Detailed Instructions for Use "IFU" for DLP & LCD printers

3Dresyns detailed IFU, calibration files, and protocols are ideal for having maximum control of resolution and printing speed. Depending on your goals, resolution and printing speed can be balanced, or resolution can be prioritised in detriment of printing speed, or vice versa. These detailed guidelines can be used for our durable 3D resins, except for special resin systems, such as our water-soluble sacrificial 3D resins for printing sacrificial moulds and other high-tech applications, which need specific and more detailed protocols and instructions for use.

Standard settings for printing 3D resins with most DLP & LCD printers:

  • Z layer or slice height or thickness is typically between 50-100 microns (0.05-0.1 mm). Lower or higher are also printable for most 3D resins
  • Cure or Exposure or z layer or slice or thickness times are typically between 1-10 seconds for the fastest resins and 10-20 seconds for the slowest resins 
    • Depending on the power of your printer, the optimum exposure times will increase or decrease. Follow our detailed Instructions for Use. Measure and fill up the data, cure thickness vs exposure time, in the curing rate table for your specific printer specifications. Alternatively, order online the curing the table for your ordered 3D resins measured with similar light power specifications with this light meter*
  • Typically 3 initial, also known as adhesion, or bottom, or base, layer, or slice, or cure bottom count exposures of 80-100 seconds are enough for having very good adhesion on the build platform for most 3D resins
  • Z lift & retract speed: low, medium, or high value of the scale (non-critical for most 3D resins)
  • Light off delay/off time/wait before & after print: 0.1-0.5 seconds (non-critical for most 3D resins)
  • Z Lift after print distance: 5-10 mm (non-critical for most 3D resins)
  • Printing temperature: before printing warm viscous 3D resins, protecting them from room light to prevent their light curing, to around 30-35ºC to reduce their viscosity and adhesion to the resin tank
    • low viscosity resins do not require any warming

    Taking into account the broad range of printer specifications (light power variability) of different printer models of even the same printer technology the optimisation of the printing settings, such as light exposure times, are required for each resin and printer unit because all printers have different light power across the vat available for curing and printing.
    Additionally, the light power also decays over cumulative operating time or working hours. As example, the following graph shows a typical light output decay vs cumulative operating time of standard multicolour RGB LCD panels, monochrome LCD panels, digital lamp projectors, and LED projectors, all typically used in SLA, DLP & LCD 3D printers.

    *Note: The curing rate table for each ordered 3D resin cured at 405 nm with a similar light power to your printer can be optionally ordered online for 40 Euro. For getting exact values we recommend you ordering the same light meter as ours, the Chitu Systems Digital UV Light Meter. 3Dresyns has chosen this model due to its affordability and realibility since its spectral range of 402-407 nm coincides with most printers light wavelength (405 nm). The ordered curing rate table can be much more accurately measured after sharing your exact printer power since this will permit the 3Dresyns team to measure the curing rate table of your ordered 3D resins with the same power as yours since we will match your light power (light power matching or synchronisation) for fast & easy finding your optimum printing settings. Learn more about the Curing Rate Table.

    For more info read: 

    As mentioned before, depending on the chosen 3D printer technology, its light power and the cumulative operating time, the light power available reaching the vat for printing may vary significantly even from printer to printer of the same model depending on their cumulative operating time.

    Since each 3D resin requires certain energy dosage (mJoule/cm2) for curing each layer, printers with relatively low or high light power (mW/cm2) need relatively longer or shorter exposure times for curing (energy dosage=power x exposure time).    

    The 3Dresyns team has designed simple instructions for finding in just simple steps the best printing settings of our 3D resins in your specific printer. Our calibration process is ideal for getting in just few easy steps the optimum exposure times in your printer.

    Printing

    Most of our 3Dresyns are photopolymer or light-curing resins which have been designed for SLA, DLP, LCD, and Inkjet printers working with lights from 200 to 420 nm and higher upon request, including wavelengths at 385 and 405 nm.

    Select your z layer thickness, or the thickness of each printed layer, typically between 10-100 microns, for example, 50 microns as standard for high resolution printing.

    Select your printing settings, supports positioning, density, tip size and exposure time.

    How to choose the optimum exposure times?

    It is crucial that the following Curing Rate Table is filled up by you for getting the exposure time of the 3D resin in your printer since the optimum exposure time needed for curing the 3D resin depends on the amount of light power available across the vat, which varies from printer to printer, and on its cumulative working hours, since any light source, suffer a natural power decay upon time, as shown in the previous graph.

    How can you fill up the Curing Rate Table? By measuring the thickness of drops of the resin cured at different exposure times.

    Exposure time (seconds)

     Curing Rate Table: Thickness of cured resin (in microns) vs exposure time

    Thickness shown below are not real values: take YOUR OWN measurements yourself!

    5

    Example: 0 microns, uncured

    10

    Example: 30 microns, soft, too tender, poor adhesion on glass, easy to break: requires more time to cure properly (feel the strength of the cured drop with your fingers and nails)

    15

    Example: 60 microns, cured, hard, strong, better adhesion and strength

    20

    Example: 120 microns, well cured, hard, tough, good adhesion and strength

    25

    Example: 130 microns, well cured, good adhesion

    50

    Example: 150 microns, well cured, good adhesion on glass.

    75

    Example: 170 microns, well cured, very good adhesion. Ideal exposure time for printing the first 2 adhesion layers!!

    100

    Example: 180 microns, over cured, very good adhesion

     

    Calibration steps:

    • Remove the build platform from the printer
    • Apply a drop of the liquid resin on a glass slide, as the ones showed in the video and pictures below, and position it on the centre of the vat or resin tank in the printer. Then, cure it for example for 5 seconds
    • Then, remove gently with tissue paper the unreacted liquid resin from the glass slide and measure with precision the thickness of the cured resin with a calliper or micrometre. Feel the mechanical strength of the cured drop and write a comment it on the curing rate table
    • Repeat the cure test again with a new drop of resin, position it close to previous one on the same glass slide but with a longer exposure time, for example, 10 seconds, then remove the unreacted liquid resin with a paper, clean it and measure again the thickness of the cured resin. Feel the mechanical strength of the cured drop and write a comment it on the curing rate table
    • Repeat this process with longer exposure times, for example 15, 20, 25, 50, 75, and 100 seconds. You will end up having x cured drops positioned in a row, with different exposure times and thickness. This will be your fingerprint of your 3D resin in your specific printer status

    Fill up the Curing Rate Table with the results of your measurements

    It is recommended to represent both, short and long exposure times, for example, 2, 5, 10, 15, 20, 25, 50, 75, and 100 seconds. These times can be custom varied if needed to adapt to different printer powers, print speeds and resin systems.

    Remember to measure the thickness of each cured drop and evaluate its green state and write a comment about its strength in your notebook or ideally in the same curing rate table.  All 3D resins pass from liquid to solid state, through a green state, in which the resin can be too tender or soft to resist the peeling or separation or lift from the vat or resin tank during printing. Choose long enough exposure times to ensure that the resin has enough mechanical resistance to withstand the separation from the tank during printing. Typically, the optimum exposure time is the time needed to cure between one and two layers, in this example, the time to cure between 50 and 100 microns, which is approximately around 14 and 18 seconds.

    It is recommended to initially start printing the first calibration file 3Dtest1 with the exposure time needed to cure 1.5 layers. Depending on the results, the exposure time can be:

    • Reduced by using the time required to cure between 1.1 and 1.2 layers if the printing was successful, with the goal of increasing print speed, or
    • Increased by using the time required to cure between 1.75 and 2 layers with the goal of increasing printability if at shorter times the printing failed
    • To have good adhesion of the resin on the build platform is important to print at least 2 adhesion layers at long exposure times at around 70-80 seconds to ensure optimum adhesion on the build platform. Alternatively, more scientifically, use the exposure time at which the resin showed optimum adhesion and cured well on the glass slide. In this example, in 75 seconds the resin cured well and had very good adhesion on the glass slide (see example on the Curing Rate Table above), so use this time for curing the first two adhesion layers. Once the exposure times have been chosen, then the next step is:

    Start printing 3DTest1: the wedge (or the coin) without any supports, using 2 adhesion layers (use the exposure times as already explained) and for standard layers use initially the exposure time needed for curing 1.5 layers:

    Print 3DTest1: the wedge, in case you are interested in printing big parts and want to have a feeling of the strength of the wedge

    • Directly print the wedge:
      • adjust the wedge size to the total surface of your prints on the build platform (optional)
      • print the wedge directly on the build platform. If it breaks during its separation with the spatula due to excessive adhesion to the platform, then print it with supports or sidewards to facilitate its removal
    • Use the printed wedge to screen the peeling or separation force, the flexibility/rigidity as well as the fracture resistance of the material 
    • After printing 3Dtest1, evaluate the properties of the printed wedge to screen its flexibility/rigidity as well as its fracture resistance:
      • Position the wedge vertically and force it sidewards gently and firmly to measure the thickness at which the wedge does not deform or bend at all. This value in mm will give an indication of the thickness threshold at which the material becomes rigid. Below this thickness threshold the material will appear relatively flexible
      • Position again the wedge vertically and force it sidewards strongly and firmly until it breaks to measure the maximum thickness at which the tip of the wedge breaks. This value in mm will give an indication of the toughness of the material. The lower the thickness of the remaining wedge the tougher the material!!
    • Design a thinner or thicker, a shorter or longer wedge depending on your needs, which will depend on the relative size of your printed parts:
      • Relatively thinner and longer wedges are ideal for small size works
      • Relatively thicker and shorter wedges are good enough for large size works
      • Relatively longer wedges help to identify smaller differences in rigidity/flexibility and in toughness since the maximum thickness, at which the tip of the wedge deforms and breaks upon pressure, can be measured with more precision
    • Depending on your initial results, test or not a more rigid or flexible, or harder or flexible, or less tough or tougher resin, considering your required flexural strength and overall specifications
    • Printing the wedge flat with the biggest possible size is ideal for evaluating the printability of big designs covering the whole vat or resin tank. This is important since printers can have poor levelling of the build platform as well as significant broad light power distribution across the vat.

    Print 3DTest1: the flat coin without supports, in case you are interested in printing small parts and want to have a feeling of the achievable xy resolution:

    • Printing the coin flat with the standard size as supplied is ideal for evaluating the printability and xy resolution
    • The flat coin is printed without supports directly on the build platform. This first calibration test helps to identify the printability of a 2 mm thick coin of 25 mm of diameter, which can be printed for example with 20 z layers of 100 microns or with 40 z layers of 50 microns. This fast calibration file consumes very little resin and provides a proof of printability with the chosen settings, as well as an indication of xy resolution since each concentric circle has certain width and depth
    • The first concentric line starts with a width and depth of 500 microns (0.5 mm), the following ones have 400, 300, 200,150, 100, 80, 60, 40, 20, 10, 5, and 2 microns
    • This fast calibration tests gives an indication of the xy resolution, since the thinnest observed circle will determine the xy resolution of the resin with the chosen printing settings

    • It there is any printing failure, reflected because the coin is not fully printed, it is crucial to determine at which stage the printing failed:
      • If the whole coin separated from the build platform the bottom exposure time (and the number of bottom layers) needs to be increased to promote the adhesion of the resin to the build platform
      • If part of the coin was printed and another part remained adhered to the build platform the normal exposure time needs to be increased or decreased:
        • Increase the exposure time several seconds in case the printed part left on the build platform is too tender: under cured
        • Decrease the exposure time several seconds in case the printed part left on the build platform is too brittle: over cured
        • Once you find the right exposure times for printing 3Dtest1 well, then you can use them for printing 3Dtest2: the flat coin with supports shown below:

    Print 3DTest2: the flat coin with supports

    • Once the flat coin is printed without defects you may print 3Dtest2, the flat coin with supports. This second calibration file provides proof of printability of the coin with supports with the optimised settings used for printing the wedge or the flat coin without any supports, as well as an indication of xyz resolution, since depending on the obtained printed thickness of the coin, the z resolution will be higher or lower. If for example, the thickness of the printed coin after removing the supports would be 2.1 mm, knowing that the theoretical thickness is 2.0 mm, the accuracy would be =(2.1-2.0)x100/2=5 % z accuracy
    • The tips or connections of the supports to the coin are deliberately quite thin to permit printing structures with minimum supports, or with minimum tip sizes, to reduce the marking of the connections on the surface of prints

    Evaluation the quality of the printed coin with supports

    • Evaluate the xy resolution as shown before by reading the smallest width and depth of the printed concentric circles
    • Measure the thickness of the coin vs the theoretical 3Dtest1 thickness, which as supplied has 2.0 mm, to quantify the z axis accuracy. This will permit you to calculate the % relative error in the z axis
    • If you are not fully satisfied with the quality, or detail, or accuracy of your prints it is necessary to fine tune the 3D resin with our Fine Tuners, and/or adjust your printing settings, e.g. by decreasing the exposure time or the light power. Depending on the origin of the print quality problem, different solutions are available.

    Basic tools needed for calibration (click on the links to find commercial references):

    Cleaning and processing of prints:

    General Information:

    • The final physical and mechanical properties of any 3D printed material depend, among other things, on the printer specifications, printing settings, and post processing protocol. Results depend on few variables such as wavelength, power, exposure time, cleansing protocol (chemicals used for cleansing, cleansing time, cleansing temperature, etc) and light post-processing or light box curing (wavelength, power, post curing time, temperature, dry light box post curing, or dipping in our Cleaning Fluids, etc).

    Consulting

    You are welcome to contact us and order more products and services by email at: info@3dresyns.com