>"Disagree, you definately need to "talk" to the cells when you print them. And in any case you need to change their (epi) genetic makeup so >the cells are stem-like in order to be able to be part of the organ. " Nope. With cell jet printing we harvest cells (coring needle) from the organ that needs to be printed. We separate the harvest into the different types of cells within the organ,by criswilson10 - Tissue Engineering
As an engineer who is working on the cell printer issues, I can say we can print some viable organs today. I don't think anyone has grown a viable one yet. At our current level of knowledge both attempted printing and attempted growing are still adding more and more knowledge to what we (as humans) know about cell and organ dynamics. Have us "organ printing" people gone amok? Maybe, but printingby criswilson10 - Tissue Engineering
Bearing choice often comes down to availability and price instead of "best" design. Gang bearings and linear bearings will both work if the correct bearing size is chosen for the design and installed correctly. Anytime you have shafts and bearings you are going to have wear of either (and often both) the shaft or the bearing. You get to chose which one you want to wear the most and the part thaby criswilson10 - Mechanics
mcmastercarr.com has them by the foot/meterby criswilson10 - Mechanics
You can a flat plate (with a hole in the plate for the rod) on both sides of the bearing and secure the plates with through hole screws. I have also seen 50mm "fender washers" used with the interior hole drilled out to be large enough for the rod and the outer ring of the washers through hole bolted.by criswilson10 - Mechanics
The issue that jumps to my mind is timing. How are you going to keep both stepper motors in time with each other? And at a reasonable cost? And what about belt slippage, balanced tension in the belts, and slippage in the motors? I think you will find that this is one of those designs that looks good on paper, but is over complicated/expensive to implement, but it would be cool if you get it toby criswilson10 - Mechanics
Maybe IGUS's definition of "dirty environment" differs from mine, but I have always found their bushings to lock down with just a little bit of dust on the shaft. Their "compensation for misalignment" is to break apart in my experience. I do like to use them in final designs, but I never prototype with them because I find them to be fussy if everything isn't perfect. The genius solution for paraby criswilson10 - Mechanics
I'll second Viktor's comments about igus bushings. I like them, but for DIYers it is tough to keep the load balanced so that the bushing doesn't tear up. Linear bearings like the LM8UU seem to be easier for DIYers to use. Of course you still need to keep the load as balanced as possible. Either way, you do want the bushing or bearing to match the shaft size. If you have a metric shaft, use a meby criswilson10 - Mechanics
Technically, they find the point with the largest diameter, which happens to be the point with the greatest friction for that belt. Rarely is that in the middle. explains it pretty well and has pictures. V drive pulleys are the ones that track to the middle and are move common, these days, in belt drives.by criswilson10 - Mechanics
If you use the tooth side against the pulley, you usually have to have a bit more belt tension - or have a gear tooth crowned pulley. In a pinch, I've use a heated, bent paperclip to burn gear teeth into a crowned plastic pulley.by criswilson10 - Mechanics
Piezo linear motors are being used in cell, tissue, and DNA research; and as Viktor mentions, you pay a price for a feedback system. It is a great concept, but there are much cheaper alternatives.by criswilson10 - Tissue Engineering
Each of the designs has its pros and cons; and the design that is best, is the one that works for you. As for the mechanical parts, there are pros and cons to each of them as well. In any design you have to balance speed, accuracy, cost, and availability of parts. Linear bearings work better than bushings, but they also usually cost 10x more. Belts are faster than screws, but not as accurate. Thby criswilson10 - Mechanics
I use crowns when I'm prototyping because I can just eyeball the pulley alignments and loosen the lock screws to let the belt align the pulley. If the prototype moves on to production, then I use "regular" pulleys to save a penny or two. I haven't tried printing one yet, I usually just screw a regular wide pulley to a drill bit, spin the drill up, and drop a 120 degree file across the belt areaby criswilson10 - Mechanics
Leather belts were ususally run at low tension, low speed, were usually 10 or more feet long and had a lot of slop, so the crown was necessary. That being said, a high tension, high speed nylon belt needs a little bit more of a crown than a leather belt. I usually set the crown height at twice the thickness of the belt and the crown length to be 75% of the belt width. Note this gives you a pulleyby criswilson10 - Mechanics
Knife cutters were around long before laser cutters. They are pretty much a reprap body with a razor blade on the head instead of an extruder. And a solid way to hold the paper in place. Look for a DIY cricut machine at instructables.com. I'm pretty sure there are instructions on how to convert an inkjet printer to a cutter there.by criswilson10 - Mechanics
You can make a cheap mini gear puller using scrap metal, a tap and a screw. Instructables has a pretty good description of how to do it atby criswilson10 - Stepper Motors, Servo Motors, DC Motors
Looks like someone finally put up an instructable on how to make the cheap mini gear puller.by criswilson10 - Mechanics
I would expect a chisel to work on wood and plastic. It might work on brass. I doubt it will work on aluminum or steel. A cheap file and a hacksaw blade will definitely work on the harder materials. Old router bits, that you don't mind destroying, will also work.by criswilson10 - General
You can use the set up to decrease the diameter of a rod or make a complex shaped part, just like a metal lathe. It will damage the drill bearings, but I've reduced and chamfered over 100 shafts with a cheap drill set up like this and I haven't noticed the bearings going out yet. I wouldn't "lathe" with my drill press or some of my more expensive hand drills, but I'll do it with a cheap secondby criswilson10 - General
In the United States those are typically called a "drill mount" Just about every home improvement store carries them, usually with the hand drill accessories. Sometimes the mount is packaged with a grinding wheel attachment or a sanding attachment. Or you can make your own with a regular 2x4, a "C" clamp and some heavy zip ties (maybe even duct tape :-) ) Anything that will hold will the drill sby criswilson10 - General
Define large! :-) Length? Width? How many times do you need to use it? oil paint is going to clog up a lot of systems And how much money can you afford? There are already commercial solutions for printing billboard signs (50 feet by 20 feet), but they are expensive. There are plotters that can print 4 feet wide by how ever long you want.by criswilson10 - General
I'm partial to PICs, but I've been working with them for over a decade. The Arduino and its spin offs are easier to get started with and start programming though.by criswilson10 - Controllers
The reason to start with yeast is because it is cheap and relatively tolerant to abuse. If you can't get yeast to print, then there is no way you are going to get human/animal cells to print. From there most people will usually move up to egg whites to see if it clogs up anything and then up to strep to see if they can get attachments to occur. If all is good at that point, then move on to bloodby criswilson10 - Tissue Engineering
The diameter/cube thing can be a bit confusing. The NEMA naming convention for stepper motors grew out out of the naming convention for traditional round DC motors. NEMA kept the term diameter in the standards and added a footnote to handle the cubes. I mentioned it above under the examples of naming, but it is easy enough to overlook, so here it is again: For a round NEMA motor the diameter iby criswilson10 - Mechanics
Over the years I have received the occasional "bad batch" of plastics from various suppliers. Sometimes it has been too hard, sometimes too soft, sometimes it melted too low, and sometimes it melted too high. Good suppliers will replace the bad product for free.by criswilson10 - General
Without going into all of the chemistry junk, basically during the etching process the Iron(III) is reduced to Iron(II). The Iron (II) drops out of solution as rusty colored mud looking mud. The dissolved copper will settle out of solution in the form or blue, green, or possibly black solid salts. Your coffee filter looks like it is mostly full of Iron(II) with a little bit of copper salt in iby criswilson10 - Controllers
I think I understand what you are making now. A hollow mushroom shape? Look for an "end rounder" in a woodworking catalog. It's a jig you add to a grinding wheel or sanding wheel to make rounded dowel ends. I've seen them for broom handles (25mm) and shovel handles (35mm). Again, be aware of the dangers of polycarbonate fumes, it's not a bio-friendly plastic!by criswilson10 - General
Polycarbonate has a melt temperature around 265 degrees C and a glass transistion temperature around 150 C, so it could be done. I know you can order polycarbonate rods small enough to fit into the extruders. The main issue I'd see with doing it would be the fumes, polycarbonate gives off some nasty toxic fumes when melted. I'm also not sure that it would extrude out clear. However, you couldby criswilson10 - General
Very nice Bob! That could solve a whole lot of problems for a whole lot of people.by criswilson10 - General
I'm a Mechanical Engineer with a minor in BioEngineering. Work in IT at a university upkeeping computers and design/build equipment for cellular research. Close to 30 years of programming experience in core languages and used most others, 15 years of microcontroller experience - mostly with MicroChip PIC but I've used a bunch of different ones. Close to 30 years of cookbook electronics, I stillby criswilson10 - General