Securing a plastic filament extruder hot end with wire

Posted by admin on July 2, 2011 None comments

I have built a lot of extruders. One solution that is often missing is how to connect a hot end to a filament drive. They are usually created by separate people and the builder needs to decide which ones they want and how to make them work with each other. I found a solution that ends up working with most combinations, and it has some peripheral benefits. I use common picture hanging wire.

  1. It’s easy.
  2. It’s cheap.
  3. It doesn’t need custom plates or outriggers, use what’s available.
  4. It dissipates heat well, better than bolts.
  5. It doesn’t require threading or tapping anything.
  6. It doesn’t rely on any PTFE or PEEK threads for support.

PHP function to output flot data from a SQL query

Posted by admin on July 1, 2011 None comments

In the hopes that other find this useful, here’s a concise function that assumes the first field is foor the date and names date, the rest are multiple series in a chart. Edit to suit.

function sql2Flot($sql){
$result  = mysql_query($sql);
//Data for FLOT =  [ {data:[[x,y]],label:”str”} ]
//row loop
$arrData = array();
$y=0;
while ($row = mysql_fetch_assoc($result)){
//field loop
$x=0;
foreach($row as $name=>$value){
//create the different series. assumes the first col is x, the rest are diff y series
$intDate = date(‘U’,strtotime($row['date']))*1000;
if($y==0 & $x>0){array_push($arrData,array(“label”=>$name,”data”=>array()));}
if($x>0){array_push($arrData[$x-1]['data'], array($intDate,$value));}
$x++;
}
$y++;
}
return json_encode($arrData);
}

reprap pascal half frame

Posted by admin on June 5, 2011 None comments

These pictures introduce the concept.

Big, Bulky, sturdy plastic pieces to reduce the amount of non plastic pieces needed, make the whole thing more stable, and easier to assemble.

These pieces use an excess of plastic to ensure that

  1. distances between bars are consistent
  2. there’s a lot of surface contact for stability
  3. support blocks are in place to prevent parts from snapping easily
  4. supports for printing angles are built in.

using the pictures as reference imagine

  1. The threaded rob on the bearing extending all the way to the top, with another bearing at the top, this will keep the z thread rod straight.
  2. The threaded rod on the bearing connecting to the z motor (similar to Prusa position) with an equal size gear on each. This removes coupling problems on Prusa.
  3. All of the rods much longer.
  4. a z smooth rod on the corner between the bearing threaded rod and support threaded rod.
  5. The 45 degree diagonal bar is only on the back side. The front will not use a diagonal rod  but will have the spot for t where other things will be mounted.
  6. 3 cross bars will join this half to the other half.
  7. You can see the Y smooth rod in place. I’ve already found that it’s too close to the midsection piece to have most type of bearings slide on it. I will have to move it further in to allow for more bearing options.

feedback is appreciated, this is obviously early stages. No need to make fun of my print quality, some of those issues are what I’m aiming to fix in this new design, a couple of them are funny gcode quirks. Then there’s a few that have been better ni the past but I am in a constant battle for reliability/durability/consistency in what I print, I’ve been told it’s probably because I’m always messing with it. :)

Small and great robotics controller

Posted by admin on May 18, 2011 None comments

When I started on my next robotics learning experience I automatically assumed Arduino was the bets and easiest way to go. The Arduino is the largest board in the pictures. The Arduino was indeed easy to program. Their IDE and language is simple. You can plug a USB cable straight into it and go. However, when I went to connect a dual DC motor driver to it (The smallest board in the pictures) I surprised at how many pins had to be devoted to it. It was a big mess and that was only half of what had to be hooked up. My other immediate concern was that there is a size constraint for the sumobot im building. the Arduino was quite bulky and difficult to design a 10cm by 10cm constraint. So I looked at some alternatives.

The alternative is in this pic as the one with wires attached. This board is known as the Baby Orangutan and can be found at Pololu.com This little board is the equivalent of the other 2 combined without compromise. It actually gives you more IO pins because the dual motor driver integration is more efficient. The funny looking solder strips next to it are my power rails, getting regulated 5v power through the board. This is good for all of the low current sensors that need to be integrated. I love how compact the solution ended up being compared to my arduino solution.
This picture shows how the strip board lines up my power rails next to the pins so that I have a nice clean way to plug everything in.

The one downside of the controller is that you cannot plug a USB cable straight into it. You have to get a special cable to program it with. This cable can be used with all ATMEGA chips without being formatted for Arduino. If you decide not to put the Arduino software on it you need to use something like AVRStudio to program it. In the end I think the extra little learning curve for the AVR IDE + the separate programmer were minor detractors compared to the benefits if they were the same price. As it stands though the Arduino + motor driver is about $50, the Baby Orangutan + programmer = $40.

Arduino + Reflectance Sensor

Posted by admin on April 3, 2011 None comments

This is a specific example of connecting a reflectance sensor from pololu:
http://www.pololu.com/catalog/product/958
to an Arduino Uno.

I’m using this for a sumobot line sensor.

1st get the library from pololu:
http://www.pololu.com/docs/0J20

Put the individual library folders in your Libraries subdirectory for Arduino.

next, connect wires as follows:
+5v -> vin
gnd -> gnd
A5 -> out

then, open op the arduino app, connect to your board and upload this code, this code is for 2 sensors, it will work fine for 1:
#include

PololuQTRSensorsRC qtr((unsigned char[]) {18,19}, 2, 2000, 255); //declares two line sensors on pins 18 and 19 this corresponds to analog pins 4 and 5

unsigned int sensors[2]; //creates thew variable
//setup is required.
void setup() {
// initialize serial communication:
Serial.begin(9600);
}

//THE MAIN PROGRAM LOOP
void loop(){
qtr.read(sensors);
delay(20);
//sends the info to serial so you can view it in the serial monitor.
Serial.print(sensors[0]);
Serial.print(" ");
Serial.println(sensors[1]);
}

upload the code to the board.

In the Arduino app goto tools->Serial Monitor. Here you should be able to see the results of the reflectance sensor.

Now in order to code it for a White line you have to determine what value you want it to react to, so give it some tests.

oince you set your linethreshold variable you can start doing comparisons like this:

if (sensors[0] > linethreshold){ stuff to do }

Pay it forward replication

Posted by admin on April 1, 2011 None comments

Still loving the 3d printing experience, even though I seem to be an expert in all of the possible issues by now. I was never really interested in printing reprap parts for profit, especially once they dropped below $200. It seemed like such a waste when I added up the hours spent on it. However, I believe in RepRap as a project. I truly believe in the ideals and methods that it continues with as kits and businesses start spinning off. I love the idea of a printed part printer, printing it’s own spares, repairs, and upgrades. The best way to advance this is to use your own parts. When you use your own parts it’s easier to see the flaws and possible improvements, create them, test them and share.

I’m proud to say I’ve reached a new milestone in my 3D printing experience, this is my 1st complete set of parts printed on my new printer (First set was printed on my McWire, and a couple of the larger parts were supplemented by the Local hackerspace).

Instead of creating a set of parts to sell I found someone who wanted to build a printer and offered to give him a set of printed parts for the cost of shipping + the promise of printing another set of parts. I’m hoping to pass those parts on to another person and continue a chain of adding people to the community at a low entry price. Here’s to hoping that my time was well invested and the recipient is able to complete his printer and print a new set.

Prusa Mendel Printed Parts

printing on kapton vs painters tape

Posted by admin on March 25, 2011 None comments

I tried several prints, and print settings with stripes of kapton and stripes of painters tape on the same build surface and same print. The result was that it always had a much higher chance of sticking to the kapton than the painters tape. One side effect is that surface printed on the Kapton came out shiny and smooth. When taking the print off of the bed it also had less of a chance of ripping up the tape.

Arcol.hu v3 hot end for 3d printing review.

Posted by admin on March 14, 2011 None comments

I have been working with open source 3d Printing as a hobby for a while now. I built a McWire printer from mostly hardware parts, and printed my Mendel with it. I have worked with a lot of people in the process, and helped them work on their 3d printers as well. There is one critical part of the whole thing that often fails for people which is known as the “Hot End”. The hot end is the portion of the printer that melts plastic at a precise temperature and allows it to flow through a tiny aperture under pressure. I have tried every design and variation I could get a hold of:

the standard old threaded insulator with an M6 bolt that is heated: using Peek, PTFE, and hybrid insulators, M6 bolt/nozzle, M6 bolt + separate big head nozzle, direct nichrome wire, threaded bushing with nichrome wire. Every combination between them.

These all had the same problems:

  1. Filament would get too hot too far up melt and jam.
  2. Pressure would blow the M6 brass bolt out of the insulator barrel
  3. separate parts would often leak
  4. heat traveled up to the printed filament drive block and started melting parts.

I also tried several experimental designs including ones with 1.75 filament… they all share the same principals:

  1. you want to keep the filament cool and rigid as far down as you can.
  2. You want to heat as little as necessary just before it exits the nozzle
  3. You don’t want any friction impeding the filament getting to the nozzle
  4. YOU CANNOT RELY ON THREADED PEEK OR PTFE FOR STRUCTURAL INTEGRITY WHILE HEATED
  5. nichrome wire is tricky to apply, and burns out

I have found 2 designs that meet my criteria

http://reprap.org/wiki/Arcol.hu_Hot-End_Version_3.0

http://reprap.org/wiki/Geared_extruder_nozzle

I think the Adrians ones are reliable, good designs that you can improve upon as you see fit.
The Arcol.hu one is an “Over engineered” thing of beauty.

I am now running the arcol.hu hot constantly. I do have a slow leak which I expect I can fix with PTFE tape, but besides that the thing is simply performing extremely well. It keeps cool where it should, it gets hot where it should and quickly. It pays a lot of attention to supports. There is a PTFE tube going down the middle to minimize friction. The kit is WAY more complete than anything I have ordered for my 3D printer from anywhere. Cables, shrink wrap, extra insulation, fire cement, all things I would have expected to need to have on hand were in there. One of the things that impressed me the most about this design is how much care was paid to the wiring. I haven’t seen that in any other design. It’s usually left up to discretion, but this one has a nicely engineered solution built in.

I was concerned that the heater block was tilting downwards. There happens to be an M3 tapped hole in the heater block that lines up perfectly with a hole in the lower support wafer, so that was easily handled by using its existing design.

The print quality that this produces as at least as good as anything else I’ve seen of similar technology, including UP printers. It’s smooth and consistent.

I would recommend this component to ANYONE building a 3d printer, but I would especially urge anyone who’s sick of dealing with extruder troubles to sign up for the next batch to be created.

Alternate Filament Drive Shaft for RepRap 3d Printer

Posted by admin on March 13, 2011 1 comments

When creating a bolt for http://reprap.org/wiki/Wade’s_Geared_Extruder I came up with this alternate. Usually, you en up buying way more M8 bolts then you are using since there is only one in the Mendel designs. So you will have a few to play with. Many of the Wades extrudres I’ve worked on have had issues with the standard way of hobbing the bolt. The teeth are shallow, get clogged easily and then don;t grip the plastic as well anymore.

My alternative is to cut the teeth into it with a rotary tool. I put a heavy duty cutoff disk on my Dremel and cut the teeth as close as I could, leaving sharp edges from the cut. I don’t recommend filing a groove into the bolt first like some of the tutorials show.

I have over 100 hours printing with this bolt setup successfully whereas I had been through many of the standard hobbed bolts and really tried to make them work well.

Filament Drive Shaft for RepRap Mendel 3D printer

Flot + Pie updates: donut, border labels, hover in IE

Posted by admin on July 31, 2009 4 comments

I have been using javascript libraries for charting lately. I find it works well wil ajax / jQuery pages very well instead of flash because they share variables and functions.The best Open Source one I could find was Flot: http://code.google.com/p/flot/ The most obvious thing missing from it is a Pie chart which was added and updated in the forums of the project. The forums can be confusing, the files have been branched changed etc so many times and the thread style of the subject makes it very difficult. so here are the latest files I could gather that include pie, and my updates.

http://anthong.com/examples/flot.pie.zip

Updates include:

Border Layout for labels: The labels are optionally on the outside of the cart square with lines pointing to the respective slice.

Donut Hole: Optionally set an inner radius for a hollow center.

Hover in IE: IE support for flot requires excanvas: http://excanvas.sourceforge.net/ but excanvas does not support a function that makes the hover easy (isPointInPath) so I added a workaround.

I hope this helps, I may make a full project page out of ALL of the flot updates + examples.

enjoy,

Anthony

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