Post by slowsl on Apr 20, 2016 13:26:33 GMT -5
Hello everyone, new here. A little background...
My name is Mike, I live in Bristol & work in Goshen. I've recently decided to build a DLP printer, however I have no other experience with 3d printing, so I'm kind of winging it and learning from mistakes as I go. I like to design & build things, so this was a no-brainer.
As far as the printer goes, I wanted to start big and see how far I can go with it. I wanted a large frame for some rigidity and design overhead, and a large build area to play around with. The theoretical build area is 11.75"x11.75"x24". So far so good, a few things that needed fixed & redesigned, but I'm getting good calibration prints. I wasn't sure of the max build size achievable, I've read a lot of mixed conclusions. I know that the X & Y are heavily dependent on light intensity and uniformity, while the Z has a lot to do with separation, so that the print does not peel off the build plate. I've removed the filters and color wheel from my projector, so I will see how far this will get me. If I can't get a large enough print area with it, I have a couple ideas on improving that. As for the mechanical layer separation, I've read that people have good luck with tilt, slide, and twist methods, so I've incorporated all of these in the design, and able to control them all with the software. So far, I'm just using tilt on the small calibration items.
I will be tinkering with this over the next couple of months, however I'd like to get some ideas on a continuous build system and incorporate that into the printer here in the near future. Does anyone have any knowledge on this? I know that oxygen will inhibit curing, my thoughts are to get a highly gas permeable plate (I've had my eye on this stuff www.mitsuichemicals.com/tpx.htm) to allow oxygen to pass through and keep a cushion of uncured resin between the vat bottom and cured layer above it. What I plan to do is make a layered "sandwich" build plate, where I use a glass plate on the bottom, then an intermediate plate with an oxygen orifice, followed by the TPX plate on top, with gaskets inbetween them all. This will create an air tight chamber under the build plate where oxygen can be piped in. I have an oxygen tank, however where I'm a bit lost is how to regulate such a small amount of oxygen. For one, I'm not sure how quickly the gas will work its way through the plate. Too much oxygen and air bubbles will form, making voids in the print, not enough and the resin will cure on the build plate. My initial thought is that 2psi or less will be needed to force the gas through the plate. How do I regulate such a small amount? My initial thought was a pediatrics regulator which will go down to .01/lpm, however the fittings only work with medical 02 tanks, and you need a prescription for those, so I will have to make my welding 02 tank work somehow. Normal welding regulators may go down to about 10psi. I was thinking maybe using some kind of stepper motor/valve to regulate the flow between the printer and regulator, but there would be no feedback with on the fly adjustment, so if I made a relief valve, anything over the set pressure will be vented to the atmosphere. Not that big of a deal, but I don't want to waste a lot of oxygen. Does anyone have any thoughts about this? I've only spent a short amount of time researching, there isn't much info out there that I can find.
My name is Mike, I live in Bristol & work in Goshen. I've recently decided to build a DLP printer, however I have no other experience with 3d printing, so I'm kind of winging it and learning from mistakes as I go. I like to design & build things, so this was a no-brainer.
As far as the printer goes, I wanted to start big and see how far I can go with it. I wanted a large frame for some rigidity and design overhead, and a large build area to play around with. The theoretical build area is 11.75"x11.75"x24". So far so good, a few things that needed fixed & redesigned, but I'm getting good calibration prints. I wasn't sure of the max build size achievable, I've read a lot of mixed conclusions. I know that the X & Y are heavily dependent on light intensity and uniformity, while the Z has a lot to do with separation, so that the print does not peel off the build plate. I've removed the filters and color wheel from my projector, so I will see how far this will get me. If I can't get a large enough print area with it, I have a couple ideas on improving that. As for the mechanical layer separation, I've read that people have good luck with tilt, slide, and twist methods, so I've incorporated all of these in the design, and able to control them all with the software. So far, I'm just using tilt on the small calibration items.
I will be tinkering with this over the next couple of months, however I'd like to get some ideas on a continuous build system and incorporate that into the printer here in the near future. Does anyone have any knowledge on this? I know that oxygen will inhibit curing, my thoughts are to get a highly gas permeable plate (I've had my eye on this stuff www.mitsuichemicals.com/tpx.htm) to allow oxygen to pass through and keep a cushion of uncured resin between the vat bottom and cured layer above it. What I plan to do is make a layered "sandwich" build plate, where I use a glass plate on the bottom, then an intermediate plate with an oxygen orifice, followed by the TPX plate on top, with gaskets inbetween them all. This will create an air tight chamber under the build plate where oxygen can be piped in. I have an oxygen tank, however where I'm a bit lost is how to regulate such a small amount of oxygen. For one, I'm not sure how quickly the gas will work its way through the plate. Too much oxygen and air bubbles will form, making voids in the print, not enough and the resin will cure on the build plate. My initial thought is that 2psi or less will be needed to force the gas through the plate. How do I regulate such a small amount? My initial thought was a pediatrics regulator which will go down to .01/lpm, however the fittings only work with medical 02 tanks, and you need a prescription for those, so I will have to make my welding 02 tank work somehow. Normal welding regulators may go down to about 10psi. I was thinking maybe using some kind of stepper motor/valve to regulate the flow between the printer and regulator, but there would be no feedback with on the fly adjustment, so if I made a relief valve, anything over the set pressure will be vented to the atmosphere. Not that big of a deal, but I don't want to waste a lot of oxygen. Does anyone have any thoughts about this? I've only spent a short amount of time researching, there isn't much info out there that I can find.
