I got my 14 yr old grandson a Wanhao Duplicator I3 for Christmas along with Simplify3D. He got it working on his own and I am impressed with how well it prints. It has a heated bed and he has printed some small parts in ABS he modeled in Inventor and they came out very and were quite strong. Simplyfy3D settings were nearly perfect as far as how the parts look, and measure. He has printed some larger part for me and the parts don't have very good strength between layers. This is an open printer and I am also concerned about a fire if left to print over night. So I am looking for a metal cabinet to put it in.
So to correct the strength issue what steps should be taken? I am thinking maybe we should increase the extruder temperature a little as a first step. I am also thinking the enclosure might be insulated too so that the print stays warmer the whole time. The layers near the heated bed are clearly better bonded than those up higher on a taller part.
I have a design for a pump impeller to be used in my job. My hope is to print one strong enough to prove out that it will work, before getting them cast in stainless. The impeller needs about 15 hours to print so overnight is needed and it is about 5 inches tall so strength is needed at the top too.
I would suggest two things, 1. raise your nozzle temp 5 to 10 degrees and see if the adhesion improves. 2. put a light coat of acetone over your part when complete and that will help chemically bond the surface into a much stronger object.
PETG is stronger than PLA, but probably not ABS. ABS will likely be superior material. Fire should not be an issue, but I would certainly want to make sure that the printer is well supported on a good surface.
Putting the printer in an enclosed space is a good first step, it will help with getting solid prints. The area around the printer needs to be warm to get good results with ABS.
I don't know that I'd apply acetone directly to the print, but I've had good results with exposing the finished product to acetone vapours. This will work for ABS, but not PETG or PLA.
I used a couple of foil roasting pans. In the bottom one, I had a small amount of acetone. I suspended my ABS printed part so that it was not actually touching the acetone, then covered the whole thing with the other roasting pan. I left them in a nice warm location for a couple of hours, until the printed part was smooth to the touch. The slight roughness of the printed layers had reduced enough to make the part feel smooth and continuous. I could still SEE the print layers, but they were much more difficult to feel with the fingers. This will leave your part more accurate than if you apply acetone directly to the ABS, since it affects less of the material. Check on it often during this phase, as leaving it too long will result in the corners looking (Well, actually BEING) slightly melted.
If your part has the tolerance for it, a coat of fingernail polish, like the kind that is used to strengthen your fingernails can also help. There is a solvent base to this that can help bond the ABS layers as well. I'd try it on a scrap print first to be sure that it won't harm the plastic. The stuff that I got at the dollar store doesn't seem to harm the plastic and does add some strength, as well as some smoothing for the printed layers.
Prusa i3 / Arduino Mega 2560 / RAMPS 1.4
Kit from a2aprinter
Beltless redesign in progress to move to T8 lead screw drive
Kit from Amazon
Some teething pains, but a reasonably good printer, just missing a heated bed.