Problem when printing flat things

[Tyger]

Hi everyone,

So i got my up a few months ago. i use it for engineering parts but i have som problems.
For one as soon as the nozzle gets hot its starts running (leaking) ABS and when i try to create something big and flat its like it is curving up because of the heat, so it is not flat anymore, but the printer keeps on going so.

Any ideas?

[wackojacko]

Try printing it vertical

www.3dprintingsystems.com

[Tyger]

Thats not a bad idea, will try this tomorow.

I think you would describe the problem as warping, the Platform Suit fixes this so never mind that. (not sure that its that what i mean)

[wilsonj]

Thats not a bad idea, will try this tomorow.

I think you would describe the problem as warping, the Platform Suit fixes this so never mind that. (not sure that its that what i mean)

What do you mean by the platform suit fixes it ? You mean warping ?

[CarryTheWhat]

Because the plastic shrinks slightly as it cools (especially ABS, I think PLA does not have this problem as much), large prints are prone to this "warping" effect (especially in cold temperature or high air flow). A heated print bed is one method for reducing this -- people have also had luck putting perf board down first (check the pp3dp store for an official adaptation, or build it yourself on the cheap), because some of the plastic goes into the holes and holds it in place. Though, this doesn't entirely eliminate the problem. Back when I was painters-taping the platform every time, I used to have to add drops of superglue to the raft in the corners!

Though I later learned, a lot of the problem was from the print bed not being properly levelled (or more properly, trammed). Especially with the odd three-screw arrangement (has that been fixed yet?) I have found it pretty hard to get the bed so perfectly levelled with the nozzle that warping is altogether eliminated.

The general rule of thumb I use is this. If one quadrant of the print bed is experiencing lifting, it is because that part of the bed is too far from the nozzle (and so successive layers are not bonded to the bed as strongly, and over time lifted off the bed entirely) --- the response would be to raise slightly that corner by maybe a quarter turn on that quadrant's screw(s).

[DrewPetitclerc]

The three screws will work if you make the changes I've outlined on this post,
viewtopic.php?f=3&t=753#p5471
I also use a "Dial Indicator" to set my level (trammed) and to identify high and low spots in my glass build plate, I cover it with Kapton tape and after the first layer is laid down I pause the printer and place drops of MEK at all the potential lift points, then resume printing without worries.

[JuliaDee]

Hi everyone,

So i got my up a few months ago. i use it for engineering parts but i have som problems.
For one as soon as the nozzle gets hot its starts running (leaking) ABS and when i try to create something big and flat its like it is curving up because of the heat, so it is not flat anymore, but the printer keeps on going so.

Any ideas?

Here is a photo of a relatively large (4-1/2 x 2-1/2") part, with a large flat area and solid fill - worst-case for warpage. You can see that it is perfectly flat with no warpage (the slight gaps at the left and right flanges are due to some strangeness in the CAD-STL process, not warpage).

The way I achieve this is by using perfboard and setting the platform initial height calibration so that the first layer pushes a lot of plastic into the perfboard holes (see the other photo). For extra-demanding parts like this one I also swab down the perfboard with MEK to ensure that there are no oils on it, and also to pre-soften any plastic that's already in the holes.

I close the fan duct damper for the first few layers in order to maximize nozzle temperature and flow, then when the raft is almost done I open it up.

The downside of this technique is that a lot of nozzle backpressure is generated in the first layer(s). If your feed gear is hot you will probably encounter pre-melt and feed slippage/failure. I printed two of these yesterday without any problems, then on the third one I stopped the print because I wanted to tweak something in the CAD. After 5 minutes to make the CAD changes and change the platform I tried to print again but just could not get it to feed, even with forced-air feed gear cooling. I turned everything off and went home; this morning I tried again with a cold machine and it's printing fine without changing anything else. I'm really looking forward to getting my Drew Petitclerc feed pressure mechanism!

I have not yet tried the Kapton + dots-of-MEK-after-the-first-layer technique and don't know if it's capable of withstanding ABS warping to this extent or not. I am only demonstrating what is possible with perfboard and the right settings.

Julia ("La Pesada")

IMG_3828.JPG (79.82 KiB) Viewed 1111 times

IMG_3825.JPG (117.9 KiB) Viewed 1111 times

[wilsonj]

Julia, I like the pink and orange poke a dots !