Thursday, May 31, 2012

3D Design Tricks

It is important to know how 3D printers operate before you design and print your design.  If you make your design knowing this you would get better results.

Some design recommendations:

1. Don’t forget the gravity. (The objects are printed from bottom to top. There needs to be a physical material beneath the extruded plastic. Rotate your design before printing so that there is less bulking of from the center. Some printer software can add support material bulking parts of your design.  If the printer has two extruders like Replicator, the printer can use water soluble plastic as a support material. This plastic can be removed after proper water treatment.  For the rest of the printers the support material is the same material as the object. The supporting part is printed with less fill factor making it weak. This enables easy removal of support material with breaking the part by hand.  If you have a design where the object has high detail near or above the support material, these parts may be damaged while removing the support part. Therefore it is wise to rotate the object in software such that there should be no support near the detailed parts on the final print.)

2. Avoid sharp corners and straight edges. (It is quite difficult to have results that have sharp corners and straight edges. That’s why most of the print outs shown have more rounded design.)

3. If your design has connection of multiple printed parts try to have larger tolerances on the interlocking parts. The printouts are not perfect.

The Hardware

Most 3D printers are sold unassembled.  The casing of these printers are made of laser cut Plymouth.
The assembly process takes around 8 hours of continuous work, normally two days or more is required to print your first 3D model.   Most parts are custom made for the printer. Therefore if you break one while assembling you need to order that part again and wait for the delivery.

Quality 3D printing requires precise placement of right amount of plastic to the right point. In order to achieve this following are required:
- Perfectly round and uniform filament
- The extruder speed and the temperature adjusted according to filament type and color
- X,Y and Z axis positioning reliably exact.

The printing process takes several hours if the quality is set to highest. The reason for this is more layers are required for fine details and for better positioning and better filament extrusion X,Y axis speeds are lowered. (You need to print more layers at a lower speed)

The printers do not have a well-established calibration and positioning systems. Therefore if something goes wrong even for a short duration, the system cannot correct it afterwards and the rest of the printing would be spoiled.
A feedback system should be developed for the printer to improve the quality. I will thing more about on this after I get my printer and start printing with it.

Long operating hours would loosen screws for X,Y axis motor mounts. This results in improper belt tension and therefore not exact X,Y positioning.
A rigid printer chases would be more suitable for such printers. Therefore I am preferring MakerGear’s M2 over others.

The short comings of 3D Printers:
1. Frequent calibration and maintenance requirement (Calibration: Positioning, extrusion speed; Maintenance: Oiling of gears, belt tension control)
2. Slow print speed  (Even with the fastest printer on the market it takes several hours to print a high quality print.)
3. Unpredictable print quality (The print quality depends on so many factors that, it is almost impossible to have a high quality output. The lack of a proper feedback system is the main shortcoming.  Additionally long print time increases the deformations on the plastic as a result of contraction of plastic due to heat differences between layers.)
4. Post processing requirement  (Some printers have serious stringing problem (Ultimaker), that requires careful cleaning of extra plastic coming out.  The removal of the support material.)
5. The operating noise of the printer (You can hardly stand that noise for hours. Therefore you cannot have it in your living room or your bedroom.  That’s a problem for those who do not have a garage or a study room)

Wednesday, May 30, 2012

3D Printing Workflow

3D Printing Workflow

Here is a summary of 3D Printing workflow written by Florian Horsch on his blog.

3D Printing Workflow

As seen from the diagram the process of 3D printing requires the use of multiple programs. During the process several files with different formats are generated. The use of these applications require skill and knowledge. In order to get a quality print you need to set profiles in your slicing application. Dave Durant has a nice blog post on importance of profiles.

It would be nice if the files we get from Thingeverse would contain recommended profiles. I don't know technically, but if the profiles are standard across different printers then this could be possible. Otherwise it is impractical to include profiles for each printer on the market.
The software behind personal 3D printing needs serious improvement before it is adapted by the end users. This work can be carried out independent of 3D printing technology.

My preferences for the software are:

  • There should be one application handling all the required steps.
  • The application can be composed of modules developed by different venders, but the UI should be same and integration between the modules should be smooth.
  • Wednesday, May 23, 2012

    First Thoughts on 3D Printing

    I started this blog to share my experience on personal 3D printing systems.

    Now I am gathering information on available 3D printers.
    My initial analysis stopped me from buying a printer now.
    I will wait for a couple of months more.

    As a result of my analysis, I decided on buying one of these printers:
    - Replicator (MakerBot)
    - Ultimaker
    - M2 (MakerGear)

    My criteria on selecting a 3D printer are as follows:
    1. Easy to assemble and use
    2. Firm and Community Support
    3. Reliable performance
    4. Quality of print
    5. Speed of printing
    6. Low frequency of servicing

    I was initially thinking of hacking a 3D printer. However, I decided to do it after I start using a more reliable system. Here are my thoughts on the printers based on my criteria. As seen there is no clear winner.

    1. Easy to assemble and use I can order the product fully assembled (+++) I have to assemble to printer myself (-) I can order the product fully assembled (+++)
    2. Firm and Community Support The firm has a well established support and the customer base is the largest among others (+++) The firm has quick responding support. Customer base is small (+) The firm has only IRC based support. Customer base is small (-)
    3. Reliable performance Hard to conclude from forum and blog posts however it seems a steep learning curve. (-) Hard to conclude from forum and blog posts however it seems a steep learning curve. (-) Metal frame is an advantage. However it is recently released therefore needs several months of user feedback (?)
    4. Quality of print Not that much impressed compared to Ultimaker (+) If everything goes well, the results are outstanding. The biggest negative is stringing!!! (++) No sample printouts yet (?)
    5. Speed of printing Slow compared to Ultimaker (-) The fastest among compatitors (+++) The speed is unknown (?)
    6. Low frequency of servicing The wooden frame may require frequent maintenance (-) The wooden frame may require frequent maintenance (-) The metal frame looks more reliable hence requiring less maintenance (++)