Thursday, November 5, 2009
Thanks for being patient.
Sunday, October 4, 2009
To make a 3DP I needed to not only automate the "reset" but also, precisely control the movement of 2 bins, switch a dc motor on an off, and be able to tell the printing computer to "wait" and not send the next page until the printer is ready. I could have built a dedicated circuit to do all this but as I stated earlier, My knowledge of electronics is limited and I don't have a clue how to program a PIC. I decided instead to go with a CNC setup. The inkjet still does all the actual printing then the CNC takes over and re setts the gantry, adjusts the powder bins,spreads the powder, and then tells the printing computer that it can send the next page. You can see in the diagram that PC 2 has replaced the pulse generator and a relay has replaced switch 2. Additionally, 2 more steppers and a 2 axis stepper driver have been added. Switch 4 gives feedback to the control program and signals the change from the print to the recharge cycle. Relay 2 breaks the connection on pin #11 of the inkjet's parallel port. this tells the PC that the printer is "busy" so it wont send another page until the printer is ready. Relay 3 is connected to the motor that runs the powder roller. The breakout board is a convenient place to make all the connections to the parallel cable and PC 2. Note that the parallel port of the PC doesn't output enough current to drive a relay directly so I used the outputs to switch transistors that supply 5v to the relays.
For the CNC control I use TurboCNC and a G-code program. The program is a step by step set of instructions which can be used to set the logic state (high/low) of the parallel port pins. Also, pins can be monitored and step pulses can be sent to the stepper drivers.
Hopefully this helps clarify what I've done. If I haven't answered your questions feel free to ask.
Wednesday, September 23, 2009
Wednesday, September 9, 2009
The utility is easy to use and doesn’t require any additional programming skills. Simply open your stl file in the slicer, pick a printer, set the slice thickness, and hit print. You can scale and rotate the model as well as shift the print position to center it on the page. One thing to note is that the measurements are in metric. You need to convert your stl to millimeters if you want it to print at the size you are expecting. My other observation is that the mesh must be clean and watertight. From what I understand, that’s not unusual for 3D printing. It’s probably also the reason the other software was so expensive. Unfortunately, my meshes are typically neither clean nor watertight (I really need to learn better 3D modeling skills).
I am modeling in Silo and using MeshLab to check and repair my meshes. Some are so hopelessly messed up that I’ll have to go back and start over. (There is also a slice feature in MeshLab but it outputs svg outlines and I need silhouettes.) MeshLab is open source and can be found at Sourceforge (http://sourceforge.net/projects/meshlab/). Silo is available from Nevercenter (http://www.nevercenter.com/about/) for a modest $99 ($159 for the pro version). They have a 30 day trial if you want to check it out and a very friendly and helpful users community. I'm still very much a Noob with Silo but I found it to be much more intuitive than Blender and WAY less expensive than Rhino, Lightwave, or any of the CAD packages (Hell, even Google Sketch Up is like $495 if you want to be able to output anything other than their own format). Again, if this wasn't a hobby (and I wasn't incorrigibly cheap), expese wouldn't be such a big issue.
Anyway, now I need to make my repairs and whip up some test files.
Monday, September 7, 2009
Oh Noooo!!!!! Somewhere around layer 170 one of the belts came loose! I'm going to have to come up with a more secure clamp. Once I get the belts fixed I'll be ready to try again. For now I'm trying to use up the ink in a new cartridge. I tried to refill an old one with the water/vodka mix but it was hopelessly clogged. I figure I'll have better luck with a new one. For now I'll keep working on getting the powder layer as smooth as possible. I also need to install a limit switch on the supply bin so it stops when it reaches the top.
Thursday, September 3, 2009
There are also subroutines to prep the printer/bins for the first page and to input the number and thickness of layers. I also have a countdown displayed so I know how many layers are left.
Tuesday, September 1, 2009
Stepper motors require a driver. There are two input signals which tell the driver what to do. The first is a step pulse. With each pulse the motor advances (turns) one step. The second is the direction signal. This tells the driver which direction the motor is to turn. The signals are 5v logic and can come from any source (a push button, 555 timer, PC, whatever). A PC running software (like TurboCNC) can be used to turn the stepper an exact number of steps, at the specified speed, in the direction of your choice. I'll use this later to reset the printer and control my bins.
NEXT UP, Resetting the printer to print more than one page.
Friday, August 28, 2009
Let me start by listing my liabilities;
- I don't have the first clue how to program a pic.
- Python might as well be a really big snake.
- Scripting is something i do to make my handwriting look nice on Christmas cards.
- Everything I know about electronics I learned from the Radio Shack " Getting Started in Electronics" book.
OK , now that that's out of the way, this is the plan.
- I will use software obtained elsewhere to "slice" my .stl file into images that will be sent from my laptop to the printer. ( more on this later)
- I will use the inkjet's firmware to handle the printing and the motion of the gantry (formerly the paper feed, now the x axis) during the printing phase
- Another PC (a worthless old PIII running TurboCNC in DOS) will control all other actions via g-code, steppers, optical sensors, switches, and a tanlge of wires. (don't worry I'll have more details when the time is right)
That's the basic idea anyway, The best part is that I didn't need to learn a whole new skill set. I was already familiar with TurboCNC, available here http://www.dakeng.com/turbo.html , and G code is no more difficult than old school BASIC (I think I just gave away my age).
One important note about TurboCNC. It allows the use of a PLC handshake (both input and output) that is vital. I didn't see the same command listed among the codes in Mach3. Be sure that whatever program you chose has the ability to pause and wait for a handshake. The importance of this will become clear when I explain the control sequence later. Oh yea, It also runs in DOS so you can use that old dusty computer you never got around to throwing away, and best of all It's Shareware.
Thursday, August 27, 2009
Here is a basic list of what is needed:
- an old inkjet (my lexmark 5700)
- some linear slides (the higher quality the better, but you can start with drawer slides)
- 3 stepper motors (make sure they are strong enough for the job)
- 3 axis driver board (Xylotex, Gecco, Stepmaster, or similar)
- a power supply of the appropriate amperage
- an assortment of switches, optical-interrupters, relays, wire...
- some timing belts, pulleys, lead scews and nuts
- a variety of construction supplies (lumber, corner braces, screws, epoxy, wood glue, aluminum angle...)
- an old pc (I'm sure you have an old Pentium II or III collecting dust next to that old inkjet)
- software to make it all work
I'm sure I left a bunch of stuff out but I'll go into more detail with each step.
There are, as they say, "Many ways to skin a cat" (apologies to cat lovers). So my solutions are just one of many possible. Please feel free to improve on my humble tinkering.
This past Spring I attended the Wonderfest model and toy show here in Louisville. (Awesome show if you're into model building/ toy collecting) Anyway, one of the seminars was dedicated to rapid prototyping. After about 10 minutes I was like "This is so cool! I must have it!". Unfortunately I didn't have $15 G's burning a hole in my pocket. What I did have however was a basic mechanical and electrical aptitude and a new obsession. Oh yes... It will be mine!!!(insert evil scientist laugh here)
A few hours research on the web convinced me that I not only could do it but I already had much of what I needed for the project . I'm already well on the way to having a working 3D printer but I'll start at the beginning and chronicle my successes (and failures) and hopefully inspire others along the way.
If you are interested in building a 3D printer or just curious, be sure to check http://tech.groups.yahoo.com/group/diy_3d_printing_and_fabrication/
I also want to thank A. Fogassa for his help and inspiration. Check out his blog at http://homemade3dprinter.blogspot.com/