It is definitely overconstrained. One reason that the walls that the sarrus arms are connnected to are so thin is to allow them to flex slightly and make up for that. The parallelogram parts of one of the sarrus elbows will try to put a torsional twist on the other elbow. The way that it looks to me, the small hinges that I am using are not strong or stiff enough to work without using a lot ofby fdavies - Look what I made!
I have made a prototype of a linear axis that uses an RC servo. I think that servos may have the following advantages: 1. Very light. 2. Servos include all necessary drive electronics. This means that you can drive them directly from a variety of commercially available boards. I have used an Arduino. 3. Servos are available in a range of prices, strengths, and robustnesses. I am goiby fdavies - Mechanics
Here is my page about a promising linear axis that uses an RC servo. fdaviesby fdavies - Look what I made!
Thanks, Wade. That did the trick. Here is a link to the new page: fdaviesby fdavies - Look what I made!
I did some experimentation with induction heating a while back. When you heat with a resistor, heat must flow from the resistor (where it is created) to the extruder head which means that the resistor must be hotter. Since induction heating creates heat in the extruder head, I had a vision of a cool copper coil heating an extruder head by induction through insulation (as jbb remarked). I didby fdavies - Plastic Extruder Working Group
Sebastien, if I give you a picture will you give me a wiki stub? I have a lot to put on it. I am sorry if I am missing something: I can edit the previous page you gave me, but I can not see how to make a new page. fdaviesby fdavies - Look what I made!
Gene Hacker: My 10-32 rod (not shown, since it is serving in the prototype of the next revision) is not perfect. Its connection to the bearing is not perfect; The nuts that hold it on the bearing put the rod at a slight angle to the axis of the bearing. That makes the rod exert sideways forces on the nut in the flexure. It tries to wiggle the nut sideways. This is only opposed by the stiffnby fdavies - Look what I made!
Well, I have done a page for the Z01. It was not as hard as I thought. I have some other ideas for pages, too, (like a description of my repstrap) but am not ready to ask for stubs for them yet. Do we ask you for new pages? My life is too complicated right now to try for the Gada prize. If my Sarrus work ends up in the winner, I would be extremely pleased. The reason I posted this is becausby fdavies - Look what I made!
Here is a picture of something interesting that I have designed. It is an attempt at a mostly printable Z axis. I have stl and aoi files to go with it, as well as ruminations on how to improve it. Now, how do I put it all on the wiki? fdaviesby fdavies - Look what I made!
You know, I believe that the earliest CNC machines used paper tape to store commands and patterns. I bet they did not have much computational brains, either. fdaviesby fdavies - Plastic Extruder Working Group
Drake, check your private messages. Fdaviesby fdavies - Texas, Houston RepRap User Group
I live in the Houston area (Clearlake) and I have successfully built a repstrap. I am a member of txrxlabs, the Houston hackerspace (http://www.houstonhackerspace.com). I go to the Friday evening meeting most weeks. They have a Makerbot Cupcake. I know that some of the other members have been thinking about making a reprap, so you might be able to find someone interested in working with you.by fdavies - Texas, Houston RepRap User Group
I have had good luck making complicated things with AOI if you use version 2.7 (not later versions) and you simplify the mesh with the solid editor plugin after every two or three boolean operations. Before I learned to do that, it was very frustrating. Fdaviesby fdavies - Reprappers
It is double sided. If I were you, I would wire up the circuit on perf board (board with square grid of holes). I have done that using an arduino type chip and the same driver chip. Wiring it up on perf board would take less time than making a single PCB. If you have to make several, then the balance changes. Thanks, Frank Daviesby fdavies - Controllers
I applaud your ambition. As far as threading rods goes, are you using lubricant (cutting fluid)? The bigger taps have an adjustment, too. Don't get discouraged, the thrill of seeing and holding your first printed object is worth it. Good Luck Frank Daviesby fdavies - Reprappers
Pinchwheel extruders do not twist the filament (unlike the original screw thread drive) and you can use a spool mounted on an axle. Frank Davies 281 483 9033by fdavies - General
I don't know what the answer is, but it is more complicated than cooling time. If you make something small, and set along cooling time, it will do something like orbit, but it will also do it with larger prints. There may be two things going on. You can turn off 'orbiting' on large things by turning off the comb function. I think that it may have something to do with wiping the tip. Frank Daby fdavies - Plastic Extruder Working Group
You know the first CNC machines used data stored on paper tape. This is the obvious storage technology for an all mechanical 3D printer. Frank Daviesby fdavies - Plastic Extruder Working Group
Well I don't have a very good measurement tool, but if I run my extruder into air, coiling itself down onto a surface about 25 mm lower than the tip, thefilament is about 0.68 mm (+/- 10%) wide. The hole that it comes through was drilled with a size "75S" PCB drill into an acorn nut. Wikipedia shows that this has a diameter of 0.533 mm. Of course the hole will be slightly bigger. I bought a bby fdavies - Mechanics
With my extruder it depends on how close the head is to the layer it is printing on as well as how fast the head is moving. Frank Daviesby fdavies - Mechanics
You might be able to get away with some sort of optical gate. This would be an opto interrupter that the tip of the toolhead moved through. It could figure out the position of the part (or even if it was there at all) by the timing of when the light was blocked. This would take considerably less programming complexity than a camera would. Frank Daviesby fdavies - Pick-and-Place Electronic Assembly (and robots!)
My repstrap uses a ball bearing slide from a small home-office type photocopier (the kind that moves a glass platen with the original on it). The slide looks very much like some kinds of drawer slides. It gives good results except for a subtle feature. It has a metal and plastic "ball cage" that holds the ball bearings in place. This moves back and forth about half the distance that the plateby fdavies - Mechanics
I am in the Clearlake area and I have a working repstrap made from printer and copier parts (see attached picture). It needs some adjustments, and I have certainly run into the warping problem that others have. I would be interested in attending a meeting and talking about the various problems that I encountered while building it. I have a lot of stepper motors and other electromechanical partby fdavies - Texas, Houston RepRap User Group
I know that this is not exactly what you are talking about, but you can color the ABS plastic quite nicely by coloring the 3mm filament with a permanent marker before it goes into the extruder. It takes a while for the color to start up, and longer for it to fade away. I suppose that this is the colored ABS in the extruder chamber being slowly diluted with new, uncolored plastic. My 11 year olby fdavies - General
I have been able to use the arduino software quite well on my XO (OLPC) laptop. I used it to program an arduino with the GCode_Interpreter v1.3 as part of putting together my repstrap as well as for other arduino projects. I figured that I could put together a little python program on the XO to take gcode files and feed them to the arduino by using the "ok" reply as flow control. I did this, bby fdavies - RepRap Host
I got two OLPCs a while ago as part of G1G1, but the kids were not very interested in them. I use one to take serial data from a USB drive and send it to my repstrap. At first I did it with a simple python program (run from the linux command line), but there were random delays that caused very frustrating blobbing. I cured this by adding some lines to the arduino code for the repstrap to impleby fdavies - RepRap Host
I tried marking the surface of the 3mm ABD filament that I am extruding with a sharpie marker and I noticed that the plastic extruded from that was tinted. It wasn't much, but there might be a bigger effect with other inks. Frank Daviesby fdavies - Plastic Extruder Working Group
The first limit on how hot it can get is the insulation on the magnet wire. Mine begins to smoke after a while. Given wire with high temperature insulation, eventually either the copper might melt or the steel would change its magnetic properties when it heats to above its Curie temperature. Of course, in practice the hotter it gets, the faster heat flows away from it by conduction, convectionby fdavies - Controllers
Inspired by the thread (http://forums.reprap.org/read.php?70,8467) in which Triffid_hunter suggested using induction heating in the extruder, as well as an incident involving the use of a steel washer in place of a ferrite core, I have built a prototype induction heater. I briefly experimented with using a single MOSFET switch to keep the circuit as simple as possible. However, the inductive paby fdavies - Controllers