The longest drive screw that I've seen on a machine was 10 feet long, 1 1/2 inches in diameter and made of stainless steel. The carriage riding on it was also on casters in a track to keep the majority of the load off of the screw. So you can use them longer distances, but be prepared to either over design it or break out the books on beam deflection.by criswilson10 - Mechanics
> 1. Make a RepRap that's accurate to 10 micrometers > (.01mm?) A much finer (and slower) gearing system fixes that issue. > 2. What kind of print head design would work best > to print an animal cell? a plant cell? There's a large amount of debate over that. HP thermal inkjet heads are often used, but you have to balance the heat to make the bubble versus the heat tolerance of theby criswilson10 - Tissue Engineering
We use a cell printer that I designed. The smallest blood vessel that we've done was 1/16" I.D. Below that value the vessels started closing in on themselves with cell growth. For connecting the printed vessels into existing vessels we flare the end of our vessels and add ringlets to make it easier to sew them in. It's pretty much the same way polyester replacement vessels are designed.by criswilson10 - Tissue Engineering
You should be able to use nubs instead of nuts without any major issues. Ideally the nub has the same diameter as the thread pitch of the nut that would fit on the screw. The easy way to do it is with a machine screw that is close to the correct diameter. Drill and thread a hole through the print head carriage for the screw, cut the screw to the correct length, and then grind or file the end ofby criswilson10 - Mechanics
The ball point pin tip as a replacement nub doesn't work real good because the threads of the screw wear out the sides of the tip and then the ball falls out, and then the tip collapses and gets stuck in the threads. I know that one from personal experience. :-) In the printer, it will extend the life about 100 pages before failure. The nubs are easily made with scrap round bar from a brokenby criswilson10 - Mechanics
"working blood vessels" A printed blood vessel made up of endothelia cells, polysaccharides, and connective tissues that are used as replacement blood vessels for bypass surgury. Clinical trials are already in progress in a third world country on select critical patients that will die without a bypass and cannot afford one. And we have published very, very little about it in order to protect thby criswilson10 - Tissue Engineering
IIRC, those printers used a bronze threaded rod (worm gear) and a mild steel follower formed into a thermoset plastic carriage. The nubs do wear out after a lot of use, but you can also change them out. On the whole, I avoid having plastic and metal sliding on one another. I know that theoretically if you have the right kind of plastic and the right metal surface treatment that there should notby criswilson10 - Mechanics
Kind of freaked me out when I heard about it, because I've never heard of the guy and this is my area of research. We have proven that we can print working kidney cells, working blood vessels, and functioning nerve clusters, but the push is on to be able to get them all printed together into a working organ. Maybe in another decade we will be there.by criswilson10 - Tissue Engineering
St. Jude Research Medical Device Division is our outside GMP contractor. They are using a medical grade PCL with a molecular weight of 120,000, the parts are manufactured in an inert atmosphere, cleaned with sterile water, vacuumed sealed, packaged, gamma irradiated, and delivered to us completely sterile. The cost for all of that is around $10,000 (USD) per kg. Usually the PCL we use doesby criswilson10 - Tissue Engineering
PCL comes in varying molecular weights with consistencies that vary from modeling clay to hard plastic. The harder stuff is available in filament and pellets; the softer stuff is usually in flakes or powder form. For testing in the lab, we us PLA for the prototypes and PCL for the final prototype. For stuff that is actually being implanted we have an outside medical device manufacturer generateby criswilson10 - Tissue Engineering
I don't think Quorm is really engineered. I think the patent covers the process to mass produce the fungus.by criswilson10 - Tissue Engineering
I've mailed "leaded" boards from the US to Italy and Spain and never had any problems. Either they are not screening for it, or I've gotten lucky several times now. It would be nice is someone from the EU could answer the question though.by criswilson10 - Controllers
Quorn is made from a fungus, Fusarium something or another, that is in the mushroom family. I think it only occurs naturally in Britain or maybe it was Ireland. Of course the marketing people say that Quorn actually contains the EU patented mycoprotein and I think the patent expired in 2010 so there may be more information about it online.by criswilson10 - Tissue Engineering
You can pretty much use any screw type that you want. I personally use "phillips" head machine screws. Socket Head cap screws are less likely to strip and look more "technical", but cost more.by criswilson10 - General
Where to begin with training? Now that is a good question. You need a good understanding of biology, microbiology, and cytology to be able understand the interactions among cells to be able to keep them alive. You need a good understanding of biocompatible materials to make sure that nothing in your design is going to kill the cells before you even output them or after you output them. You needby criswilson10 - Tissue Engineering
Have you considered a large box fan with a few bags of ice hanging off of the front of the fan? It's not pretty or efficient, but it will lower the air temp a few degreesby criswilson10 - General
The bone replacement is gradual, but the dissolving pattern of the PCL mixture is unpredictable. For example, if you replaced your entire femur (upper leg bone) with PCL there is no way to predict how the PCL will dissolve. What are you going to do if it dissolves all the way through in the middle first? Well the person is definitely going to fall over and lose muscle control for one thing...by criswilson10 - Tissue Engineering
The design that comes to mind to me is essentially a drill with a tapered screw chucked in it and then have a nozzle attached to the drill body so that the screw rotates inside the nozzle and the nozzle stays still. Kind of like how a drill bit guide works. For the nozzle I would use 1020 round steel stock for prototyping and stainless steel for the final version. For the taper angle, I would stby criswilson10 - Tissue Engineering
The acronym PCL, in this case, is polycaprolactone. It is a polyester with a low melting point (125 degrees F) that is biodegradable and the medical form of it is biocompatable, so it can be implanted inside the body. PCL is already in use as sutures (stitches), adhesion barriers, time release pill coatings, and dentistry. I've heard that is being tried with some implants in animals to test to sby criswilson10 - Tissue Engineering
The HOA2001 will work, but just about any opto-interrupt switch will work. You could even build your own opto interrupt switch if you wanted to. Or forget the opto-interrupt switch and use a momentary on push switch.by criswilson10 - Controllers
Over the years I have made my own stepper circuits from transistors, bought driver chips to make the circuits, and bought break out boards. They will all work. The choice you make is up to you and what you feel comfortable with in cost, time, and ability. Although, I would recommend not going with your own transistor control circuit. It's a great learning exercise that will make you appreciateby criswilson10 - Controllers
When the lawyers figure out how to make money off of the lawsuit, then it will happen. The patents, copyrights, and trademarks that are in my name were created mainly to keep someone else from copying my ideas, patenting them, and then suing me for infringement. Believe it or not, there are actually people out there that make their living by doing just that. I personally hope that karma gets theby criswilson10 - General
Chip size with saw blades is roughly based on the tooth depth of the blade and clearance between the blade and housing. If you use a rough cut circular saw blade with 3/4 inch long teeth, you will get bigger chips than if you use a fine pitched "plywood" circular saw blade with 1/8" long teeth. If the clearance between the blade and the housing is only 0.001 inches then no piece bigger than 0.0by criswilson10 - General
I'll second the gorilla glue for use with the wood pulleys. If you have a good drill press you can also drill through the pulley and motor shaft and use a tension pin for the connection.by criswilson10 - Mechanics
The milling cutters would work well and older machine shops may have some sitting around, that are used to the point that they are not safe for steel, that they may give to you. I got a whole set that way. They still work great on plastic and light metals for hobby stuff. I have seen a design somewhere that had a row of 4 inch diamter circular saw blades, each separated with a couple of washers,by criswilson10 - General
Dielectric grease is a type of silicon grease. You can usually buy it cheaper from a home improvement store in the electrical aisle. It's often used to join aluminum conduit and lube wires before pulling them through conduit - so you can get a good sized can of it. It even comes in handy squeeze bottles. Personally, I use silicon grease on plastic parts because it does not react with plastic.by criswilson10 - General
Cost for me for ABS for reprap is around $0.30(US) per cubic inch. There was some mention about overhangs in architecture models. If possible I orient my models to print so there is no overhang by either printing the model on its side or upside down. Sometimes I add 1/8" diameter supports that expand out to the flat surface and then remove them with a jewelers saw and file after printing. Somby criswilson10 - General
Cost to print a 1" reprap cube for me is around $0.30 (US) I'm sure there is a supplier out there may be cheaper, but I'm too lazy to spend hours searching to save a penny or two. Cost to print a 1" cube from my university's Vflash plastic printer is around $4.25(US) for the material. Not including power and labor; that's just how much the material costs from the manufacturer. Obviously, the maby criswilson10 - General
Mostly to create custom plastic parts for other mechanical designs.by criswilson10 - Reprappers
That printer in the video is a thermal type inkjet printer and the firing circuitry is modified from a "normal" thermal inkjet printer to match the microboiling temperature of the cellular solution. Boiling the cells to death is a major issue with this type of bioprinting, but it is the cheapest, easiest way to do the experiments. Essentially you are relying on the liquid holding the cells in sby criswilson10 - Tissue Engineering