It's mocking me!

I've mocked up a quick 3d of my design concept. As I said before, I'm going to use easily obtainable budget priced components whenever possible. I plan to use MDF which I will seal with paint, glass, Plexiglas, aluminum and steel angle. I can get most of the construction materials from Home Depot or a local plastic supplier. I'll break down the materials as I build. I've started collecting what I'll need so I can begin building soon.

Until then here are some more screen shots of the design. This was just a quick mock up so the sizes are approximate. I'll work out the exact dimensions as I build.

Here we go again

Here is a quick sketch of the basic idea. As you can see it's a little different from the previously mentioned lesson plan. In the example in the lesson plan the image is projected on the surface of a tank (in that case a beaker) of resin and the part is submerged into the resin as it is solidified. A variation of this method is to expose the resin at the bottom of the tank to the UV and have it stick to a plate which is raised up out of the resin. Each new layer sticks to the previous one and is lifted upward. I chose a bottom up method because then I don't need a resin tank deep enough to contain my maximum z travel. Also the submersion tank method requires a large volume of resin from the start. A shallow tray only requires a small volume of resin be maintained (and possibly exposed to the degrading effects of unwanted UV and moisture). Also the Z build height will not be limited (theoretically) by a fixed tank depth or my financial ability to fill said tank. Most of the designs I have found in my research place the projector vertically directly under the resin tank. I am going to place the projector horizontally behind the z axis. Initially I plan to borrow a projector as I see this as being the single most expensive component. By placing it behind I can easily remove/replace the projector and also have much more flexibility over the focal distance. This also will keep the total height of the printer smaller. If I went all vertical the total height would probably end up close to 4 feet. Lastly, since the projector won't be mine (at least initially) I really want to protect it from any resin drips!

I'm going to try and keep this as simple (basic) as possible. I envision a build plate that is in a carrier so it can easily be removed when the print is done. Also the resin tank needs to be removable for easy cleaning. Then there is the matter of preventing the cured resin from sticking to the bottom of the tank. I think some combination of non stick surface and mechanical movement. As you can see it will be easy to get very complex. I'll have to resist the temptation to over engineer. I'm working on a more detailed design mock up that I'll have ready in a few days.

My goal is to create a 3D printer that can be built with readily available, easily fabricated and affordable components.

I hear you thinking..."He must be MAD! It just can't be done!"

Only time will tell.... Cue the manical laughter.

It's a Brand New Day....

OK, I've been kicking around some ideas. The basic idea is presented here.

https://www.nano-cemms.illinois.edu/media/content/teaching_mats/online/3d_printing/docs/guide.pdf

As you can see it's really not that complicated (mechanically at least). For this project I'm going to try to stick with 2 principles. Keep it simple and make it cheap! My intention is to build a functional 3d printer within my almost non-existent budget. Later, if successful and as finances allow, I can upgrade components to achieve higher precision.

I can break this project down into 3 parts:

1. Hardware
2. Software
3. Chemistry

I'm confident that I can build the hardware portion of the printer. It's actually much less complex than the inkjet/powder printer. In fact, I'm going to harvest much of what I need from that progect. I'm working on a design sketch which i'll post soon.

The software... well, I would love to be able to purchase comercial RP software (Magics 15) but there is no way that will ever happen. I think it's considered the gold standard because you need a pile of gold to buy it! It seems that any software that does everything I'll need (including generating support structures) falls into the catagory of "If you have to ask you can't afford it". Since I don't have access to a pile of gold, I'm going to make due with what I can afford (free) and what I already have (Powerpoint). I'll have to make due with manually adding support structures. I'm really hoping that the open source community will develop something for that.

Lastly, the chemistry. I'll worry about that after I get the hardware working. I see this as being alot like the ink/toner of 2d printers. The real money is in the consumables.

Now to sketch up some designs and start collecting materials.

Stick a fork in it!

As you can probably guess by the title of this post I have officially given up on the powder based printer concept. I never could get the lexmark cartridges to work quite right. I couldn't get them to work well after they were refilled and the plaster dust kept clogging the nozzles of the brand new ones. Perhaps if I had started with a better donor printer. I seem to remember there was a reason I put the lexmark inkjet in the closet in the first place and that reason was that the cartridges sucked. Oh well...

While I'm done with the powder based concept I have not lost my interest in developing an affordable 3d printer. And when I say affordable I mean one that I can afford (Meaning as cheep as possible). I'm really excited by some of the work being done on DLP 3d printers and have decided to shift directions and pursue this technology.

Check out what Junior Veloso is doing with his DLP printer!
http://3dhomemade.blogspot.com/
If that doesn't get you fired up then youre reading the wrong blog!

There's also an open source project by TJ Snyman that's in the development stage
http://tjsnyman.com/tjsnymanblogspot/?page_id=531

The good news is that I can cannibalize the powder printer for the electronics and mechanical stuff. Now to start gathering materials and start planning.

OK, Now it's just embarasing!

Unfortunately my workshop is out in the garage and I'm what you might call a "Fair Weather Tinkerer". It seems that I ran out of motivation at the same time that the temperature dropped, making it all too easy to find other distractions to occupy my time. Now that spring is here and the comfort level in the garage has improved, I promise I'll get get back to it (just as soon as I can clear a place to work!). I can see by the counter that many of you have been waiting patiently for an update. Be assured that the project is not dead (it's just been hibernating).

Thanks for checking back.

Where has the time gone?

I can't believe October came and went so quickly! (It's way too easy to get sidetracked.) Anyway, I just received some new Dental plaster and some additives to try out so now I have no more excuses. Time to roll up my sleeves and start testing. Hopefully it won't take a month this time to show some progress.

Thanks for being patient.

I could use a thousand words or.....

I was asked to describe how the various components interact. Instead of a lengthy (and confusing) description I offer these diagrams and a (hopefully) shorter description. The first step to building a 3DP is to modify the inkjet into a flatbed printer. To that end you need to have a way to move the entire printer over the paper instead of the paper under the printer. There are 2 problems with moving the printer body directly with the original paper feed motor. First, it probably isn't strong enough and second it will probably make unwanted movements as the printer tries to ready a new piece of paper. My solution was to place a homemade encoder on the paper feed motor that would supply "step" pulses to a second more powerful stepper motor. In this way I could easily interrupt the pulses and stop the gantry movement even if the paper feed motor was still moving. Another source of pulses can be used to return the gantry to the starting position. Switches 1 and 3 are "safety" limit switches to prevent over travel of the gantry. Switch 2 swaps the source of the pulses and changes the printer from "print" to "reset". Also, you will need some way to tell the printer when the "paper" is present and "out". Usually there is an optical sensor which you can block/unblock at the appropriate times. This setup works if you are printing only one page at a time and don't mind resetting it manually each page. Of course, you could design a circuit to automate the switching process and replace switch 2 with a relay.

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.