Introduction: Hot Glue Gun Extruder for Your CNC Machine or 3D Printer
There are many parts to a FDM printer and in this instructable I am going to concentrate on the extruder. I will briefly go over the XYZ computer controlled plotter (mechanics, hardware, software). I use a home built CNC router for this. After showing you how to build the extruder and how to attach it to your XYZ Plotter or CNC router type machine I will go over the software I use along with settings (these are very important) and show some example models that I printed out with it in pictures and maybe a video or two.
Before I get any further I would like to extend a big "Thank You" to the open source community and all of the people who have contributed to the 3D printing community. Without all of their work I would have had to put in a lot more work to accomplish goal.
So let's get started shall we.
Just in case you want to see it in action before you do some reading, view the video below.
Here are some more videos of printing with the Hot Glue Gun Extruder:
Mario (at least the front half)
Apple Logo (the one with the bite out of it)
The Pink Panther Woman Bust
The apple turned out the best. Mario really was a terrible quality print job and the Pink Panther Women didn't turn out too great either. The apple was really nice. I used 0.5 mm layer height on that one. It took forever... but it came out nice.
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Step 1: Stuff You Will Need
Materials are first. The tools you can improvise. You will need the following items to build the HMA (Hot Melt Adhesive) Extruder:
* 3/8" Plywood (~6.5" x 4.5")
* NEMA17 Stepper Motor (Unipolar - match up to your driver) with Gear (8mm - 16 teeth)
* Large (46mm - 100 teeth) Nylon (or some sort of plastic gear) with teeth that fit your Stepper Motor Gear (I got mine from a Lexmark Inject Printer)
* 4 Metal Bearings - mine are 15mm outside and 6 mm inside.
* 9 to 10 - #8 1.5" Bolts and/or #6 Bolts
* #8/#6 Washers (I used about 20 in this design)
* #8/#6 Lock Washers (I used 2)
* #8/#6 Nuts (8 to 10 used)
* #6 0.5" Screws (I used 4)
* Metal L Bracket 1.5" x 1.5" with 2 holes in each side
* Mini Hot Glue Gun - Low Temperature (HiTemp is shown in picture - Do Not Get This) from Walmart ($2.97)
* Mini Hot Glue Sticks - Low Temperature - Bag of 30 from Walmart (~$3.00 or so) *** You can get colored ones and different kinds from Craft Stores such as Micheal's or Benjamin Franklin's (on the East Coast). Walmart just has 1 kind. Be careful ... some are .27" in diameter... some are .28" in diameter. You will want to just get 1 diameter and stick with it otherwise you will have to adjust your bearings again.
* Popsicle Stick
* Slotted Metal Bracket ~2" Long (slot needs to be able to fit #6 or #8 screws)
* Big straw or tube of some sort ~4" long and ~3/8" inside diameter... make sure a glue stick will slide freely using gravity.
* Wire - around 4 feet long with enough conductors to wire your stepper motor to your stepper driver. My wire had 6 conductors and was 28 gauge (an ex PS2 keyboard cable I think).
* Small Zip Ties
* Piece of Glass (I got mine from scanner) to print on
* Isoproply Alcohol for cleaning the print surface (glass)
* Computer to talk to your printer's electronics.
* Software (I use Pronterface => https://github.com/kliment/Printrun )
If you do not have the 3D printer electronics already like I did not then you will need those too. I am using an Arduino Uno with Teacup firmware. I have built a custom stepper motor driver for my Extruder. I use a 3 axis stepper motor driver from HobbyCNC.com (http://www.hobbycnc.com/). It is a really nice kit and works great. Instead of using the parallel port from the computer the Teacup firmware and Arduino control the HobbyCNC stepper driver through a shield I made that basically wires some pins to a 25 pin DSub to pretend it is a printer port. The custom stepper driver I made I basically designed on my own using 2 ULN2803A chips stacked on top of eachother to give 1 amp per coil. I regulate the current with an automotive lightbulb (not sure how many watts). I then modified the Teacup firmware to control the 4th stepper motor for the extruder directly instead of using a driver with step and direction control.
and finally you will need some sort of computer controlled XYZ platform such as a CNC router or RepRap. I made my router from parts from Lowes and plans from Solsylva.com -> http://solsylva.com/cnc/13x13x5.shtml . It is their 13x13 machine and it cost roughly $100 in parts to build (without the motors and electronics). You will need the Stepper Motors and Electronics too. This is probably where most of the other money lies in a 3d printer besides the extruder cost. There are some really great Instructables that feature how to build low cost CNC machines that will work great. One of the least expensive and most popular would be the McWire CNC Mill -> https://www.instructables.com/id/Easy-to-Build-Desk-Top-3-Axis-CNC-Milling-Machine/
* Hot Glue Gun - Hi Temp for gluing stuff to wood.
* Screwdrivers (Flat Head and Phillips Head)
* Drill (Hand drill is fine)
* Step Drill Bit (http://www.harborfreight.com/3-piece-titanium-nitride-coated-high-speed-steel-step-drills-91616.html)
* 1/8", 9/64", and 1/4" Drill Bit and a few others ... just a set from Lowes - I have a set by Dewalt which are nice.
* Dremel Tool with Router Attachment and 1/4" router Bit
* Dremel Tool with some sort of wood eating bit
* Wood Chisel
*** This is used to recess the hot glue "Hot End" into the wood so the glue stick is even with the gear and bearings (which are right above the surface of the wood).
* Needle Nosed pliers for adjusting nuts and stuff.
* Exacto Knife
* Side Cutters
* Soldering Iron and Solder
* Electrical Tape and/or Shrink Tube
Step 2: Step 1 - Making the Extruder
Time to actually make the extruder. This is probably the easier part in my opinion. If you haven't gotten all of your materials and tools together now is the time to do it. Please refer to the previous step if you are unsure as to what exactly you will need. Or if you are the adventurous type read on. This is a guide and not exactly down to the micron instructions on how to build a Hot Glue Gun (Hot Melt Adhesive or HMA) based Extruder for most CNC XYZ machines.
The first thing you probably will want to do is get your glue stick. The 4" x 0.28" one. You will need this pretty much for every step when adding things to make sure it still is a tight fit. The drawing of the extruder was done in Inkscape (another great open source software package - once you get past the GUI learning curve). It is pretty much to scale and can be used a reference for how I built my extruder. Yours will invariably be different in some way.
Another tip is if this is your first time doing anything like this, get a piece of cardboard 4"x6" and prototype it on that. Just leave the stepper off. This way you can get the feel of how everything is laid out before hacking up your plywood.
Before you start you will want to wire up your motor and make sure it works. I have based projects on a particular motor and then found out it didn't work when I finished. It is also handy to use for testing at various stages.
I started with the main 100 tooth gear. I made the glue stick path to the left of the extruder and the motor fits on the right. You may feel like you have to center the glue stick but in the end it really does not matter as long as it works. Mount it by drilling a hole with a 9/64" drill bit. You will need to use a screw driver to insert the #8 1.5" bolt from the back (motor mount) side of the plywood. If your gear has a bigger or smaller hole than a #8 bolt. Find a bolt, washers, and nut to fit it and don't forget to find a drill bit (don't drill a hole that the bolt fits loosley into ... you want it tight... like a tiger). Now put 2 washers onto the bolt, then the gear, then 2 more washers followed by a nut. Tighten down the nut so it is snug but still allows free movement of the gear. Now add another nut on top. Snug it tightly against the first nut. This should lock the first nut in place. Check the gears movement again.
Now is a good time to add the motor. You can add this later but I am going to do it now. The hard part is lining it up so that the gears mesh correctly and then drilling the hole in the correct spot. I basically places the stepper with gear on the shaft in the spot I wanted it. Traced around it with a marker or pencil. Then drilled the hole out to around 0.75" in order to leave room for adjustments. I used the step drill to drill this hole as the only other drill bit I have that is big enough is a paddle bit and it tends to tear up the plywood as it exits the other side. The step drill makes a nice smooth hole. Next place the motor on the motor side of the plywood with the gear in the correct spot with the gears meshed together. Mark your stepper mounting holes (my motor had a mounting bracket attached which made this step easier) and then mount the motor with bolts or screws. I used #6 0.5" Screws. Make sure your screws or bolts do NOT interfere with the main gear. Once you are done make sure your motor can turn your main gear without trouble.
Now that the main gear is in place it is time to attach the bearings that press the glue stick against the main gear. The bearings are 0.6" apart and on my extruder are nearly touching (the drawing I think has them a bit wider). Place a hot glue stick vertically next to the main gear. Next place the bearing snuggly next to the glue stick so that the stick is pressed firmly up against the main gear. Mark the center of the bearing with a marker or pencil. Drill a hole where the marks are with the 9/64" drill bit for the #8 1.5" bolts. Screw the #8 bolts in all the way with a screw driver. These should have a tight fit. Next place a washer, bearing, washer, and then nut onto the bolt. Now time to adjust and tighten the bearings down. Push each bearing up against the hot glue stick (it is still there right?) so that the hot glue stick begins to bend slightly around the main gear. Then tighten the nut that holds the bearing down. Repeat this step for the 2nd bearing. You should now have 2 bearings pressing a glue stick against the main gear. The glue stick should curve a little bit around the main gear. See the picture of the built extruder for detail on this. The bolts are too small for the bearing holes on purpose. This allows some adjustment before tightening the nuts.
Next it is time to attach the Hot Glue Gun internals. First remove the insides from the hot glue gun. There should be 5 screws to remove and then the plastic shell should come apart. See the picture of the hot glue gun insides (this one is a little different looking than the one on the extruder I used in the pictures, however it is nearly the same in every dimension). You will need just the part that gets hot that the glue sticks go into (the one with the cord attached). The rest of the parts are not needed. Maybe you can make a toy? gun or something for your kids with it.
Now comes the hard part. You are going to need to carve out about 1/4" deep space for your hot glue gun internals into your plywood. The dark brown area on the drawing. I used a dremel tool with a 1/4" router bit and a router attachment so I could slide it around and carve out a nice space. You can just use a dremel tool with a bit that eats wood or just a plain chisel and hammer. It doesn't need to be perfect or really flat ... just 1/4" deep and big enough to fit the Hot Glue Gun internals into. You may have to make it deeper than 1/4". The idea is to keep the glue stick almost flat against the wood. You can test fit this by putting a glue stick in your glue gun insides and press it into the hole with your fingers. If the glue stick looks like it is even with the main gear then you are good. If it is not even (sticking up above it) then you will need to make your trough a little deeper. Take your time otherwise you will have to start over. 3/8" plywood is not very thick. I had to use a popsicle stick to raise the metal part of the glue gun up a little bit because there is a silicone (or some sort of rubbery heat resistant material) tube on the inlet to the metal part. This is a bit bigger in height than the metal part. So in order to lay flat I put a popsicle stick under the metal part. It is underneath the hot glue gun bracket in the drawing however if you move the bracket in Inkscape you will see the stick.
Next you secure the hot glue gun internals by drilling 2 holes. One on each side of the metal part (see lower part of drawing) using a 1/8" drill bit. Screw in a #6 1.5" bolt. Then put the 2" hold down bracket on top of the Hot Glue gun internals. Secure with a washer, lock washer, then nut. Make sure it is tight and the glue gun stuff does not wiggle. There will be lots of force applied by the glue stick when this thing is working. Be careful as this bracket gets HOT too!
Now is a good time to drill the holes for the zip ties that hold down the AC wires for the Hot Glue gun. I used a drill bit big enough so that the zip ties loop around and hold the wires to the board. See the black holes below in the drawing. Secure your wires with the zip ties now. This is so they don't break off and have to buy another $3 hot glue gun.
Next we need to add some items that prevent the hot glue stick that is being forced into the hot glue gun from bending and going wacky tacky on us. This consists of 2 bearings to straighten out the hot glue stick (just below the main gear) and 2 bolts that hold the silicone tube that is attached to the metal part of the hot glue gun. This tube needs to be straight otherwise your pressure and extrusion quality may vary.
To do this put a glue stick about 2/3 of the way through the main gear pinch section. The glue stick should want to bend towards the motor side of the board. Place one bearing on the right of the glue stick to straighten it up. Mark your hole and drill using a 9/64" drill bit for the #8 1.5" bolt. Screw the bolt in place. Then place a washer, bearing, washer, nut on the bolt. Adjust the bearing to make the glue stick straight so it points directly into the hot glue gun silicone tube and then tighten down the nut. Make sure the bearing rotates.
Next attach another bearing on the left of the glue stick. This keeps it from going to the left and missing the silicone tube. Use the method in the above steps to secure the bearing to the extruder board. Make sure it rotates too.
Now time to place the bolts on the sides of the silicone tube. I simply just drilled 1/8" holes on the right and left (about 2/3" up from the bottom of the tube). Then I screwed in 2 #6 1.5" bolts. This holds the tube in place and does not allow it to bend much from side to side (which it wants to to do...).
Take the 3/8" x 4" long straw tube thing (I got mine from some household door seal kit ... it held screws.. you could probably find something similar in the plumbing section at your favorite hardware store ... Like Ace Hardware, they have everything especially a super duper great selection of nuts and bolts). Anything will do just as long as a glue stick slides effortlessly through it using just gravity alone. To mount it I used Hot Glue! Test place it on your extruder in the position shown in the drawing. Drop a glue stick in it. If it slides without getting stuck into the waiting jaws of the main gear and spinning the main gear grabs the glue stick then mark its position and glue it down with a bead down the back and a couple of spots on the sides. Careful not to melt it with the glue gun tip.
Lastly we are going to attach the L shaped bracket to the wood. This bracket allow you to attach the extruder board at a right angle onto your CNC machine's Z Axis. I used a 1/4-20 bolt and nut just as my router uses to attach to the Z Axis. I am sure this part is going to be somewhat custom so play around with it and do what is best for your setup. Look at the pictures in this instrutable and at the drawing to get some ideas on how I did it.
Congratulations, you now have a contraption that looks neat!
Next we move on to testing the extruder.
Step 3: Step 2 - Testing the Extruder
This step is probably the easiest.
Here is a list of the Software I am Using:
Slic3r (comes with Pronterface)
Teacup Firmware (for Arduino Uno with ATMega328P)
I am going to gloss over all of the hookup of the stepper motor and CNC machine because this article is mainly about the extruder. There are quite a few How-To's on this subject however since non of them have done it exactly as have I will probably post an addition to this article in the future in order to illuminate this involved process.
I am using Pronterface for the Windows/Computer interface. This program communicates with the Arduino UNO G-Code Interpreter.
I am attaching my Slic3r and Pronterface configuration files to this instructable so you can see the settings I used.
So to get things going to test you do this:
* Plug your Hot Glue Gun AC cord in (and turn your CNC machine on)
* Give your extruder a few minutes to heat up
* Start Up Pronterface
* Click "Connect"
* Click the "Extrude" button.
If all goes right, your stepper should move and you should see some hot glue come out. To change the speed at which it comes out you can do:
A) Adjust the e_feedrate in the Options
B) Adjust the STEPS_PER_M_E in the Teacup firmware config.h (requires a recompile and program)
While extruding hot glue out at the speed of light to make big noodly piles is neat and all, you ultimately will be extruding very very slowly. For example when printing my extruder stepper ticks about once every 3/4 of a second. Kind of sounds like a noisy clock.
If you try to move too fast the glue gun cools down and you will make a mess.
If you try to move too fast the molten glue might seep out of the bottom of the silicone tube on the hot glue gun and will make a mess.
Do not touch the glue gun extruder. It is hot.
Now that is is work correctly, let's mount it and calibrate the extruder. Then we can finally make a print.
Step 4: Step 3 - Mounting and Calibrating the Extruder
Mounting is easy! Basically the Extruder is bolted with a single 1/4-20 2" long bolt to the Z Axis of a CNC machine. 1 bolt tightened is enough to support it. Remember there is no cutting happening here. Just squirting out hot glue. We just have to support the extruder and hot glue. There is a little drag with the extrusion but not much.
This is the really time consuming part. I have included my Slic3r settings as a config file on the previous page as well as screen captures of the settings with some notes thrown in. I am again going to gloss over this step somewhat. I will provide some links to some theory and how to's.
Pronterface Calibration Tutorial: http://richrap.blogspot.com/2012/01/slic3r-is-nicer-part-2-filament-and.html
Machine Calibration (recommended in the Teacup Firmware) -> http://blog.arcol.hu/?p=157
Skeinforge Calibration (Skeinforge is another Slicing Software) -> http://rapmanv3.blogspot.com/2009/09/more-skienforge.html
40mm x 40mm cube (a good object for calibration) -> http://www.thingiverse.com/thing:477
MakerBot Coin (good because it is a short print) -> http://www.thingiverse.com/thing:648
I will first recommend you read the Print step (the next step in this instructable) and at least one of the calibration tutorials linked above (the 1st one is great!). It will go over how to turn your STL object into a printable thing in Pronterface.
Here are some settings to tinker with while calibrating. These are illustrated below in the Slic3r settings screen captures:
Filament Diameter -> Hot Glue Stick Diameter. I have mine set to 10 mm although the real diameter is 7.something mm in diameter (0.28"). This controls the speed of the extrusion (speed of the stepper) without having to edit the firmware or tinker with any other settings. I found that 10 to 12 works well... 12 being a little on the edge of too slow but might work with a smaller layer height or nozzle diameter.
Nozzle Diameter - I measured mine (the hole in the Hot Glue Nozzle where the glue comes out) at 1.5 mm.
Layer Height - 0.75 mm - too small and your glue might back up. Too big and the object comes out chunky and not connected.
I basically ran a print (often aborting early using the Pause Button). Adjust a setting (remember to adjust 1 thing at a time otherwise you will get confused as to what actually is doing what). Rinse and Repeat. Do this until you get a good print or you discover some mechanical thing that needs tweaking.
Once your print looks good. You are ready to Download or Design and Print Some Objects. Go on to the next page to learn how.
Step 5: Print!
The first thing to do is find some objects to print.
You do not have to look far because there is an ocean of objects on Thingiverse! => http://www.thingiverse.com/thing:648
I have printed the following items successfully:
If you do not want to install anything but just want to tinker around... try TinkerCAD. It generally works really well. I have used it to design a few simple things. One big bonus is that it lets you modify other STL 3D model files without having the source model.
Now that you have a model it is time to run Pronterface and Load a model (slice it). Here are the steps that I use when starting a print.
1) Plug in your stuff and let your hot glue extruder warm up a couple of minutes.
2) Start Pronterface.
3) Jog to the X/Y home position (where ever that might be). I recommend putting a sheet of white paper under your glass and mark on that your home position and axis labels and maybe some goofy drawings....
4) Press the Extrude Button until a little bit of Hot Glue comes out. I have my settings to extrude 1 mm at a time.
5) Jog to home Z in... squish the little blob of hot glue flat on the glass.
6) Disconnect then reconnect and Reset the printer (all buttons on Pronterface). This set the ZERO for X,Y,Z axis. This is very important.
7) Jog Z up 10 mm (just to make sure it isn't stuck or anything).
8) Load your STL file (you should have already set your Slic3r settings in the previous step).
9) Edit your GCode file to remove the Set and Wait for temperature. IF YOU DON"T YOU WILL WAIT A LONG LONG TIME.
*** Before you click print make sure you check out how big the model is and make sure you are willing to wait that long for it to be printed. Slic3r lies to me about how long it takes. Pronterface will tell you in the Status bar!
10) Wipe your glass down with a liberal amount of Isopropyl Alcohol. This should help in making the hot glue easier to get off once the print is gone. If you skip this step be prepared for it to be S T U C K.... this is glue after all.
11) Click the Print button.
If you have not printed much then keep your fingers near the power OFF switch to the XYZ axis so you don't wreck something. Please remember that this is a DUMB machine and will do exactly what you tell it. For example ... I was printing out the Pink Panther Girl (for 2 hours) and when it finished ... the machine decided it was a good idea to run the extruder right down the middle of it (Z down first in homing). I managed to save most of it because I turned the power off. Do not depend on the Pause button in Pronterface to save your butt. The Teacup firmware buffers your commands and it may take a little bit of time for the machine to actually stop. Imagine if that was your hand instead of your model!
Hopefully a little bit (or a long bit) later you will have a Hot Glue 3D object.
Now comes the Fun part of getting it off of the Glass. Wait a a few minutes for it to cool some more. Take a flat razor blade and scrape your model off. CAREFULLY. The model should be somewhat sturdy but it is also somewhat squishy and it might deform. Scrape off any extra leftover glue too. Reclean the glass with the alcohol.
Be sure to look at the Notes and Links after this step.
Step 6: Notes
This section contains stuff I noticed and didn't put elsewhere and stuff about future things to try.
Colored Hot Glue? For sure. Look at the picture below.
Harder Hot Glue? For Sure. Look at the picture below.
-> Both found at Micheal's craft store. I have not tried these yet.
Need to find that "How To Make Your Own Hot Glue Sticks" I saw on Make's blog a while back.
How to tune corners?
How to print a whistle so it is NOT filled in?
The Maker Bot Coin is an excellent short print. It prints very quickly.
You do not need to download Slic3r in addition to Pronterface. Pronterface (PrintRun) includes Slic3r.
Securing the glue gun internals onto the board is very very important The force of the hot glue stick will try to make it move instead of melt.
Need to try High Temperature Mini Hot Glue Gun.
Need to include a Cooling Fan. This may improve the prints.
How to tune overhang?
Need to calibrate the extruder retracting in Slic3r. The default settings work OK but probably could work better.
Step 7: Useful Links
I am not the first to do this. However I think the extruder in this instructable does a good job with Hot Glue and is easy to make.
Here is one of the designs that inspired me:
There is another one that just made tubes found here:
This is another dude who has a nice 3d printer tutorial instructable. It is really thorough:
CNC Router Plans (where I got mine from): http://solsylva.com/
3 Axis Stepper Driver Kit (where I got mine from): http://www.hobbycnc.com/products/hobbycnc-ez-driver-board-kit/
Some instructable links:
CNC Machines: https://www.instructables.com/id/CNC/ and https://www.instructables.com/id/DIY-CNC/
I will post more pertinent links when I find them.
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