Prusa i3 ruining my life

davidbananas999

Prusa i3 ruining my life
November 30, 2015 11:12PM

Registered: 8 years ago
Posts: 41

Hey guys. I just built a Prusa I3. I have been able to print stuff with normal speed settings and temps around 205 but they're not that great. Gear teeth are sloppy and round etc. Not perfectly straight lines etc. So im trying to dial my settings in to print slower and more accurate. Here are the setting for slicer and pics of my test. Im printing with 1.75mm Shaxon PLA.
problems I see:
strings
squished base

thank you! this is driving me nuts!

edit: added screenshot of speed settings, oops

Edited 1 time(s). Last edit at 11/30/2015 11:16PM by davidbananas999.

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Downunder35m

Re: Prusa i3 ruining my life
December 01, 2015 02:28AM

Registered: 8 years ago
Posts: 778

Your bridging speed is too high and you need to tune the retraction to avoid the strings.

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o_lampe

Re: Prusa i3 ruining my life
December 01, 2015 03:42AM

Registered: 8 years ago
Posts: 5,232

205C seem to high. Especially when you print slow. Stringing happens with high temp,low retraction speed and retraction length.
190C, 80mm/s and 2-4mm are good values to start with.

The part is so shiny, are you sure it isn't PETG?
Olaf
PS: Don't be such a crybaby winking smiley

We all have spend time and tons of filament to get it right. Print some calibration cubes and go from there..

Edited 1 time(s). Last edit at 12/01/2015 03:45AM by o_lampe.

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RRuser

Re: Prusa i3 ruining my life
December 01, 2015 08:21AM

Registered: 10 years ago
Posts: 444

There are no bridges there. I'd say the travel speed at 30 is way too low; gives too much time for nozzle to drain (esp PLA).

Also looks like retraction is turned off. Need to be on; I'm using 2mm at 20 mm/s.

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davidbananas999

Re: Prusa i3 ruining my life
December 01, 2015 06:24PM

Registered: 8 years ago
Posts: 41

Next Test:

I have included a couple pictures of my latest test print with new settings. Remember this is 1.75mm pla.

Problems:
large spikes
stringy
squished base

settings:
layer height 0.2mm
fill density 40%
no support
extruder multiplier 1
extruder temp 180ºC
bed temp 70ºC
nozzle diameter 0.4mm
retraction length 3mm
lift z 0
retraction speed 80mm/s
(see attachment for speed settings)

I appreciate any tips, thanks.

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o_lampe

Re: Prusa i3 ruining my life
December 02, 2015 04:35AM

Registered: 8 years ago
Posts: 5,232

70C bed temp is only required for prints on sheer glass. With blue painter tape you can lower the temp to 45ish. => less squishing

The corners of the object look like you have loose belts or otherwise play in your mechanics. ( low budged linear guides? )

Don't expect to print parts, you don't need to clean up afterwards.
-Olaf
PS: The part is still very shiny, I haven't seen that with PLA before. confused smiley

Edited 1 time(s). Last edit at 12/02/2015 04:36AM by o_lampe.

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Downunder35m

Re: Prusa i3 ruining my life
December 02, 2015 06:00AM

Registered: 8 years ago
Posts: 778

I have a white PLA that is quite shiny too winking smiley

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davidbananas999

Re: Prusa i3 ruining my life
December 02, 2015 08:11PM

Registered: 8 years ago
Posts: 41

my kit was pretty cheap. what are the linear guides, and do you have a link to some decent ones?
Also I have my belts are as tight as i can set them, should i use s clips or something? im just going to print some anyway to try it

ty

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Downunder35m

Re: Prusa i3 ruining my life
December 02, 2015 08:56PM

Registered: 8 years ago
Posts: 778

Just do a search on Ebay for 8mm linear bearing and you will find plenty.
Some people started to print those bearings as simple sleeves in Nylon and claim it works great.
A problem with many kits is that you literally get what you pay for, so if you buy low end you can not expect high end quality prints or insane speeds.
If you just finnished the build and try to get it running start by using silicone oil on the moving parts and just let the machine work all axis for 2 or 3 hours - this takes care of most things that are still binding and causing too much friction.
After that move by hand what can can be moved by hand and check if it runs smooth.
Sometimes a slight twek in the rod alignment can have surprising results, half a mm difference can be the difference between a smooth ride and failed prints.

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RRuser

Re: Prusa i3 ruining my life
December 05, 2015 06:22AM

Registered: 10 years ago
Posts: 444

Still looks like there is no retraction at all. I thought there was no bridging, but I see it there now.

At 80 mm/s retraction speed, mine would just buzz (skip) and not retract much. Reducing to 40 helped most of the time, and reducing to 20 works every time. Yours might be skipping on retraction too, and if so, you are getting no retraction.

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