Hi folks! I've been lurking here for a while, soaking up info in hopes of being a micRo owner in the future. I registered today because I had an idea to share for discussion.
In a nutshell: selective laser sintering, using powder coating as the medium.
I don't know much about 3D printing or powder coating, and I don't know if this possibility has been explored before (though I've never seen it). But it seems like this could be done inexpensively (as far as 3D printing goes), in the DIY domain, and make cheap, strong, finely detailed parts.
Here's some Wikipedia quotes regarding powder coating, and my thoughts on the potential for 3D printing.
"The most common polymers used are polyester, polyester-epoxy (known as hybrid), straight epoxy (Fusion bonded epoxy) and acrylics."
So there's a variety of materials, with at least some readily available and mass produced, for different physical properties you might need in a part. And in different colors too! I found polyester powder coating on Ebay for $6.00/lb, in single pound quantity. Not bad at all, considering you only consume the material actually used in the part, and the rest of the powder used as a support can be reused over and over.
"...most powder coatings have a particle size in the range of 30 to 50 μm..."
Sounds like it would allow for fine details, and smooth uniformly with a powder rake.
"When a thermoset powder is exposed to elevated temperature, it begins to melt, flows out, and then chemically reacts to form a higher molecular weight polymer in a network-like structure. This cure process, called crosslinking, requires a certain degree of temperature for a certain length of time in order to reach full cure and establish the full film properties for which the material was designed. Normally the powders cure at 200°C (390°F) in 10 minutes... The application of energy to the product to be cured can be accomplished by convection cure ovens or infrared cure ovens."
Perhaps it's possible to quickly fuse the powder into a cohesive part, using an inexpensive infrared diode laser. The relatively weak part could then be fully cured to full strength, while supported by a different powder medium (inert, not thermoplastic), in any oven.
Building this machine could be as simple as adding a powder tray, powder rake, and laser to a micRo.
Your thoughts on this?
Full Version: 3D Printing Idea - Does This Have Potential?
To be honest, I don't think we had even considered selective laser sintering of powdered thermoplastics... It's an interesting idea, and might have legs. We do have plans for a laser attachment (that would likely be either laser diode or solid-state diode pumped laser), so this could be a relatively easy transition.. Especially if we go with a SSDP Neodymium Yttrium Arsenide Garnet type laser (which can be frequency doubled to cut organic materials, or left at its native frequency- in the infra-red range). Fineness of detail accomplished by SLSed powdered thermoplastics would be limited by the beam width..
However, there are practical considerations:
-finding the balance between a useful laser wattage/frequency without the need for elaborate safety precautions (this limits laser strength to the single-digit watt range).
-designing a powder rake that can easily co-exist with our current design.
-interfacing the powder rake (both software and electronics)
The main disadvantage would be in the powder-rake.. Which is why we've leaned towards more "additive" 3d printing methods.
A clever implementation of DIY 3dp has been developed by the University of Washington's mechanical engineering department that uses a combination of powdered slip (the ceramic) and selective bonding via a mixture of water and alcohol (also known as vodka). But, it requires firing in a kiln (major disadvantage for those of us without a kiln handy- though I suppose you could possibly fire it in a bonfire... and come to think of it- that could create an interesting social scene). The advantage of powdered thermoplastics would be that parts could be "fired" in a toaster oven..
Anyways, neat idea.. We'll have to talk it over I think, but, as always, it'd be great to see some of our users develop something cool like this.
However, there are practical considerations:
-finding the balance between a useful laser wattage/frequency without the need for elaborate safety precautions (this limits laser strength to the single-digit watt range).
-designing a powder rake that can easily co-exist with our current design.
-interfacing the powder rake (both software and electronics)
The main disadvantage would be in the powder-rake.. Which is why we've leaned towards more "additive" 3d printing methods.
A clever implementation of DIY 3dp has been developed by the University of Washington's mechanical engineering department that uses a combination of powdered slip (the ceramic) and selective bonding via a mixture of water and alcohol (also known as vodka). But, it requires firing in a kiln (major disadvantage for those of us without a kiln handy- though I suppose you could possibly fire it in a bonfire... and come to think of it- that could create an interesting social scene). The advantage of powdered thermoplastics would be that parts could be "fired" in a toaster oven..
Anyways, neat idea.. We'll have to talk it over I think, but, as always, it'd be great to see some of our users develop something cool like this.
I've seen several different sintering methods. One uses the same idea you describe, a fine white plastic powder, and there is a version that uses a metal powder too. The sintered part has a strength that is relativity low for the size of the metal, but due to the high porosity and low pore size, the part is fired to promote bonding, then if higher strength and density is required, it is infused with (iirc) bronze, leaving the part at about 70% the strength of an equivalent mild steel part.
Another "almost sintering" system uses stereo lithography, using UV lasers to fuse a liquid. BC has done some work on this on the site, but using a novel system to apply the polymer, rather than a fluid bath, and a high powered UV LED at close range.
Another one is a system that uses a tape laying machine and an ultrasonic welder, but I don't recall the way that worked. The result was basically a block of solid aluminium made up from many tape layers welded together.
Finally (off the top of my head - these are systems I've seen over many years) there was a robot spot welder which applied accurate spot welds to other spot welds, consuming a roll of wire as it went, and building up the target object.
There are other systems of course, but they aren't even vaguely related to the powdered sintering style.
Your main problem is going to be keeping the layer of powder you deposit over the top even and also keeping the whole thing ultra-clean, as even the smallest speck of dust or a hair will wreck the build. It will also be expensive as you have to fill the entire volume with powder - the start point is an empty chamber, and the machine first lays down a thin base layer, then sinters that, and then works upwards filling the chamber to the height of the part. From memory the commercial machines have a vacuum system to help clean stuff off.
The main issue with using a micro for something like this is the limited z travel. If you really want to try something like this, the reprap would do a far better job - it simply doesn't require the solidity and strength that a micro is going to have for a process that requires no force at all, and it has about 4 times the z travel. It wouldn't support a milling cutter or anything though, it's a totally different beast.
Another "almost sintering" system uses stereo lithography, using UV lasers to fuse a liquid. BC has done some work on this on the site, but using a novel system to apply the polymer, rather than a fluid bath, and a high powered UV LED at close range.
Another one is a system that uses a tape laying machine and an ultrasonic welder, but I don't recall the way that worked. The result was basically a block of solid aluminium made up from many tape layers welded together.
Finally (off the top of my head - these are systems I've seen over many years) there was a robot spot welder which applied accurate spot welds to other spot welds, consuming a roll of wire as it went, and building up the target object.
There are other systems of course, but they aren't even vaguely related to the powdered sintering style.
Your main problem is going to be keeping the layer of powder you deposit over the top even and also keeping the whole thing ultra-clean, as even the smallest speck of dust or a hair will wreck the build. It will also be expensive as you have to fill the entire volume with powder - the start point is an empty chamber, and the machine first lays down a thin base layer, then sinters that, and then works upwards filling the chamber to the height of the part. From memory the commercial machines have a vacuum system to help clean stuff off.
The main issue with using a micro for something like this is the limited z travel. If you really want to try something like this, the reprap would do a far better job - it simply doesn't require the solidity and strength that a micro is going to have for a process that requires no force at all, and it has about 4 times the z travel. It wouldn't support a milling cutter or anything though, it's a totally different beast.
QUOTE (rturner @ Nov 17 2009, 04:42 PM) 
The main disadvantage would be in the powder-rake.. Which is why we've leaned towards more "additive" 3d printing methods.
True, although I know it can be done with some degree of success. Are web links allowed here? Until I know if that's ok, I'll say that you can find a DIY implementation by Googling "homemade3dprinter", made primarily from the guts of an inkjet printer. That was my first inspiration for the powder coating idea.
QUOTE (rturner @ Nov 17 2009, 04:42 PM)
A clever implementation of DIY 3dp has been developed by the University of Washington's mechanical engineering department that uses a combination of powdered slip (the ceramic) and selective bonding via a mixture of water and alcohol (also known as vodka). But, it requires firing in a kiln (major disadvantage for those of us without a kiln handy- though I suppose you could possibly fire it in a bonfire... and come to think of it- that could create an interesting social scene). The advantage of powdered thermoplastics would be that parts could be "fired" in a toaster oven..
That was my second inspiration. The article I read on that stated that the normal supplies for 3D ceramic printing cost $30-$50 pound, but they created their own version for less than $1 per pound. It occurred to me that powder coating material might show a similar price reduction vs. powder made/marketed specifically for laser sintering, due to economies of scale. And that's when I thought I might have an idea worth sharing.
QUOTE (-soapy- @ Nov 17 2009, 06:09 PM)
I've seen several different sintering methods.
Thanks for the info, I didn't know about some of those techniques. I did know about BC's hybrid method, and I'm watching his progress with interest.
QUOTE (-soapy- @ Nov 17 2009, 06:09 PM)
Your main problem is going to be keeping the layer of powder you deposit over the top even and also keeping the whole thing ultra-clean, as even the smallest speck of dust or a hair will wreck the build. It will also be expensive as you have to fill the entire volume with powder - the start point is an empty chamber, and the machine first lays down a thin base layer, then sinters that, and then works upwards filling the chamber to the height of the part. From memory the commercial machines have a vacuum system to help clean stuff off.
The main issue with using a micro for something like this is the limited z travel. If you really want to try something like this, the reprap would do a far better job - it simply doesn't require the solidity and strength that a micro is going to have for a process that requires no force at all, and it has about 4 times the z travel. It wouldn't support a milling cutter or anything though, it's a totally different beast.
The main issue with using a micro for something like this is the limited z travel. If you really want to try something like this, the reprap would do a far better job - it simply doesn't require the solidity and strength that a micro is going to have for a process that requires no force at all, and it has about 4 times the z travel. It wouldn't support a milling cutter or anything though, it's a totally different beast.
Excellent points here. Speaking personally, I'd be happy with the capability to make plastic parts with a maximum height of just a few inches; and a few small defects, even an occasional wrecked build, would be acceptable. My specific interest in setting up a micRo for this is because I already want one, but want to avoid acquiring any other large tools such as a separate Reprap. As it is, I've got a compound miter saw and drill press set up on my living room coffee table, for lack of space.
QUOTE (rturner @ Nov 18 2009, 08:42 AM)
To be honest, I don't think we had even considered selective laser sintering of powdered thermoplastics... It's an interesting idea, and might have legs. We do have plans for a laser attachment (that would likely be either laser diode or solid-state diode pumped laser), so this could be a relatively easy transition.. Especially if we go with a SSDP Neodymium Yttrium Arsenide Garnet type laser (which can be frequency doubled to cut organic materials, or left at its native frequency- in the infra-red range). Fineness of detail accomplished by SLSed powdered thermoplastics would be limited by the beam width..
However, there are practical considerations:
-finding the balance between a useful laser wattage/frequency without the need for elaborate safety precautions (this limits laser strength to the single-digit watt range).
-designing a powder rake that can easily co-exist with our current design.
-interfacing the powder rake (both software and electronics)
The main disadvantage would be in the powder-rake.. Which is why we've leaned towards more "additive" 3d printing methods.
A clever implementation of DIY 3dp has been developed by the University of Washington's mechanical engineering department that uses a combination of powdered slip (the ceramic) and selective bonding via a mixture of water and alcohol (also known as vodka). But, it requires firing in a kiln (major disadvantage for those of us without a kiln handy- though I suppose you could possibly fire it in a bonfire... and come to think of it- that could create an interesting social scene). The advantage of powdered thermoplastics would be that parts could be "fired" in a toaster oven..
Anyways, neat idea.. We'll have to talk it over I think, but, as always, it'd be great to see some of our users develop something cool like this.
However, there are practical considerations:
-finding the balance between a useful laser wattage/frequency without the need for elaborate safety precautions (this limits laser strength to the single-digit watt range).
-designing a powder rake that can easily co-exist with our current design.
-interfacing the powder rake (both software and electronics)
The main disadvantage would be in the powder-rake.. Which is why we've leaned towards more "additive" 3d printing methods.
A clever implementation of DIY 3dp has been developed by the University of Washington's mechanical engineering department that uses a combination of powdered slip (the ceramic) and selective bonding via a mixture of water and alcohol (also known as vodka). But, it requires firing in a kiln (major disadvantage for those of us without a kiln handy- though I suppose you could possibly fire it in a bonfire... and come to think of it- that could create an interesting social scene). The advantage of powdered thermoplastics would be that parts could be "fired" in a toaster oven..
Anyways, neat idea.. We'll have to talk it over I think, but, as always, it'd be great to see some of our users develop something cool like this.
You can use a small optic to converge the beam. This would allow smaller wattage lasers to be used and finer detail.
Depending on the light properties of the thermoplastic, the conical shape of the focused laser could be used to bond a layer at a desired z depth. Thus simplifying the powder rake problem to maybe just using a simple vibration to add 3mm of powder at a time.
Sure, I don't see why you couldn't post links.. I've watched the University of Washington (pronounced "you dub" if you've ever lived in the north-west) project with some interest, and from the looks of it they're continuing with their innovations... However, they presume that anyone using their materials recipe already has a $10k 3d-printer. The powder-coat idea is a pretty good one- once we get the laser system past the research-phase, we'll have to try it out. FWIW, while the micRo was designed primarily with small-scale machining in mind (hence the monolithic construction of the v2, and higher TPI leadscrews verses something like the.. and it pains me a little to utter the word... RepRap- which is built for fast mid-accuracy low-torque printing..), we want to expand the tooling possibilities, so developing an off-set mount for extending 3dp Z depth is a high (and easily accomplished) priority...
QUOTE (Darkcobra @ Nov 18 2009, 07:27 AM)
True, although I know it can be done with some degree of success. Are web links allowed here? Until I know if that's ok, I'll say that you can find a DIY implementation by Googling "homemade3dprinter", made primarily from the guts of an inkjet printer. That was my first inspiration for the powder coating idea.
That was my second inspiration. The article I read on that stated that the normal supplies for 3D ceramic printing cost $30-$50 pound, but they created their own version for less than $1 per pound. It occurred to me that powder coating material might show a similar price reduction vs. powder made/marketed specifically for laser sintering, due to economies of scale. And that's when I thought I might have an idea worth sharing.
That was my second inspiration. The article I read on that stated that the normal supplies for 3D ceramic printing cost $30-$50 pound, but they created their own version for less than $1 per pound. It occurred to me that powder coating material might show a similar price reduction vs. powder made/marketed specifically for laser sintering, due to economies of scale. And that's when I thought I might have an idea worth sharing.
Right, the beam focus could be used to control the height of the... uhh... and I think I might be making this term up... sintering plane. While I don't think that this is really an issue, detail would still be limited by the beam width/shape (most economical lasers don't output circular beam cross-sections) with regards to the fact that the powder coat particle size is measured in micrometers. It's my understanding that most plastics have the best performance with laser light in the green-to-ultra-violet frequency range, so that automatically makes CO2 lasers un-fit (though, there are a host of other reasons, not the least of which is cost/complexity and size). Fortunately there are tons of DPSS lasers and laser diodes that work in that range.. The issue of power, while it's true that energy density will be improved with a tight focus (though might not be feasible, depending), starting out with a modestly powerful laser will make sintering go considerably faster.. Also, because time is an issue, too tight of a focus can vastly multiply the amount of time it would take to make a part... Of course, finding the right balance is just going to take more research and a bit of experimentation....
Making a functional powder rake system though... Seems so far (in my mind) to be a series of uncomfortable compromises..
Making a functional powder rake system though... Seems so far (in my mind) to be a series of uncomfortable compromises..
QUOTE (DAZZZLA @ Nov 19 2009, 06:51 AM)
You can use a small optic to converge the beam. This would allow smaller wattage lasers to be used and finer detail.
Depending on the light properties of the thermoplastic, the conical shape of the focused laser could be used to bond a layer at a desired z depth. Thus simplifying the powder rake problem to maybe just using a simple vibration to add 3mm of powder at a time.
Depending on the light properties of the thermoplastic, the conical shape of the focused laser could be used to bond a layer at a desired z depth. Thus simplifying the powder rake problem to maybe just using a simple vibration to add 3mm of powder at a time.
It is amazing what can be built with a hammer and some nails...
We have a new hammer here...
We have a new hammer here...
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