Seek and ye shall find.

I had what I thought was a good idea, put a normal ink cartridge in the 3D printer, one with ink in and then see if it would print, that would rule out binder issues and perhaps I would get to see some printing. The printer's cartridges are based on Canon BC-20's and they simply decapitate them, remove the ink and wadding and glue a plastic screw top vial that has had its bottom cut off over the hole in the bottom of the cartridge. These vials have a screw cap which is compatible with the machine hose lines. I was given a bag of the vials so just hooked the lines to an empty one, it certainly proved that the binder pumps OK.  But alas still no joy, now I was getting errors, too many deprimes! This seems to be when the fluidic connection between the reservoir and nozzle is lost, seemed unlikely it was caused by the fresh out of the package ink cartridge. A guy on the forum suggested it might be the flex pcb type ribbon cable that runs to the cartridge so I took it off and had a look. And it seems it is definitely damaged.

This is the part that contacts with the cartridge. Now let's get all CSI on its ass, zoom in on sector D5.

And there is our problem, one of the tracks has broken and even peeled back, now give me a hard copy of that. But BladeRunner references aside the cable and I have a date under the stereo microscope with some very thin wire and a very small soldering iron. I'd better lay off the caffeine now! Fingers crossed this is the issue because I am so close now to printing something.

Spinnage is good for you

I managed to get the polygon mirror scanner rotating nicely, it was actually very simple once I convinced myself I had the right pin out. Then I tried to get the laser to fire up, this time it was a little harder because I only have printer service manuals to go by, I think I got the right connections but failed to get it to fire. I may have damaged the laser. Anyway it doesn't really matter as that laser is of the wrong wave length, would have been nice though.

Scanning based 3D printer

Talk on the diy_3d_printing_and_fabrication Yahoo group has turned recently towards the possibility of using the polygon scanning mirror and lenses from a laser printer to create a resin based 3D printer for large areas. The scanner scans a line with a laser and then you move the scanner to "develop" a layer, then repeat. Basically the same idea as a SLA or DLP based resin projector just a different method of imaging. A few guys have done this sort of thing to try and image PCBs directly in photoresist. The visible light curing resins that can be used in 3D printers may however work a lot better than the etch resist.

I have a Samsung laser printer with a perpetual paper pick up problem so decided to take it to bits to investigate. It is a pleasingly simple module, pictures now follow.

The scanning module as it is found in the printer, very possibly this is a part obtained from a 3rd party. It is a really neat sealed unit just waiting to be mounted into a machine.

The other side

At the bottom left we have the spinning mirror, at the top is the weird looking lens that corrects for the variation in distance from the mirror to the drum in the printer, probably does some focussing too, not sure.

This is a brushless motor controller by Rohm especially designed for polygon scanners. The control is very simple from what I have managed to work out, there is a clock to set the speed, a start/stop input and an output to say then the PLL has a lock (i.e. the speed is constant). Then power which is 24v (up to 36 but I suspect 24).

The optics consist of a collimator, a metal aperture and then a focussing lens with a long focal length. The mirror is very thin so perhaps the aperture stops stray reflections from other parts of the motor.

The collimator

The laser diode, a simple uncollimated source. At the very top you can also see a photodiode which is used to sync the control signals to the diode with the rotation of the mirror. The beam hits a small mirror at the other end of the correction lens and then shoots over to this sensor.

Should be quite easy to get a basic system up and running, I'll probably use the propeller microcontroller which should eat the task up but I will need a UV laser to do some real tests, not to mention some resin. And I have the Zcorp to finish! Argh, maybe tomorrow!

Progress slowing

Well I got the printer back together and it turned on again without incident, tried adding some powder and it spreads but not every time, sometimes the gantry just stopped. But I thought I would press on so after adding a little grease to the rails I set it to print. No joy, I got an error concerning the print cartridge and then the software running on the machine crashed. Today I put in another cartridge which I am sure is knackered and it started to go through the motions but no juice came out, then I got an error related to the serial buffer which may be because I am using a USB to serial converter but I have no idea. I think I have one normal ink cartridge that will fit so I may try this just to check the signals are getting through OK. I also have an old PC with a parallel port which I can try. Starting to lose some confidence I can get this going but must push through that, do things step by step and get in to the details

Spread em! The cover over the print section is removed here, as are the curtains the gantry pushes through.

Random thoughts on 3D printer mechanics

While I was cleaning the Zcorp I started thinking about what it actually does and indeed what most 3D printers actually do. That is not very much really, I mean they do make things and are very cool but they don't tear through solid metal with multiple HP cutters and they don't get showered with abrasive sparks like CNC plasma cutters. Nope, most are almost office machines, they just move around a bit, not much load and not always that much speed. Mechanically these things should go on and on or at least what goes wrong should be pretty easy to repair. The real issues are in those little chips containing propriety code or things like the print heads which are very specific to the machine. I know if this machine had been DOA I could have done all the basic electronics myself with very little effort (things like the pumps and the build and powder bins etc etc) but the printer part? Not so much, not unless I cheated like I did on my own attempt to build a printer and that again leaves you locked in to another specific printer which they may only make for so long. This probably could be a post about property ownership and hackers wanting to be able to control every aspect of the gadgets that they own (unlike my ipad) but it won't because for me it is all about the worry that the thing I own will stop working and I won't be able to fix it. I hate not being able to fix it!

I have to wonder if a range of open source retrofit boards would be popular for these machines, this one was definitely going in the direction of the scrap yard and its PC based brain is almost certainly going to die long before its body does.

Looking like a real machine

 So this is the initial reason for the clean up, the "car wash" was really encrusted with powder and binder. But look a few minutes in hot water, a little tooth brush action and then a little more with a tooth pick and it is good to go, quite a transformation.

At the bottom you can see the squeegy that wipes the print head and above that a little box that makes a seal with it to stop it from drying out. That rocks in to place when the carriage hits the little button at the bottom right. If you need to clean this thing then you just need to disconnect the ribbon cable and the fluid lines from the printer assembly (the upright bit on the gantry) and then lift it off the machine. The car wash is held by a single screw but mine needed prising because it was glued in place with binder.

That looks a lot better doesn't it. The chute for the excess powder is removed in this picture for cleaning too and next to the hole you can also see I replaced the velcro strip. I think this is for cleaning the powder spreading roller. You can see at the back of the machine the "curtains" though which the gantry enters the build area, this keeps powder from the back of the machine, at least it did! It seems to be the braid that is used to protect cables laid flat with some soft plastic sheet inside. I should be able to source something similar to replace it.

And the Gantry all cleaned up. The main gantry went in the shower for cleaning, then I blew it dry with dry compressed air and oiled the bearings etc. Top left is the printer assembly, this just had to bee wiped carefully, not something to dunk really. I cleaned the linear rail, wiped the limit switch (on back of carriage) and not much else, will grease the ways at some point. Top right is the funky plastic thing that passes through the curtains, pointlessly complex design if you ask me. Reassembly should happen tomorrow night, maybe...

Lack of educayshon

Corrected the spelling of tomorrow in the title image. How embarrassing.