Replibot Prime

Drag and Drop Slic3ring

2012-01-22T05:58:00.000-06:00

I am excited to see that Slic3r 0.6.0 is out!

Some new features of this new revision are:

Thin walls
New output file name format
Option to create output file names using configuration option values
Automatic retraction at the end of the print

The new naming option inspired me to write a batch file for drag & drop Slic3ring. It ended up to be pretty simple. Here's the setup I have at the moment.

On my desktop I have 3 batch files for 3 different print qualities:

draftSlic3r.bat

goodSlic3r.bat

bestSlicer.bat

Each batch file uses its own configuration file and has a customized output file format See the Slic3r readme for details.

Heres the contents of draftSlic3r.bat:

echo on
cd %~p0
C:\slic3r\slic3r.exe --load "C:\Documents and Settings\bjbsquared\My Documents\My Dropbox\slic3r_mosaic_draft.ini" %1
pause

When an STL file is drug and dropped on one of these, the batch file will launch Slic3r, load the configuration file and slice the STL. Theres not much feedback with Slic3r working in this mode. There is no GUI and you only know Slic3r is done when the command window says "Press any key to continue..." . I don't know if there is any warning if Slic3r had problems because I haven't had any yet.

Start and End Alterations

2011-12-26T10:21:00.000-06:00

So now that I have all the minimum end-stops installed and working, I am able to do more automation and get closer to a "plug and play" print experience. I did this by changing some Skeinforge settings and adding code to the start.gmc and end.gmc files.
Skeinforge Adjustments:
I wanted to print in the middle of the bed so I activated Multiply and enter the bed's center coordinates.

If the names of the alteration files should be different than the default they can be change under the Skeinforge Preface tab.

Alteration Files
If you are using pronterface/sfact they should be here: ...\Pronterface\sfact_profiles\alterations\. If you are using only skeinforge they are here: ...\Pronterface\skeinforge\skeinforge_application\alterations\. My goal on writing these little snippets of g-code was to automate the things I have to do every time I print.

Right now I am using PLA and it tends to ooze out of the hot end between prints. So, before each print I want to prime the extruder. It seems to work best if it is primed in two steps with some delay in between. The extruder works on an absolute filament distance so, unless you know the current absolute distance, it needs to be reset in-order to move it a relative amount.

start.gmc
G92 E0 ;reset extruder position distance =0
G1 E10 ;Prime extruder
G28 ;Go Home ( woot! +1 for end-stops!)
G1 E20 ;Prime extruder 10mm more (10+10=20)

I am still tweaking this and it seems as it is never perfect but I enjoy the automation as it is still better than nothing.

Most of the things I print now are 1 each so at the end of each print I want the following:

Retract the extruder by 20mm to prevent ooze
Maneuver the platform to a place where the part can be taken off
Disable stepper so I can move axis by hand and also saves power
Turn off bed heater
Turn off extruder heater
Turn On Cooling Fan (set skein forge "Cooling" not to turn it off at end)

end.gmc

G92 E0 ; reset Extruder counter
G1 E-20 F900 ;Retract extuder 20mm at 900mm/min
G28 X0 Y0 ;Go Home but keep Z height
G92 X0 Y0 Z0 E0 ;reset all locations and extruder
G1 Y80 F3000.0 ; Move platform so part can be removed
M84 ;disable steppers so they dont get hot during idling
M140 S0 ;turn off bed heater
M104 S0 ;turn off extruder heater
M106 S255 ; Turn on cooling fan

To make sure the code is going to be used, the g-code can be examined in a text editor. After skeining, the g-code is in the same directory as the yourPart.stl file. There are two versions. The yourPart_penultimate.gcode version is the one with the comments and is easier to read . The Alteration code should be included and wrapped in <alteration> tags. Such as:

(<alteration>)
G92 E0 ;reset extruder position
G1 E10 ;Prime extruder
G28 ;Go Home
G1 E20 ;Prime extruder
(</alteration>)

The start.gmc and end.gmc should be at the start end of the file as expected. If not make sure the files are in the proper directory(SFACT uses same directory names) and the files are named properly.

Mosaic End Stops for X and Y Axis

2011-12-19T16:25:00.000-06:00

On my old McWire printer it was some what of a ritual to do prints. Assuming the hot end was warmed up, the task of moving, cleaning and priming the nozzle, putting the extuder to the middle of the build plate and then locating the perfect height off the print bed. Afterwards, I mentally went through the checklist again to make sure I didn't miss a step.

minX End-Stop

My Mosaic came as a kit and was easy to build but I was basically going through the same ritual of cleaning priming and positioning with this as well. The only thing I didn't have to do is set the Z height because it had a minZ end-stop. But just that one end-stop made a huge difference in the pre-print routine. It took some fiddling to get the bed height just right using the end-stop but once it was working I felt like things were much easier.

This end-stop inspired me to put on the minX and minY end-stop . The switches for them were in the kit but there was no way to mount them so I went browsing on Thingiverse. I grabbed these Mosaic end-stops and printed both parts out. The minX was a friction fit that straddled the wall and held the switch. The only was to fine tune the switch was to move the braket. It took a few tries but I eventually I got it where I wanted.

Old Version of minY End-Stop

The minY end-stop would not work. The high part of the bracket was hitting the leveling plate of the heated build platform. I figured if I could move the part of the bracket that held the switch it would work. So I fired up SCAD and did some modifications. I actually made two versions. A plain one and one to hold an LED if I wanted one in the future.
When I first tested them out I had gotten the minX and minY connectors mixed up and had to cut power to the motors because they wanted to keep driving past the ends of the axis. What I should have done, and eventually did, was to hold the switch down and see if the movement worked in the direction of that end-stop using short movements. When it would not go I knew that it was doing it's job.

New minY End-Stop Design

Configuring end-stop can get confusing because there is more than one way to set them up. Here is my printers current setup:

Firmware:

//// ENDSTOP SETTINGS:
// Sets direction of endstops when homing; 1=MAX, -1=MIN
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

#define ENDSTOPPULLUPS // Comment this out (using // at the start of the line) to disable the endstop pullup resistors
// The pullups are needed if you directly connect a mechanical endswitch between the signal and ground pins.
const bool ENDSTOPS_INVERTING = true; //set to true to invert the logic of the endstops

const bool min_software_endstops = false; //If true, axis won't move to coordinates less than zero.
const bool max_software_endstops = true; //If true, axis won't move to coordinates greater than the defined lengths below.
const int X_MAX_LENGTH = 135;
const int Y_MAX_LENGTH = 135;
const int Z_MAX_LENGTH = 135;

As can be seen in the code the end-stop are setup as inverting. That means they are active low. The signal is pulled up by RAMPS and when the end-stop is triggered, the switch pulls the signal down to ground. This means the only lines that need to be routed to the switch are the end-stop signal and ground. However I decided to +5V to the switch as well encase I wanted to turn on an LED when the end-stop activates. For now though the S and - are the only ones hooked up.

Wrong Turns I Made Bringing My Printer Online

2011-12-14T14:10:00.000-06:00

I'm back. And now I'm a proud new owner of a Mosaic printer from Makergear.com but had some challenges setting things up.

First I want to thank the experts on #makergearv2 and #reprap IRC for all the support they give. I know that I learn a bunch just being in stealth mode and watching printer problems being solved.

So, I hope this is of help to beginners like me. I want to point out what went wrong and also what really worked well for me so far. So FWIW I have a new Mosaic and printing with 1.75mm, red PLA on blue 3M
tape.

I used the guide at Makergear Google groups to get the initial software chain on my old Dell laptop.

Here are some things that I had questions about while using the guide:

“At the time of writing, this is the current accepted standard and works
well with Makergear Prusa printers.”
Mosaics are not mentioned but yes, it works with Mosaics too.

“Python 2.x: http://python.org/download”
I think this is just an isolated issue for my machine. I had problems running Pronterface with python. The version I downloaded was 2.7.2. I’m not sure if it is my computer that already had python 2.6.5 screwing things up but it only works with the context menu “open with” for me. Someday I will wipe python and start over but for now it is working and if it is not broken I’m not fixing it... yet. It’s probably a Windows XP issue.

“Download latest Arduino IDE + Firmware http://www.arduino.cc/en/Main/software
Firmware: (Optional) http://groups.google.com/group/makergear (select Sprinter for Prusa or Mosaic respectively)”
I could not get spinter to verify with Arduino. Grrr.
I downloaded Arduino 1.0 but later found out that sprinter had this in it’s readme:
“Get the arduino software version 0018 (0023 works for RAMPS), uncompress it in a directory. Arduino software v1 DOES NOT work with Sprinter yet!”
I tried 022 that I already had installed and it worked as well.

I knew about MakerGear Google Groups SF43 Setting for Mosaic but in all the software installation/trouble shooting chaos, I forgot to install it. I thought I did but It’s not in the guide so I did not realize i missed it. It actually ended up in my “down loads” folder and I never moved it to “MakerGear_Source_Files” directory. Ugh!

First Print:
Everything worked under manual control X,Y,Z but when I went to print, the extruder headed for (infinity,infinity,0) and slamed the x and y stops faster than I could react. Then It tried to print on top of the binder clip in the +x,+y corner of the platform. I think I screamed like Homer Simpson. I was smart enough to power the two power supplied with there own power strip when I realized it was actually printing the box I told it to. So that caught my attention and my finger left the power button. I let it finish. It was a cube. It was sloppy, ugly and beautiful all at the same time. At the time I did not know about multiply and the default size set in SF was much bigger than Mosics build area. I got on the IRC and they set me straight.

Things that worked great during this whole experience:

Building the Mosaic was easy. I did it in my spare time over a week. Some times I would get the order of attaching things wrong but nothing was unrecoverable. I just had to take things apart and try again. Some how I made the hard things easy and the easy things hard but that’s just me. All in all it was a great kit to build.

PLA on Blue tape - It actually worked when I had the extruder too high. It printed bad for a few layers and then was ok. It still stuck even though the initial height was off by about a layer. Went back to the IRC and found out the “Bottom” plugin was likely to be on and messing with my starting height. I turned it of and now things are good.

IRC channel - Sometimes I can’t sleep I wake up between 2 and 4am. There was always someone on either #makergearv2 or #reprap that could point me in the right direction what I was looking for. The bot kthx rocks but has an attitude. (Don’t mention Siri, It’s a sore point I think.)

Stealth Mode Off

2011-07-16T17:29:00.002-05:00

Ok, Replibot is back online. It has been over a year since the last post. Work and moving into a new fixer upper has taken all my time but I’m starting to get back to some normalcy.

I had a question from a friend that I’ve been wanting to get to and today I had some time :

“I've watched several clips about these printers and still don't understand how they measure and then 'print' allowing space for an object (axle/shaft/etc.) to turn in or a key way in which something can move back and forth in etc. If you can explain I would really appreciate.”

So I have to say that I am clearing out a few cobwebs that developed over the last year so I hope others will speak up where correction is needed.

When I have an idea for a design the first thing I do is to capture it using pencil and paper. Actually I use a black ink pen and a blank piece of paper. Sometimes it’s graph paper but I really don’t like following lines until I need to.

Then I get the idea into the computer. What tool I use depends on what I am trying to achieve and my mood at the time. My favorites are Google Sketchup (http://sketchup.google.com/) and Open Scad (http://www.openscad.org/). There are others I use but these take care of 90% of what I need. Both are FreeWare.

The design then needs to be exported so it can be processed by another program. The most preferred format is the *.STL. I think STL stands for Stereo Lithography and that’s all I know about it.

At this point the design is still not at the point where you can click print. The STL need to be processed by a G-Code generator. The only one I have ever used is Skeinforge.

Skeinforge is an remarkable piece of software. It is python scripting that knows everything about the printer and the material you are using. It knows how far the print head travels for each step of the motor, how big the nozzle is, speed, width ,temperature - (and the list goes on). It knows because you or someone else told it by filling in a BUNCH of attributes about your printer and the material being melted to build the printed part.

For 3D printers, it’s using this information to slice the design into layers. Each layer is the vertical resolution of the 3D printer. You can think of each layer as a separate drawing that is stacked one on top the other like a stack of cards. One card by itself is really almost 2D but a deck of cards has a definite 3rd dimension. Vertical holes are made by not extruding material in the area where the holes exist. That area is avoided by the printhead for each of the layers penetrated by that hole. The same reasoning applies to horizontal holes but is a bit trickier because of gravity. I have clean horizontal holes out with a drill bit because of deformity due to gravity. So holes that are critical should be placed vertically if possible by aligning the part that way. Also overhangs can only be made at a certain slope. Skeinforge takes care of a lot of stuff to help with this.

It’s not only 3D printers that Skeinforge is good for. Any tool where the path is robotically controlled could use Skeinforge to generate G-Code for the design.

Another tool I use is Pleasant3D which is a STL and G-Code view for Mac. You can orient and locate STL files and see the tool path of G-code files. Pretty colors are the G-Code and grey is the STL.

Introducing a New RepStrap design: Auger

2010-03-02T05:36:00.005-06:00

Introducing Auger

A New and Still Hopeful RepStrap Design

Well, having built a McWire I frankly am not satisfied with the performance. For large parts it print fairly decent even good. The smaller parts have been problematic. Mainly due to the course extrusion control. The smaller Items print better when I use multiply in skeinforge but it lengthens an already too long print time.

I'm sure that I could probably make due with the McWire but I just can't stand the slow speed. I also think that I can do better starting with a blank slate. That being said I have changed my sights from building a Mendel to a design with the following attributes.

*The mechanical parts should be available at the local home center (Except bearings, electronics and motors)

* Relatively inexpensive

* No printed parts should be needed anywhere in the build to get up and printing.

* Keep the part type and parts count to a minimum.

* Speed should be comparable to the MakerBot. (I'm trying to do this without belts and pulleys)* Easy to make (although a small drill press is required)Hopefully this design will be something that would be good enough that it could be your first and last 3d printer if you choose not to make another bot.

So far I think I am on track. I have a sketchup model for the X and Y and am 80% through the build.

Here are the major build steps to get Auger printing from here:

* Mount the X and Y motors

* Join the motors the drive shafts

* Move the Mendel Z sled assembly to the Auger base plate and adjust the height.

Basic Construction

Auger uses a skate and rail system to glide the X and Y axis. #10 hardware is used throughout to hold the bearings in place and mount the skates to the platforms. The X and Y skate and rails are identical. The platforms are 7"x7" made from 3/16 inch luan plywood. The two are identical except for the holes to mount the upper stage to the lower. I think the X and Y sages could be made to work with a rack and pinion system but I am working on creating drive screws to move the stages.

Skates

The skate were inspired by the design found here at the GilesBathGate Blog.

They are made of 1"x1"x1/8" Aluminum angle. The skate bearings are inexpensive skate bearings ordered from VXB. One skate uses opposing 45deg angled bearing to keep alignment while the other uses inline 90 deg to give glide to the other end. #10 hardware is used to hold the bearings in place and allows enough play to tweak in each stage making it level and square. Washers are used to space the bearings from the brakets. The Sketchup file has the ideal distance but I used a number of washers that was closest and that seemed like it was good enough. All the screws bite into tapped holes in the aluminum and medium (blue) thread lock was used because of the high vibe environment.

Rails

The rails are made of two parts. The same aluminum U channel that McWire had in its design is used as a base to hold 0.7 inch electrical conduit. The conduit really inexpensive and is used to provide the rolling surface for the bearings and gives height between the sleds for the drive screws. This conduit is very rigid. We paint it and use it for curtain rods inside our house. Dry wall or wood screws go through the bottom of the ply wood, through the U channel and grab the conduit to hold the rails in place.

Base

The base is made of 1/2" ply wood. I'm actually using an old cabinet door that was in my scrap wood pile. Anything of that type would work. The main purpose of the base is to hold the rails and give a place to mount the Z sled. The Z sled is not designed yet but eventually will use the same design concepts as the X and Y sleds. In the mean time I will be using the Z sled from my McWire.

Drive System

I have had this wild idea that I could make a drive screw to move the stages. So far it has turned out pretty good but I have hit a few bumps along the way.

The Jig

To create the drive screw I have come up with a jig. I call it my Augering jig. It basically consists of a platform that fastens the the base of my drill press. It has two rails that form a channel. The channel is adjustable to guide rods 3/4 to 1 inches. Two 1/4inch bolts are used to hold and clamp a bracket over the rods. That bracket holds a razor blade angled by a wedge. The wedge in the picture is 15 degrees. I have made it so the wedge can be swapped out for one of a different angle. The bracket is tightened down so that the razor blade gets a good bite into the rod. When the rod is rotated the angle of the razor blade translates this into a linear displacement. This displacement drives the rod forward in to a bit that cuts a spiral grove into the rod. The jig works amazingly well.

The Drive Screw

I first tried the jig out using a 3/4" poplar dowel. After a few attempts I was able to come up with a precise cut. At first I was turning it by hand but that got tiring. Then I drilled a hole in the end of the dowel where I fastened a 1x2 piece of wood. I centered it so I could turn it with two hands like a ships wheel. I was able to turn it easily but the rotation was not smooth because my hands had to trade positions. Then I attached the 1x2 at its end and steadied with my left hand and turning it with my right. I was able to keep constant pressure on it in a smooth rotation. I found out later that pausing had not ill effects on the cut but reversing did as there is no support in the opposite direction for the razor blade and it flexed easily.

I used some calipers to measure the variation in thread distance in one rotation and they were less than 0.005" of one another from thread to thread. (It's really kind of hard to tell. I will have to measure the accuracy under operation.) Then thought it would be better if the rod was made of a lower friction material. I placed an order with McMaster Carr for some 1 and 3/4 inch UHMW HDPE.

I tried cutting some this weekend but had some problems:

* The 3/4 inch rod I ordered was actually 0.81 inches in diameter or about 13/16". All I have is a 3/4 paddel bit to make the nut. I cut threads in it anyways. perhaps I will pick up a bit this week.

* The HDPE has a low melting point and as a result likes to be cut slowly. My drill press on its slowest speed and an 1/8" bit still melted it as it cut. I was able to cut the 3/4" rod ok but the 1 inch rod melted too much and was not really useable. It seemed it was a slightly different material.

* The 1" inch rod had bulges in the diameter I think caused by the extrusion process.

* All the rods had a bend in them. I was able to correct this by hand.

If the razor blade had bidirectional support I think one could do gradually deeper cuts by going back and forth without too much loss in precision. I think that would be key to cutting plastics without melting. The bit I was using is a downward cutting spiral bit. A bit with 2 flutes and less surface area may help the melting issue as well.

Drive Nut

The dive nut is pretty simple in construction. I made it block by glueing two pieces of plywood together and drilling a hole that matched the drive rod. I marked the diameter of the circle and transferred those marks to the top. I placed a 15 degree wedge under the block and I drilled a hole just inside the markings. This made a hole that is parallel to the threads of the shaft. I then put the 1/8" drill bit in smooth side first and cut it off flush to the top using the Dremel tool. This made the thread of the nut.

On one of the nut and rod pairs there seemed to be some blacklash that is comparable to McWire's rod and coupling nut on the other there was hardly any at all. I will have to wait for actual operation to see how good it is though. I have some more ideas on how to make these better that I will be exploring.

Software and First Prints

2010-01-17T08:08:00.000-06:00

Lately, work has been crushing me. I have still managed to put some time in almost every day and made some good progress during this last week. Here are the highlights.

Installed Software

Arduino Environment - I had this software already installed but I made sure I was using the current version. I had to configure the IDE to be used with a Sanguino Microcontroller. The instructions are here. This all seemed to work fine.
Firmware - I had some problems getting the firmware to compile. In fact it never did. While browsing through the MakerBot Google group I found that I did not need to compile these as they come with and can be installed by ReplicatorG. It would have been nice to have known that up front as it would have saved me a bunch of time.
ReplicatorG - I down loaded ReplicatorG from here. At first this would not work on my computer. When it ran a Java run time window would pop up and say something like. "Could not find main class, progam terminated." I reinstalled Java and it didn't fix the problem. Then I read on the RepRap forums that a complete uninstall and then reinstall should fix it. So, I tried that and it did. I made a copy of machine.xlm and then added the xml code McWireReplicatorG.xml You need to do "View Page Source to see the XML code in the browser and then copy and paste using a text editor.
Python - I down loaded Python from here.
Skeinforge - I down loaded from here. I decided to change the environment path to include python so Skeinforge could be run from my tool bar. I made a batch file containing "python skeinforge.py" and stuck a shortcut in my tool bar.

Power up

Extruder Test - I am currently using HDPE for my extrusions. I'm seeing that ABS is popular and PLA is coming on strong but these were not in stock when I ordered my things from MakerBot so I got HDPE. From the MakerBot Store site: "This is HDPE plastic aka High Density Polyethylene aka Milk Jug plastic. This is a nice, smooth, high quality plastic. It comes as a filament in 5lb coils with a diameter of 3mm.
This plastic is cheaper than ABS, but has a higher shrinkage factor which makes printing large objects more difficult. It does have a much lower coefficient of friction so you can print things that are very smooth."
Endstop Test - The endstops work great but are useless. In fact they are worse than useless. When an endstop is triggered, the ReplicatorG and the motherboard freezes up. I think they pickup noise also so I removed all 6 endstops.

First Prints
My first prints were piles of goo. But, I have learned a bunch about the tool chain during this last week. Basically it's pretty easy. Once you go through it a few times. The instructions are here.

The key is to get the skeinforge settings right. I started with the settings from Binary Construct blog.
"Here are some of the more important skeingforge settings I am using:

PWM Motor Speed: 215 to 225 (depending on the object)
Extruder Temp: 225 C
Speed: 80mm/s (i think the threaded drive has some effect on this no being accurate)

Layer Height: 0.7mm"

These settings allowed me to start printing test cubes that are15mm on a side. These are kind of like the "hello world" of 3D printing.

Tweaking Skeinforge

I have been learning about Skeinforge settings from Bits From Bytes Blog. I think I have tweaked the McWire to the best of it's ability. The prints are very useable but slow and course. The basic problem with it is that the X and Y sleds move to slow because of the gearing with respect to the minimum extruder flow rate. Right now I'm running at 200/255 PWM rate on the extruder motor. Any slower risks a chance of stalling. The 80mm/s in the above settings is being limited by the settings in ReplicatorG. I Adjusted those and found they are best left where they are. So for right now there is not much, if any, of the desired filament stretch during the extrusion process. This could be fixed by going to a larger thread pitch on the drive screws.

Here are the key skeinforge settings I have going right now.

Thunder Cats are GO!

2010-01-12T04:48:00.002-06:00

A bunch of progress has been made since my last post. Two major steps have been achieved .

Mounting the Gen3 boards
Wiring the Electronics

Mounting the Electronics
This started with making a template by exporting the layers out of Eagle to a dxf file and then took that into my CAD program where created the board arrangement. I used some glue stick and pasted it to a piece of plywood and cut it to size.

I made some home made standoffs from drywall mollies. I used some washers to get the desired spacer length and cut them with some good size wire cutters.

Here is a driver board with the standoffs. Also you can see that I added the right angle headers for the opto endstops. I didn't bother taking out the CAT5 connectors.

I had a nice hefty bracket for mounting large curtain rods and used it to mount the electronics board. I wanted to make sure that the electronics were off the bench so the machine does not take up so much room. All but the power supply is off the bench and I am working on getting that mounted some how.

Wiring the Electronics
Here are some notable points I had for the wiring:

I unsoldered the molex connector pulling the pins out one at a time and soldered in screw terminals for hooking up the stepper motors. Digikey: A98168-ND TERM BLOCK 4POS SIDE ENT 3.81MM
I found some sprinkler wire at a home center to hook up the stepper motors. It worked out great. It is multicolor 18AWG solid core wires with 7 wires in the bundle and has black PVC sleeving.
I wired up the opto couplers and with Red (+5V), Black (ground) and yellow(signal). This wire was connected to 0.1" female connectors. (Digikey: S7001-ND CONN HEADER FEMALE 3POS .1" TIN) on both ends.
I used right angle 0.1" spaced header pins on the driver boards that are right underneath the cat 5 connectors. I didn’t bother to remove the cat5 connectors since they were not in the way.

At this point the McWire is completely wired and ready for action. The next steps are firmware installs, softwares and then printing!

McWire After Build Issues

2010-01-04T06:08:00.000-06:00

Some short comings of the McWire design have shown themselves after the build.

The first one concerns the method of attaching the drive screw to the Z sled. I seems the constant pressure on the tape covered coupling nut made the tape move over time. It telescoped out until the holding pressure in the conduit ran out. Then slipped out of the strap.

My solution was to build a bracket that presses the coupling nut against the Z sled, holding it in place. Overall this is a better way to go as you can adjust the height from the Z sled with a shim to get the drive screw parallel to the sled. This was a pain to do with the tape wound design.The X and Y have not been changed out but I will use the same solution if they become a problem.

The bracket material came from an L bracket that is used to hold drapery rods. A piece of 1/8"thick aluminum would do as well. It's held in place by 2 - #10 screws and tapped holes in the sled.

Another failure that has been occurring is breaking swing arms. They are not standing up to the task. I think it is the constant pressure of the spring and the size of the 5/16 hole plus counter sink relative to width of the swing arm. I have reduced the spring pressure as low as I fell comfortable with but failures are still occurring. I had 4 spares made when I ordered the laser cut parts and those are used up and now I am making parts to replace them.

I think the newly designed swing arms are working great and are easy to build. I used 3/16" press board because that’s what I had on hand. 1/4" thickness might be better. 1/8" aluminum would work nicely.

To make one of these :

Use a template to mark the outline and hole locations.
Cut it out roughly with the outline markings and the drill 1/16" pilot holes for all 3 holes. (larger for aluminum)
Drill the clearance hole (23/64") for the 5/16" bolt holding it to the sled.
Mount the bearing with a small washer (M5) under it using a dry wall screw.
Screw in a #2 sheet metal screw to hold the spring.
Dremel off the length the the screws protruding from the other side and grind them down just below the surface so the don't scratch the plastic on the sled.
File the shape of the swing arm down to the outline marks.

McWire and MK4 Plastruder

2010-01-03T06:36:00.001-06:00

Well it took some tweaking and figuring but I have the MakerBot Mk4 Plastruder successfully mounted to the Z sled. It was not as hard as I thought it would be and it came out better than I envisioned.

I built up the complete assembly according to the instructions at wiki.MakerBot. Then I started to brain storm ways of attaching it. In the end, there was only one practical way of mounting it. Here is the configuration I came up with:

Both the dinos had to be removed. They made the whole assembly as large as the Z sled. I set them free and they are able to rome around the shop and feed on future discarded prints.

I laid the plastruder assembly down on some graph paper to get the relative distance from the extruder nozzle to the mounting holes.

I wanted to create a template for an adapter plate that would hold the extruder board and the remaining of the plastruder assembly. So, I down loaded the Eagle files for the extruder board and exported the Dimension and the Holes layers as a dxf file. This gave me the hole pattern for both the extruder board and the plastruder since they bolt to one another using these. I then arranged these in my CAD software such that the nozzle was centered on the Z sled. From there it was easy to see that the inside mounting holes for the PTFE bearings would make good mounting holes for the adapter plate. The adapter plate was made out of 3/16" fiber board. It's what I had on hand.

After mounting the extruder board and the plastruder to the adapter board and on to the Z sled I saw that it needed to be lowered about a good 2". A quick run to the hardware store and I got some different lengths of pipe to adjust the Z sled height. I ended up swapping out the 12" piece with two 5" pieces and a coupler.

The Y alignment is not quite centered yet. Good enough for now though.

Over all I think it came out pretty good and will be easy to swap out print heads. I'm thinking of putting longer screws in from the other side and securing the board with some screw on knobs or wing nuts.

Plastruder Build

2010-01-01T08:06:00.000-06:00

I was a little nervous when it came to building up the plastruder. It seems like a place that many things could go wrong. I got the MK4 plastruder from MakerBot. The build instructions on their wiki are pretty straight forward. Also, I am thankful for the makerbot google group for the support they give. I have been trolling and learning some of the pitfalls people have had in building the current revision. I see the wiki has been updated to address those. Awesome!

Now that I have built one and all measurements look good I feel like i can tackle another without too much problem. The hardest part for me was the fine wire of the thermistor. It was like to hairs and a spec of glass. I felt that if I sneezed, it would be gone.

I thought I would take pictures of the way I wound the wire on so encase I have any problems I could show the experts and see how it could be improved.

The next challenge is to mount the plastruder to the Z sled.

McWire Motor Coupling

2009-12-31T08:15:00.000-06:00

The Structure Is Built
The basic McWire cartesian structure has been built. The last step was to couple the drive screws to the motors. I was undecided on the way to do this. The stepper motors I have a D shaft. I was a little concerned about using the suggested aquarium tubing with them. I was in the hardware store on my way to find some tubing and I came across the PEX pipe. It's a semi rigid plastic pipe. It was cheap and very sturdy. It's even rated for hot potable water so I though i would give it a try. I meant to pick up some tubing as well as a fall back incase this didn’t work but, I was so focused on making the PEX pipe work, I forgot.

The Coupler
It's 3/8" OD and ID about 7/32". At first, I tried to slide it on the the motor shaft with a good amount of pressure but it was a no go. The motor shaft diameter is a 1/4" so I drilled it out to 15/64" and tried it again. No joy there either. Then I tried a 1/4"drill. Finally the motor shaft slid in - but not without a significant amount of pressure.

I decided to use a 2" piece for the coupler. This would allow 3/4" for the motor shaft and 1" for the threaded rod with a 1/4" gap between. On the drive screw side I tapped it about 3 turns worth of 1/4"-20 and then using a jam nut configuration screwed the threaded bar into the pipe about an inch. Looking back I think 1/2" would have done but the wheels were already in motion.

On the final assembly I kept the jam nuts on the rod to help get the pipe off if ever I need too.

Yet Another Spacer
I discovered another place a spacer is needed. When I attached the coupling nut using the 1/2" conduit strap to the X and Y platforms, the added assembly was running into the end support. I lowered the end support from the rails with 1/4" of PEX pipe for a spacer. This was only a problem on the X and Y as the Z coupling nut assembly is not at the end of the platform.

Another option was to take off the end support completely as it seems it's only function is to hold the opto-endstop and I think that could be done in a different fashion. For now I will leave it.

McWire and Opto-Endstops

2009-12-30T05:29:00.000-06:00

So I didn't have as much build time yesterday as I normally do but did manage to get the opto-endstops built and mounted. These came along with the GEN3 electronincs that I got from MakerBot. At first, when I poured the contents of the bag O opto-endstops out, it looked like I was in for a bunch of work.

I called up the link that was on the outside of the bag that had the assembly instructions and no problems with assembly except inserting the 5 leads of the optical sensor into the hole. Lining up all 5 spindly leads at the same time was a challenge for me so I trimmed each of the leads at a different length so that they would go in one at a time.

I stuffed and soldered in all of the components except for the connector which I left unsoldered. I wanted to do a fit check at each of the locations before committing to having it on the board. It's a good thing I did because it would have definitely interfered with the Z motor shaft. Given that I decided to go with a right angle header solution. This option was smartly designed in so it was easy.

After the boards were fully soldered I tested them using the Arduino board I got from Adafruit Industries. It was a simple cut and paste of the code from the MakerBot sight and the program was running on the board. I did have one problem while testing. At first it didn't work. I checked all my wiring and hookups and made sure that the board had power and ground. I thought, ok I'll just move on to the next one and get back to this one. Well, none of them worked! Then I was suspicious. I noticed in the photo on the assembly and test web paged used a thick piece of cardboard so I changed the piece of white printer paper I was using to a piece of cardboard and it worked. In fact now all tested good. I then colored the piece of paper black with a marker and tried that. That seemed to do the trick as well.

Once the boards were working, I started mounting them to the McWire. Some location were fine and some were iffy. I think I will end up moving one or two of them. I will see as the build progresses. The one closest to the Z motor had the highest probability of interference.

McWire Build Session 5

2009-12-29T05:23:00.000-06:00

I am approaching the end (for now) of the Mcwire build effort. Just a few small things to do and I'll be tackling the extruder. The things on the list before the extruder are:

Solder up and mount the opto end stops.
Mount the rest of the motors (2)
Couple the motors to the drive screws
Attach coupling nuts to the platforms

I came across another challenge this session. There was a large discrepancy between the laser cut holes in the plexi and the holes in the flange to mount the Z platform to the structure. I thought about using some smaller screw with big washers but I thought that would put too much localized pressure on the plexi that usually leads to cracking. Instead I opted to make an adapter plate that would interface between the two. Also it helps distribute the load along the length of the plexi. Adjustments might have to be made for the proper over hang distance. I will adjust that once the extruder is mounted.

McWire Build Session 4

2009-12-28T06:34:00.000-06:00

Things progressed nicely to day. Here are the highlights.

X Rail Spacers (continued)
I finshed the X-Y stack and started the Z sled. I adjusted the spacers between the pipe and the X rails. I cut the inside of the spacer flush with the rail because the nut holding the bearing to the swing arm was hitting it. The outside part still protrudes out and I like that because it's easy to hold with your fingers when lining things up. I also removed the washer between the rail and the spacer. It wasn't needed as I did not account for the height the PTFE bearing were lifting the platform up.

Y Rail Spacers
Just as with the X, there needs to be a spacer between the Y rail and the X platform. I thought about cutting some U channel to do this just as with the X but that would have made a spacer longer than the 5/16"x3/4" screws could handle. The final solution was to use a 5/16" nut between the X platform and the Y rails.

Progress: Z Platform
The lessons learned with the X and Y platforms made the Z Axis go smoothly.

McWire Build Session 3

2009-12-27T17:15:00.000-06:00

So, my lessons learned the first two build sessions are starting to pay off. I managed to get to the hardware store and picked up the 5/16" washers and some metal blades for the saber saw. That made all the difference. The builds are progressing at a stead pace now and not too many surprises.

So far I have only used 3 screw types.

5/16" flat head, 3/4" long ( That I think would be better at 1"long) are used to attach rails, swing arms and bearings using counter sunk through hole and nut.
#10-24 pan head, 1" long (That I think would be better at 1/2" or 3/8" long) are used to mount motors, PTFE bearings and the end supports to the rails. These are use with tapped holes in either the plexi or the aluminum. This is a little more work than the though hole and nut but gives a nice precise fit.
#4-40 pan head 1/2" long are used to hold the springs to the swing arms in leu of the small nails suggested. These are drilled and tapped.

Im sure the nearest metric equivalent would work fine for those who are so inclined but holes in the laser cut pieces should be adjusted.

Here is the time lapse...

McWire Build Session 2.5

2009-12-26T08:40:00.000-06:00

I got out to the shop early this morning to make a set of spacers to lift the X rails off the pipes to let the bearings slide by. Much to my surprise I had a little mishap in the middle of the night.

My method of attaching the spring to the swing arms was with some small sheet metal screws. Well, I think the pilot hole I drilled was not quite big enough. That coupled with the presser of the spring blew out one of the swing arms.

Luckily I ordered 2 extra of all the small laser cut parts. I will be drilling and tapping those hole for 4-40 panhead about 3/4"long.

After I assessed the damage, I set the gears into motion. My best solution for the things that I had on hand were to use a piece of leftover U channel for the majority of the spacer and a washer for that extra little bit. The channel gave a nice flat place for the rails to rest and sat on the pipes nicely. It might need one more washer for the clearance but I won't know until after get back from the hard ware store.

McWire Build Session 2

2009-12-26T05:41:00.000-06:00

Happy Holidays everyone!
I learned a lot on the 2nd McWire Build session. One of the main things is that I have to be more careful when ordering parts online. I messed up on at least 2 items. Oh well it's all a learning process. Also, some of my mistakes worked anyways.

Here are the highlights of the build:

Shortly after cutting the aluminum angle for the X supports I discovered it was only 1"x1"x1/8" instead of the 1.5"x1.5"x1/8 called out. Drilling the holes for the bolts to mount it to the X rails would have blown out the edge of the angle. So I drill and tapped for a #10 screw. It worked great.
The countersink bit that I had was not big enough for the 5/16" flat head screws. I had to counter bore about 3/16" with a 5/8" paddle blade to get it to work.
The 5/16" flat head screws are working by are little short. I ordered 3/4" long but I think 1" would work better. I'm using 0.25" plexi which might be thicker than the original size.
The 5/16" washers are too big in diameter. They are bigger than the bearing LOL!. Oh well, I drilled out some #10s that I had for this session and I'll pick some up tomorrow.
The bearing arm assemblies like to become loose when moved so I used medium (blue) thread lock to keep the nut from spinning.
The original design calls out 10-24 and M5 hardware. I would either choose one or the other and save about $7. Certain holes would have to change accordingly. The M5 holes for the PTFE bearing were the perfect size to tap for the 10-24 screws.
I finally got the assembly together and discovered that the bearing hit the pipes and will not allow the sled to reach it's end-stop locations. Spacers under the X rails are needed to let it slide past.

Here is another time lapse of the epic struggle...

McWire Build Session#1

2009-12-24T18:59:00.000-06:00

Today I had my first McWire build session. It was the first day of my Christmas vacation.

The first part of the build was cleaning the bench from the last project(s).

Highlights of the build:

Life is SO much easier with a drill press. - Just say'n.
The "stickers" for the pipes didn't work for me. There was no good reference to line things up with them. I ended up using masking tape and created my own drill points. I put masking tap on the top of the two base pipes. Then took the aluminum channel, put it on top of the pipes, applied a good amount of pressure and scraped it along the top of the pipes. This scribed a nice straight line indicating where the top of each pipe was.

The hole locations for the X u-channel did not match the structure. I ended up adding an extra hole in the channel
I used the one of the stickers to get the location of the 1st hole. I used the u-channel mounting holes, the scribed "top of the pipe" line and a square to get the locations of the other 3 holes.
The self tapping 10-24 screws I bought did not work in the pipe. 2 of them failed and I had to grind them out. I think I should have bought the ones with the bigger grove that deals with the shavings. Luckily I have a tap and dye set and used that to make the threads for the screws. I used a 5/32" drill bit for the hole.

Here is a time lapse of the build session. I think a higher vantage point would be better. I'll try that next time.

McWire Laser Cut Files

2009-12-14T06:06:00.000-06:00

Well, I have decided to get laser cut parts instead of using that piece of MDF that I had in my shop. I just received an order of laser cut parts for 3 small projects I've been working on. I love that it comes coated in paper that you can scribble notes on while you do the initial fit. I think it was the look of acrylic that did me in. Taking off the paper and revealing the plexi is like uncovering a diamond. It's shinny and mesmerizing.

So, given all that, I down loaded the files for the McWire V1.2 from SourceForge. In all the files looked pretty good to me but there were some changes I wanted to make. They are the following:

The layout file were scaled in millimeters. Since I mostly work in imperial units I scaled it down by 25.4. Note: If your CAD system accepts LISP commands as input this is easily done by entering in (/ 1 25.4) which calculates 1/25.4 instead of typing in a bunch of digits that is prone to error by rounding or having fat fingers.
The LIMITS of the files was change to 11.75 x 23.75 inches.
The parts were rearranged for more efficient laser cutting - combining edges of the same type of parts to save on cutting time.
The text and shapes that were to be etched were removed - again to save on cutting time.
Two of the smaller parts were added as spares. Yes, It's adding cost but I think it is value added. I hate to be dead in the water because of breaking one part... or even two.

Anyone is welcome to use these files. They are in AutoCAD 2004 DWG and DXF format. I also scaled a copy back up to millimeters for those who use the saner form of units.

They can be found at: XYZ_Layouts.

If you use these, please let me know if there are any bugs in them.

I placed in a request for quote at Pololu for the XY and the Z layouts. I did not find information about thickness on the McWire page. Searching the forums I found an estimate of 1/4 inch so that’s what I went with.

I can't wait until all my parts arrive! I will be finishing up my 3 small projects. That should keep my build addiction satisfied until then.

The Gathering

2009-12-12T05:17:00.000-06:00

Well it looks like things are coming together as far as the task of gathering parts for the McWire RepStrap. I saw a tweet last night from MakerBot say that the Gen3 electronics were in so I jumped at the chance to get them on order. I've still have to get to the hardware store to get the structure, U channel and aluminum angle.

I have a nice piece of MDF that came as packing from our new dishwasher so that might be recycled for the sleds. I'm also thinking that acrylic sled would be nice as it shows the mechanics of the sleds. I'm sure the RepStrap will be a great show and tell item for all those who see it. You can also see if something has become loose within the sled drive.

Applicable Shipping Changes Will Be Added

2009-12-11T04:39:00.000-06:00

I have just placed an order with McMASTER-CARR for my McWire. It shipped the same day and should be here even before I have a chance to get to the hardware store for the rest of the stuff. Their website is awsome but what's with the "Applicable shipping charges and tax will be added."?

Even after the package has shipped I can't get the amount.

Starting at 0,0,0

2009-12-09T05:20:00.000-06:00

So I have decided to take on the project of building a McWire in order to RepStrap up to a Mendel. I'm starting to gather parts so I can start and hopefully finish building the majority of the structure over my Christmas holiday. Until then I have set out to study the various electronic set ups. All seems pretty straight forward. I did, however, find a small mistake on the PWM Driver 1.1.

In reviewing the schematic, I have found that the free wheel diodes seem to be connected incorrectly. The free wheel diodes are D1, D2 and D3 that are the 1n4004. These diodes are used to deal with inductive loads. Inductive loads such as a relay coil will want the current to keep flowing until the inductive energy within the load is dissipated. These diodes, as hooked up now, are not creating a path to deal with this energy. If an inductive load is used, most likely there will be a large voltage spike on the collector of the TIP50 transistors. V=L*dI/dT so the faster it is turned off, the higher the current or the larger the inductance the higher that spike will be.

If noise has been an issue for your system or your burning up PWM drivers this may be a major contributor.

I would recommend moving the diode or adding an additional diode. The hook-up would be anode the the TIP50 collector and cathode to Vss.

The existing diodes are fine where they are but aren't really doing anything.