rev:Alpha Meter, Meter Panel Eater

Ok, stupid title but sometimes thou gotta let one out.

Anyway, here  rev:Alpha of my ShapeOko upgrade on GitHub.

Overview

Overview

In general I think I have met all my design goals. The only compromise was the over all size. At one time I did experiment with what overall size it would take just to load in a 24"x24" panel. The savings did not justify the effort of trimming down the extrusion nor the wood. Leaving the extrusion  at 1 meter and foot print 48"x48", the cutting area is about 40"x31".
So size was a compromise but I have room for it and I think this space will be worth it. Unlike other things in my garage this will "pay rent".  I may have to do some spring cleaning and  "evict" some junk to find this a home.

X-Rail and Gantry Improvements

X Gantry Box like design

Because of the noticeable give in my current ShapeOkos gantry I really wanted to solidify the X rail and carriage. I scanned the forums and extracted what I thought was the best ideas for doing so.  The upgrade are:

Double X-rails with wlanfox Blocks  - It was pretty much a consensus that a Double-X rail would be needed for the meter span. I also thought that the wlanfox Blocks  were an excellent idea and be made of 3/4" plywood. I will use M5 threaded rod and nylock nuts to span the distance of the blocks. I think using nylock nuts all around is a good idea as I have had some nuts loosen and fall off  in the middle of a job. Also 4 more V-Wheel Kits are needed.

Gantry Underside

Standard Wheel Carriage Plate - Using these instead of the existing motor plate lowers the X-Rail so that the resulting moment arm is reduced. Forces in the Y direction should have less twisting effect on the Gantry and X-Rail assembly. The draw back of this mod is that the Y motors have to be relocated.  You can see in the overview picture that they will be mounted on a fabricated item I call the Motor-Buttress assembly (blue).  This will require longer timing belts and two additional Smooth Idler Wheel Kits.

Standard Wheel Carrage Plate

 Part Fabrication

Idler Butress Assembly

I will use the ShapeOko to cutout the parts to make the Idler and Motor Buttress Assemblies as well as the wlanfox Blocks. I'm hopeful that I get it right before I tear down the ShapeOko for upgrading. If not then I will have to resort to my skills with hand tools which will be a big time suck and an exercise of patience but we will getr done.

ShapeOko : The next step

So I have been running jobs on my ShapeOko cnc mill for a few weeks now.  I think I know where I want to take the upgrades.

These are in no particular order.

Up Sizing

The cutting area I have now is roughly 8x8 inches. A standard plywood Hobby Panel from a hardware depot store is 24"x24 inches. I think I would be using these in various thicknesses for the majority of the projects I will be doing.  The  Maker slide extrusion only comes in 200, 375, 1000 and 1800mm. This translates into 8, 15, 39 and 71 inches.  Not a lot of choices here. The closest size for my use is 1000mm.  When I consider the extra space needed for the machine the overall size is going to be roughly 48x48 inches. About a half sheet of plywood. This is a bit bigger foot print  than I wanted but I can't bring myself to cut down the extrusion. It would just seem like a waste of money.

Mitigate Y Lag

wlanfox great ideal to add blocks to stiffen carriage.

On my machine there is  a very noticeable Y lag that is evident in the oval holes created.  This is happening mainly because of 2 reasons:

1. Probably the biggest  and clearest shortcoming of the ShapeOko is the unpowered Y rail. I will be going to a 2 motor configuration.
2. The carriage stiffness needs to be improved. I will be doubling the X rail and using wlanfoxBlocks to stiffen the X carriage assembly.

Another Idea I had was to lower the X rails so the moment arm against them is not so big.  This would be limiting to the Z range but might be worth it.

Spindle

In a sense I have already upgraded my spindle. I have replaced it with my 15yr old dremel tool. This is because the rotatory tool that came with the machine would not hold the bits in reliably. There is a push button on the rotary tool that is used to stop the chuck from moving while it is being tightened. The button is unable to resist the pressure given when tightening and the chuck skips past the stop for some reason.

The spindle caused milling failures twice by releasing the bit mid-run.  On the second time I cut the cord off and threw it in the trash. I figured I could use the cord on a project and no one should use this tool in this dangerous condition.

I'm thinking that the DW660 would suit my needs. It seems like the bigger brother of the Dremel tool I have now. I will have to research this further but for now, this is my target.

My new ShapeOko CNC router is up and going.

 http://youtu.be/jqMCSxWVY4Y

Kossel Build Continues

The Kossel build continues. This is an easy build for sure if you already have a 3d printer. The parts for the top part of the frame were printed and assembled over Thanksgiving holiday. The leveling and calibration maybe where the real challenges are.

I have been using AutoDesk 123D Design to create parts with. The effector and the rolling carriage were redesigned just because I wanted some CAD practice with the software and wanted some customized touches such as beveled hole entries  and more mounting features. From OpenSCAD I exported the Kossel master files to an STL and then imported into SketchUp. From there I made measurements and dimensions that helped me get it into 123D Design.

I had one redesign spin (so far) on the roller because I forgot the hole for the top endstop. In all the roller turned out great. The bearings are sitting very nicely centered on the flats.  The roller uses 6 - 623 bearings. Three on each side.  M3 screws are used all around with the exception of the string attachment which is is and M4. The four nuts that are used to pull the two halves together are nylocks.

Once I had all three rollers assembled and installed I worked on the top part of the frame.  I inserted the bearing into the line tensioners. At first it appeared to be too small to hold the bearing but I worked at it more and got it centered on the axial holes and it was fine. I inserted the plastic axel and the bearing spun freely. The tensioners and the axial were original Kossel designs.

The rest of the top frame pieces went together without much trouble. Assembly method was similar to the bottom frame but easier since there was only a single frame to contend with. Keeping all screws about a turn from fastened so the frame pieces can move allowed for theme to come together.

Installing the fishing line was a bit fiddley but the time I did the last one i kind of got the hang of it. I printed the clamp and followed the method described in this video.
Fishing Line Install on Rostock Kossel using Clamp




For the most part the string does well winding and unwinding neatly. I'm not quiet sure of the tension needed. For now I will not worry about it as I will turn my attention on making the rods and attaching them to the effector


Santa will be bringing a Panucatt Azteeg_X3controller. I will be using an old ATX power supply from the old McWire to power it.

New Project: Kossel

After seeing the Rostock DeltaBot in action I knew i had to have one. I orderded bearings, screws and nuts last week. So, i took advantage of Thanksgiving holiday/weekend and started printing parts.

At first I only printed one of the lower corner sets to see how it would fit together. The latest GitHub master had fixed alignment problems and everything fit well together.

My main tools for assembly were a 2.5mm ball end driver and some spring loaded tweezers. Forceps would work as well.
Here Re some instructions that go with included pictures. I am writing this with my phone and will have to make them inline later.

Instructions

Populate these four hole locations of each frame_motor piece with 3 x 8 mm screws and jam nuts.
Attach each corner with two and M3 x 20 screws. All screws should be loose at this point.

Slide the extrusion onto the loosen screws as shown.

Load the other two corners with screws and nuts.Work these in to the extrusions at the same time with the screws loose.



Slide in vertical extrusions.
Once together go around and firm up the screws.

You can test mount the motors with M3x8 screws. Using tweezers can really help with this step.

Drag and Drop Slic3ring

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

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

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

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

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

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

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!

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!