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Plastic Extruders, mostly - > http://objects.reprap.org/wiki/Extruder
Re: What metals/alloys would you make use of and why? - 10 years ago
Sounds like a 3d printer I made back in the mid 1990s. The bed was the size of kitchen table. It had a 3 foot tall gantry on top of it to move a laser around. Another large table was beside it that acted as a hopper and plastic or metal powder was in the hopper. A set wipers moved the powder from the hopper to the kitchen table. Zcorp made one a lot like it. Plastic powder and titanium powder wby criswilson10 - General
Re: Affordabe printable biomaterials - where to get from? - 11 years ago
Creative Tools out of Germany is still selling the 1.75mm 135 Euro I'm sure that there are others. Last time I had to print with it, I had to extrude my own filament from granuals.by criswilson10 - Tissue Engineering
Re: Coil-Threaded Rods - 11 years ago
Coil thread rod is nice because it doesn't jam, rarely clogs, and nuts move across it quickly. They've been used for years in screw jacks in the automotive and construction industry. Rust doesn't really affect the nut travel because the nuts fit loosely with a mm or so of slop. The nuts are designed to wobble on the rod. Postion repeatability of a coil thread rod and nut combination is around 3 mby criswilson10 - Mechanics
Re: Smooth Rods - O1 Tool Steel, Stainless, Delrin, PTFE - 11 years ago
High Speed Steel is essentially tool steel with tungsten in it. The tungsten allows the steel to get hotter without losing its tempering which keeps blade edges sharper. This allows drill bits and saw blades to be run at a higher speed (getting hotter with friction) than with plain tool steel and stay sharp. Thus the name high speed steel. Rod made of tool steel that has been heat treated properby criswilson10 - General
Re: Smooth Rods - O1 Tool Steel, Stainless, Delrin, PTFE - 11 years ago
For the metal properties Chrome is harder than stainless and stainless is harder than untreated tool steel. A chromium rod has a surface hardness around 65 HRC A 304/316 stainless rod has a surface hardness around 40 HRC Non heat treated tool steel has a surface hardness around 30 HRC Heat treated 01 tool steel at best has a hardness around 60 HRCby criswilson10 - General
Re: trees - 11 years ago
GPS controlled lawnmower pulling a billy goat seeder would do it. Cost around $2500 (USD)by criswilson10 - Tissue Engineering
Re: Screw / nut blanks for threading with tap + die - 11 years ago
I've had pretty good luck with with printing the holes a bit smaller than final and shafts a bit larger than final. Carefully threading/tapping the part and then covering the whole thing with plaster. Let the plaster dry and then cook the whole thing in a toaster oven for an hour on 500 F. Let it cool and then bust the plaster off. Essentially I'm letting the plastic layers reflow into one solidby criswilson10 - General
Re: trees - 11 years ago
OK, the plants won't get loose, but there pollen can and then crossbreed with the natural plants. Like the genetically modified corn that cross breeds with regular corn.by criswilson10 - Tissue Engineering
Re: trees - 11 years ago
There's more grant money available to develop human tissues - so the research is on human tissue and not plant. There is also the the environment to consider. You mess up a human tissue you kill one human. You mess up a plant tissue and it gets loose in the wild and you can wipe out a whole species of plants. See American Chestnut Trees.by criswilson10 - Tissue Engineering
Re: Sterilise printed objects - 11 years ago
You might want to check and see if what you want to make has to be sterile. If it goes inside of the body it has to be sterile and a biocompatible plastic. If it goes on the outside of the body it only has to be disinfected (usually). For instance sutures (stitches) have to be sterile because they go into the body, but a blood pressure cuff only has to be disinfected.by criswilson10 - Tissue Engineering
Re: Sterilise printed objects - 11 years ago
I haven't tried sterilizing anything printed yet, but a typical autoclave runs around 250 degrees F. I'm pretty sure PLA would absorb the steam and break. For plastic things you usually sterilize with EtO (Ethylene Oxide) or an ionizing radiation burst. You have to make sure the plastic is compatible with the EtO, you don't want the plastic absorbing any of it. Bleach and alcohol are disinfectaby criswilson10 - Tissue Engineering
Re: Medical Grade PCL and PLA - 11 years ago
Well it won't be medical grade after it runs through a reprap, but I think carries it.by criswilson10 - Tissue Engineering
Re: Reflective sensor - 11 years ago
If we are talking about same thing, (something like ), then they are not used to measure distance, they only measure a change in light level. They typically have a working range of 0.1 to 0.5 inches. If you are talking about a laser range finder (aka laser tape measure), the home improvement store versions have around a 25 foot range and are accurate to about one sixteenth of an inch. Cost is abby criswilson10 - Reprappers
Re: ABS/PLA safety during Pregnancy - 11 years ago
I don't' know of any "long term" studies that have been done on either ABS or PLA, but ABS can put off some nasty fumes when it is overheated. Even at proper temperature, I've seen asthmatics react to ABS fumes and a few people complain about headaches. I haven't seen those reactions to PLA, but that doesn't mean that PLA is any safer. Carbon filters rated for plastic fumes (like a respirator)by criswilson10 - General
Re: Medical Grade of Polyglycolic acid - 12 years ago
Medical grade does not only include the additives, but the manufacturing and packaging process as well. As far as additives are concerned, it can't contain anything that is toxic or hazardous. You could start by comparing your PGA to Surgicryl a PGA absorbal suture. I think there is another PGA product called Kurdux (kurdex, curdex, curdux, somthing like that) used for tissue scaffolding, but I'by criswilson10 - Tissue Engineering
Re: Health and Safety advice - 12 years ago
Congratulations, the first hurdle has been cleared. Since I'm in the USA my knowledge of COSHH is limited, so definitely verify my advice with a safety person in the UK. I'd start with reviewing the following: Most likely you will need to have a 3 ring binder put somewhere prominently in the room and labeled COSHH or MSDS or SDS. Inside the binder you will need to have the MSDS sheets for PLAby criswilson10 - Reprappers
Re: ABS fumes harmfull to Aquarium? - 12 years ago
PLA is just a starch that has had the monomer changed into a polymer by heat. Water alone will dissolve PLA within a few months. Add in a few bacteria and it can be dissolved within a few weeks. I haven't seen any formal papers on what the bacteria do to the PLA during composting, but if i had to guess I would say the bacteria convert the lactide polymer into a lactide monomer and then into lactby criswilson10 - General
Re: ABS fumes harmfull to Aquarium? - 12 years ago
ABS is used pretty often in aquarium pumps, so I assume that is safe for the fish. ABS is salt water tolerant. As for printing close to an aquarium, I can't say that I have ever tried it, but I do know that ABS fumes that react with water will float on top of the water like a rainbow colored oil slick. So if you see an oil slick in the aquarium the answer would be no and use a paper towel to soby criswilson10 - General
Re: Good CAD program for Mac OS X - 12 years ago
VectorWorks is a mac based CAD program, but I seem to remember it being pricey. AutoDesys makes FormZ that is also a mac CAD program that is cheaper. Rhino for mac and AutoCad for mac will do basic CAD work but sometimes get flakey with advanced stuff - they are working to make them more stable. And I guess there is Google Sketchup as well.by criswilson10 - Reprappers
Re: Health and Safety advice - 12 years ago
We let the students have direct access to the equipment so that they can learn to use it (with the exception that pregnant women are not allowed to use the 3d resin printer because of the mutagenic dangers of the resin - it's a low risk, but one we're not willing to take). We do keep a work study student (cheap labor) in the lab area during its open hours to handle problems and questions - theirby criswilson10 - Reprappers
Re: Health and Safety advice - 12 years ago
I support an area that has a 3d fab lab at a university. The room is maybe 500 square feet in size. Along with a reprap, it has a couple of laser cutters, a BfB 3000, a 3d powder printer, and a 3d resin printer. I set up its air system for an exhuast of 1250 CFM at 6" static and a supply air of 1000 CFM. Most of that exhaust air is for the laser cutters, but I stuck a couple of snorkles near theby criswilson10 - Reprappers
Re: Looking for printers that work with aluminum - 12 years ago
Earlier in the year my university ordered a small low end unit and its cost was around $800,000 (USD) plus operating costs with shield gas and powder. The surface finish is terrible and the parts are very porus. For most things, you can machine a solid block faster, cheaper, and with a better finish/tolerance.by criswilson10 - General
Re: reprap printing carbohydrate glass 3d blood vessel molds - 12 years ago
Basically, Boland is trying different methods and comparing them for feasability. His dream is that all hospitals and universites will have a reliable and cheap (under $10,000 USD) desktop organ printing machine. His motive is push this kind of research to be cheaper and in the past decade we have seen the prices come down. Viktor, danke. I'm familiar with the method you attached. I think I eby criswilson10 - Tissue Engineering
Re: reprap printing carbohydrate glass 3d blood vessel molds - 12 years ago
I try my best not to do that much publishing, writing articles just isn't my thing. I think the last thing I published on tissue engineering was back in 2003 in Anatomy Record A. My partner does most of the publishing and the link to his publications is at Publications. Several articles there cover our work with thermal and piezo inkjet printer type devices. Shear stress is still an issue witby criswilson10 - Tissue Engineering
Re: reprap printing carbohydrate glass 3d blood vessel molds - 12 years ago
The vascular grafts (for bypass patients) have worked surprisingly well - no rejections, no occlusions, no blowouts...yet. It is still way too expensive of an option to actually use on a regular basis though. The skin we have printed works, but we haven't gotten the blood flow pattern correct yet or the pigmentation correct. I built a custom piezo inkjet style printer for the cells to be printby criswilson10 - Tissue Engineering
Re: reprap printing carbohydrate glass 3d blood vessel molds - 12 years ago
In many ways, it is the same modification that allows rerap to print cake icing for cake decorating. I know somebody in the forums is doing this, but I can't remember who. A search of the general forum for sugar or cake should steer you to correct discussion thread and I think the rough recipe (3 parts sugar to 1 part water???) was listed in the discussion.by criswilson10 - Tissue Engineering
Re: problems making a ring gear - 12 years ago
Are you sure the teeth are the same? You might have to change the clearance between the teeth a bit.by criswilson10 - General
Re: Maglev print bed to level? - 12 years ago
I think the control system would be expensive. You would have to monitor the bed pretty closely and change the magnetic field strength as material is extruded out. And you would have to find a way to balance the magnetic field as the extruded material shifted the center of rotation of the bed.by criswilson10 - Mechanics
Re: Over Constrained Linear Systems - 12 years ago
"It's probably because cars have four wheels that we are accustomed to seeing it that way." In an ideal world it is the better way to design it. It looks better on drawings, my favorite CAD program shows it lined up better, and my favorite motion analysis program shows it to work the best. Of course we don't live in an ideal world and simulations don't always predict the real world or practicalby criswilson10 - Mechanics
Re: Training to a suitable level - 12 years ago
I don't think the cells would like the 200 degree heated extruder. ;-) In theory you could replace the extruder head with a piezo head, micropump, or a lower temperature thermal head; and then use that to print out cells. I guess you could also rework the body to hold a culture dish and put the whole thing into an enclosure full of nitrogen. And then..... figure out why you chose the wrong tooby criswilson10 - Tissue Engineering