Powderbed Machine

Thanks for getting the info on the WIKI Sebastien. I know that I agreed to do that some time ago but I never actually got it done.

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Kevin

Always use the right tool for the job, and the right tool for every job is a hammer.
Note - the above is not true but some days it feels like it's true.

[kevins3dprinter.blogspot.com]

I have put the recoater design on the wiki, it uses one motor to drive the roller and slide movement, the plan is to use a small tape measure tape as a sort of wire drive, the motor is dc 12v from rapid electronics, although I have seen similar from elsewhere, I shall post drawings when its built.

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I have built the recoater and added some images to the wiki, will add drawings next,
I think this looks like being my next project, [www.youtube.com]
am I the only one to always find another project before finishing the present one?.

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You are definitely not the only one to find new projects in the middle of a ongoing project. I've got several stacked at the moment, and I'm afraid the pile keeps getting deeper. At least your powderbed project is progressing nicely.

I've been trying to avoid the project you linked to, but the quality/precision of the parts is so good that I probably will not be able to resist. My only concern at this point is whether or not the parts would be robust enough to make useful pulleys and other small functional parts. On the other hand the quality is high enough that just being able to print decorative objects would probably make the project worthwhile.

Hello Madscifi,
DLP is the best way to go with this, but I proposed using LCD some time ago, someone said that UV would damage the lcd, so i did not persue it, we get lcd coming through as scrap now ( very often the backlight inverter dead) so will see how one stands up to UV.
( the video is time lapsed, but what if it could work at that speed?)

Anyway, back to the powderbed, I suppose the next step is to mount the recoater and rig up some electronics to have it working with powder for a few hours to give it a good test, alternatively press on with the printer side of things, I must not loose momentum otherwise my mind will start thinking of other projects.

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madscifi
I've been trying to avoid the project you linked to, but the quality/precision of the parts is so good that I probably will not be able to resist. My only concern at this point is whether or not the parts would be robust enough to make useful pulleys and other small functional parts. On the other hand the quality is high enough that just being able to print decorative objects would probably make the project worthwhile.

There is a post process step necessary but then they should have about the same strength as ABS.

The resin is very expensive!

If he can come up with a way to make the resin at a reasonable price then I am definitely interested with a resolution of 50 microns!

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

It is true that the uv resins are expensive. They would be a poor choice for making Mendel vertices, for example. On the other hand they might be a good choice for making pulleys for 2mm belts. Or so I imagine at the moment.

Here's a valuable link to the photocurable thing: [forums.reprap.org]

If you follow the link there, you find the keyword: Photoinitiator. There exist photoinitiators for several kinds of resins, like Polyester or Epoxy. Simply mix the intitator into a generic resin and it becomes UV hardening - somehow. Googling a bit, the initiator apparently costs somewhere around $10, sufficient for 1 gallon of resin. - - - so far my quick googling analysis.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Probably not the best place to post this but this [www.gom.com] looks useful for mesh edits etc, and its free so we likes it.

True the resins are expensive, but I did come across low cost alternatives and recipe some time ago when looking into doing
a UV machine, so I would not let the resins put me of doing one, the beauty of the system is its simplicity, very few moving parts, and less to go wrong, although the thought of spending all that money on a DLP, then taking it apart makes me have a cold sweat.

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johnrpm
he thought of spending all that money on a DLP, then taking it apart makes me have a cold sweat.

YES, but then you don't need to buy a new one. With luck you can find one where what you need works but is otherwise damaged that could be purchased at a low price over EBay. Just a thought...

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

There is a thread about this machine in the Resin photopolymer section. The projectors are about £115 I think. It does look very nice

Taking the industrial market as a lead, powder laser printers seem to be very popular, which leads me to believe that UV curing resins still have many issues. Probably resin cost / resin stability and machine running costs. I am following your machine wiki with interest, Your powder boxes are particularly nice and have applications for many machine types. What type of printing are you going for, laser or some sort of wet ink cartridge printing?

YES, but then you don't need to buy a new one True, we likes a bargain.



have applications for many machine types. What type of printing are you going for, laser or some sort of wet ink cartridge printing?

I was thinking of using a standard low cost printer, I have bought a HP2050 for £35 for the job,( now on offer at £30, typical)
I wanted one that is in current production so others could use it, initially use the recipe from open3dp, then look into polymer powders fused with IR lamp, then maybe have scratch built piezo printhead on an XY plotter for thicker binders, then maybe
cobble together a laser, but I have learned not to plan to far ahead cause things change.

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Taking the industrial market as a lead, powder laser printers seem to be very popular, which leads me to believe that UV curing resins still have many issues. Probably resin cost / resin stability and machine running costs.

Even at $500/kg, resin costs are almost neglibile for the industrial level. The problem common to all resins is, you can't take finished parts right out of the machine and use them. Coming out of the machine, parts made from resin drip, need to be washed, need to be UV-postcured. So you have to use quite some chemical equipment, wear gloves, not exactly convenient for an office printer.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Seen this on the interweb, wood dust used to make parts similar to MDF on a 3d printer, link
This area is where the scratch built piezo head may be useful in the future, with some more development that is.

Edited 1 time(s). Last edit at 04/09/2011 06:29AM by johnrpm.

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The printing in wood link turned out to be a April fools joke. Open3dp released a real recipe for printing with wood on April 5th.

Edited 1 time(s). Last edit at 04/10/2011 10:25PM by madscifi.

That Just goes to show ........ I am a fool all year round, not just one day of the year.

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I am working on the interface board, the plan is to use octal darlingtons for the steppers and l293 for the dc motor, driven by a mega, mounted in a control box which will allow for machine setup in manual mode, I am using fritzing but it seems to crash often, I will post the circuit when done for comment.

I have got a lcd from the scrap bin, works but dim, so may be a
backlight problem, I want to see if uv will pass through and how much, I have a uv c light source, bug killer, any suggestions for a better uv source.

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This makes interesting reading, [open3dp.me.washington.edu]
it seems that the patents are running out on powderbed printing from this article, although they seem to be trying for others.

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I have done a pcb in fritzing, (no laughing), I realised why it was crashing, the auto-router dos not rip up, so put multiple wires on top of each other, after finding my mistake it does not crash, I must say I do like it, the parts bin or library has the stuff I use and have in stock (not all of course) whereas designspark is a nightmare trying to find parts, the library is just to big, OK for serious stuff but fritzing is for me, although I have a paid for version of circuit wizard.

The pcb has ratnest wires that I can not delete, although they do not appear on the pdf???.

The PCD has two octal darlingtons, one for each motor, with pins doubled up to take 1 amp per phase, the l293 is for the dc motor and 3 transistors for driving outputs, one of which is a solenoid.

I spent a whole day trying to isolation mill a board using gerber output from fritzing and line grinder for gcode, I have not tried this approach before, normally use laser and hot iron, the results are sort of OK, but not as good as hoped, I do not have time to perfect my technique at present so will go back to hot iron for now.

If you see anything I have missed or is wrong please comment.

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I know this is the wrong place to post this but I have been doing some stuff with LCD screens whilst waiting for parts to arrive for the powderbed, [reprap.org]
Please join in and add to the page.

Edited 2 time(s). Last edit at 04/20/2011 10:34AM by johnrpm.

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Great John. I would suggest you perform the following simple test: Load a test picture into the photo frame. Get a 300W floor lamp (or shop light). Remove the UV filter (piece of glass) from the lamp. Set the photo frame a few inches above the light (you'll have to find a distance that doesn't get too hot). Turn the whole contraption on and check back every couple of hours. See if the image on the frame degrades. I'd be really interested in hearing the results!

Get a 300W floor lamp (or shop light). is this halogen???

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I was thinking halogen, yeah. You can get a 300w floor lamp from walmart for like $20. It's my understanding that halogen bulbs throw off a lot of UV. (you might need a more specialized UV bulb, but this would be a good start. I'll look for a cheap way to measure the uv flux)

You could also buy a Mercury Vapour (aka High Intensity Discharge aka Metal Halide) bulb, but you would need to find one which does not have a UV filter. I see a couple on bulbs.com for cheap that fit standard edison sockets, though you'd need a fixture with a proper ballast.

There are black light flourescent bulbs available too, but I can't find any over 60W. (Although, 60W of UV only might be as effective at curing resin as 300W of broad spectrum light. That could be worth a test too.)

Whether you use HID bulbs, or Halogen bulbs without the filter, be VERY careful not to expose yourself to the UVB, UVC light. I am reading that you can sunburn your skin and damage your eyes.

Another question will be just how much of the UV will be absorbed by the glass and plastic of the LCD. I suspect quite a lot. If so, there won't be much left to cure the resin, and the absorbed UV will eventually turn the plastic brown and brittle. LCDs are getting cheap enough though that it's worth testing!

Alternatively there might be a resin that will cure at near UV visible wavelengths, in which case we wouldn't could use a filtered halogen bulb without worrying too much about damage (except for heat).

Edited 1 time(s). Last edit at 04/20/2011 11:05PM by NuclearNerd.

NuclearNerd , thanks for the info, I have been doing the electronics for the powderbed so time limited, but I had a bit of an accident whilst ironing the board, just knocked the digital photoframe with the iron and chipped the corner, so it no longer works, (you can imagine the expletives) but have done the monitor for tests, I must find a use for the backlights.

I was wondering how to quantify the amount of UV getting through the lcd, if I had some paint that glows under uv light, then the brightness may indicate amount of uv getting through, I tried this with a security pen and uv led, the text was faintly visible, but the led is very low power, which seems to indicate that UV is getting through.

The reflectance meter measures approx 1/20 th of light getting through, ie, 20mv direct and 1mv through lcd using the bug killer, which is 4watts.

I have an old strobe light, wonder if they emit UV ?, I am concentrating on the powderbed, so the lcd thing will be as and when time permits,

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I was looking at an old overhead projector, and wondering if the general layout would work with the LCD, but instead of the optics enlarging they reduced the image size, various bulbs could be tried and the resolution would be increased, in fact the image could be variable size.
I have my hands on an ancient digital projector, with LCD screen, (size of a bus) so may use it for some trials, I did intend to use it for a structured light scanner, the workshop is now full to bursting.

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The powder bin steppers and recoater have been on test all weekend, and I am now confident with the design, at first with the salvaged steppers the darlingtons were getting a bit warm, so I used the trick of stacking them, they only get slightly warm now, next I need to fit limit switches on the recoater and both bins top and bottom, I shall try reed switches, as they are cheaper and easier to wire, I will do a video to show it all running, but really must have a clean up first.


P.S I took the plunge a couple of weeks ago and bought a HP1000 for £35, despite having bought a HP2050 ( thought the scanner may add complications), today I saw the HP 1000 in asda (wallmart) for £19, isn't that just typical.

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Your recommendation needed Please

I am using the standard stepper library for the arduino, it works well, but other library's, accelstepper and lab3, have extra features that I think would be good, (ramping, power reduction, continuous run etc), can anyone recommend which stepper library to use, I really like the idea of lowering the power to the motor whilst it is not in use, also continuous run whilst a button is pressed.

P.S I have received the reed switches so will fit them soon, also bought some of these [www.rapidonline.com] I had not seen them before, look usefull.

Edited 2 time(s). Last edit at 05/18/2011 02:25AM by johnrpm.

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can anyone recommend which stepper library to use,
If you don't get any nibbles, try reprap-dev?

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

No nibbles yet.


Madscifi pointed this out, [open3dp.me.washington.edu]
this will advance printhead work for 3d printing and help development in this area, a big thank you from me for sharing it,
reading the pdf, it explains some of the mysteries of firing printheads.

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