3D print quality

[JuniorJack]

Hello,

A newbie here. And my first post.

I bought a Chinesse CNC machine last year for some hobby projects prototyping. I had to master SolidWorks in order to get any useful results, and now i think I have reached the limit of what this machine can produce as quality. So this is the reason i started to looking on ebay for 3D printers and Google a bit about what is possible. Still after two days of reading I can not decide if anything useful could be done with a 1000-2000 GBP printer from Ebay. That is why i hope for some help.

For example i see this item here:

http://thingiverse-production.s3.ama...w_featured.jpg

and the result here:

http://thingiverse-production.s3.ama...w_featured.jpg

So my question is - is this absolutely the best that could be expected as output quality ? Even with expensive 3D printer ? Do you need to machine the items after printing ?

Thank you!

Chris

[MysteryAlabaster]

No, this is by far not the best quality you can get. I see things like this all the time and wonder why they're printed at such a low resolution. Now I realize it's because that's how the printer is made.

For me, with my Makerbot Replicator 2 I could produce a part that looked near perfect when compared to a professionally machined part (only made of plastic and not metal).


//EDIT: Our printer is free for a bit today, so next time I'm in the lab I'll print this at the highest resolution I can, should take about half an hour.

//EDIT: Also, eBay? Really? Why would you trust some random idiot on the internet with that much money? Buy it from a recognized distributor.

[JuniorJack]

Hi,

Thanks for they reply. I would appreciate a nice picture of what is possible. Regarding Ebay, i have not done enough research yet and not sure what is the best place to buy yet. It was just the first place i looked.

BR

[MysteryAlabaster]

I would appreciate a nice picture of what is possible.

Here you go, the red one was printed on a Replicator 2X and the white on a Replicator 2.

WP_20140225_001.jpgWP_20140225_002.jpgWP_20140225_003.jpg

[JuniorJack]

Thank you for the effort! The white one looks really great. Is this some settings related or the 2X much worse than the other model ?

BR

[3dkarma]

Printed on a basic reprap. The top came out nice and smooth. Nothing that special about the printer - just quality components and a lot of time spent calibrating as per the reprap wiki calibration guide. http://reprap.org/wiki/Calibration

IMG_2607.jpg

[JuniorJack]

I see. So it is the same case as CNC machining - you can design an object for 10 % of the time, then the rest 90 % is optimizing the CAM program to actually have it correctly cut, without breaking milling bits, etc.

Thanks again for the time guys, so i guess the conclusion is i should choose the best possible resolution when choosing what to buy.

BR

[3dkarma]

You will spend a lot of time optimising the slicing software to give you the best print for your particular printer - that's largely what the calibration guide is about. Once that's done you don't generally need to touch it again for a while.

Getting your printer to print fine detail well is about three things: 1. how well your printer is tuned (I'd include layer height and extrusion width in this); 2. the positioning accuracy along all three axes (although there's not a lot of difference between printers out there) and 3. your extruder nozzle diameter. The print above was done with a 0.5mm diameter nozzle and the detailed turned out pretty well. I've another printer that's set up with a 0.3 diameter nozzle which gives finer detail and a smoother finish, but takes a lot longer to complete a print, involves much more work to calibrate and has problems with overhangs due to the extrusion size (although it does do bridges extremely well).

[ralphzoontjens]

And make sure that your plastic adheres well to the printbed. If I'm not mistaken the curling up of the red model is due to a lack of adherence between the filament and the print bed. It needs to be heated properly and putting some glue stick or hairspray on can solve it. Honestly that red one looks like a mess, would be totally unusable for most applications to me. What is that mess on the top caused by?

I would also advise to try to find detailed accounts of people who have already used the 3d printer you are intending to buy for similar purposes, and see if there are unforeseen issues you may have to deal with.

[3dkarma]

Absolutely right on the print bed adherance. I use dilute PVA painted on a heated print bed to keep PLA from curling / lifting.