TechZone Tip Assembly

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The instructions on this page are for assembling the tip and extruder kit(s) from TechZoneCommunications.

The information may be useful for general assembly of tips and other designs, but no attempt is made to address them specifically in this document.

If you purchased a kit from TechZoneCommunications, and are having difficulty, please contact us (TechZoneCommunications) at Our Contact Page


Here at TechZoneCom (short for TechZoneCommunications) we have learned the hard way, that the tip is probably the hardest and most finicky part in the RepRap. Unfortunately that set us up to cause a lot of problems for many of you (our customers and design users).

When we first released the LaserCut Mendel (LCMendel) we thought it would be a piece of cake to make and deliver hot ends, after all, everyone with a RepRap has a hot end and we presumed that they worked just fine. In the weeks (which became months) that followed we found out that we were Fools (notice I capitalized that word). We probably spent far too long re-inventing the wheel, and should have bitten the bullet and purchased everyone their favorite tip and called it good. That certainly would have saved us some money!

Even with the current version of tips that we have shipped, I am not completely content with the design, I am certain that there are some improvements to be made. However, what we currently provide (Aug 27, 2010) is a good design, and I am confident it is no more finicky or flawed than the many other designs out there. I did break down and order several in from other vendors and set them up and compared their performance before I finally released our tip.

With that in mind, you should know that tweaking the settings of your machine, will improve, or impare the performance of your printing - ALOT. I suppose that many of the more experienced RepRap users know this already, but, for those of you who are new to RepRap, this may be your first "warning."

Hot End Assembly

Parts included in the Hot End Kit
Here (on the right) is a picture of the parts we include in the Hot End kit:

Included in the Kit

  • (1) Brass tip; it is machined from a solid bar of brass and threaded to a standard 7mm thread, bored with ~3mm bore until it is about 1mm from the end, the end has a 1/2mm hole in it and is ground with a taper.
  • (1) Oak Insulator, with Teflon insert; We played with several insulators, and didn't like any of them we even had trouble with the standard Teflon and/or peek insulators, then we found on a chart that Oak is 1/10th as conductive as the Teflon or peek! So, we make the insulator out of oak. We recommend some care in your firmware and tip construction, Wood is flammable....
  • (1) Nichrome heater wire; This wire is insulated with fiberglass, but that fiberglass is just wrapped on the wire, so we overcoat that with high temperature silicone so that it doesn't unravel as you use it.
  • (1) Type K thermocouple wire; This is insulated in a fiberglass braid, it has two wires in there, one wrapped in Yellow the other wrapped in red.
  • (1) 1cc of High Temp Goop; we use two different kinds of "Goop" one is a high temperature silicone - which is copper colored - purchased from an auto parts store, the other is a silicone cement - which is black - purchased from a hardware store (both come in large qty packages, so we repackage it into a small syringe).
  • (2) small brass or copper crimp connectors (these are shipped to you in a small envelope)
  • (2) Small screws to attach the Oak block to the extruder body

Hot End Assembly Instructions

Before we start the assembly, I strongly recommend that you test the thermocouple to make sure it has a low resistance, it should be well under 6 ohms. You test it by putting the red and yellow leads onto the ends of your multimeter and seeing what it shows. It should basically look like a short. I recommend this, because there is nothing worse than putting your whole end together and then finding out that the thermocouple was made poorly; Then you have to tear your tip apart and do it all again.

Insulator with Tip
First, thread the brass tip into the oak insulator, it should be firm against the Teflon insert, but do not over-tighten, as the Teflon will distort under too much pressure and your filament will then have trouble fitting through the Teflon into the tip. A picture of the insulator, with the tip inserted is shown on the right:

Bend the Thermocouple to the contour of the Insulator and tip.
Second, Take the thermocouple and bend it to the contour of the insulator and the tip, the end of the thermocouple should be just short of the end of the tip (as shown in the picture on the right). This step makes it much easier to transition from step three to step four (where you don't have enough hands). For now, set the thermocouple aside, we will use it again in step four.

Note: It may be easier to scrap, crimp, and solder the ends of the nichrome wire to leads, before wrapping and adding goop. It may save you a lot of headache later if you realize now and think about the processing you will need to do to the tips of the nichrome wire. Read ahead a couple of paragraphs and decide if you are going to solder/crimp before or after fixing it to the brass.

Nichrome wire wrapped on the tip.
Next, Wrap the nichrome wire in the threads of the tip. I use a piece of tape to hold one end of the wire in place as I wrap the wire from the insulator side out towards the end of the tip. I try to leave enough wire when I get to the end of the tip to make two more wraps of the wire (explained in the next step). See the picture at the right for an image of this step: Also, both ends of the nichrome wire need to be left long enough to connect power lead wires to them.

Nichrome wire wrapped over the Thermocouple to help hold it in place.
Fourth, Wrap the remaining two wraps worth of wire (about one and a half inches) around the thermocouple, with the wraps moving the end of the wire back towards the insulator. These wraps will help hold the thermocouple in place while putting the "goop" onto all these wires and such. I use another piece of tape to hold the end of this wire in out of the way (similar to the first end) Both ends of the wires should be long enough to connect lead wire to them.

Add Goop to the tip.
Next we add the goop to the tip. We ship this goop in two kinds:
  • One is a hight temperature silicone we purchase from an autoparts store, it is good up to ~350 degrees Celcius. It also remains flexible after it cures - give it about 24 hour to cure. it can be handled and you can finish the assembly after about one hour. It is copper colored.
  • The other is a Silicone Cement product we get at a hardware store. It is good up to ~535 degrees Celsius. It is Hard and rigid when it cures, I would give it 24 hours of cure time as well. It can be handled after about 2 hours. It is black in color.

Both of these are shipped to you in a small syringe, you can use the syringe to apply the goop to the tip, I find it is helpful to use a toothpick to help press it into place and spread it around the way I want it. Sometimes, it will get stuck in the small end of the syringe (especially the black stuff, it has chunks and fibers and stuff in it) I just use a toothpick to clear the end of the syringe (picture in gallery below) If you don't like the syringe, you can just cut it apart, we use the syringe for ease of packaging and shipping (and to keep it from curing before you get to use it).

One cc is more than enough to do your tip, you can save the extra for a second tip, or you can apply the extra to your tip to act as a better insulator as I have done (see gallery below for photo).

Let your tip dry and cure for an hour or two before continuing. Go watch a movie, or take your sweetheart to dinner (it may help make up for the long hours you have spent on this project!)

Two pieces of wire, to use as lead wires.
After your tip has dried and cured sufficiently to finish (Let it cure for a full 24 hours before trying to heat it up), we need to connect some lead wires to the heater wire. I use a couple of 12 CM (about 5 inches) wires that I cut off of one of my motors - you do cut the extra wire length off of your motors don't you?

Use a sharp knife to strip the ends of the wire.
We need to strip the Nichrome wire, I use a sharp knife and remove the fiberglass insulation from the last 1/2 CM (aprx 1/4 in) of both ends of the wire, if you left lots of wire sticking out you may need to cut it a little shorter, remember, ALL of the nichrome wire will be getting very hot. you also need to scrape the dark colored enamel off of the end of the wire, your sharp knife can do this or you can use a small piece of sandpaper.

put both a nichrome and a lead wire through the crimp.
Put one end of the Nichrome wire, and an end of the lead wire (strip it too first) through the brass crimp, I like to put them in opposite ends, they should go all the way through the crimp.

Use pliars to squash the crimp flat.
Flatten the Crimp with pliars to make a good mechanical connection.

Fill the crimp with solder for a better connection.
If you have crimped correctly, it should be good enough to use (once the goop has cured). However, for a better connection, fill the crimp with solder. To do this, heat one side of the crimp, while applying solder to the other side of the crimp, you may need to swap sides if the solder doesn't flow through.

All this effort is made, because the nichrome wire does not solder well, in fact it solders very very poorly.

Thermocouple A-D converter with OneWire

Parts included in the Thermocouple Add on
Here (on the right) is a picture of the parts we include in the Thermocouple Add On:

You may already have a Thermocouple A-D (of a different type) Information about it can be found here

Included in the Thermocouple Add On

  • (1) Thermocouple A-D converter with OneWire
  • (1) Cat 5 cable with one RJ45 connector
  • (1) 3 pin connector
  • (1) Small mounting screw
  • (1) --If ordered separate from the tip kit-- Thermocouple wire (not shown in photo)

Connection Instructions (Pinouts)

(If you have an updated kit, you don't need to worry about this. It should have Rj45 to RJ45 from the tip manager to the board.)

Cut the shielding off of about 5 CM (2 inches) of the cable.
We need to cut the shielding off of the end of the cable, so that we can connect the wires to our Extruder controller where they belong.

Close Up of the RJ45 end.
This picture shows a close up of the RJ45 end, The end from TechZone is not in the same order as an end from an ethernet cable. If you need to replace your cable, any cable with an RJ45 end should work, but you will need to adjust the wire colors based upon the order which they are in the end. In other words, the color of the wires we use is not what is important, but the number position is what is important.

Our wires happen to be in the following order:

  1. Striped Orange
  2. Solid Orange
  3. Striped Green
  4. Solid Green
  5. Striped Blue
  6. Solid Blue
  7. Striped Brown
  8. Solid Brown

If your wire colors are in a different order, then just substitute your color order for mine. Like if Solid Green-#4 and striped blue#5 are reversed, then every time I say Solid green you would use the striped blue and every time I say Striped Blue, you would use solid green.

The Blue and Brown wires are used to carry the power down to the heater wire. If you don't want to use them, then you don't have to. It is for convenience, I had a really hard time using a cat5 cable for this and not using all the wires, and one of the things that irritates me is all the wires all over the place, so I consolidated here.  Tie the Striped wires and Solid wires together.
Cat 5 wires are a little small for providing all the power that our Nichrome heat wire is capable of pulling, so I used two wires for each lead. I use the Two stripes as one Lead and the two Solids as one lead, the picture on the right shows them tied together.

The remaining wires as connected to the three pin connector.
A three pin connector is used to power the A-D chip, and to get the digital reading back to the processor. The Solid Orange and the Solid Green are ground (cut one off on this end - see photo in gallery below) The striped Orange is our signal wire and the striped Green is our 5v.

I use a small screw driver to press them into the connections. I STRONGLY recommend using a multimeter to test the connection when you are done.

Connecting the A-D to the extruder.
Connecting the A-D to the extruder (close up of 3 pin).
To connect the A-D to the extruder, take the two sets of twisted wires (brown and blue) and connect them to your heater terminals. Plug the three pin connector onto the I2C connector on the extruder board as shown in the picture on the right.

Connecting the thermocouple to the A-D converter.
For those of you who understand thermocouples, you know that a thermocouple is polarized. But... Ours isn't (actually it is, but we compensate in the software) so you can hook it up either direction (mix up the red and yellow, id doesn't matter) Just make sure that they go under the two terminals on the side of the chip.

Connecting the heater lead wires to the A-D converter.
The other two terminals are used for connecting the heater lead wires.
An assembled and updated techzone Tip and Manager.

Firmware Files

You will need to install firware from this zip file for this A-D to work.

This firmware is for the RepRap Host software and probably won't work with Makerbot's Replicatorg software (you are welcome to try and let me know). Kurt (the programmer for TechZoneCommunications) has created this great page, which explains all the software changes we have made to the firmware. There is also a schematic for the adapter on that page.

Connection to the Extruder Body

The oak block connects to the bottom of the extruder body using the two screws provided. The screws are normally installed at a slight angle. Drill a pilot hole for the screws to follow (it is mighty tough to drive a screw into oak without a pilot hole). Be careful not to put the screw into the Teflon sleeve.

The A-D converter can be mounted anywhere on the extruder body, I try to mount it a little further away from the motor, but that isn't required. There is a single mounting hole and a small screw provided for this purpose.