tape. (This spool will last a long time).   Kapton tape link
Some use blue painters tape, but Kapton works for me better because it gives a smoother part bottom surface.

First I clean off the printbed with alcohol so the kapton tape adheres well.
Then start applying the tape from the back side of the printbed and use a credit card to apply the tape to the printbed. It takes a little practice to get it on without bubbles, but does not take long.
Then cut the tape with the exactor knife at the end of the printbed. The tape can be used for several prints. If it has tears in some areas from removal of a prior part, I just place the next print around it or re-apply new tape.
(When removing the tape, start at the back side and then pull the tape off the printbed towards the front, and hold the front of the printbed down a little so the printbed does not get pulled up in the front during tape removal).

The 5" wide tape fits most of my prints. If there is any larger print, I place the tape side by side.

You can search the web for different ways to apply the kapton tape.

For example, you can apply some windex onto the printbed and then put the kapton tape on top and position it, then squeegee out the excess windex and heat up the bed to dry it out.
Note: Don't spray windex all over the system etc., wipe excess off with rag.

Here is my printing routine:
  • Assuming there is already kapton tape on the printbed, for PLA part printing, use a rag with alcohol to clean the top printbed surface. For smaller ABS part printing, clean top printbed surface also with alcohol. For larger ABS part printing, wipe the top printbed surface with acetone slurry, which will improve ABS part adhesion. The acetone slurry will leave a "foggy" looking film on the kapton tape. 
  • Note: Do not use the acetone slurry for PLA printing. Clean off acetone slurry with alcohol before PLA part printing.
  • Turn on the printer and the heated printbed power.
  • Hit the "Home" menu button. This will raise the printbed and therefore open the heated printbed shut off switch. (The heated printbed should be on now).
  • Select the desired temperature. (Default for ABS is 110deg, PLA 70deg.).
  • While the printbed is heating up (2 to 5 min) I prepare the printfile and copy it onto the memory stick.
  • Now I check and clean off any filament debris of any print jets. This can be done from the left side access in the CubeX when in "Home" position.
  • Then I select the "z-gap" menu button and check / adjust the z-gap if needed.
    • (With the z-sensor relocation kit (included in heated bed kit), the z-gap has been more consistent).
  • Then select the "Print" menu button and the file I want to print.
  • I still always watch the first few layers being printed and make sure all is going well.

Heated bed temperature settings:
PLA Printing:
In general, 70deg is good.
But sometimes I turn it down a little. Here is an example where a too high temperature caused a problem on a PLA part.
With the print bed at 70deg. the legs at the bottom of the PLA part stayed too warm and the part flexed a little, causing the part on top to get messed up.

Reprinting the part with the print bed at 60deg, solved the issue.

ABS printing:
In general 110deg is good.
Very large parts with large flat bottoms, I have printed at 120deg to make sure it adheres well and won't lift.

If the ambient temperature is cool and I am printing a larger ABS part, I also drape a towel over the CubeX to cover the left and front open sides to keep the heat in the print area to avoid cracks or splits in the part at higher print layers. Also crank the heated bed up to 120C.
Several smaller ABS parts I have printed at 100deg so they are easier to remove after the print.

So with different settings you can adjust to a certain degree how well the part will bond to the print bed surface.

It is best to let the print bed cool down after a print, before trying to remove the part. The part will come off easier then and also less chance of marring the part because it is cooled down and harder.

PLA parts seem to be easier to remove after printing than ABS parts. When I create the build file, I often add a "helper pad" underneath a corner of the part, which gives me an area to get the spatula underneath the part for easier removal without marring the part. The helper pad can then be easily be cut off afterwards.
 Helper disks zip file

It is nice not having to use the sticky glue anymore and messing with that and not having to take the print platform in and out.

Using the alcohol and acetone slurry with a rag is clean since it mostly evaporates.

General CubeX stuff:
For more advanced users, you can also adjust the print jet temperature.
The first layer is usually printed with a higher print jet temperature to maximize filament adhesion to the print bed, then the print jet moves away, cools down a little and then continues the print at a little lower temperature.

It seems like you can also change the filament feed speed, but it changes during the print, depending on the features, so it seems to jump back to the programmed value.

I have not yet played much with tweaking the print temperature values, so I don't have any advise yet, besides "try at your own risk".
I will have to do some web search to find out more about tweaking the print jet temperature for specific prints.
Currently, when the build file is created, it determines the "best" temperatures for each individual part, which can vary depending on the part and material.

I am printing right now this Theropod Dino skull in PLA and then again in ABS to compare how they come out.
Planning to do a Post about ABS vs. PLA, pros and cons about each, and my experiences.

1 comment:

  1. Can someone please post all the settings for the print bed heater all mine got messed up and I can't figure them out!! Thanks


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