Installing the Makerbot Stepstruder upgrade on the Cupcake Ultimate (now called a CUPTHING)

Oh boy, upgrading to a MK6 stepstruder was an adventure. It would be nice if future versions of ReplicatorG would have support for cupcakes upgraded with a MK6. However, for those who can't wait for a pre-configured edition of ReplicatorG to appear, here's how you can upgrade right now! Given that you have the MK6 upgrade kit and three long bolts to mount the stepper board above the extruder board, you should have everything else provided by the kit. Here are the general steps I followed:

• Print out a stepper board bracket so the stepper board can mount over the extruder board. (I tried having Makerbot make the holes in the correct spot but I finally just drilled some mounting holes manually)
  
• Take apart mk5 extruder. Then use mk6 plates and new stepper motor.
  
• Hardwire in a fan to the unused 4-pin connector from the power supply. I didn't bother putting mine on a switch so the fan just stays on when power supply is on. Use a volt meter to find the correct voltage for the fan.
  
• Plug in stepper motor to 12V supply. Then calibrate the stepper motor pot voltage values as described HERE
  
• Make a custom control cable to connect stepper board to extruder board.
  
• Use Ubuntu Linux 10.10 and download replicatorG24.
  
• Make a new .xml "cupcake MK6 with HBP profile" file with stepper motor .xml tags in it (see below)
  
• download precompiled firmware for extruder board and put into correct place (see below).
  
• Make reference to it so I can use Replicator program to upload firmware to the extruder board (see below)
• Install rpmify script so post processing can substitute geared motor for stepper motor Gcodes (see below)
• Edit the "start.gcode" file (see below)
• Make a new Replicator profile that works using the new stepper motor.
  

For mounting, I recycled my DC bracket I used for the earlier H-bridge problem. Fortunately, the boards were practically the same size. As for standoffs, I found using 6/32 screws with cut tubing for standoffs works well. Don't bother buying tubing. You can use a bit of tubing that comes with the makerbot reel holder.

Wire-wrapped connections should be wired to make the equivalent circuit as described in this diagram HERE. If you're lucky enough to have some ribbon cable with with dip connectors on each end, cut the ribbon cable in half, then glue the two dip connectors together with superglue. The pins plus the use of a wire-wrap tool make a nice break-out box. That way, there is no soldering needed plus it's easy to troubleshoot and correct if the pin-outs are wrong. I also found using the edge of a 6 pin connector on the extruder's 3 pin connector is easier than soldering together a 3-pin connector to ribbon cable. Also, by accident, I discovered getting pins 7 & 8 reversed makes the circuit act like the motor has either noise problems or a firmware problem. Once I discovered that, I got out the wire wrap tool and was able to quickly correct that connection. Since then, I've had NO noise problems!

Now, for the software changes. I'm using Ubuntu Linux 10.10 with a downloaded version of ReplicatorG ver.24 . Also, remember to make sure you're using JAVA 1.5 and Python 2.5. There are several really handy pages to refer to:

http://wiki.makerbot.com/stepstruder-mk6-with-gen3
http://wiki.makerbot.com/stepper-driven-extruder#toc12

So, let's first make "Cupcake with HBP and Makerbot MK6 stepstruder" appear as a profile choice in the menu. This is important since we're going to be turning on a GUI control not normally seen if a Cupcake is just using a geared motor. To do so, go into the ReplicatorG directory structure. Go to the "machines" folder. You'll see all the profiles available. Let's make a copy of the "cupcake.xml" and call it "cupcakeWithMK6.xml" Then, in text editor, find the .xml "tool" tags and replace any "pinch wheel extruder" settings with this string instead.

name="Mk6" stepper" type="extruder" material="abs" motor="true" fan="true" heater="true" heatedplatform="true" motor_steps="1600" default_rpm="1.9"
Oh, and for the profile you're likely to use, don't forget to change the description tag to something like "cupcake with Mk6".

Once that is done, go into ReplicatorG, then pick "Machine" then "Driver" and see that a new entry for a cupcake with a Stepstruder now exists. Yay! Pick it. Now, go into the control panel and you'll now notice the old PWM box that controlled DC motor speed is still there. However, there is now a new RPM box below it that allows entry of stepping rate. Usually for an extruder test, "Full speed" for the DC motor was 255. However, an equivalent RPM speed using a stepper would be something like "1.8" So, now we have a new text box GUI control, we'll exit ReplicatorG and come back to this screen later.

We now need to make our extruder board be able to drive a stepper. So, we'll need to upload a new version of firmware to the extruder board. We COULD install all the packages required to compile our own firmware, then upload it to our board manually. Fortunately, we don't need muck about doing that! A very nice person compiled firmware that works great with the MK6 stepper. If you are using Linux and have GIT, you can download the Koenkooi pre-compiled firmware HERE. I use the pre-compiled hex file version 2.5. To install using a file manager, make sure you can view hidden files. Place this downloaded hex file the ".replicatorg" directory which is located in the user's home directory (usually this directory is above the desktop directory)

Now, make the firmware entry appear in the ReplicatorG firmware menu. Edit the "firmware.xml" file. There should be entries for other firmware choices that would appear in the ReplicatorG "firmware" menu items. Just make another "firmware" tag to point the hex file you just downloaded.

Once the firmware upload capability is in ReplicatorG, just take the programming cord, plug it into the extruder board, then use the menu to upload the pre-compiled firmware to it. Easy!

Inside ReplicatorG, Skienforge also needs to be adjusted. I've decided to only configure the Skienforge35 settings. That means when I generate Gcode, I pick Skienforge35 rather than going with the default Gcode generator.

Now, the really clever bit. You COULD post-process the Gcodes to substitute all the PWM speed codes (M 108 S) codes for RPM speed codes (M 108 R). However, you can instead add a script to do this automatically in Skienforge. This feature can also be turned on/off via check box. The script has instructions for installation right in it. The first step tells you where to copy the script to. The second instruction adds the script functionality to the menu. Get the script HERE.

Also, one last thing. You might want to set other initializations in the Skienforge profile you're working on. Here's how...
Go to .../replicatorG/skein_engines/skienforge-35/skienforge_application/prefs
Make a copy of one of the Thing-o-matic profiles that use an HBP, then rename it SF35-CupcakeWithMk6-HBP. Inside the directory structure, there should be a directory called "alterations" with a file called "start.gcode". I found it was helpful to take out the "homing" commands since my build area is smaller than a Thing-o-matic. If not, when the build starts, the platform will try to move the length of the larger build area with obvious bad consequences.

Once I reached this point, I found my simple shapes came out about as well as using the geared motor and they had the benefit of having fewer strings. However, raftless prints were disappointing. So, I made some tweaks to the replicator profile but that process is worth a whole different posting!

A bad extruder motor?

For the heck of it, I decided to find out why the motor failed. There was a remote possibility the motor gears might just be jammed. Maybe a bit of oil is all it needs! So, I took it off the extruder assembly. The gear box in front of the motor seemed OK.I then separated the gearbox from the motor. I then powered up the motor with a 9V transistor battery. It seemed to run but it was a bit rough. However, since I have no idea how the motor normally operates, I decided to put it all back together and give it another go. Just for good measure, I also decided to put a lighter grade of oil in the gearbox. A 9V battery was still able to turn the motor once the gearbox was reassembled.

I then re-installed the motor. Using the control panel, the motor-gearbox seemed to have no trouble extruding a steady stream of plastic. It also started and stopped OK many times under the control panel. However, when doing a print job, it would still fail unpredictably when doing a raft. Sometimes it would make it as far as the 2nd or 3rd layer. However, I could not get a reliable extrusion past that point no matter the thumbwheel setting was. Taking some measurements showed that the DC driver circuit seemed to be doing it's job and the status lights on the extruder board are also helpful in showing that the circuit section is either working or not. Taking apart the motor showed that the gearbox seems OK. However, I've still declared the motor officially broken.

By broken, the motor rotates without it's gearbox, but it runs rough. I suspect when the motor is at a rough part, this causes the extruder board to sense something strange is going on. So, the extruder board then shuts the channel down. This is easily observed when lights on the extruder channel stop working. I eventually learned that shutdown can be prevented by going into Skienforge to put a smaller maximum extrusion value. If the motor is stalled, voltage levels are still maintained so it seems that the board is doing it's job. However, all that doesn't matter since the motor doesn't rotate! What is interesting is that the same behavior was seen even with the add-on driver board. So, maybe channel shutdown is caused by a noise issue? Maybe the motor momentarily shorts (or opens)? Hard to say without having another known good motor to compare this behavior to.

Of course, Makerbot is out of these replacement motors. The community has mentioned that the geared motors don't hold up well and even Makerbot admitted that they now know they had a bad batch of motors go out the door. Makerbot does not offer these motors anymore. So, I ordered a batch direct from Kysane. Since they have a large minimum order, I'll be selling what I don't use via Ebay. Note, this order was en-route PRE-Earthquake so these motors are NOT radioactive Yay!!

DC driver board is built, works nice, but now there is another problem.

Ok, so I finally build and add on the DC driver board. As you can see, I did some part substitutions. It's ugly but it w seems to work. Unfortunately, on the 3rd print, the plastic feedstock had a problem being pulled into the extruder. I guess that's what I get for leaving my bot alone for a few minutes! By the time I got to the printer to untangle it, not only was there no plastic being printed but I also noticed a faint electrical smell too. Never good! The new extruder board's heavier H-Bridge chip was really hot! So, I'm thinking if I'm lucky, maybe the chip simply went into thermal shutdown. If so, maybe a heat sink is all I would need! Fortunately, when I built the board, I used a socket and I have an extra chip if I need it.

So, let's see what damage was done. Let everything cool. Untangle the plastic, disengage the pinch wheel so the motor is free to move, then do some testing. I reset everything. I figure, maybe the driver chip fried. So, I use a volt meter to check the DC output using the software control panel. 6V at half speed, 10V at almost full speed. Using a multimeter, I decide the driver circuit is probably OK. So, I test the resistance of the motor by itself. It reads 1 ohm which is really low even for a motor. According to this article they should read more like 47 ohms. So, I'm expecting that the motor may have an internal short.

AAARGH! Another board problem.

For the past month, my Makerbot Cupcape extruder had progressively more trouble extruding. After some research, I found others had this problem too. It seems to be due to an undersized "H-bridge" chip driving more than it should.

A few weeks ago, I decided I should have another complete set of Gen3 electronics on hand just in case I had a failure such as this. That way, I could swap boards if one went bad and not be "down" while I repaired the other board. However, the Gen3 board set has been consistently out of stock at Makerbot for a couple months. In the mean time, I'm not completely out of options. It turns out that there are two extruder motor driver circuits! In Skienforge, going into the extruder board settings, you can change from the primary extruder driver (using 1A, 1B) to the secondary driver (using 2a, 2b). Still, that just solves the symptom, not the problem. The real cause of this might just be my motor is drawing too much. For now, I've hooked up the extruder motor to the secondary extruder driver circuit. But I'm thinking that this failure is likely to happen again. So, what are my longer term options?

Option 1) Install the Makerbot Stepstruder upgrade kit. Even though this upgrade is listed as "Experimental" I have a reasonable expectation that this would work. My order is in, but it will be a while before this solution arrives.

Option 2) Replace this chip with another of the same kind. I probably could rush order the chip from Digikey and try my hand at soldering it in. However, even if I did accomplish this tricky surface mount soldering operation, it's likely the new chip might just blow out again!

Option3) Replace the wimpy chip with something a little heavier. Fortunately, someone else decided this was a good idea too. So, they documented the fix!
http://wiki.makerbot.com/gen3-hbridge-fix. Makerbot even lists the kit on their site!

The problem with option3 is that Makerbot is now out of those parts too! Fortunately, they still had the bare board available. So, between what I have in stock in my workshop, a rush order from Digikey and a trip down to Radio Shack, I now have the parts needed to make that repair. Since my secondary circuit still works, I'll be printing out a bracket so I can mount this secondary board directly above the extruder board. Hopefully, my secondary extruder circuit will last long enough to do that print!

I am disappointed in the supply problems Makerbot seems to have. As you may have guessed, buying components from several places then paying retail prices per-component, has boosted the cost of this fix by quite a bit.At times like this, I'm reminded of the Monty Python Cheese Shop.
http://www.youtube.com/watch?v=B3KBuQHHKx0

However, in spite of these problems, Makerbot still has one really good thing going for it. It's the fact that the device is an open design. That means I have a fighting chance of fixing this myself. If this product was proprietary with no schematics and secret firmware, and the company went out of business, I would be totally out of luck. Even though the Gen3 electronics apparently aren't very robust, they are at least an open design with a vibrant user community. That means this repair is annoying rather than impossible.

Using the Cupcake automated build platform

I finally assembled the build platform hoping I could start kicking out several parts at a time. Unfortunately, I was in a hurry and I assembled the belt inside out. But hey, stupid me, I decided to go with it anyway - and discovered I couldn't print anything since the belt surface was too slippery! Turns out the plastic has two sides. One side is very slippery and the other is not as much. So, word to the wise. If when you're done, the stripe appears on the right as in the photo...you did it wrong too.

The other parts of the build were rather straightforward in having images for every major step. That is, except for one. I couldn't find a photo where the build platform motor plugs into a board. I eventually figured it out. How? Well, when looking at the instructions, it turns out, I had to read rather than just look at pictures. So, for those of us who like looking at pictures rather than reading, I made a quick reference image to show what wires go to what connectors.

Anyway, the second time I used the platform with the belt on the proper way, all did not go well. The makerbot briefly lost it's brains and tried forcing the hot extruder head through the platform. This then melted the plastic conveyor belt. The next instruction then dragged the extruder head over the belt making a giant gouge in the belt and also dented the metalized platform.

So, rather than repair the conveyor, I've decided to just use the heated build platform by itself. Someday, I may go back to using the build platform but I'll need to stock up on some spare belts first!

From useless to useful!

Yes, I sometimes do trash pick. Such was the case with this nice looking tripod that was being thrown out. It was missing a small but critical part called a quick-release. Normally, that would make a tripod like this rather useless. But not for me! After taking some measurements, I designed a basic plate and then printed! Now that I have a plate, I'll only need to stop by the hardware store to buy a screw that fits the camera mount. Sweet!

A print from Sketchup

I decided to print a gear using Google Sketchup. To generate a sample gear, I used the gear add-on module. To use it, I had to back down to version 7.1 rather than 8.0. To export the design to Skienforge, I had to use a DFX exporter add-on too. To install both components, simply download and save to the Google Sketchup directory called "plugins". Once installed, the new controls appear in the Sketchup pull down menu.

The components are available in multiple places, but also available HERE

Above is the progression of prints I tried. The night I printed, the Cupcake was being rather fussy. When I last turned it off, the last print it did was a pretty good calibration cube. Unfortunately, after sitting nearly a week, I found the printer was not quite a "turn on and print" device. For some reason, the extruder motor would not energize. Pushing the "reset" button on the motherboard solved that issue. I also have the impression the rods have become a little wobbly, possibly due to being under constant tension from the z-stage drive belt. It was clear from the raft on the first print that I was going to get a stringy mess so I aborted the first print. What I think happened was that the nozzle was clogged with something. I'm guessing either dust or a cat hair. Fortunately, I was able to flush out whatever it was by going to the control panel and running the nozzle at 255 until the plastic started coming out nicely again. The next print came out better, but still, not great. After manipulating the Gcode settings having to do with layer thickness and density, the next print came out much better. A copy was then made which I consider would be a usable end product. I can see right now that one really nice upgrade would be some stiffer z-rods and of course a MK6 extruder upgrade. However, for now, the printer seems to do what I want it to do.

First successful test print from file - it works!

Since I was continuing to have extruder problems, I decided to check my hypothesis that the drive gears in the MK5 simply didn't line up properly with the plastic. Sure enough, the teeth didn't line up at all. The Makerbot instructions I used are wrong. However, that's how I installed it. So, the intermittent behavior I saw was when the Allen bolt would occasionally catch the plastic & the gear would work for a bit. Then, it would work very poorly since plastic was against the smooth part of the gear. I'm surprised it worked at all. After reversing the drive gear and re-installing the motor with a washer on each motor bolt (for spacers so the gear lines up better) the extruder unit worked beautifully!

Once the extruder could squirt out plastic on demand via the Skeinforge's control panel, I figured it was finally time for the first test print of a calibration cube. So, I used the control panel to manually warm up the extruder to 220c (room temperature 18c). Only the default settings were used since I wanted to establish a baseline of performance.

I tried my first print from the PC. Even though the bot was at operating temperature, there was a significant delay before the print started. The bot first raises the print head to do a test extract (which you grab with tweezers). You then confirm you're ready to print. Only then does it lower the print head to start the job. The first print came out rather nice and was fascinating to watch. The extruded plastic at first was a bit wavy (seen by the raft under the cube) This was solved by adjusting the extruder knob so it pinched the plastic just a bit more.

Due to a better pinch knob setting, the second print came out much better. I tested printing the same design from SD card using the default settings. I also wanted to test that I could launch a print, then disconnect the PC. So, after launching a card print, I hit the disconnect icon in Skienforge, then shut down Linux. The print still continued and the second cube turned out even better! Not bad for an evening's work! No problems having the raft of plastic detach from the build platform either. That might be due to using blue painters tape. The tape seems to give the raft something to adhere to. It also makes part removal much easier.

The object produced did produce some small plastic bumps on the far corner of the cube, probably due to a delay in z-stage lifting. I suspect tweaking some settings might be able to make those bumps go away. If not, some fine-grit sandpaper should be able to remove those kind of defects.

Test fire! Making sure the extruder works.

The replacement stepper motor board has been installed. As expected, that immediately solved the Y-stage movement problems. Now, it's time for an extrusion test!

So, I go to the control panel in ReplicatorG. Put the temperature up to 220C. The power relays have an audible "click" as they engage, then turn off as temperature is reached. There's also a graph so temperature progress can be seen. It takes around 5 minutes to achieve temperature. The first heat, as expected, vaporized the oil coated parts and that produced a smoking effect. It doesn't last too long but I managed to get a quick photo of it. I then verified by thermocouple that the thermistor was working properly. I noticed my thermistor reading was 2 degrees lower than the thermocouple. Close enough!

Once my reading was done, I manually fed a section of ABS feedstock through the extruder. That worked well. However, tightening down the pinch head so the motor could force plastic through didn't work so well. I suspect my guess on the position of the gripper wheel was a little off. So, ill need to let the unit cool down and take it apart later. Once it's apart, I suspect I'll only need to loosen the hex pin, then push the gripper wheel on the drive shaft a tad bit more towards the motor so the grabby section of the wheel can grip the feedstock better. Ah, problems. Just gotta keep in mind that big journeys are completed with lots of little steps and some of them may be backwards!

No print today....bad stepper driver board

So, I think I'm ready for my first print. Just a final check of the motors to make sure nothing has changed since I last calibrated everything and then I'll be ready for a dry run, hopefully followed by a test print using plastic!

However, all is not well. The "Y" motor has been running rough on occasion in one direction. Platform movement seems to have almost equal resistance in each direction when I disable the stepper and just use my hand. Just in case, I put on some graphite oil to loosen up the movement anyway. No effect. Upon power-up the movement now only goes one direction in Jog even if Y+ or Y- is selected! This is getting strange. Time to do some reading and basic troubleshooting.

• Ok, maybe connectors vibrated loose or aren't set properly. Power down & Re-seat the connectors. The motor now only goes in one direction? Re-seat again. Try a jog again. Same effect.
• Ok, test to see if it's perhaps a communication problem with the PC. Restart Linux. Restart bot. Next attempt, no motor movement at all! Ok, go down a version and try using the "old" way of communicating that the previous release used. Reload firmware. Same effect. X and Z can jog but not Y. The stepper motor circuit lights like other boards but no movement.
• Ok, let's try a totally different software environment. Let's use the Windows Skienforge version instead. Boot into WinXP instead. Install software & prerequisites. Reload firmware. Still, no movement in the "Y" axis! OK, I still can't totally eliminate software as being a problem since the software is a port. However, I figure if it's something this bad, lots of people would be screaming about it on Google Groups. Try something else.
  
• Heyyyy. On the stepper motor board, I see a pot! Maybe it's out of adjustment? Try various positions. No effect. Light intensity changes but no matter what position is tried, no movement. However, I sometimes hear a high-frequency noise depending on the pot position.
• Ok, let's just make sure the ribbon cable and motor are good by using another controller board to drive the "Y" motor. Now, "Y" Movement is responsive! Looks like I have a bad driver board.
  

So, I try to order a replacement from Makerbot. Crap...the gen3 boards are out of stock. Whoa! So are ALL the gen3 electronic boards! Apparently, since the Cupcake is an end-of-life product, they ran out of boards! They say they are having more manufactured for a final run but they don't say a date other than "sometime in the spring". Fortunately, Ebay came through for me. So, this bad board incident is a small delay rather than a major setback.

Ok, but what if I didn't happen to find that replacement board on Ebay? In theory, I could etch a PCB board, find the parts and eventually make my own board. However, this is very expensive in terms of shipping and time. Fortunately, I don't need to go down that road right now.

A SCARY ELECTROSTATIC MOMENT

While taking a voltage measurement on the relay board, I saw a little electrostatic shock happen off my meter probe The whole system then abruptly shut off! Power cycling the power supply didn't cause the fan to turn on. Pressing the little switch and even the "reset" button on the motherboard didn't fix it either.

However, there were some interesting symptoms. Although the motherboard didn't power up, it did sometimes flash some red lights near the USB connector when "reset" was pressed. I suspect this was due to USB having power from the PC.

So, here's the first attempt at solving the problem. Maybe the power supply was confused. Unplug the connector from the motherboard. Short the green & black wires together. All boards other than the motherboard then came back to life. This was good.

Second attempt. I read that even though the power supply FAN wasn't working, the motherboard may indeed be getting power from the supply. If so, it might just need it's firmware reloaded. So, I figured, what the heck. Give it a try. So, I found the "update firmware" option in the menus. Tried the latest edition. The blinking light changed to a steady red & I got a notice that firmware reload was successful. Whew! Amazing as it seems, that recovery procedure worked.

First power on!

Just a few more connections to go. The blue cable connects the extruder RJ45 to one of the RJ45 connectors on the motherboard. (why they have 4 connectors is a mystery since they all are the same, but it was handy since space was kind of tight). Then, the USB connector cable was plugged into the 6-pin connector on the motherboard. The only clue to it's orientation is that there is a "bk" on one side which I take to mean the black wire on the connector should go to that pin. So, black to the right, green to the left.

The green Ethernet cords are for end-stops. They aren't needed right now. However, they will be handy in the future in case a wrong command is given that causes the platform to move beyond it's designed range.

Now, plug in the AC. Hit the toggle switch on the power supply. Then hit the tiny slider switch on the motherboard. The fan powers on, all the boards have tiny lights on them!

Now, here are the steps I did to install replicator G previous to this power-on moment.
Download ubuntu iso image ver. 10.10 then Burn image to CD & set PC to boot from CD.

CD boots & gives a choice between running from CD & installing. I found I needed to use an older PCMCIA WiFi card since the internal WiFi wasn't recognized.

Once I established linux would work on that PC, I decided to install. Inspecting the pull down menus, Ubuntu gives a choice of using the whole hard drive or a multi-boot install. Amazingly, it auto launches into a partition utility and installs itself WHILE STILL RUNNING in CD EVALUATION MODE!

After install, I decided to install "blender" as my CAD program. This has the ability to generate a .stl file. But where to get it? Simple, from a repository! From pulldown menu --> Administration --> synaptec package manager. Then do a search for "blender"

Finally, let's get the software for the makerbot! Go to makerbot site. It used to be that skienforge and ReplicatorG were two separate programs. They are now one program. Skienforge slices up .stl file and ReplicatorG generates tool path code.
Written in JAVA so the program is cross-platform (Linux, Windows, Mac)

Prerequisites for Linux are JAVA 1.5 and Python 2.5 or higher.
Again, go to the repository to get those two programs installed.

Finally, use firefox to download REPLICATORG-0022 package.
Once downloaded, auto-archiver will automatically open the file. Drag to a spot on the desktop & put in an uncompressed directory.

Inside directory structure, there is a file called 'replicatorg'. Double click to start file. Can either 'run in terminal' or just 'run'. You can also select an .stl file. Then simulate!

Now, back in the present world, here's the fun bit. Boot up the Linux system. Then plug in the USB cable from the makerbot.
On the pull down menu, select
Machine --> Driver --> Cupcake basic
Machine --> Serial port --> /dev/ttyUSB0

Then, on lower toolbar, find the "connect machine" icon.
Then from pull down menu select Machine --> control panel.
You now see a menu which allows you to manually control the stepper motors and extruder temperature!

Make sure the stepper motors go back and fourth under manual control. When "enabled" the motor driver boards light up. The motors will also be a bit noisy when moving. Speed and distance can be set in the GUI. Motors can also be disabled. When this is so, the driver circuits are not lit. Disable the motors if you need to move the build platform by hand. Otherwise the motors will resist any movement as they try to keep that platform in place!

Plastruder attempt2

My thermistors arrived earlier than I expected. So, I tested the two that arrived before rebuilding the extruder. These components also appeared to test open. Three bad components? No way. Then I noticed my ohm meter was set at the high range. Ok, expensive lesson learned here. After switching to the lower range, they tested fine. Even the "bad" one.

So, I re-wrapped the extruder assembly with one of the new thermistors. (Hey, might as well use good looking components) As an experiment, I also added a "K" type digital thermometer probe to the other side of the extruder block. This is from a Harbor Freight digital thermometer (cen-tech 92242) to calibrate or at least be a real-time check of the extruder assembly's temperature.

Post construction note: I'm really glad I installed a separate thermocouple thermometer. Although the software control panel can show temperature when in the control panel window, I can't display that window when I do a build. By having a separate digital readout, it's possible to "see" what the bot is doing. This is handy to establish if the bot is simply waiting to get up to temperature or if there is a problem.

Installing end-stops

The end stops didn't come with the kit but they seem like handy little things so I ordered 6. However, unlike the main boards, these need to be soldered together. The four for the X and Z end stops are pretty straightforward. Just solder them together & connect them to the stepper motor boards with pre-made Ethernet cords. When mounting to the side walls, I found they mounted straighter if I used some tiny rubber washers as spacers since the back of the boards were a little lumpy due to my lack of soldering skill. So, mount them to the walls of the bot & run Ethernet wires to the stepper boards. Each end-stop is for a specific side rather than stopping movement entirely. So, experimenting will quickly show which end stop goes where.

The two end stops for the "Y" stage are much more interesting. Due to size constraints, the "Y" stops don't use RJ45 connectors. Instead, the instructions say to connect the alternate 3-pin connector in the end stop kit. The Wiki even shows the nice photo on the left which shows what wires go where. The first problem I found was that none of my end stop kits came with the nice blue connectors featured in the photos nor the male connectors either! So, I had to make my own. First, I soldered on connector pins I had left over from a previous project. For female connectors, I again look to my junk drawer. Fortunately, I have a pair of 3-pin connectors that are normally used to connect an old style IDE CD drive to a PC motherboard. Yipee! They fit good enough.

So, the problem seems solved. However, just as I was going to connect the other end of the wire to an Ethernet male connector, I decided to double check the Ethernet colors. After all, there are two types of Ethernet cables (type A and type B). My worst fear is confirmed. Inspecting the colors shows that green isn't always green!

So, checking the rep-rap site & inspecting the board suggests that for my T-568B type cable, it will be fine if connect my type-B Ethernet cord using the color order as the Makerbot Wiki photo suggests. (If I was using a "T-568A" cable, the green would be orange) As for the orientation of my connector (up or down), Looking at the board circuit & comparing it to the end stop schematic on the rep-rap site, it looks like Brown is ground. This then tells me to make sure my connector is plugged in so brown traces out to ground on the end stop board. Fortunately, the ground is noted on each end stop board.

The yellow arrows show the end stops installed. As for neatly running wires along the Y stage, bent paperclips come to the rescue again! Here, you can see how 3 hold the wire with the help of some X-stage bolts, then join the Y-stage stepper motor wires which go out the side. I experimented with wire-wrapping everything in a big bundle but found that the wires look less likely to jam if they are just left loose.

The Y and X stage provide slots for end stop triggers. I read that some people use Popsicle sticks for triggers. So, after a quick Popsicle eating orgy, I gathered enough sticks for the task. Here, you can see that i had to extend the X stage sticks (note hex nuts) and cut down the Y stage sticks. The Z-stage doesn't have ready made slots for installing end stop triggers. I'm thinking the bot could probably fabricate some glue-on "L" brackets at a later time. Meanwhile, the Z-stage works fine without them. Also, the little white squares on the Y stage are just spacers that I'm using to level the platform.

extruder assembling - attempt#1

Finally! Here's what I anticipate would be the hardest part of the build. Fortunately, the instructions are very good so I have very little to add. It takes a while. Also, I used silver solder on the resistor heaters rather than regular solder. Hope it holds! Once done, this assembly looks like it's all ready to bolt into the plastic arch I constructed earlier. But wait! Let's do a final electric test. Resisters test as they should. Darn! The thermistor tests open! After cutting the Klapton tape off and carefully removing the white insulation strips to inspect the component, I concluded the solder joint was fine but the component is dead. So, I need another. Since I have a habit of breaking delicate parts such as these, I ordered two more & I figure I might as well also order a motor mount insert kit too since shipping is such a large part of the order. Hopefully, the law of spares will prevail and I will only need one of the two thermistors.

POST CONSTRUCTION NOTES:

• Upon testing, I found that plumbing solder (with silver) worked great for connecting the heater resistors. Higher temperatures (even to 260c) were no problem.
  
• It turns out I didn't need to order another thermistor after all. After ordering, I discovered that I had my multimeter Ohm setting set to the high range! Setting to low showed all thermistors working fine. Doh!
• Also, there is ONE change to the extruder instructions for the MK5 to be aware of. It is the orientation of the drive gear. In the instructions, it MIGHT have a photo of the gear installed backwards. If so, that's wrong. See photo below as to why (click to enlarge).

Some wire connections and installing the relay board

Time to connect all the stepper motors to their relay boards. One issue I ran into was with the Y-stage stepper motor wires moving with the X-stage. It looks like the wires would get caught under the X-stage as it moves back and forth. So, using a bent paperclip, I made a wire holder to raise the wires out of the way as the X-stage moves back and forth.

The relay board (green board, upper right) will accept a signal from the plastruder board & energise one of two relays that then allows a much greater current to go to the plastruder. The relay next to the plastruder relay will eventually be used to power the automated build platform. Soldering together and mounting the board was uneventful. However, when it came to connecting the power, the remaining power supply connector would not reach! No re-arrangement seemed to help. What to do?

Fortunately, I happened to have a power supply extending cable that I salvaged from a dead PC from years back. I'll admit that my habit of salvaging useful looking parts from dead equipment rarely pays off. However, when it does, it's nice.

When it came to making the ribbon cables connecting the motherboard to the stepper controller boards, I divided the provided rainbow wire into equal 3rds so all cables are interchangeable with each other. I also noticed the connectors I was provided with have no strain reliefs. So, I'll need to be extra careful not to wiggle those wires too much! I also discovered that spinning the stepper motors causes indicator lights to illuminate on the stepper motor controller boards even though I haven't applied any power yet. I take this to be a good sign.

Assembling the filament spindle

I decided to splurge and get the makerbot filament dispensing kit too. Although I could have made something similar, I didn't want to have this step be a project stopper.

Just like previous parts of the kit, you get a box of wood and some hardware to put it together with. Since I really didn't want to take a lot of time on this step, I didn't bother finishing the wood before starting.

I found I had to sand a few tabs to pre-fit some of the parts. Unlike the instructions, I decided to construct the main box first. After screwing it together, I also decided to put hot-glue on the joints which might help reduce dust and moisture that could cause problems later.

After assembling the main box, I assembled the bottom part of the reel, then did a test fit inside the box. Perfect! Testing the reel top, I found I had to sand the rib tabs before the top of the reel would would pre-fit. Even using sticky tape to hold nuts in each of the reel ribs, it took a while to line all the pieces up for a test fit. Finally, the plastic coil was put on the reel, ribs lined up, bolts put in. Then the whole assembly was lifted into the box and bolted in. The steps I took are shown below.

Before the final step of screwing the cover on, be sure to feed some plastic out the top (see upper right where plastic comes out the brass fitting). And....we're done for tonight!

Makerbot assembly moved to Auburn

I've decided to move the Makerbot back to it's home base in Auburn. It was a difficult decision but my January schedule just won't allow me to make it to the Syracuse Hackerspace. I really like the space but my schedule just won't allow it this month!

So, time to unpack and resume assembling. Now, it's time to peel off the protective paper from these plastic bits to put together the plastruder! These pieces are sandwiched together with bolts - all quite clever. The Makerbot site has really good photos of how all this is put together.


Here's how it looks so far.