MakerGear Forum

When I was at the Maker Faire this weekend I seen quite a few 3D printers from various manufacturers. I was happy to see that in general the prints I have done come out pretty close to what they were printing or otherwise displaying in their booths. I did notice a couple things that were clearly coming out nicer than what I have been able to do to date.

(1) The overall finish. Theirs seem to be shiny all over where as mine seem to only have a shine on a portion of it. I think the shine seems more likely on the side where the fan is mounted. I did verify the models were printed using PLA just like mine were.

(2) There were several models that were of items that come to a point such as the horn on a unicorn. I seen several models having this sort of feature that looked considerably better than anything I have been able to do. The main reason being is that my prints seem to get somewhat irregular on these types of items meaning the uniform taper expected is not uniform but instead a wavy.

(3) The base of a model that has a flat bottom but gradually gets wider as it goes up. The portion that is low on the model ends up with defects on the back side away from the fan. These defects seem to end up starting around a 1/4" from the plate and may continue for a 1/4" to 1/2" up the model where they seems to gradually taper off.

Any advice you can give me on improving these items is appreciated!

Thanks

1. Printing with higher temps in PLA will give you a glossier finish. What temperature do you normally print at?
2. Prints with very small cross sections suffer from insufficient cooling. Are you running your fan at 100% for those models, and slowing down the print to enforce a minimum layer time? (were they printing multiple copies, that can help too).
3. Again, insufficient cooling. Don't understand why the defects would stop, though, perhaps the overhang is getting less as the model gets higher. You can try rotating the model, unless it is radially symmetric, or try printing a fan duct that collars the nozzle. I haven't found one I liked, though.

1. Printing with higher temps in PLA will give you a glossier finish. What temperature do you normally print at? - I normally print at 215C

2. Prints with very small cross sections suffer from insufficient cooling. Are you running your fan at 100% for those models, and slowing down the print to enforce a minimum layer time? (were they printing multiple copies, that can help too). - Yes the fan is at 100% but I haven't made any adjustments for the minimum layer time. What minimum layer time do you suggest?

3. Again, insufficient cooling. Don't understand why the defects would stop, though, perhaps the overhang is getting less as the model gets higher. You can try rotating the model, unless it is radially symmetric, or try printing a fan duct that collars the nozzle. I haven't found one I liked, though. - The models that I can think of that this happened on were symmetrical. Does placing a fan behind the printer provide any benefit. If you have any suggested models for a fan duct please provide a link.

Thanks

Check out this article on the effects of temperature on PLA: http://richrap.blogspot.com/2014/02/tem ... nting.html
Note that you should probably add 20C to all the temps for the v3b.

Minimum layer times, I haven't run tests. I normally run with 15s, but I think someone here found they were getting good results down to 5s. There was also a [ur=https://groups.google.com/d/msg/makerge ... Y3o8D_aEJl]thread on Google Groups[/url] about printing tests using the hollow pyramid, you can look at that for suggestions. There were some good prints.

For the overhanging model, is it something you can link to or provide? Yes, a back side fan will help. You almost can't have too much fan with PLA, unless it starts to physically blow stuff around.

I haven't seen a fan duct of the kind I'm talking about. See the Mendel90 fan duct design at the top of this. There is the Tapir Shroud for M2 on on thingiverse that I would like to try, but that is for an older extruder version.

jsc wrote:You can try rotating the model, unless it is radially symmetric, or try printing a fan duct that collars the nozzle. I haven't found one I liked, though.

Maybe an M2 fan duct would be a good project for the next Modeling Challenge. I was thinking it would be good to practice designing a part that fit to something that already existed. This would be a case of that, and useful to myself and others here as well.

Good idea Toby. I actually printed one out the other day and then discovered it was for the old style hot end. whoops!