Monoprice 3D Printer IIIPv2
This Little 3D printer is about the minimum usable, as well as inexpensive, machine available. Amazon.com/monoprice $250 at this date.
2 years ago I purchased this little machine, with it’s 200mm x 200mm ( 7.8″ x 7.8″) build plate, so my grandson could get acquainted with this new technology along with his computer abilities. Last fall with the nearby Camp Fire and attendant bad air quality, I was reminded of the need for my water based air cleaners. I REALLY needed to get new ones built! even if just for me and other family members. So I set the printer up next to my computer and began the design. see: A new old project & The new old project continues. My sister prevailed on me to help launch this new business, it became important to share what I have learned, so she and her son could become familiar with the technology without starting from total ignorance..pg
The question of the cost to be a part of using 3D printing was posed and after some thought I replied; “ I am amazed at how little I have spent for the things that this little IIIPv2 printer, Optiplex780 computer and I have accomplished over the last 3 months. For less then a thousand dollars we have created things that would cost me tens of thousands and 2 years, 25 years ago. The 21st century is an Amazing place to this 20th century man…pg”
An excellent pdf on filament printing for a beginner starting out…pg
Back in 1986 I took a temporary job fabricating equipment for the Silicon Valley electronics industry. Equipment such as tanks, containment trays, fume duct work and fume scrubbers created from shaped plastic sheet stock parts Hot air welded together with a hot air welder and plastic rod. Plastic welding requires that the material be heated to the point that it will flow and stick, but not yet a fluid as one uses in metal welding. Plastic is made up of long chain hydrocarbons much like spaghetti that must be heated to the point that it is much like wet cooked pasta that will flow and stick but not break up or have it’s structure destroyed, a rather fine line of temperature that is particular to that type of plastic or alloy of plastics. 3D printing of plastic filaments is carried out under much the same conditions. In this case a miniature extruder under the control of a computer directed robot is laying down “welding rod” to create an object.
The job of the operator is to evaluate the conditions, manage the heat energy and material applied, to create the conditions for a good weld buildup of the part.
Due to the nature of the device being used the building part must remain solidly in place on the build bed during it’s creation. Much of the problems encountered in 3D printing center around keeping the building part in stuck in place. Then, at the end of the build the part should be easily removed so that the bed alignment is not disturbed, the bed surface is not damaged or warped, and the next part can be started.
New printer setup:
First thing, check all fasteners for tightness, Modestly tight, not finger tight, not OMG tight, but well fastened. All attachments must remain stable. The software assumes a stable machine and the printer does not self correct for any displacement during operation.
Set printer on a resilient bed such as ridged foam, hard rubber foam, etc. This will greatly reduce noise transfer and reduce resonant movements as the build bed and the mass of the printed object is rapidly moved under the Extruder head. Tie down the “Z” towers solid to frame, with angle braces or attachments to enclosure frame. The towers MUST be stable to the frame, there must be no chance of induced wobble during print bed movements. Any wobble can result in the nozzle encountering the solid work piece, causing a displacement that will ruin the work and may damage the printer.
We will be using ABS so heat management is critical for best results. The operating printer bed must be in a very warm, draft free environment, so an enclosure of some kind is important for consistent results. Being able to see the results of the printer’s operations as they happen is valuable, so the operator can observe, make any adjustments needed is very useful, so a “window” should be considered.
Periodic service before printing:
To insure that the part remains “stuck” to the print bed during it’s creation is critical to success. Be sure to clean bed covering of all dust and oils. Isopropal Alcohol works best, Acetone will work but will damage PEI coverings. Or add a glass covering, glass will require additional time to heat up ( 15-20min.), any glass will work and is less likely to be damaged by use, thicker glass will be less likely to warp, but glass will need additional fasteners to prevent movement on the bed table. Glass adds to the mass of the bed that will be in motion as well as it requires changes in the bottom limit switch position due to it’s additional thickness. We are using a Borosilicate glass covering as that has the best”stick” while hot and best release when cooled. Do not touch the bed covering after cleaning. To improve “stick” of the part to the build bed, various materials are often used to act as temporary “glue”. We are using ABS dissolved in Acetone as our sticking agent for most parts and sometimes Painters tape for really difficult to stick, critical large parts. The Painters Tape is the last resort as it is difficult to remove after the completion of the print. Also used by others are Hair Spray, paper glue stick, as well as salt and sugar. All water based that will stick hot and pop lose on cooling. many people print small and light pieces with no glue and others use special build plate coverings that seem to work with no additional adhesion. When printing with ABS it is critical that the piece remain warm and well adhered to the build bed during the build process. Any draft that might cool the bed, part or Extruder can ruin the work as well as the “stick”to the bed. Temperature MANAGEMENT is critical while working with ABS!
It is critical to adjust the machinery to be properly aligned, the Extruder must move parallel to the bed to lay even layers onto the surface of the build. In our type of printer the part creation bed moves back and forth in the “Y” plain under the Extruder. The Extruder moves in the side to side motion of the “X” plain and is supported by it’s carriage that is moved in the “Z” direction up to lay down the layers. In our case the Extruder carriage is controlled by two stepper motors that sometimes get out of synchronization, measure the distance of the carriage rods over the bed to be sure they are parallel to the bed. If not, they can easily be rotated into alignment while the printer is off. While energized they are electrically locked together.
To “level” or trammel the bed to printer nozzle there are adjusting thumb wheels or nuts in each corner of the bed. These are adjusted corner to corner, at least 3 times around. As you adjust one corner the diagonally opposite one will change as the bed teeters on the other two corners. Typewriter paper works well as a thickness gauge. Nozzle should just barely “grip” the paper to the bed. This must be completed on a “Hot” bed to be true for heated operation. It is very important that the first layer be properly stuck to the bed. We use “brim” as an attachment enhancement, as it adds no additional height to the parts, something that is critical to maintain measurements when several parts are assembled together. Once the printer begins the “Brim” the first deposition from the Extruder can be examined for good attachment to the build plate as well as the proper “squish”width and thickness.
It is at this time that I do final adjustment of the bed.
There are also now add-ons that will test the bed surface distances and read into the Gcode the needed nozzle position to properly stick that first layer.
After the print is completed and the print bed cools I slide a sharp thin blade under it to help release it from the bed. The more gently you can remove the part the better to prevent warpage or displacement of the bed adjustments.
Sharp thin blade tool:
I took a good quality, flexible putty knife and ground one side into a wood chisel like sharp edge. To assist lifting the part or for scraping the build plate I use it bevel side up to get under the brim and part to begin lifting them. Caution! Do not use this on a warm soft build plate cover material such as PEI, it will cut right through them, use only on glass or other hard materials.
Software We are using:
Acad 17 is being used to model the parts and export them as stl ‘s. There is also 360 Fusion available to private users as well as several free 3D modeling programs. These stl’s are actually cross-sections of the parts that are being exported into the Slicer that reads these files and then computes the needed instructions that the printer carries out. Printers are dumb, they are a very simple computer that only handle specific movements and temperature. Slicers convert the object into step-by-step directions for the printer to follow. Things like, maintain temperature, start extruding, move x-axis 10 mm and y-axis 2mm, and so on. Most of those commands start with a G, hence the name Gcode. A slicer translates the model slices into the needed movements, speeds and temperatures that are set in configuration instructions which the printer understands.
“Repetier-Host”, A freeware program, is being used to import the stl files and manage the “slicer” that creates the Gcode files and serves those instructions to the printer. Cura, A freeware program, is a slicer that is used to create the needed Gcode files that instruct the printer on how to execute the creation of the required piece. These Gcode files are the instructions that operate the “printer” to build the object one layer at a time by depositing material in amounts and position as dictated by the results of information developed by the “Slicer” program . The needed Gcode is specific to the printer being used and the slicer instructions are set in configuration before the slicer is engaged. The Gcode files are served to the printer through WiFi, or a USB connection or via. a SD card by Repetier-Host the server program that the “slicer” it is embedded in.
Early problem was prints were so porous that water would readily go through the walls but the tops and bottoms were quite solid. Found that tops & bottoms set were default set at 3x and the walls at 1x. I reset the tops & bottoms to 2x as well as set the walls to 2x. This increased the time required and material used but resulted in a substantial improvement in part quality.
increased the extrusion rate 10% to get a stronger more solid part and the result was…
As I was attempting to print the third of 3 motor bases, again I hear this pop and the printer dislocates the “X” axis at about the 1.1 inch line, What the heck! This was 3 times in a row at about the same point, damaging the print. now I will have to section off the top quarter of an inch of the model and print 3 of those and repair all 3 motor bases. But why ? I sleep on this problem and… of course! the extrusion is too high. We have been making the layers just a bit too thick and after an inch of layers the build was too high and during a travel move from side to side the no longer high enough nozzle impacted the build so hard that the “X” belt jumped the sprocket and the machine lost it’s registry of position, always at about the same spot. Reduced the extrusion rate, end of that problem.
notes from 3D Printing: