Pleasant Hardware

My first design of a printable extruder (the “Printruder”) was quite a success. Not only that I printed lots of objects with it, there are also several other MakerBot operators, using a Printruder successfully as a drop in replacement for the MakerBot Extruder MK3/MK4.

Nevertheless, I tried to simplify the design of the Printruder since a while for several reasons:

• Reducing the number of parts to print
• Easier loading/undloading of filament
• Easier adjustment of pinch pressure
• Stylish design : )

Here’s what I came up with:

The Printruder II

The Printruder II is built from only 2 printed parts (click on the images to zoom in):

• The Motor Block is now self-supporting, so no more base plate. I also integrated the insulator retainer plate. So instead of three printed parts in the Printruder, we now have only one:
  
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• The Idler Block is much smaller than the idler block in the first Printruder design. It’s now integrated inside the motor block. With this design, it’s now possible to press the idler wheel against the pinch wheel with only one bolt. This makes it very easy to load/unload the filament and also to adjust the gap between idler wheel and pinch wheel:
  
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Download the STL files for all printable parts at thingiverse.com: http://www.thingiverse.com/thing:1980

Intructions

Here’s what you need to build a Printruder II:

• Printed Motor Block^*)
• Printed Idler Block
• 3 x M3×20mm bolt
• 1 x M3×16mm bolt
• 1 x M4×40mm bolt
• 3 x M3 washer
• 1 x M4 nut
• 3 x M3 nut
• 6mm pipe or rod, 20mm long (alternatively a M6×20mm bolt)
• 2 x M6 washer
• 2 x 626 ball bearing
• Kysan DC Gear Motor
• MakerBot pinch wheel or better: 10mm worm-gear style pulley^*)
• MakerBot heater section
• Extruder controller board

Optional:

• Printed PCB holder (2 parts)
• 4 x M3×16mm bolts
• 4 x M4 nut

Most likely:

• Printed extruder holders

^{*) Please note that there are two slightly different versions of the motor block: one for the original timer belt pulley (pinch wheel) and one for the 10mm worm-gear style pulley. Be sure to print the correct one!}

Step 0:

Print all printed parts.

As always, it’s a good idea to clean all holes with a drilling machine (or something like that) after printing.

Step 1:

Insert a M3 nut in each hole in the bottom of the motor block (left and right of the filament path). These captive nuts are needed later to attach the heater section to the motor block. Handling the M3 nuts inside the motor block is a very fiddly thing. Also they tend to fall out when turning the motor block over later. Thus I strongly recommend to use (a little!) hot glue on the M3 nuts when inserting them. Don’t use too much glue! Just a little bit on the outside of the nut.

The best way to insert the nuts is to stick a long M3 bolt though the hole in the motor block (from the outside). Then put the nut on the bolt, apply a little bit of hot glue and then pull the bolt back until the nut sits nicely, all the way down, inside the hole. Wait a few seconds for the glue to set, then unscrew the bolt (see also this image).

Step 2:

Now assemble the idler wheel: Put a M6 washer, the 626 bearing and then the other M6 washer on the 6mm axis (I use a 20mm piece of 6mm aluminum pipe, but you might also use a M6×20mm bolt or something). Press this assembly into the printed idler block, so that the two M6 washers are inside the brackets, acting as spacers for the ball bearing. The axis should snap into the brackets and hold the bearing snugly inside the idler block.

Step 3:

Insert a M3 nut in the hole on the backside of the idler block. The nut’s only purpose is to give the M4 set screw (see later) some target to press on (the ABS plastic is too soft to hold the pressure alone). Then insert a M3×16mm bolt into the hole on the side of the idler block. This bolt, again, doesn’t hold something down, but simply stabilizes the M3 nut. That way, the M4 set screw cannot sink into the idler block later.

Step 4:

Insert the whole idler assembly in the motor block. Be sure, that the head of the M3×16mm bolt is on the front.

Step 5:

Put the M4 nut into the hole on the right side of the motor block. The best way to do this is to use the M4 bolt (same thing as for the M3 nuts in step 1). Only this time, you can let the M4 bolt where it is when finished. It also might be helpful to use some hot glue on the nut (just a little bit!).
Finally, move the insulator block to the right.

Step 5:

Attach the DC motor, including the pinch wheel, to the motor block.

Use three M3×20 bolts with M3 washers to bolt the motor to the motor block:

Tighten the bolts, but remember that the motor block is out of ABS plastic! Don’t overdo it…

Then put a 626 ball bearing on the end of the motor spindle. Be careful not to block the idler wheel with the motor’s 626 bearing! It’s probably not necessary to push the ball bearing all the way on the spindle. If needed, use a drop of hot glue to fix the ball bearing, but be careful not to glue down the ball bearing itself!

If you’re using a worm-gear style pinch wheel (what’s a good idea for several reasons), the motor’s ball bearing is probably not necessary, since worm-gear style pulleys usually need much less pressure from the idler wheel to grip the filament properly. Your milage may vary.

Step 6:

Attach the heater assembly (a new one or one cannibalized from a Mk3/Mk4 extruder) to the motor block, using the two M3 nuts from step 1.

Be careful not to push the captive nuts out of their holes!

Success:

That’s it, you built a Printruder II:

At least the non-optional part…

PCB holder:

Since it’s a nice thing to know where to put the extruder controller board, I designed an optional PCB holder for the Printruder II (and maybe other extruders). The PCB holder is composed of 2 printed parts:

Clip the front holder on the DC motor and move it towards the motor block.

Clip the other holder on the motor…

… and use 4 M3 bolts to attach the extruder controller to the PCB holder:

Using the Printruder II  with a MakerBot

Although the Printruder II can be mounted in a MakerBot with the original acrylic dinos, you’ll most likely end up with a nozzle too high, depending on the heater section (especially the heater barrel):

As you can see in the above picture, the nozzle is on about the same height as the lower end of the dinos. If this would be attached to the z stage, you’ll never get the nozzle low enough to touch the build stage.

Therefor I also designed printable replacements for the dinos. You find the designs on thingiverse.com: http://www.thingiverse.com/thing:1912

What’s the story with the worm-gear style pulleys?

The worm-gear style pinch wheels have much better grip than the timing belt pulleys, used in the original MK3/MK4 extruders. That’s why they don’t need so much pressure on the idler wheel, which not only gives the motor bearings some rest, but also results in much less damage to the filament (i.e. less need to floss the gears).

Unfortunately, there’s currently no way to buy worm-gear style pulleys anywhere (at least to my knowledge).

MakerBot Industries did some test with CNC manufactured worm-gear style pulleys. But I have no idea if they (still) plan to sell them in the MakerBot store and if yes, when.

I manufactured mine on my lathe:

Although I’m getting better (and faster) in building these pulleys, it’s still a lot manual labor involved (I don’t have a CNC lathe!).

Due to the time-consuming manual production:

1. these things ain’t cheap (25 Euro + tax (if applicable) + shipping)
2. when out of stock, I’m not sure when I have the time to built more.

The pulleys are made out of brass (outer diam. 10mm, inner diam. 6mm.) and they come with a M3 set screw.

If someone’s interested in one of these, please contact me (mail [att] pleasantsoftware [dot] com). I have a couple of them lying around as spares.

Today, I release Pleasant3D v2.0 to the public and when reading the list of changes, most people might ask why there’s such a big step in the version number:

What’s new in Pleasant3D v2.0:

• More intuitive (trackball) view rotation
• Panning views with right mouse button drags

Well, as you might have guessed already, that’s not all. The main change is that I finally merged the former other, larger project and Pleasant3D to … well, Pleasant3D v2.0. So the missing point in the above list is:

• Initial release of “the real Pleasant3D”

Foreplay

Back in June 2009, after I ordered my MakerBot Deluxe Kit, I was in state of anticipation and impatience, most of you other MakerBot operators probably know from own experience: The order’s finally placed, but it takes 4 to 6 weeks until the kit eventually ships.

I read all reports on building and operating a MakerBot in the internet (there wasn’t that much blogs on this back then) and of course, I downloaded ReplicatorG and Skeinforge to play around with them.

As a (very) long time and hardcore Mac user and developer, I quickly thought about a nicer, cleaner and faster way to produce GCode and eventually print objects than ReplicatorG and Skeinforge.

Don’t get me wrong: I think Skeinforge is a really amazing piece of software, it’s ability to process “incorrect” 3D objects and the GCode it creates is just great. I also think that MakerBot Industrie’s decision to provide cross platform support on the software side with ReplicatorG as printing software and Skeinforge as GCode generator is absolutely great and important (I’m still struggling with my Mendel because the native Reprap software currently doesn’t really support Macs).

But I also think, that it would be nice to have an alternative – not that universal, but maybe better – way to handle 3D processing for printing stuff.

That’s why I started to develop Pleasant3D, to play around with something during waiting for the MakerBot Kit to arrive.

My plan was to create a tool to not only provide a native way to preview STL and GCode files, but also to transform STL files to GCode.

I didn’t (and don’t) want to provide another cross platform tool for those tasks, struggling with GUI and performance tradeoffs caused by the need of portable code. I explicitly decided to develop a high performance, native GUI tool for the system I’m working on (which is obviously Mac OS X, sorry Windows and Linux users), using all cutting edge technologies available in the most recent OS (which is Mac OS X 10.6, sorry PPC and Leopard users).

Failure

My first approach was, to port Skeinforge’s open source Python code to native Objective-C code. I started with Skeinforge’s Carve tool and it was a disaster. Not only it was kind of uncreative and boring to port existing code to another programming language, but the resulting code was also even slower than the original code.

The reason for that is, that each programming language has it’s pros and cons. One of Python’s pros is, that it’s very fast in creating objects. Unfortunately, creating objects in Objective-C (like C++ also based on C) isn’t its fastest feature. So by porting the Carve code 1:1 to Objective-C, the code still used the original algorithms, based on the creation of zillions of objects during carving a 3D object. Not a good idea in ObjC.

The Carve tool is the first step in processing a 3D object for 3D printing. It slices the object horizontally. For comparison I used a nice object from Thingiverse: Eggcup With Salt & Shell Trays

Carving this STL file (containing 5486 triangles) takes about 9 seconds in Skeinforge (0.4mm layer thickness, 2.8GHz Intel Core 2 Duo MacBook Pro):

When carving the same file with my first version of the ported Carve tool, it took more than 12 seconds with the native code!

So I started to optimize the ported code, implemented caching collection classes, reusing memory and objects whenever possible and so on.

I finally got a version of the native Carve tool, running faster than the Python script:

Speeding up the carving process by factor 2.3 doesn’t sound too bad, but I couldn’t believe that this would be the best possible result. Especially since the porting process was really boring!

So I threw away the whole thing and started from scratch again. This time by creating my own, new algorithms and pulling all the stops Snow Leopard provides: GCD & OpenCL.

Success

I called the new tool “Slice”. Changing to a new algorithm and OpenCL really paid off. But see for yourself:

That’s more like it: 39ms, 230x the speed of Skeinforge…

Present and future

Please don’t throw away Skeinforge yet! Pleasant3D is at a very, very early stage. It’s fragile. It needs clean STL files with normals. And there’s not a complete set of tools yet. The whole thing still needs a lot work.

Pleasant3D v2.0 is still the same tool we love and know for viewing STL and GCode files (including moving/rotating/resizing STL objects). It also contains the same QuickLook plugins for STL and GCode. All these features are more or less stable.

In addition to that, there’s a new kind of document: The P3D document

You create a tool chain by dragging & dropping available tools from the toolbox panel to the tool bin. Each tool gets its input from the previous tool’s output. If you change settings in a tool at the begin of the tool chain, the results of these changes automatically “ripple” through the whole tool chain. With the current speed of the few available tools, this happens almost instantly.

Here’s a teaser video of the whole thing:

The deal

The Slice&Dice part of Pleasant3D isn’t ready for prime time yet! It’s work in progress.

I decided to publish it anyway, since I’d appreciate any help with the tools and printer drivers.

So here’s the deal:

Pleasant3D is a free download (as usual). The GUI part of the project is still kind of semi-closed source (more on this some other time).

However, all tools are implemented as plugins. So are the printer drivers. And they will be will be open source. I’m currently working on a way to publish the sources. Very likely they’ll be available through public access to a Mercurial repository.

You can start developing tools right away. All you need is a copy of Pleasant3D v2.0 (or later), a working installation of Xcode v3.2.1 (or later) and the following shell script:

InstallDevSupport.zip

Copy Pleasant3D to your /Applications folder (no subfolders!). Then run the InstallDevSupport script:

• Open a Terminal window
• Go to the folder containing the InstallDevSupport script (cd <path to InstallDevSupport.sh>)
• Run the script (sh InstallDevSupport.sh)
• Enter your admin password

Re-launch Xcode after that. When you now create a new project in Xcode, there should be a Pleasant3D project template available. Use this template to create a new Pleasant3D tool project. Please read the ReadMe.txt file inside the new project folder for important additional information.

In addition to the sources of the current tools, I’ll try to provide some additional sample code as soon as possible.

You can download Pleasant3D v2.0 from the Pleasant3D download page.

That’s it for now. Stay tuned for more shortly.

As you might know, I’m in the process of building a Mendel.

There are two reasons why it’s not printing yet:

On the software side, I still didn’t manage to bring the Reprap software to life on my Mac. After tinkering around with some Java frameworks, settings and class paths, I was eventually able to launch the host software. But somehow I wasn’t able to establish a connection between the host software and the RepRap firmware on the Mendel.

Right now, I switched back to the MakerBot firmware, in order to be able to use ReplicatorG to test drive Mendel’s mechanics. When I solved the remaining problems on the hardware side (see below), I’ll probably try again to use Mendel’s native RepRap firmware/software.

On the hardware side, I still don’t have a high torque NEMA 17 motor on my hands. However, I have a NEMA 17 stepper laying around. It’s the same cheap, low torque type, I’m using to drive the X,Y and Z axis.

This stepper is rated to provide a holding torque of only 0.23Nm, which is obviously too low for using it in a RepRap Thermoplast Extruder v2.0.

I tried it anyway:

To grip the filament, I put a treaded pulley on the motor’s shaft. I built it on my lathe and tried keep the shaft’s diameter as low as possible: the pulley only adds 1mm to the motor’s shaft diameter, so it now has effectively 6mm diameter.

According to the rated torque, theoretically this motor should be able to pull the filament with about 76N (i.e. around 7.5kg on the balance).

But when I tried this setup, the motor started to skip steps at about 2kg on the balance (i.e. ~ 20N). That’s way to low, even for PCL filament.

I guess, the main problem is, that I don’t use a real stepper driver to power the motor, but the RepRap/MakerBot extruder controller with the “2x DC motor drivers  -> stepper motor hack”. So the stepper motor probably doesn’t get enough current to produce it’s rated torque.

The obvious solution for this problem would be to buy a high torque stepper motor and/or use a well dimensioned stepper driver. Well, maybe I’ll eventually end up doing exactly this. But then again, I had this idea some time ago, when I lathed my first threaded pulley, to use one of these threaded pulleys as part of a worm gear.

I decided to first give this idea a shot…

Here’s the design, I came up with:

I drilled a 5mm hole in a piece of M8 threaded rod and added a set-screw, so it can be attached to the shaft of the stepper motor:

The central part of the gear box is the following part. It’s made out of brass and has two threaded grooves, one M8 (for the worm gear) and another one (M3) to grip the 3mm filament:

Ok, this is earlier than expected: Pleasant3D v1.2 is out.

The quick update was necessary due to a nasty bug in v1.1 which caused wrong positioning of STL objects in some cases. This issue is fixed in v1.2. I also smoothed out some remaining problems with the 64-bit build. So if your computer supports 64-bit applications, Pleasant3D v1.2 will be one of them…

Finally I added automatic update checking (thanks to the Sparkle framework). From now on, when I  screw up a version (as I did with v1.1), you won’t need to manually download a new versions a few days later. The automatic update window will pop up and offer an easy one-click update.

However, if you’re still on v1.0 or v1.1, you definitely want download Pleasant3D v1.2 manually.

I’m happy to announce the release of Pleasant3D v1.1.

There are some awesome new features in the new version:

• Pleasant3D now includes QuickLook plugins for STL and GCode files!
• The preview views are now zoomable.
• Objects can now be rotated by arbitrary angles.
• … and many more.

Check out Pleasant3D’s brand new home page for a full feature list.

I recorded a short movie, showing off the new features of Pleasant3D v1.1:

Thanks’s to all of you, sending me feedback!

Pleasant3D v1.1 is available for free download here: http://www.pleasantsoftware.com/developer/pleasant3d

I’m back from Berlin. Happy new year to all!

The highlight of my Berlin visit was definitely meeting Bre from MakerBot Industries on 26c3 (Chaos Communication Congress).

We had a great time talking about this , this , this and that , and some other awesome stuff.

Of course, I’ll write on all this in much more detail, as soon as the above projects are a little more developed and mature.

Afterwards I had eventually the opportunity to see Bre’s talk on MakerBot and other frontiers at 26c3:

The talk is available as MP4 video. There are several mirror servers for the 26c3 videos, check this page, if the above link doesn’t work, and look for talk #3637.

It was a really great evening.

I’ll be definitely at 27c3…

Tomorrow morning I’m leaving for 26C3 in Berlin for a few days. I plan to meet Bre Pettis from MakerBot there. If anyone else of you 3d printer operators is around, I’d love to meet you too. Just send me a mail…

My Mendel is almost finished (at least the mechanical assembly).

All printed parts were successfully printed raftless in black ABS on my MakerBot with heated build platform.

Although I’m quite fond of Mendel’s overall construction, I changed the design of a few parts.

For example: the timing pulleys. In order to attach an original timing pulley to the motor, one’s supposed to file two flats onto the motor’s shaft. I tried it on one motor and it was a pain in the ass. Maybe it’s all about the right tools, I don’t know. I used a full sized file and a vise, but I didn’t manage to get the flats right. In addition to that, I rather don’t do any irreversible modifications to expensive parts (i.e. stuff I have to order, like stepper motors). After all, once you messed up a motor’s shaft, you cannot use it anymore…

So I aborted my luckless attempts to get the drive shaft right and rather changed the pulleys’ design to have normal, round holes. I designed the holes to be exactly 5mm wide, but due to ABS shrinkage they turn out a little bit smaller. After cleaning the holes with a 5mm drill, the pulleys fit very snugly on the original motor shafts.

Since the force on the X/Y/Z axes aren’t that high, I’m pretty sure that the pulleys won’t slip on the shafts. And if they do, it’s probably much easier and more reversible to drill a hole for a splint pin through the whole assembly…

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Another problem to solve was the pinch wheel part in the pinch wheel extruder. I decided to go with a threaded pulley.

In order to keep the diameter as small as possible, I lathed the threaded pulley with an outer diameter of about 9 mm; with the 5mm hole for the shaft and a M3 thread groove, the pulley adds only 1 mm to the drive shaft’s diameter.

Unfortunately, the steppers I have are way to weak for a Mendel’s extruder. So I hadn’t a chance to test the pulley in a working extruder yet.

If anybody has easy access to one of these high torque NEMA 17 motors and likes to send me one of these in exchange for one of my threaded pulleys, please feel free to contact me!!

Actually, I’m really thinking about selling these threaded pulleys. Anyone interested? Here’s my official pack shot:

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After completing the mechanical assembly, I’m now about to wire the whole thing up.

Which brings me back to my concerns on doing irreversible (or better: hard to undo) modifications on expensive parts: According to the build documentation, several “adaption” on the motherboard and other PCBs are needed.

Although I’m ok with desoldering the RJ45 connectors for the endstops on the stepper boards (I always found the Ethernet cables way to clunky for connecting the endstops…), I really don’t like the idea to remove the ATX power connector from the motherboard.

Besides the technical challenge and a childish “must-have” attitude, one reason for building a Mendel was (and is) to have a mutual backup for/by my MakerBot. That not only includes the convenience of being able to print replacement parts for the other machine, but also the to use the identical electronic hardware as a backup. By removing the ATX power connector from the Mendel motherboard, I’ll loose this advantage. And I’d rather not.

I hope I’ll find a way to use the unmodified motherboard in the Mendel (adding the I2C connector is ok, that’s adding, not removing…). There must be a way, maybe by doing a few firmware changes…

Does anyone have experience with this? Any help appreciated!

As mentioned before: among other projects, I’m currently in process of printing a Mendel.

Thanks to the heated build platform in my MakerBot I’m able to print in ABS without rafts. That not only saves a great deal of time and plastic, it also eases the process of cleaning up the parts after printing significantly.

I print all parts with an infill density of 30% (.3). The black ABS is extruded at 225°C, flow rate 243 and feed rate 28mm/s.

So far,  I had no problems with printing any of the parts. Even the larger ones (like x-carriage-lower_1off or x-carriage-upper_1off) printed out nicely without warping.

Due to the absence of rafts the amount of wasted plastic is amazingly low so far.

Actually, the only two failed prints were caused by “external” problems, i.e. filament jams outside the MakerBot. I really need a good solution for putting the filament on spools as soon as possible…

Of course, there were minor problems like bad manual homing of the extruder head and such things, but these problems are usually noticeable during printing the first layer of an object. Early aborting one of these bad prints doesn’t waste much plastic nor time.

***

A week ago I received the metal parts of my future Mendel. I ordered them -except the ball bearings- from the German branch of the company mentioned by the RepRap project in the Mendel assembly data sheet. Because of the much lower price, I ordered the ball bearings from another company (e.g. 624 bearing @ .78€+tax instead of 1.15€ + tax).

I bought all bolts, nuts and washers from a local bolt-nuts-and-washers-dealer nearby (… always support your local dealers, right?)

Besides printing Mendel parts on my MakerBot (about 80% completed so far), there’s some other stuff to do:

1. trimming the bars and studding to the correct length
2. somehow creating the “thick sheet” parts without a laser cutter (which I unfortunately don’t have any access to)

Lucky me: my brother owns an organ builder workshop (actually founded by my father), only a 1.5 hours driving time away. So why not doing a nice visit before Christmas…

Having access to the workshop’s machines made it much easier to do the trimming of the rods.

I created the “thick sheet” parts out of plywood. With help of a scroll saw I was also able to cut the weird shaped “y-chassis” piece.

I had problems with the long slot holes in the “motherboard-plate” and “stepper-plate”. I tried to machine them with a router, but I couldn’t get them nice and straight. Eventually I figured that most of these slots are only needed to universally mount arbitrary PCBs to the plates. So in absence of a laser cutter or a CNC router it’s probably the easiest way to skip the long slot holes completely and just drill the holes needed for the PCBs you’re actually mounting to the plates…

Concering the “y-chassis”: I wish there would be a way to use a more or less rectangular shape for the actual thick sheet part and rather print the funny shaped parts. Something like this:

That way, it would be much more easy to create all thick sheet parts with common tools like a circular saw and/or jig saw. That’s already true for all other thick sheet parts.

***

Today I ordered the last missing pieces for the Mendel: The stepper motors and the electronics kit.

I ordered these parts not from MakerBot, but from an electronics internet store located in Germany. Considering the (rather high) international shipping costs at the MakerBot store, plus the potential tax and customs fee (if the package doesn’t slip through customs), the parts are about the same price when ordered from a domestic distributor. The electronics kit was (and is, again) out of stock in the MakerBot store anyway.

So far, the costs for my Mendel are (plus VAT):

Bearings	52,80 €
Fastener	32,62 €
Bar/Studding/Belts	69,10 €
Electronics + Motors	171,41 €
	325,93 €

Not yet counting the ABS for printing parts and some minor other stuff (power supply etc.).

However, it looks like I’m still in the £309,33 (about 344,13€) range, the Mendel-m4-assembly-data-sheet declares.

Assuming the printing of the remaining Mendel parts doesn’t take more time as expected, I should be able to finish my Mendel by end of the week. I’ll let you know…

As regular reader of my blog, you already might have noticed that I’m working on several different projects at the same time. Recently these are mainly the heated build platform/raftless printing, a LCD display and last but not least, a .3mm extruder.

After breaking my trusty Printruder during my first .3mm nozzle tests, I had to reprint broken parts for the Printruder, which lead to a heated build surface, which lead to modifying the extruder firmware, which lead to integrating a I2C-LC display… After my recent tests with raftless printing, I eventually came back to the original project: the .3mm nozzle.

Since it was a bad idea last time to use my one-and-only Printruder for the nozzle tests, I started to design a new extruder for this purpose. My first tests with a stepper motor driven extruder weren’t too promising (… the lack of force it was able to push the filament with. Probably a design flaw of mine. I already started redesigning the whole thing, but this is yet another project…), I plan to drive the new extruder with tested and proven mechanics: Printruder motor/gear brackets and MakerBot DC gearmotor with a threaded pulley. For the heater section, I already started to build a PTFE/insulator free design a while ago. After a couple of drawbacks, I finally did a successful first heater test today.

The heater barrel is definitely inspired by nopheads extruder barrel designs:

But there are several differences:

1. I used brass instead of steel. This might be a disadvantage, since brass has a way higher heat conduction. But I only had brass rods laying around and I’m also not sure if it is more difficult to turn such part from steel. I suppose it mainly depends on the type of steel. So I stick with the metal I am currently used to, after all I’m still a greenhorn when it comes to working with a lathe…
2. I designed the barrel to hold a heat sink, since the Plastruder doesn’t contain any large aluminum parts I can use for this.
3. I still use nichrome wire to heat the nozzle.
4. The barrel has a M6 thread on one end in order to mount a standard MakerBot nozzle on it.

The thin part in the above photos is still 5mm in diameter since I was afraid to rupture the barrel (there’s a 3.5mm bore inside, you know…?).

But that was a real problem during my first heater test: Probably also due to the high heat conduction of the brass material, it was impossible to reach decent nozzle temperatures. Instead, the heat went straight to the heat sink and the upper end of the barrel.

So I disassembled the whole thing again and boldly turned an additional 1mm off the thin part. It’s now 4mm in diameter which means, that the wall thickness is only .25mm.

Here’s an image of the reworked heater section, right before the new temperature test:

Reducing the wall thickness did the trick!

It’s now quite fast and easy to reach ABS extruder target temperature (220°C).

I tested the setup for about 10 to 15 minutes. Here the results:

Target Temperature (Replicator G)	Themistor (Replicator G)	Nozzle outside	Top barrel nut	Heat sink top	Heat sink down
220°C	217°C	180°C	60°C	61°C	69°C
240°C	234°C	193°C	70°C	81°C	88°C

So far so good!

Now I need to print a special retainer plate to attach the heater section to a Printruder and eventually try to extrude some ABS…

It might take a few days since there are all this other projects… And to spice things up, I just printed my first part for a Mendel yesterday