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Re: Additive manufacturing about to shake up portable electronics - 14 years ago

It sounds like they print all the layers (with powder and binder) first and then combine the layers. That makes sense for a factory, the time to print a part would be close to the time needed to print a single layer.

by SnailRacer - General

Re: Acceptance testing for individual components - 14 years ago

There's a test part in the mendel files. build-benchmark-v1-0

by SnailRacer - General

Re: forum error - 15 years ago

Yeah, I see it too... both in Firefox 3.0.10, and in IE 7

by SnailRacer - Administration, Announcements, Policy

Re: Lasers! - 15 years ago

If you want to use a focusing lens instead of a laser, just use a large Wattage light.

by SnailRacer - General

Re: Quick'n'dirty extruder - 15 years ago

You could stick mica washers between the heating resistors and the big washer and pipe end. That would help keep the heat in the tip.

by SnailRacer - General

Re: Cricut Automatic Paper Cutter - Hackable? - 16 years ago

Ron, It's my understanding that "Sure Cuts a Lot" flashes the firmware in a Cricut to implement its own custom commands. The original Cricut firmware has two fonts packaged with it, they aren't really on the cartridges in those cases... this means there is plenty of extra room in memory for a few new commands. The firmware is compiled into binary before it is flashed. None of the details of the

by SnailRacer - RepLab Working Group

Re: Alternate heat source? - 16 years ago

-> John T Schiffer Jr I'm sure the heat exchanger on an air conditioner might get hot enough to melt plastic, but it probably isn't viable for the RepRap.

by SnailRacer - Plastic Extruder Working Group

Re: Acrylic RepRap files on Ponoko - 16 years ago

In order to adapt the laser cut Ponoko design to be cut on a water-jet or a milling machine there are several changes to the SVG files that need to be made... 1) The thickness of the laser cuts are assumed to be near zero, so the parts must be repositioned so that the shared cuts where adjacent parts are near each other account for the thickness of the cutter. 2) Some parts are nested into hole

by SnailRacer - General

Re: Cricut Automatic Paper Cutter - Hackable? - 16 years ago

Emma, This forum is hosted by the RepRap project and doesn't condone software piracy. You should be able to use the original key to install your software, if that doesn't work call Cricut for support.

by SnailRacer - RepLab Working Group

Re: Why are there Nichrome wire ends sticking out of the extruder barrel? - 16 years ago

Aluminum oxide, aka Alumina, is the predominate ingredient of most of the high temperature adhesives (Cerastil, Resbond). If you can figure a way to oxidize a thick enough layer onto an aluminum barrel it might work. Make sure to use fuses if you experiment with this! Also, solder will not stick to nichrome, that's why you need to leave a bit out to crimp on to.

by SnailRacer - Mechanics

Re: metal-spinning with a lathe - 16 years ago

You can vacuum form plastic sheets. Spinning metal bowls on a lathe is more impressive though.

by SnailRacer - General

Re: Could one use PTFE tape... - 16 years ago

I think that has been tried already. The nichrome wire actually gets much hotter than the inner temperature, enough to burn PTFE. It's hot enough to burn JB weld. Fire cement, or a high temperature adhesive like those made by Aremco is needed to make it reliable. The design of the heater isn't optimal, because of thermal stresses the nichrome, and the barrel, push outward. Most high tempe

by SnailRacer - Plastic Extruder Working Group

Re: Instructable: Make potato plastic. - 16 years ago

I'm sure many pressure cookers are over designed, thus a well built one wouldn't fail at an increased pressure. Some are obviously poorly built, the only way to tell is to use them a few times and be prepared for the potential blast. I agree that there's always stories floating around, just do your best not to become the next anecdote.

by SnailRacer - Plastic Extruder Working Group

Re: Novice question about freeduino - 16 years ago

I think the Freeduino is compatible, the picture of the NKC kit has the USB showing. There's serial versions of Arduino around though.

by SnailRacer - Controllers

Re: Instructable: Make potato plastic. - 16 years ago

A relative of mine had a pressure cooker explode under normal use a long time ago (30+ years), there was a lot of damage and severe injury involved. Water can be superheated by heating it in a microwave, so there's no real reason to risk life and limb to cook a bit of starch. It's OK for the water to boil off anyways. The process is similar to corn starch Playdough, but has a good science expla

by SnailRacer - Plastic Extruder Working Group

Re: New Diagnol Tie for Reduced part count and build time - 16 years ago

They sell cable tensioners and swivels and you probably could get away with using an eye-bolt for tensioning without the tensioner but with all the crimps and stuff it's probably cheaper to just use a metal rod. They make very good poly-line now, a 1/8" (3 mm) line is rated over 2000 lbs (900 kg) and has very little stretch. A 1/2" rope of the same material is rated 34000 lbs (15000 kg). With

by SnailRacer - General

Re: Beginning a build - 16 years ago

I would consider filling some old socks with pea gravel and just slide that into the base pipes, you could take it out when you need to, and no one would see it once the end caps are on.

by SnailRacer - Reprappers

Re: Cartbot with all three axes controlling the toolhead - why not? - 16 years ago

The overhead cartesian design is very scalable in size. The US navy uses a multi-ton overhead gantry CNC plasma cutter to make ships. It rolls on wheels, and the weight makes it stable, and despite it's massive size it is driven down its tracks by a threaded rod.

by SnailRacer - Mechanics

Re: Water Jet Cutting - 16 years ago

Yeah, MDF wouldn't be a good choice for material. I suspect the belt gear portions wouldn't hold up in MDF anyway. Some sort of engineered hardwood would be better, or aluminum I'm probably not going to follow this path for a RepStrap, it's quite a bit more money than a McWire, or Tommelise type frame, but it would be doable in an apartment, without excessive tools.

by SnailRacer - RepLab Working Group

Re: Water Jet Cutting - 16 years ago

Indeed! If your friend has access to some free waterjet time you could cut the corner brackets out of something strong like aluminum at least. According to Carl there is 0.030" lost to the cut width, and smaller parts probably should be attached with small tabs to keep them from falling into the catch tank if there isn't a waterjet stone to be used. He also says that wood cuts 10x faster than s

by SnailRacer - RepLab Working Group

Re: Water Jet Cutting - 16 years ago

Steel might survive the baggage handling gorillas. Although aluminum is probably more practical due to weight concerns. This would be for a RepStrap, the more options people have to get started the better. The idea is good because it follows the Darwin design, so parts might be interchangeable with Darwin once the kinks are worked out.

by SnailRacer - RepLab Working Group

Re: Water Jet Cutting - 16 years ago

I wonder if a set of 1/4" steel waterjet RepStrap parts would be much different in price than the plywood ones from Ponoko.

by SnailRacer - RepLab Working Group

Re: The extruder motor and changes needed in extruder robustness - 16 years ago

Yes, bubbles in the plastic will cause the extrusion to be inconsistent. That is the reasoning behind the variable pitched extruder screw, it should squeeze out the air. It's simpler, just one melting pot, and a vacuum pump. Under a vacuum it should be possible to heat the plastic a bit hotter without it burning, then "agitate" the melting pot to get the bubbles to rise. When it is ready to ex

by SnailRacer - Mechanics

Re: The extruder motor and changes needed in extruder robustness - 16 years ago

Liquid plastics are more like bubble gum covered in glue than like water. There are issues with getting the air out of melted plastic, it must be forced out, gravity will not remove the bubbles. It's possible that forcing the plastic through a nozzle might remove some of the larger bubbles, but the small ones will remain. I would think that a single airtight melting container might be able to re

by SnailRacer - Mechanics

Re: A snap-together RepRap? Faster, easier, and RP friendly? - 16 years ago

I think that you probably could print plastic blind rivets. Like these... This would have the benefit of being able to buy them, and still be one less non-printable part. They do come apart, though they're a bit harder to get apart than they are to put in.

by SnailRacer - Mechanics

Re: Membrane-less water filter - 16 years ago

This is a straightforward idea, the real complications in the design comes from requiring multiple pumps, otherwise there's no water pressure in the output. It also is a good example of something difficult to make with subtractive machining.

by SnailRacer - Let's design something! (I've got an idea ...)

Re: Alternatives to "FDM"? - 16 years ago

Replicating Extruded Prototyping, Rapid Additive Plastic?

by SnailRacer - General

Re: conductive polymorph powder? - 16 years ago

Laser toner is a mixture of plastic and dye, the black dye might have some carbon in it, but I think they use black iron oxides. Most importantly it probably has a high electrical resistance because of the plastic.

by SnailRacer - Plastic Extruder Working Group

Re: what all on REP RAP - 16 years ago

The details of the Arduino based electronics is at

by SnailRacer - Plastic Extruder Working Group

Re: Good examples? - 16 years ago

A RepRap key fob...

by SnailRacer - Let's design something! (I've got an idea ...)