ABS Cooling Crack Repair

[Christian79]

I am currently printing ( http://www.thingiverse.com/thing:308335" onclick="window.open(this.href);return false; ) @ 100% and was sad to see no less than 6 CRACKS in the print. By no means ruined, but still saddening. I have been using a heat gun ( http://www.harborfreight.com/1500-watt- ... 96289.html" onclick="window.open(this.href);return false;) to help cleanup my prints and thought that I would try to reflow the ABS a bit to remove the cracks. Much to my delight CAREFULLY heating the ABS causes the entire heated area relax without deforming, and the cracks melted back together beautifully. The larger cracks 1/16" went back together with only a minor misalignment present while the smaller cracks disappeared completely.

I hope the helps anyone who is dealing with these ABS issues.

Tips:

1) Where cloves these heat guns WILL burn you.
2) Keep the gun moving over the print you are trying to heat the surface and the support structure under it, not just the surface.
3) If you deform a small protruding surface element a small knife will help you put it back in place and hold it there why the ABS cools.

[ApacheXMD]

Do you have a before and after picture by any chance?

[Christian79]

Unfortunately I do not. While I was repairing the piece with the heat gun I was so caught up in how well it was going I forgot to take pictures.

[Christian79]

These are very small cracks (may have to click on image to see them), but they disappear when you heat the ABS. To me this indicates what many have already said about printing in ABS and needing a heated chamber. I believe this is a patented method (Stratasys, or 3D systems) ( ) but you can do it for yourself without much fear of reprisal.

[Tinyhead]

That's a pretty good idea! I'm actually surprised it doesn't create more surface distortion. Looks like it smooths it right out. Good work!

[nitewatchman]

I wonder how well a hot air plastic welder would work. Basically a heat gun but focused through a small nozzle (1/4"-3/8").

I'll put it on the list to try. Currently it will come to the top of the list bout November.

nitewatchman

[Christian79]

There is no noticeable surface deformation IF you keep the heat moving. My major reason for using a heat gun rather than my plastic welder was that I wanted to heat the entire area to see if I could relax the internal stress that cause the crack rather than try to melt the crack together.

[Eaglezsoar]

These are very small cracks (may have to click on image to see them), but they disappear when you heat the ABS. To me this indicates what many have already said about printing in ABS and needing a heated chamber. I believe this is a patented method (Stratasys, or 3D systems) ( ) but you can do it for yourself without much fear of reprisal.

From what I have understood the Statysys heat chamber patent only applies to Cartesian Printers but I may be wrong.

[bdjohns1]

I wonder how well a hot air plastic welder would work. Basically a heat gun but focused through a small nozzle (1/4"-3/8").

I'll put it on the list to try. Currently it will come to the top of the list bout November.

nitewatchman

I got a hot air rework station from sparkfun to use for this. Haven't tried it yet though.

[Eaglezsoar]

I wonder how well a hot air plastic welder would work. Basically a heat gun but focused through a small nozzle (1/4"-3/8").

I'll put it on the list to try. Currently it will come to the top of the list bout November.

nitewatchman

I got a hot air rework station from sparkfun to use for this. Haven't tried it yet though.

They have those neat "pens" now that take the filament in and melts it to a .4mm tip. Those should be
handy to fix cracks, etc.

[geolupulus]

I tried this with an ABS print that had 4mm thick shell, (we'll be hammering on it, it needs to be STRONG) and the cracks did disappear! For a minute. When the part cooled, they came back. We then clamped it between two boards and heated it again, this also worked temporarily. We heated the part, cracks closed, the clamp kept the crack from opening again. Then when I took the clamp off, POP. The layers separated again and the cracks reappeared. How thick was your shell? Did you use infill? I used 15% infill.

[gestalt73]

Splits in a print are usually a symptom of not printing hot enough for the size of the print.

You can get away with printing small objects with very low temperatures, but they're fragile as a result of poor layer adhesion.

For ABS prints, they're easy to repair, with a helping of thick abs/acetone slurry, and some sanding.
(You may need to employ clamps or vise if the split has deformed your surface.

In case it helps anyone else, here's what I do when I need to print something big
(This is for an E3D hotend, if you're using a stock hotend, I think your upper limit is 240c)
(we're talking 7"x8"x5", 200 micron layers)

Bed temp is 120c
Hotend temp is between 270-280, depending on the characteristics of the filament
Enclosed build chamber
Print more slowly than you would normally print, The print I'm currently running is @30mm/s perimeter, 40 solid infill, 50 sparse infill
(hopefully I get away with it, last time I tried this print it was at 20,30,45)

[rymnd]

I wonder how well a hot air plastic welder would work. Basically a heat gun but focused through a small nozzle (1/4"-3/8").

I'll put it on the list to try. Currently it will come to the top of the list bout November.

nitewatchman

I got a hot air rework station from sparkfun to use for this. Haven't tried it yet though.

They have those neat "pens" now that take the filament in and melts it to a .4mm tip. Those should be
handy to fix cracks, etc.

I have a 3Doodler and got it specifically to fix repairs. In my experience, it's absolutely horrible for that purpose. The problem is that the ABS cools too quickly once it exits the nozzle (by design), so it doesn't really seep into the cracks. Also, the pen overall is very bulky, so it's difficult to get into tight spaces.

I've had much better luck either friction welding with a dremel and piece of filament (shown here: http://diy3dprinting.blogspot.com/2014/ ... -with.html) or with a hot iron like this one: http://www.amazon.com/dp/B0000302YM/

[Demolishun]

IANAL

Okay, so heated enclosure for a Cartesian coordinate robot?

What does that mean? Well, if I have a heated build plate and a heated extruder in my machine and put an enclosure around it, does that make it a heated enclosure? I am not specifically heating the enclosure. I am heating the bed and heating the extruder. The enclosure is there to control drafts. Now if I add fans to "control" the temperature am I adding heat?

From what I understand the machines from Stratasys that have a "heated enclosure" actually have heaters with blowers to put heat on a specific layer. I am not so sure they can claim infringement for putting a enclosure around a printer just because it has a heat source in it. One could make the argument that the enclosure is there to keep the surface temperature of the heated bed consistent and uniform by reducing drafts. I guess someone with a keen eye could review the patent to determine if the patent is broad enough to encapsulate that usage. In the meantime I think Delta printer owners should flout that they have draft control enclosures to set precedence that these are not "heated enclosures" unless you are specifically adding a heat source other than a heated bed and an extruder. That way nobody can patent that setup.

If the patent is bogus I think it would be good to challenge it. I do not believe the heated enclosure is a particularly unique and non obvious invention. I would bet these types of enclosures have been in use for quite some time for plastics and even additive manufacturing.