my first design

i never done anything like this before.
still its my first design i made.


with a powder 3d printer you can print the most complex things as the powder layers will build its own support.
none heated powder can be re'used.
for the laser diode am still searching what would be the best.
a red 150mw laser diode could be enough but not for white powder it would just reflect the light.
one could add a black pigment to the powder.
these is a laser diode that can be found in 16X dvd writers.
cheap laser ill say.
you'll only need a laser housing ( for the focusing lens).
wich cost about 3 euro.
for the X-axis and Y-axis i would base my first design on a old printer ( mechanics ).
the Z-axis would lift up the print array to gain more work area.
to replicate the work station it self.
you could make the big box plates in sepperate plates and make them fit like a puzzel.
this would remove the dimention of replication.
one could make it as high long or wide as he wants.
the resolution of the printer would be much beter.
so printed things would not only look beter but would be stronger to.
multipel prints could be done at once as long if they fit in de desginated work area.
eventual the final build of this printer you will only need 4 iron lift rods.
and the electronic parts the rest it build it self.
even pcb's could be build if you replace the print head with a dremel like drill.
it could cut away the copper facing and make the ciruit. and eventualy drill the holes trough.
this reprap project has no limites.
( the only thing missing on it is a addon were you could actualy make your own lift rods ) i dont know the name in english for that machine.

please dont flame me just want to contribute to this project.
greetz.

Call it shittybox

Have you ever extracted a laserdiode from a burner?
Or do you just talk about things you've read on the internet?

Powder? YES!
Laser? NOPE!

There is a very good reason for ZCorp using cyanacrylic glue instead of a laserbeam to fuse the powder even in the monochromatic zPrinter

diego de almanazar

Quote

There is a very good reason for ZCorp using cyanacrylic glue instead of a laserbeam to fuse the powder even in the monochromatic zPrinter

That isn't any reason not to try a laser sintered powder approach. In fact, other people not doing something is probably one of the worst reasons ever not to try it yourself.

Obtaining suitable feedstock, and assembling capable optics and a suitable cartesian robot on the other hand, is probably going to be difficult enough so as to make this project impractical as a reprap any time soon. But that's no reason to be rude, now, is it?

This is an interesting approach, and I can see some of the advantages it has over FFF. How would you quickly and evenly build up each layer of powder? That seems like the most unique challenge to this design. I'm sure there's a good way to do it, but I don't know it.

Quote

How would you quickly and evenly build up each layer of powder?

I forsee a two step process, involving a hopper full of feedstock, a waste powder collector, and a blade.

The hopper traverses the long axis of the build area, liberall coating it with powder. More powder than is needed, so that everywhere is covered. The blade is then lowered, so that the height between the base of the blade and the top of the previous layer is the desired layer thickness. The hopper than traverses back along the build area, the blade pushing the excess powder along the build surface and ultimately off the end and edges. It falls into a waste powder collector.

This necessitates having quite a bit of powder in the hopper; more than the volume of the build area to account for wastage. You might to do clever things like have a big static hopper, and a small mobile hopper which is filled automatically when it returns to its home position. You could also have an automated feed to transfer collected waste powder back into the hopper.

Candyfab does this process manually, but it has a fairly coarse resolution. I wouldn't want to do it for each of several hundred layers in a fine resolution device!

But powder spreading isn't the tricky bit here, its the optical part, first and foremost. You might get away with a fairly low powered laser with perhaps only a few watts of power, and so get away with a small solid state device. Collimating the beam still isn't going to be easy. But Andy Kirby and Viktor have already said lots about lasers elsewhere, and actually know something about the subject

Well..

as I said elsewhere, extracting a laserdiode from a dvd-writer is no fun at all.
And the just extracted diode will not be sufficient in any way of fusing the powder.
Why I am sure? Because I took apart now ten DVD Burners, for exactly that reason (in fact not exactly, but to burn holes in black things And it's not as easy as you may think)

I think it needs something more powerful than one of those diodes to do the job.
Maybe a fibrecoupled diode with more than 1W can, never tried.

But then there's the need for a giant cooler not to blow the diode and you will have to take security measures not to blind yourself or get stinged.

That isn't a reason not to give it a try, but that is a reason not to try it myself

Fusing the powder with glue is much cheaper, simpler and less risky.
(I think that's what diego intended to say)

[EDIT]
I think something like a roller should do a better job, because it compresses the powder slightly in the same step.

'sid

Edited 1 time(s). Last edit at 07/12/2008 12:00PM by sid.

Quote

I think something like a roller should do a better job, because it compresses the powder slightly in the same step.

Yeah... I'd just remembered the work that Scorch had been doing and posted about in another thread (zcorp ink one, maybe?). He used weldwood powder rolled out with water sprayed on to set it.

spraying water on is a very good idea.. less dust you breath

gypsum powder and water (not sprayed on but as the adhesive component)?????

A bit fuzzy quality will be the result, but hey god made sandpaper, doesn't he?

'sid

... if you want to work with salvaged diodes, then the best way isn't laser-sintering but laser-cutting or engraving of thin sheets of black plastic or such.

It's called LOM-fabbing (something as Laminated Object Manufacturing or Layered Object - ) and i already posted some ideas about in the forum ...

Here you stack thin layer on layer of good laser-absorbing material (e.g. black paper or plastic-foil) and cut the contours of the actual slice with some separating raster-lines in the layer.

As you mustn't process every point of your object, but only the contours, it's thousandfold faster in fabbing speed too ...

Viktor

Cutting paper with the laserdiode...

I've tried, and I've tried alot.
I've even asked a friend to test the one or other diode (between 180 and 220 mW)
none of those could cut paper, that ultrathin black garbagebags, yes; but not paper or thicker foil.
Okay with enough patience it could burn thicker foils, but with a cuttingline that reminds of tearing something apart not of cutting it with a scalpel blade

'sid

But then there's the need for a giant cooler not to blow the diode and you will have to take security measures not to blind yourself or get stinged.
1 watt laser omg your just need it to fuse not burn it lol.
i have a 400mw red laser points ( with potentio meter ) on lowest input it already burns.
step to a green 140Mw point laser wich arent that cheap but payable still.
it will do the job.
to cool it you dont need a fan near the diode it self thinking comptuer style water cooling system.
still come to think of it after long use so the diode becames warm it loses abit of its strenght this can be overcome with some kinde of temp sensor and give it a lil more power at a serten temp.
burning point calibiration ( this points has a like 1.5cm hot point tip when focust to burn stuf so that wouldnt be the problem at all. and if you worry about that add a extra servo and a opctical eye on the print head so it can compensate its height automaticly.
the rolled idea came to pass my mind to of some kinda press down force as it passed the object to.
the feeder box ( you can make it so you can easely add more poweder to it or even develop a auto feed for it with some kind of transport from A to B.

come to think of it the roller could be a good pre event too.
if you look at the workings of a laser print feed.
and you could use the roller as a pre heater for the powder to this will need to be very acurate temp to boost the printing procces. to cold and it is useless.
to hot and you render your powder useless for the next print.
this could be a later stage development.

btw yes i exracted few laser diodes out of dvd bruners.
i always scraped my old defective devices form usefull components.
the laser housing i would get from a shop like www.velleman.be.
its a full alu casing.
and if you should add the dremel head to it it could even make its own water circuit hardware too.

and you could print out the tubes wich can be in solid places wich dont move out to. you just need some tube wich are cheap too.

second powder printing advantages are much beter then to work with layer by layer build with extruders. for one the glue kinda mess it leaves behind you wont have that.
second it lays layer on layer. leaving a bigger space for defects.
with a good laser setup it will fuse the powder over and over again making it stronger. the build time will be a lil longer but the object it self would increase in durablitety.

for the roller system and blades you could use two.
one for upward X - axis
one for downward X - axis movement.
use a electro magnet to lift or the invalid roller blade system.
so the feeder roller and blade should be infront of the laser at the moment of printing.

greetz and thanks for your intrest in this design and comments.

Go ahead and measure the output of your 400mW Laser in it's lowest setting.

You'll find it to be somewhat like 260 to 300mW and that you cannot generate with a dvd writer.
below a specific input there will be no laser emitted at all.

But still, go ahead try it yourself, and you'll find out that there is no way of doing that with a dvd writer salvaged diode.

green lasers are simply stupid!
a green laser is made by firing a crystal with a higher powered ir-laser,
so all you do is loose powerd for a nicer color.
technically that's useless, expensive aaaand STUPID!

btw: drawing a shoebox and writing things on that is not what you can call a design.


Nevermind, I'm off

diego

Please diego, you can disagree if you'd like, but keep it civil!

Many a viable product has begun its design life as a shoebox and an idea - a lack of a polished model should NEVER be used as proof that something won't or can't work, especially in the initial stages.

Kyle Corbitt Wrote:
-------------------------------------------------------
> Please diego, you can disagree if you'd like, but
> keep it civil!
>
> Many a viable product has begun its design life as
> a shoebox and an idea - a lack of a polished model
> should NEVER be used as proof that something won't
> or can't work, especially in the initial stages.

Precisely!

Spoocke2, I run SLS Machines daily for a living. I think I could give you a few pointers.

Unfortunately you probably won't get away with this with anything less than a Watt of power. I've mentioned this before, but the less power available to you through your laser, the more accurate your bed temps will have to be. This is because when laser sintering, the large majority of the energy going into the material to melt it is actually coming from internal heaters bringing the bed temp to just under melting point. The laser then scans along and selectively melts the area.

With a low laser power you would have to bring the powder bed very close to melt with the internal heater so only a tiny amount of energy is required to melt. Now usually layer times are quite quick as a pair of servo's direct the laser at around 5metres/sec, whereas you will access to around 5 centimetres/sec. So we have to hold that temperature extremely accurately for minutes at a time between layers, otherwise extremely heavy curling will occur while the layer is still sintering. If you go over the temperature, you'll just have a pool of molten plastic.

As for powder layering, SLS machines use a counter rotating roller to push a layer of powder from a feed bed to the other side, and back again.

Generally, we use a Nylon 11, but there are literally thousands of materials out there suitable for laser sintering. The majority have never been tried. Its half the fun in using machines like this.

I would imagine some low temp waxes could be your first experiments, we've done this in our Sinterstation, it's very messy, but it requires very little power.

Your first challenge, and one I recommend you tackle before going the whole way with it, try to keep a bed of powder at a constant temperature. Get the bed warm and the material rolling properly before you even attempt to sinter.

diego
as for one your comments arent construtive at all.
second of all can you read what i said when i wrote i already did such experiment with a dvd writer laser.
you need glasses i think.
the design is my first its called a first brain wave prototype.
if your brain can coprohand that omg.
and you only know the outcome of this when you realy tested it.
btw i do post a drawing of something in my mind here.
didnt see you do this.
comments are fine good or bad but you behavior is the proof of a narrow minded.

proto Wrote:
-------------------------------------------------------
> Kyle Corbitt Wrote:
> --------------------------------------------------
> -----
> > Please diego, you can disagree if you'd like,
> but
> > keep it civil!
> >
> > Many a viable product has begun its design life
> as
> > a shoebox and an idea - a lack of a polished
> model
> > should NEVER be used as proof that something
> won't
> > or can't work, especially in the initial
> stages.
>
> Precisely!
>
> Spoocke2, I run SLS Machines daily for a living. I
> think I could give you a few pointers.
>
> Unfortunately you probably won't get away with
> this with anything less than a Watt of power. I've
> mentioned this before, but the less power
> available to you through your laser, the more
> accurate your bed temps will have to be. This is
> because when laser sintering, the large majority
> of the energy going into the material to melt it
> is actually coming from internal heaters bringing
> the bed temp to just under melting point. The
> laser then scans along and selectively melts the
> area.
>
> With a low laser power you would have to bring the
> powder bed very close to melt with the internal
> heater so only a tiny amount of energy is required
> to melt. Now usually layer times are quite quick
> as a pair of servo's direct the laser at around
> 5metres/sec, whereas you will access to around 5
> centimetres/sec. So we have to hold that
> temperature extremely accurately for minutes at a
> time between layers, otherwise extremely heavy
> curling will occur while the layer is still
> sintering. If you go over the temperature, you'll
> just have a pool of molten plastic.
>
> As for powder layering, SLS machines use a counter
> rotating roller to push a layer of powder from a
> feed bed to the other side, and back again.
>
> Generally, we use a Nylon 11, but there are
> literally thousands of materials out there
> suitable for laser sintering. The majority have
> never been tried. Its half the fun in using
> machines like this.
>
> I would imagine some low temp waxes could be your
> first experiments, we've done this in our
> Sinterstation, it's very messy, but it requires
> very little power.
>
> Your first challenge, and one I recommend you
> tackle before going the whole way with it, try to
> keep a bed of powder at a constant temperature.
> Get the bed warm and the material rolling properly
> before you even attempt to sinter.

hmz intressting.
there are a few designs i had in mind.
like the pricical of a laser printer wich draws a image on the foto sentectic rol.
now if that rol would transfer the powder to a heater rol and drops it layer by layer. these are just theoretics for now need to setup a lil build lab.
it will be challange.
but that is what it makes it fun.
i dont realy care about printing speed at all.
i just want it very clean and strong.
and my first step would be to work on the area mechanics not the head.

am looking for very fine tabbed rods for my system.
accuratie is my main goal for the work area.
once i assembled the work area then ill go deeper into the head('s)
so it could be a reprap or a lil cnc machine or even a ploter.
friendly greetz.

what do you think ??

spoocke2 Wrote:
-------------------------------------------------------
> diego
> as for one your comments arent construtive at
> all.

I did say, that you will not a sufficient output with a dvd writer's diode.
that is a good hint, you just ignored that.

> second of all can you read what i said when i
> wrote i already did such experiment with a dvd
> writer laser.
> you need glasses i think.

I _do_ wear glasses but you CANNOT use such a diode,
because it will NOT work.
And yes I do know.

> the design is my first its called a first brain
> wave prototype.
> if your brain can coprohand that omg.

I comprehent more, even words that are close to unreadable

> btw i do post a drawing of something in my mind
> here.
> didnt see you do this.

Because I don't like that halfrare stuff to be posted, so I don't do it myself

> comments are fine good or bad but you behavior is
> the proof of a narrow minded.

Wow!
And YOU tell ME I should stay civil?
ROFL.

Oh,
I told you about 200 mW aren't sufficient, you laught
sid told you you need at least 1 Watt, you laught even louder.

Now fortune sake proto told you that anything less than 1 W will not do the job.
(and he does lasersintering for a living!)

Where the heck is your laughter now?

diego?

hat I think?
I think you should get aware of the edit-button

Hm...

he's right somehow.

'sid

I did say, that you will not a sufficient output with a dvd writer's diode.
that is a good hint, you just ignored that.
nope i did not i told you i have a 400mw laser pointer. wich dust melt plastic easly. i tested this a long time ago.
i did extract diodes form dvd writers and they do exaclty the same.
what you cant seem to corprohand is that this are ideas for now.
and not yet been tested in they way of printing head.
if you would read and wear your glasses you would see that my main target for now is the work area development.
and not the printing head.

and did you even see the print head i posted???
cause your all words of critics wich is fine.
but there other ways to express your self.
greetz

I'm going to steer clear of the laser argument

The one thing that keeps bothering me about powder-based RP machines is that it seems like you have to apply much more powder than actually ends up in the final product. The unused powder can, of course, be recycled into the system, but it still seems sub-optimal to me. Maybe it presents no major problems in practice, but I imagine it might lead to contamination of the powder days, weeks, or months before it is used.

In any case, is there any powder that floats on water? That would be cool; you could use a sort of tank, and the bottom would have a thin layer of water, and then you would pour in (or automatically spray out) powder (perhaps from the toolhead, or at least the toolhead's height level for minimal splashing). After the surface of the water is coated in powder, the RP process can begin. As the desired portions of powder solidify together, more powder is spread over the surface to maintain the powder film over the water (which I suppose could be multiple layers of powder thick). After finishing a vertical layer, water is pumped in from a tube at the bottom, raising the level of the film ever so slightly. The process would repeat until completion, at which point the water would be drained, perhaps in such a way that the powder drains with it to a filtering chamber - the powder could be extracted from the filter there, and then stored (dried first if necessary).
Anyway, the granules would have to be less dense than the water, and they would have to not react with or dissolve in the water. Alternately, I suppose some other floatation liquid could be used which follows the same rules (I chose water for its abundance in most of human society).

Anyway, it's a cool idea (I think), but probably not the most practical solution (Rube Goldberg mechanics, anyone?)...

Actually, now that I think about it... maybe macroscopic rapid prototyping based on classical mechanics isn't the most practical solution, either... hm...
Then again, maybe it is the problem which is being addressed, rather than the solution itself.

Played with some powder proto types. The seemed flimsy and non-funcitonal though they had great detail and complexity. Wouldn't be much use to me as I want to do functional prototypes. For concepts and artists, I think the laser sintered method would be cool.

As for the laser argument...feh. You need more to do if you feel the need to tell people over and over that they are wrong. Go build something.

Demented