Thursday, March 13, 2014

A Better Cooling Fan for PLA

You need lots of cooling air when printing with PLA in order to keep the plastic from moving around and deforming. I have a MendelMax 2.0 printer, as well as a Makerbot Replicator 2 (which I won). At first I wasn’t that excited about the Makerbot because I had heard about how it wasn’t a good design and had problems. Until, that is, I tried it. The Makerbot nearly always produced better prints than my MendelMax.

The Makerbot produces better prints in two ways: it has no Z artifacts that I can see, and it is amazing at handling overhangs and small features. It was a while before I realized that the secret to the overhangs was the choice of fan on the Makerbot. Unlike almost all FFF 3D printers on the market, the Makerbot doesn’t use a standard 40mm case fan. Instead, it uses a 50mm blower fan (more on this later).

My Journey

The MendelMax came with a single 40mm fan that mounted to the front. I was actually pretty happy with this fan at first. But then I found some designs were harder to print, and I read about Ohmeye’s use of two 40mm fans to increase the airflow.

So I designed my own version, which looked like this:


I was very happy with this design until my experience with a Makerbot Replicator 2 that I won in September 2013--it did a much better job ad made me realize there was much more room for improvement with my MendelMax 2.0. Since then I’ve been working on improving my MM 2.

I decided to try making a fan duct that would pressurize the air around the nozzle to provide even better cooling. I started out with a fairly small slot at the end, but not much air came out. I kept enlarging the hole until I ended up with this design:


The opening at the end of the duct is larger than I wanted. I wasn’t sure why the smaller slot didn’t work well, and then I noticed air was being blown back out of the fan around the outer ring. In other words, when I placed my hand near the fan (to the left of the fan in this picture), I could feel quite a bit of air hitting my hand. That meant more air was being blown back out than was going through the nozzle.

So how much of a difference does it make to have a fan duct instead of two fans? The photo below shows the difference, looking from the bottom of the parts. I printed the part on the left with my original two-fan setup, and the part on the right was printed with the fan duct plus an angled fan. You can see I got much better results replacing one of the fans with a ducted fan:


In other words, yes, good cooling really makes a difference, especially with the overhang in this design.

At this point I probably could have stopped. However I took a better look at the Replicator 2 and discovered they used a completely different type of fan. The fan they used is a centrifugal fan (also know as a blower fan or squirrel cage fan) instead of an axial fan. These fans seem to be much better at pressurizing the air, and therefore can provide a faster flow of air over the nozzle.

Here is the fan I purchased for my MendelMax:

This is a 24 V fan since the MendelMax uses 24 V for the heaters and fan.

The “Final” Design

I designed a new fan duct to use the centrifugal fan, and I decided to if this single ducted fan would be as effective as my two fans (with one being ducted). It was.


I’ll have this design up on Thingiverse soon. Right now it’s not letting me publish a new thing because it keeps forgetting about the STL files that I’ve included. You can find the files here:

Sunday, January 19, 2014

Building the 3DR “Simple” Delta Printer, Part III

3DR “Simple” Delta Printer, Part I
3DR “Simple” Delta Printer, Part II
3DR “Simple” Delta Printer, Part III
Building the 3DR “Simple” Delta Printer, Part I
Building the 3DR “Simple” Delta Printer, Part II
3DR “Simple” Delta Printer Firmware Settings

This time we’ll look at building the effector, extruder, and finishing up the build platform.

Assembling the Effector

There are five parts that make up the effector and hot-end mount. Begin with the three parts shown below. Place the hot end into the slot, and also place the push-fit connector into the smaller slot. These will both be held in place firmly once you have all the screws in place.


Next use four 6-24 by 1 inch (or 1 1/4 inch) screws (you could also use M3 x 26 screws) to bold the three parts together as shown. Use Nyloc nuts on the back side to ensure they won’t come lose over time. You should have a gap of a couple of millimeters between the two larger parts before you bolt them.


Next, using three M3 x 24 screws, attach the effector to this assembly. Note that the assembly fits onto the effector in only one orientation. The image below shows the effector before attaching the rods, but you can just as easily install the hot end after installing the effector—it’s easier to photograph before it’s been installed.


Finally, add the fan holder to the bottom. The fan holder has slots for M3 nuts:


The fan is held in place by two M3 x 12 screws and nuts.


Building the Extruder

I built the extruder using the files from RichRap’s site, and you can find the links in Part I of my series. The only change I made was to add a spacer, shown in yellow below, to provide more clearance between the larger gear and the carriage.


I mounted the extruder so the yellow extension is half way between the top and bottom of the printer. The PTFE tube from the extruder to the hot-end is about 400 mm long, and I put this, as well as the wires (thermistor, heater, and fan) inside a stretch tube to keep things neat and tidy. I also used another stretch tube to run these wires as well as the stepper wires back to the Printrboard mounted under the top of the printer.

Leveling the Print Bed

I found it much easier to manually level the print bed than to get the calibration just right. Some people have suggested that I use the M666 g-code command. I took RichRap’s firmware and plugged in my own numbers, and his version doesn’t have M666 support. So I took a different route. The Printrbot Simple comes with four springs used as part of the bed leveling system. I decided to use the same approach on my printer, so I created these Bed Clips.stl.


Print three of them and clip them onto the bed, evenly spaced. Also print three thumb wheels: Although I designed these thumb wheels for the Printbot Simple, they work just as well for this printer:


Insert the M3 x 20 screw through the knob and hold in place with an M3 nut (you can see both in this photo). Then place one of the Printrbot bed-leveling springs under the bed and insert the screw. By the way, the print bed here is a 1/8” thick laser-cut acrylic bed that I’ve been experimenting with in place of the glass. Since it’s not a heated bed, the acrylic works just as well, and doesn’t require the clips. You can find the cut file for this part here: Acrylic Plate.dwg.

Filament Holder

I tried various filament holders for my 3DR “Simple,” and then I found the perfect one, by Reprap Forum user Funkymonk: GOYO 3DR SIMPLE SPOOL HOLDER.stl along with this Thingiverse part: 3-size spool holder:


This filament holder requires two 608ZZ bearings, one M8 x 60 bolt, two M8 washers, and one M8 nut. I thought I might have to create a guide for the filament, but this the filament role turns so easily and smoothly that a guide isn’t required. I must say this works very well, and I’m very happy. Thank you Funkymonk!

Firmware Settings

I’ve updated my previous blog post on firmware settings to reflect the latest design: 3DR “Simple” Delta Printer Firmware Settings. There you’ll find numbers to use for the different firmware settings. RichRap also has a very good tutorial on setting up the firmware: 3DR build tutorial Part4 Firmware.

Here are some links to information on downloading firmware to the Printrboard:

Tuesday, December 3, 2013

Building the 3DR “Simple” Delta Printer, Part II

This is the fifth part in my series on a delta printer that I designed, which started life as just a few changes from RichRap’s similarly named 3DR RepRap Delta Printer. Here are the previous posts:

3DR “Simple” Delta Printer, Part I
3DR “Simple” Delta Printer, Part II
3DR “Simple” Delta Printer, Part III
Building the 3DR “Simple” Delta Printer, Part I
Building the 3DR “Simple” Delta Printer, Part II
Building the 3DR “Simple” Delta Printer, Part III

In my last blog post, I covered printing all the parts and assembling the top and bottom frames. The next step is to disassemble your Printrbot Simple as you’ll need the various vitamins to continue this build.

Finishing the Top Assembly

In this step you’ll mount the Printrboard and end-stop switches. Use two M2.5 x 10 screws and nuts for each micro switch. You’ll want to ensure the free end of the lever is towards the center, as shown here.

Next use two M3 x 10 screws to attach the Printboard to two of the posts. The board will need to be attached next to the wing with the extension for the power connector, as shown at the top-right of the photo above. Plug the end stops into the correct slot of the Printboard as shown above. The center socket is attached to the micro switch in the upper-right corner.

The power connector is designed to be held in place with the nut on the back. Unscrew the nut and slide the wires through the slot, with the nut on the inside. Place the nut into the slot and then turn the power connector to screw it into the nut. Once this is tight you can plug the square power connector into the Printrboard.

Next, each smooth rod is held in place with an M4 x 10 screw and nut. Place one M4 nut into each of the six slots next to the smooth bar holes. Then screw in an M4 x 10 screw so it’s all the way into the nut, but not projecting into the smooth rod hole.

Adding the Carriages

Add one LM8UU bearing to each smooth rod. Then use four zip ties to attach one carriage to each pair of smooth rods. The carriage should be oriented so the rod connections are on the top, like this:


Make sure the zip ties are very tight.

Installing the Top

Now install the top, with the Printrboard facing down. Carefully slide the parts over the extrusions, and then over the smooth rods. Work it down until 20 mm of extrusion is extending out of the top of each corner. Then lock in place with an M5 x 8 screw and washer that attaches to a T nut in the extrusion. Finally, tighten the six M4 screws on the top corners that hold the rods in place.

Installing the Stepper Motors

The cords on the stepper motors are much shorter than you’ll need. Obtain some 26 gauge stranded wire. You should use the same four colors as on the original motors: red, green, blue, and black. I chose to use new wire and connectors, and also to install connectors on the bottom between the stepper motor and where the wire enters the extrusions. This will make it easy to change stepper motors if I need, but I’m not sure it was that important. In any case, you’ll need to cut the wires on the stepper motors and either splice in new wires, or use a connector like the one shown below.


The connectors I used are Molex 1625-4PRT .062” 4-pin connectors, although you can use other connectors. These have both a male and female part, and the pins crimp to the wires. To ensure a secure connection, I also soldered the wires to the pins after crimping. Ensure you have the colors matching as shown before you push the pins all the way into the body:


For the wires that will be attached to the Printrboard, cut wires more than long enough to go through the extrusions and to the Printrboard (you can cut them to length later when you know exactly how long you’ll want them).

Once you have the connector attached to the long wires, fish the cut ends of the wires through the rectangular hole on the bottom part and into the hole in the extrusion. Keep feeding them until they come out the top.

Mounting the Stepper Motors

Cut three lengths of Spectra fishing line. RichRap recommends two meters each. It’s better to have them too long than too short. Thread one end through the holes in the spool so it looks like this:


The two lengths of string coming out of the spool should be about the same length. Next wrap the string around the  spool in opposite directions. Each one should be wrapped eight times around. Secure in place with a piece of tape. Make sure you wind all spools the same way.


The nuts and screws can be a little tricky to install on the spools. Using a round object inserted in the hole can help hold the nut while you place the screw, as shown here:


Now attach the spool to the stepper motor shaft. There should be a small gap of about 1 mm between the spool and the stepper motor. Tighten each of the three set screws in turn so you keep the spool aligned with the shaft. Make sure the set screws are all quite tight. You might wish to place some thread lock on the screws to keep them from coming loose.

Finally, attach the stepper motors to the lower mount and connect the cables. It will look like the following picture once you’ve finished string the fishing line. Remember to install the bottom end cap on each extrusion so you don’t scratch your work surface.


For now, tape the fishing line to the top surface of the base:

Running the Fishing Line

First create the idler assemblies. Each one consists of an M5 x 20 button head screw, two 625ZZ bearings, one M5 nut, one M5 washer (a wider penny washer would be better, but I didn’t have any handy), and finally an M5 T nut:


You’ll need three of these assemblies, with one for each extrusion. Insert these into the slot closest to the center, at the top of the extrusion. You can either leave the T nuts loose or tighten them ever so slightly to keep them in place. Make sure the regular M5 nut is very tight against the back of the bearings. If it’s not, the fishing line could work it’s way down between the two bearings and get stuck.

Now tape each carriage so it’s towards the top of the tower, but with enough distance so you can get in there to tie the fishing line to the carriages. You’ll want it to look like this when you’re finished:


Note: Although this photo shows the rods attached to the carriage, it’s easier to tie the fishing line to the carriages before attaching the rods.

The fishing line shown on the right loops over the top of the idler bearing you installed and then down to tie onto the top hole of the carriage. While the other side of the line coming from the spool ties to the bottom hole in the carriage. Try to make these somewhat tight when you tie them on.

Then push up on the idler bearing as much as you can and tighten them in place. The strings should be fairly tight, but will loosen a little after some movement, so you’ll need to re-tighten every now and then.

At this point you can remove the tape holding the fishing line to the spools and move the carriage up and down to ensure they work smoothly without any binding.

Making the Rods

I found a really nice jig on Thingiverse by ichibey: Print out two of these and add two M3 x 20 screws from the back. Then use two M5 x 10 screws to attach them to one of the extrusions (using two T nuts, of course):


As you can see, these two printed parts make it really easy to set the length exactly the same for all six rods. If you’re using 200 mm rods, like I am, the carbon fiber tube needs to be cut into six lengths of 160 mm each (the printed adapters and joints add 40 mm to the total length). I used 5-minute epoxy to glue the tubes into the printed adapters (shown in yellow above), and the Traxxas joints into the other end. Do one rod at a time, and before the epoxy sets, fit the assembly onto the jig as shown above and adjust so it’s a loose fit. Also make sure the flat parts of the Traxxas joints line up with each other.

Take your time on this step. It’s very important to have all six rods exactly the same length for the best performance of your printer.

Attaching the Effector

Once you’ve finished all six rods, you can move on to attaching them to the carriages and to the effector platform. First attach them to the platform, as shown here, using M3 x 16 screws and nuts (this is looking at the bottom of the platform):


Next attach the other ends of the rod to the carriages with M3 x 16 screws and nuts, as shown here (make sure the attachment points on the platform are at the bottom, as shown here):


I used a tape roll on the print bed to help hold it in place, which made the work a little easier.

Print Bed

To make things a little easier, I designed clips that allow leveling the bed and slight adjustments between the bed and the nozzle, shown in the previous photo. These clamps use three of the bed leveling springs from the Printbot Simple, along with M3 x 20 screws and nuts. The nut slot under the frame is tapered, which allows you to trap the nut firmly in place. Before installing the clip, add the nut to the bottom side of the frame and then screw an M3 screw all the way in, pulling the nut firmly in place. Then remove the M3 screw.

Attach the clips to the print bed and then use an M3 x 20 screw through the clip, and then through the spring, to hold the bed in place.

Next Up, Extruder

There are two more parts I expect to publish. Next up will be building the extruder and hot-end mounts, and finishing up the wiring. The final part (I think), will be on installing new firmware onto the Printrboard and getting the printer running.

Saturday, November 30, 2013

Building the 3DR “Simple” Delta Printer, Part I


The previous three posts provide background information about this printer. This is the first part of how to build the “final” version of this printer.

3DR “Simple” Delta Printer, Part I
3DR “Simple” Delta Printer, Part II
3DR “Simple” Delta Printer, Part III
Building the 3DR “Simple” Delta Printer, Part I
Building the 3DR “Simple” Delta Printer, Part II
Building the 3DR “Simple” Delta Printer, Part III

Since my last post, I’ve redesigned almost every part of my 3DR “Simple” Delta printer. Yesterday I got it printing, and it works really well. I have one final parts I’m working on, which is a combination fan and ring LED mount. Once these are done, I’m going to declare this complete.

Sourcing Parts

The idea of this project is that you can start with a Printrbot Simple, which is a very low cost printer. You can use the Simple to print all the printed parts required for this build and then start the build. You won’t need to disassemble the Printrbot Simple until you’ve assembled the printed parts. Then, and only then, you can disassemble the Printrbot Simple and use it’s “vitamins” to finish the build. Even so, you’ll need to purchase some additional parts, such as the smooth rod and extruded aluminum.

You’ll need to decide how tall you want to make your printer. My printer has a maximum print height of about 80mm, which works very well for me. However, you’ll most likely want a little more height. The first version of my design had the same dimensions as RichRap’s 3DR RepRap Delta Printer and had a larger maximum height. However, when I discovered I couldn’t use the full diameter, I widened the printer, which resulted in longer rods, and therefore reduced my maximum print height. So, here is what I would recommend:

Smooth Rods: 500 mm
Extrusions: 550 mm

This will give you a maximum print height of about 150mm. You can, of course, choose different lengths. Just make sure the smooth rods are 50mm shorter than the extrusions. Here are some links on Msiumi’s US sight for these parts:

Note: The 400mm long smooth rod is about $12 per rod. But as soon as you increase this to even 401 mm, the price goes up to $19 a rod. So if you’re happy with 80 mm maximum print height, go with 400 mm rods. Otherwise, you can go up to the maximum of 500 mm length for the smooth rods. I’ve also listed T nuts that have a spring to hold them in place, and can be inserted after the fact, which is really handy. When I added the above to my shopping cart, the total came to $147.

There are some other supplies I got from

If you purchase 180 mm rods, you won’t be able to get the full 170 mm diameter—it will probably be closer to 160 mm. If you plan to assemble your own rods instead, you’ll need to purchase some carbon fiber rod:

Electrical Connectors

The following electrical connectors are optional, and you’ll only need them if you choose to use new connectors instead of simply splicing new wires into the stepper motors (covered in the next installment):

  • (optional) Molex 1625-4PRT .062” 4-pin connectors (to connect the steppers to the wires that go up the extrusions)
  • (optional) Molex WMLX-102 .100 4-pin connectors (to replace the stepper-motor to Printrboard connections)
  • (required) 26 gauge stranded wire in red, blue, green, and black

Screws and Nuts

I’m still working on updating the list of all the screws required. Here’s what I have so far:

  • M3 x 6 button head (9)
  • M3 x 16 screws (12)
  • M4 x 10 screws (39)
  • M4 x 20 screws (18)
  • M4 nuts (57)
  • M5 x 8 (6)
  • M5 x 20 button head (5)
  • M5 Washers (9)
  • M5 Nuts (3)

Extruder Parts

The extruder needs some parts that don’t come with more recent Printrbots, and perhaps the easiest (and even most cost effective) way to get these might be to order the hard-ware only kit from Makerfarm (they call it the No Printed Parts option, which is $15 at the time I’m writing this):

  • M3 x 50 (2) for extruder
  • M8 x 20 (1) smooth or threaded rod (no head)
  • Hobbed bolt and other extruder parts (not included in direct-drive Printbot Simple kits)

There are various M3 nuts and screws. However, I believe all of these can be reused from the Printrbot Simple.

Printrbot Simple Parts

Here is a list of parts I reused from the Printbot simple (so you won’t have to buy them)

  • Stepper motors (4)
  • Hot end
  • Printrboard
  • Power supply
  • LM8UU bearings (6)
  • Hobbed bolt and other extruder parts (not included in direct-drive Printbot Simple kits)
  • M3 x 10 screws (12)
  • M3 nuts (24)

If you have a Printrbot Simple V2 with the direct-drive extruder, you’ll also need a hobbed bolt (which is what my V1 came with): Alternatively, you can purchase the hard-ware only kit from Makerfarm (link in previous section)

While you’re there, you might choose to use their injection-molded gears instead of 3D printing the gears:

Other Parts

You’ll need a 170 mm diameter print bed. I purchased a 170 mm round Borosilicate plate from Trinity Labs: Without a heated bed, you don't really need Borosilicate glass. So you might be able to get a glass place to cut one for you.

Assembling the Lower Frame

As I’ve mentioned before, all the printed parts are designed to be printable on a Printrbot Simple, with a 100mm x 100m print bed. That means you should be able to print all the printable parts on just about any printer.

For most of the parts, I print with 0.2 mm layers, 20% infill and either two or three perimeters (I’m not sure it makes much difference).

Print 3 of 3DR Bottom Motor Mount Simple.stl:

3DR Bottom Motor Mount Simple

Print 3 of Wings.STL:


Print 3 of Wing Mirror Long.STL:

Wing Mirror Long

Connect the base pieces with M4 x 10 and M4 x 20 screws and nuts. The wings connect to each other with four sets of M4 x 10 screws and nuts. While the wings connect to the motor mount with a pair of M4 x 10 and another pair of M4 x 20 screws. Assemble these on a flat surface and ensure the screws are tight:


Milling the Extrusions

There is enough room inside the extrusion to run wires for the stepper motors. You’ll need to mill a slot on each end of each extrusion in order to accommodate the wires. Here is what the slot looks like on the bottom:


You can see that the slot is toward the middle of the printer. On the top, the slot should be to the side shown here:


Take your time to ensure the slots are milled in the correct location, and that they’re smooth so they won’t cut into the wires.

Insert a T nut into the extrusion and then insert the extrusion into the base. Fasten in place with an M5 x 8 screw and washer. You’ll need to make sure the T nut is aligned with the hole first, of course. Once you have the screw started in the T nut, and before you tighten, make sure the extrusion is flush with the bottom of the base, as shown in the first image of this section.

Print three of these end caps and install them on the bottom of the extrusions (so you don’t scratch your work surface):

misumi_2020_extrusion_cap two Ts

I modified these end caps from this Thingiverse part:

Once you’re finished, the base will look something like this (without the carriages, stepper motors, and bed):


Assembling the Upper Frame

The upper frame, like the lower frame, is made from 9 printed parts. Note that the three parts for the top all have the same file names as the corresponding bottom parts, but they’re in a folder named Top on Github. In case you’re curious, both the top and bottom files are contained in the same Solidworks file, which is why the STL files have the same name.

Print 3 of 3DR Bottom Motor Mount.STL:

3DR Top Motor Mount Simple

Note that this has the same file name as the bottom motor mount, but it’s a different file (it’s in the Top folder in Github).

Print 2 (note, only two)  of Wings.STL:

Wings Top

Print 3 of Wing Mirror Long Top.STL:

Wing Mirror Long Top

Print 1 of Wings with Power.STL

Wings Top with Power

Assemble on a flat surface using M4 x 10 and M4 x 20 screws and nuts, just like you did for the base. Once assembled, it will look like this (without the electronics, of course):


Printing the Remaining Parts

Before you can complete assembly, you’ll need to print some more parts (while your Printrbot Simple is still assembled and working):

Print 3 of Spool.STL:


Print 3 of Carriage for LM8UU.STL:


Carriage for LM8UU

Print 12 of Bearing Shaft Coupler.STL (assuming you’re going to make your own rods with 3 mm inside diameter carbon fiber rods):

Bearing Shaft Coupler

Print one of Platform.STL:


Print one of Hot End Holder.STL:

Hot End Holder

Print one of Hot End Holder Tabs.STL:

Hot End Holder Tabs

Print one of Hot End Plate.STL:

Hot End Plate

Print one of Extruder Spacer.STL:

Extruder Spacer

Print Extruder Parts

For the extruder, I used RichRap’s parts without change:

Print one of 3DR_Extruder_body_V2_Test_001_RTP.stl

Print one of RichRap_Greg_style_Guidler_Modified_with_grab_lever_For_1_RTP.stl:

Print one of herringbone-gear-large.stl:

Print one of herringbone-gear-small.stl:

Next Steps

In the part II, I’ll continue with the assembly instructions. You’ll need to ensure you have all the parts printed and they’re of good quality before you continue, as the next step will be to disassemble your Printrbot Simple so you can reuse parts form it.