Re: PLA Curling while printing

[Pascal POECK]

Are you sure that your build plate is actually flat? Seem's that a lot of people had to ask for a new one at MakerBot...

Le mercredi 6 février 2013 16:20:08 UTC+1, Antonio Bruno a écrit :

I have been having a lot of issues with my Replicator 2 when printing larger objects. I am getting a lot of curling that is preventing a usable print. I was assured by the reps at Makerbot, that the PLA was optimized and should show less than a .1mm curl at 10 inches. NOT! I am getting massive curling in less than 5 inches withing the first 4 layers of printing (.27 layer size). I have tried using painters tape, but the curling is so strong it actually lifts the tape off the build plate. Does anyone have any suggestions? I am beginning to think I made a poor choice in printers and should have gone with a 2X just for the heated build plate. I have found that when I contact MakerBot for support on other issues, it takes them more than a week to respond to emails, so I didn't even bother trying to contact them on this problem.

[Antonio Bruno]

I have had some problems with leveling the platform on the outer edge. Initial 3 points go perfect, but the outer corners always seems to be a little looser. I have not had problems with builds sticking on the outer part of the platform when I did a test print is multiple locations on the plate, so I assumed it was ok. What you are saying does make sense though as the curling only seems to happen farther out on the plate. Do you think the glass plates people are referring to might be a better option for accuracy?  

[Joseph Chiu]

What are you printing?  In a couple prints that I did a month back, I had what looked like shrink-induced curling -- but that was from printing a curved overhang, and I think it might have had more to do with the extruder "pulling" on the still-soft plastic that was just extruded.  My overall experience with PLA is that it doesn't shrink.

Just as a sanity check -- are you *sure* that you have PLA?   I know that at least one guy was printing troublesome PLA for a while until he finally found out that he was printing ABS all along...  

Also, you might try printing at a lower temperature -- it could be that you're running too hot. 

Oh, and if your design is laying down a big slab of PLA, it could be that the PLA isn't shrinking - instead, the build plate could be expanding as it warms up from the heat of the PLA.  I seem to recall someone else having that problem a few weeks back.

Joseph

On Wed, Feb 6, 2013 at 7:20 AM, Antonio Bruno <icepi...@gmail.com> wrote:

I have been having a lot of issues with my Replicator 2 when printing larger objects. I am getting a lot of curling that is preventing a usable print. I was assured by the reps at Makerbot, that the PLA was optimized and should show less than a .1mm curl at 10 inches. NOT! I am getting massive curling in less than 5 inches withing the first 4 layers of printing (.27 layer size). I have tried using painters tape, but the curling is so strong it actually lifts the tape off the build plate. Does anyone have any suggestions? I am beginning to think I made a poor choice in printers and should have gone with a 2X just for the heated build plate. I have found that when I contact MakerBot for support on other issues, it takes them more than a week to respond to emails, so I didn't even bother trying to contact them on this problem.

--
You received this message because you are subscribed to the Google Groups "MakerBot Operators" group.
To unsubscribe from this group and stop receiving emails from it, send an email to makerbot+u...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.
 
 

[Justin Leone]

I think it happens on edges for 2 reasons.  One is that the acrylic build plates are often slightly convex, so you don't get as good adhesion around the edges.  A glass plate would most likely help here.  The other reason is leverage.  When a piece warps, it's because the top layers are cooling and contracting.  The bottom layers are printed to a fixed object and can't contract much, but when the top layers cool, they pull the lower layers inwards.  If the force of adhesion to the build plate is less than the force of contraction (which will be increased by distance to the center of contraction), the piece will curl up in the corners.

The only fully reliable way I've found to prevent it is to add a single-layer extension to the extremities of long objects (like these: http://www.thingiverse.com/thing:38272).  Since it's only 1 layer thick, they won't add to contraction forces that warp the object, but they greatly increase the adhesion at the corners.  Of course, they can be annoying to cut off, and require a bit of sanding on the leftover edge.

[Antonio Bruno]

I am pretty confident that I am using PLA. I purchased it from Makerbot's store in Manhattan (it was a fun filled afternoon). I have seen the overhang issue, you are referring to, but this seems to be real curling. I just ran another test, and it does seem to olny occur on the right side of the plate, so I am now thinking it might be an adhesion issue and a not true plate as others have mentioned. The temp is set to 230c, but i have read some are seeing temp errors on the internal sensor. I never thought about the build plate warping under heat. that makes a lot of sense also.make me think Glass may be a better plate overall.

[Enginwiz]

Antonio,

 

you are not alone. I have the same massive curling problems with several brands of PLA

(including Makerbots) on the acrylic build plate if I try to print larger parts.

The bottom of the printed part typically looks like a banana. Large engineering parts

for assemblies don't fit together.

 

Two weks ago I found out that larger parts (240 x 40 x 40 mm and bigger)

permanently warp my acrylic build plate during printing. The acrylic build plate is not

strong enough to survive the bending forces of large printed parts. This is ridiculous.

Printing large parts with mimimal warping is what Makerbot is still

advertising on the website and in the brochure for the Replicator 2.

 

You will have to get yourself a stronger build plate to print big parts. Float glass and

Aluminium in a thickness of 8 mm to 3/8" were recommended in this group.

Today I ordered a float glass plate 287 x 167 x 8 mm to get out of this mess.

 

There are other painters tapes that are stronger than Scotch blue 2090.

TESA 4309 has a smoother surface and a stronger glue on the back.

PLA at 230°C sticks to the surface of TESA 4309 quite well and

is still easy to remove. This is my favourite tape at the moment.

You can buy it in 50 mm wide rolls like the Scotch blue tape.

 

[Wingcommander whpthomas]

Enginwiz: I too can unfortunately confirm this. I printed some large 150 x 250 x 15mm parts and warped my 9.5mm acrylic build plate. I ordered 2 new 8mm float glass plates which I am picking up this afternoon.

I have been using Scotch Blue 2093 - only one in 50mm - but requires a good rub down with Mentholated spirits to get parts to stick.

[Steve]

The acrylic build plate that came with the Rep2 was warped. This causes larger prints to curl up on the ends, as they do not stick to the build plate where the warped build plate increases the distance to the nozzle. If you can print small parts in the center of the build plate, but have trouble with larger parts curling up, then check the flatness of the build plate using a metal straight edge and a flashlight. 

I had a new acrylic plate made for eight bucks, and it worked great. However after a couple weeks of printing the new one started to have problems as well. If you just print small parts in the center of the build plate the acrylic is maybe a reasonable thing. To consistently print larger things the glass plate looks like a better idea. I had to custom order the glass, but there is a shop nearby that cuts 3/8 acrylic while you wait so I had another acrylic plate made to use for printing until the glass gets here.

[Antonio Bruno]

OK, so here is an update on my progress. I have been working with MBI support for a bit now, and I seem to be learning more from everyone here. That is a HUGE thank you to everyone.

What I have found and not found so far:

My build plate is true. I verified it with a steel ruler on both sides. There appears to be no warping at room temperature. I have found the arms are definitely unstable and tend allow the plate to wobble a bit. There is significant play in the build plate when clipped into place allowing for the plate to drop left to right while it wbbles.

I seem to get the best reliability by using the following prep procedure. It is a combination of several different posts that I have found throughout the forum. 

1) Wipe down the build plate with Isopropyl Alcohol and allow to air dry

2) Cover plate with blue tape

3) Using a rounded plastic wand, burnish the tape to be sure complete adhesion to plate

4) Using a diamond sharpening stone, sand the surface of the tape to rough up polishing effect caused by the burnishing.

5) Wipe blue tape down with Isopropyl Alcohol again to remove any oils that may have been on the tape and allow to air dry

6) Add 4 pieces of 20# paper to build plate bed to raise and secure the bed from "wobbling" - This made a BIG difference in the stability of the build plate (a more permanent solution is in the works)

7) Level build plate.

8) Level the build plate again

9) send print from Makerware

Any additional suggestions are always appreciated.

[Wingcommander whpthomas]

6) Add 4 pieces of 20# paper to build plate bed to raise and secure the bed from "wobbling" - This made a BIG difference in the stability of the build plate (a more permanent solution is in the works)

I used stick-on felt surface savers and described the process here http://www.thingiverse.com/thing:43050

However these days, I am sticking the felt on the under surface of the plates themselves - because I have 8mm glass, 8mm bakelite (for nylon) and 9.5 mm acrylic - so each plate has different pad thicknesses stuck underneath so they all insert into position firmly.