Print The Porto

A collection of tips about 3d printing.
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How to calibrate your 3d printer for accurate printing

Most people don't realize it, but you can get reasonably accurate prints with just about any 3D Printer, even with low-end clones. With a little bit of time and measuring, prints can be within .05mm accuracy. Having an uneven X and Y is where a 20mm cube will print 20.5mm on the X-axis and 19.95mm on the Y-Axis and cause circles to be over or under-sized and eleptical.

Most machines will come with preset steps configured, based off of the stepper motor and belt configuration. There is a great article written bt Matterhackers on how this is all configured https://www.matterhackers.com/news/3d-printer-firmware-settings-stepper-motor-configuration

To calibrate your axes, follow these steps:

Step 1

Print a calibration cube and be sure to orient it to match the proper X and Y axes for your printer. It is important to keep track of which direction X and Y is.

You can get it at http://www.thingiverse.com/thing:214260

20mm calibration cube from thingiverse

Find the step-per-mm values for your printer. In most slicers there will be an area you can type in GCODE commands. Typing M501 will let you read parameters from EEPROM. For marlin and smoothie firmware, this should be the M92 value for each axis.

Step 2

Measure the printed object with a pair of calipers.

Using the following formula lets calculate the new steps-per-mm value:
(OLD step value * DEFINED object length) / MEASURED object length = NEW steps per mm value.
For example the old step value for X is M92 X114.20 and we measured 19.625mm on the X axis of the printed cube. Using those numbers in the formula
(114.20 * 20) / 19.625 = 116.382 Our new X axis steps is M92 X116.382. Enter that in the GCODE area and save it to the EEPROM by typing M500.

Repeat this calculation for the Y axis and print again. Repeat these steps until you are satisfied it is close enough. In case you were wonder what is close enough, Anything that measure 19.955 on any axis is pretty damn close.

Setting the Z steps requires a different method. Since most printers use a mechanical leadscrew this will be set in stone. Make sure to find out which type of stepper motor and lead screw you have and input that information using Prusa's excellent calculator. http://prusaprinters.org/calculator/#stepspermmlead Once you get that number, input it back via the M92 gcode.

While you are at the Prusa calculator, you will notice the next widget they have, is for optimal printing layer height. Just put in the layer height you want to print at and see if will work with your configuration. I recommend keeping a list of the exact layer heights you can print at. This will dramatically improve your accuracy. If it comes up red, avoid it like the plague.

Step 3

This leaves the last motor to be calibrated, the extruder. The method is very similar to what's been done previously. So go ahead and follow the steps outlined on how to calibrate your extruder steps. Don't worry, we'll wait for you here.

Step 4

Last but not least, after all this is done. You should follow up with calibrating extrusion thickness. This last part is on a per filament basis, so It's always going to change and it's a good habit to record and keep track of how each roll prints.

With all this done you should be getting near perfect prints.

Categories: Calibration, tips

Tags: Calibration, tips

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Printing Ninjaflex TPU filament on the E3D titan extruder

I recently upgraded my eclips3d printer to use an E3D Titan extruder, which has been printing out pretty great once I dialed in all the settings. I needed to print a bunch of rubbery feet for a wire shelf. In the past I've used my printrbot simple to print with ninjflex, so I was curious to try the titan since it is seriously grippy when handling other filaments.

TLDR;

All the normal rules on how to print with ninjaflex still stand. But on the Titan extruder, you need to lessen the tensioner bolt to 1 bar. Looser is better anything higher and it jams.

Try and try again

Following the guide I wrote to myself on how to print with ninjaflex I started up a new print and it constantly kept failing. The filament would actually get squeezed past the geared teeth and bunch up causing it to bind within the netheregions of the titan extruder.

Pile of failed ninjaflex prints
Pile of failed ninjaflex prints

Pile of failed ninjaflex prints with a bad infill
Still looks bad from the top

Printing super slow at 10mm/sec seemed to help, but eventually it would still happen. Scouring the internet I did find a little gem of information on the solidoodle forum with a user who installed the titan on his machine. The most pertinent info came from Sanjay who works for e3d.

We've been printing TPUs of various types on Titan without much drama. The usual flexible material caveats apply in terms of making things go a bit slower (Start @10mm/s or so and work up, depending on the stiffness/softness you should be able to do 20-30 with most), having a bit more retract than usual (1.5mm works for us). Temperatures for TPU are extremely sensitive and I usually find there is a tight 3 degree window in which they work best. For Ninjaflex this seems to be around 227C on a standard E3D-v6.

The most important bit of info is how soft the specific TPU you're using is. Our softest TPU that we've used is Ninjaflex which is Shore 85A (or around Shore 40D). Which TPU are you using, and do you know the hardness?

Sanjay

Using this new information I changed my settings, but still wasn't quite successful. By chance I saw a great review for the new flexion extruder by Maker's Muse. Seems like a great extruder, but didn't understand why the titan would be much different. Until he mentioned how he lowered the tension in order to print with ninjaflex/tpu on the flexion. The light bulb went on in my head and I checked how tight the tensioner was on the titan; It was pretty tight.

Starting up a new print, printing at 15mm/sec and with the tensioner set to 1 bar and it printed beautifully.

Good prints

Some zits on the side due to using the volcano hot end and large nozzle diameter
Some zits on the wall due to retraction not being dialed in for ninjaflex
Good smooth prints
Smooth layer lines. 0.44mm layer height.

Test updates and findings

After spending some time printing up a couple of test pieces seems I found a good tension for ninja flex on the titan as you can see below, setting the tension to 1 bar, had the best success rate. Results shown from left to right all printed with saphire blue ninjaflex at 20% linear infill.

  1. Layer height .44mm at 20mm/sec speed at tension bar 2. win
  2. Layer height .44mm at 30mm/sec speed at tension bar 2. fail
  3. Layer height .44mm at 30mm/sec speed at tension bar 1. win
  4. Layer height .32mm at 40mm/sec speed at tension bar 1. win
  5. Layer height .32mm at 45mm/sec speed at tension bar 1. outer wall which printed at half speed win, infill was sloppy and under extruded fail
  6. Layer height .32mm at 45mm/sec speed at tension bar 2. fail
  7. Layer height .32mm at 50mm/sec speed at tension bar 1. fail

The larger version was made to test printing faster, when it was smaller the slicer would always slow it down due to it not having to cross so much distance. Making it larger did work and would have been a successful print had I completed the infill at 30% and printed more solid top layers.

Categories: Ninjaflex, tips, Filament

Tags: Ninjaflex, Filament, tips

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How to calibrate extrusion width

First make sure you've calibrated your e-steps.

Using a digital caliper, measure the thickness of your filament at 5 different points and get the average. You'll find most filament is not actually 1.75mm in width, but usually less. Enter the measured filament diameter in your slicer.

Download a 20mm calibration cube from http://www.thingiverse.com/thing:271736

Using the cube load it into the slicer and set the following:

  • One, single perimeter (1 wall)
  • No infill
  • No top and bottom layer

You should get a print that looks like this:

Use your caliper and measure the top layers of the wall at several points to get an` average thickness. I got measurements around 1.07mm with my current extrusion multiplier of 1 and extrusion width set automatically to .96mm (120% of nozzle width) for my .8mm nozzle. Using the formula below, lets calibrate the extrusion.

Extrusion Formula
(desired thickness / measured thickness) * old extrusion multiplier = new extrusion multiplier

.96/1.07 * 1 = .89

I changed my extrusion multiplier to 0.89 and printed the model again. I still didn't get the correct thickness, so I repeated the process until, the magic number appeared.

Having the proper extrusion thickness should help with printing out correctly sized and properly extruded models. This is a process that might be needed on a per filament basis. Otherwise, just make sure to always measure your filament, prior to printing, otherwise it throws off all your hard work.

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