Glass Nozzles
Release status: Experimental
| Description | Glass Nozzle to replace PTFE/Brass combination
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| License | GPL
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| Author | |
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| Based-on | |
| Categories | |
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One of the most frequently described failure modes for a working reprap is an extruder failure. This often occurs because the brass nozzle works loose in the PTFE thermal break, or slight mismatches in drilling create choke points that jam. Using a single material for both nozzle and thermal break would greatly simplify the construction of extruder nozzles, eliminate the drilling mismatches, and reduce or eliminate the nozzle working loose from the thermal break. Recent discussions about reducing the heat flow from the nozzle to the ABS mounting bracket pointed out that even stainless steel, a very poor conductor of heat, was still way to good for any normal length nozzle. The only way to reduce the temperature of the stainless steel tube in that short a distance is to add many washers or other heat sinks to cool the metal before it melts its mounting bracket. But this cooling wastes lots of power, and releases heat inside the reprap where it does no good. The only solution so far is to use glass or ceramic nozzles. Ceramics can be machined, but not formed or molded,and we are limited to ceramic nozzle shapes already produced.
The glass can purchased in bulk and worked with a welding torch to create a very orifice. It can be made easily in two forms, one a blunt nosed tip in which the glass closes off the interior hollow by surface tension, and creates a blob tip that can be ground down until reaching a funnel shaped section, and then ground further until the desired orifice size is reached. The other is to heat the glass tubing in the middle and draw it out, just like making a micro-pipette. This can also produce small orifice sizes, but leads to very thin walls at the tip also. The blunt nosed nozzle is very strong and should be able to resist breakage even after a Z axis crash. The drawn tip is not a strong and may break. Both types can be fitted with a flange at the other end to make a simple saddle clamp a secure mount, or left as is for compression fitting mounting.This page present methods to wire up a glass nozzle, and to build simple mounts for them
Contents
- 1 Forum/Mailing List
- 2 Mounting a Flanged Glass Nozzle
- 3 Forum thread?
- 4 Text
- 5 Files and Parts
- 6 Sub Assemblies and Related
- 7 Downloads
- 8 Photos and Drawings
- 9 More Examples
- 10 Huge Image
- 11 Forum thread?
- 12 Text
- 13 Files and Parts
- 14 Sub Assemblies and Related
- 15 Downloads
- 16 Photos and Drawings
- 17 More Examples
- 18 Huge Image
Everything below this point is working notes.
Step 1 Here is a photo of the material needed to start. A glass nozzle, of course. This one has a flange and index key as well. Scissors to cut the Kapton tape as well as the nichrome wire. A thermocouple has been prepared from extension wire by twisting and soldering the tip. A multimeter that read both ohms and degrees C from a Type K thermocouple.
| Description | Quantity |
| glass nozzle | 1 |
| Kapton tape 1" | 1 |
| nichrome wire #30 | 1 |
| thermocouple | 1 |
| Ohm meter | 1 |
| scissors | 1 |
Here is a complete list of all the parts and materials and tools needed.
Step2
Cut off a 10 ohm length of nichrome wire. This will set the maximum heating rate to be 15 watts. For 30 gauge nichrome wire, this is a length of about 12 inches or 30 cm. The wire is so thin it is hard to see in this picture. Use the ohm meter to verify the resistance before you start. Remember the value, as we will check it again when done to test for shorts.
Also make sure your thermocouple is ready to install. You can simply strip the ends of the thermocouple extension wire and twist them together, but it is better to solder or weld them together so that there is never any loose of continuity. Since the voltage differential is generated by the temperature change across the each wire, it does not matter if they are soldered together instead of welding. But don't splice any other type of wire to the thermocouple to extend it to the electronics. If you must extend it, use more thermocouple wire.
Step 3
Cut a piece of Kapton tape long enough to go at least twice around the glass nozzle. Start the first little strip to get it securely bonded to the glass nozzle. Place the edge as far down the nozzle as possible. To get good flow rates, the very tip needs to be hot, and unlike the brass nozzle tips, glass does not easily conduct extra heat here. Having the tape all the way down means that the first few loops of nichrome wire will be that far down, too.
Step 4
Insert the thermocouple first. It is th emost difficult to keep in place, and needs the strongest taping. Notice that the thermocouple wire and the glass key index match up. This will help later when mounting the nozzle.
Step 5
Pull the tape firmly to get a good hold on the thermocouple, go about half way around and then stop. Now place the nichrome wire cut off in step 2 so that one end just sticks past the top of the nozzle. This will allow connecting it to the power leads using the same bolts that hold the mount the nozzle to the extruder base. The long end should run straight off the tip of the nozzle. Once again, the edge of the tape should be as close to the tip of the nozzle as possible.
Step 6
Finish wrapping the tape on to the nozzle. This will hold the thermocouple and the starting point of the nichrome wire spiralling back up the nozzle.
Step 7
Prepare the second piece of Kapton tape BEFORE you begin winding. Once you have the wire tightly wrapped around the glass, you will not be able to let go until the loose end is secured.
Step 8
Now coil the wire as tightly as possible without have one loop touch another and short out a section. Don't worry too much if this happens once, but if it happens in several spots, stop, relax, and start over. You want to have as many loops as possible close to the tip. When you get near the other end of the wire, start spacing out the loops much further apart with each loop. This will cause a more gradual drop if glass temperature and reduce the chance of thermal stress induced breakage.
Mounting a Flanged Glass Nozzle
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Text
Text text text text Example text text text! I, (Example_User) made it because it's cool and Interesting, because I made it with a RepRap, text text text text text text text text innovative new RepRap. Share and Enjoy! (This page was made using the wiki page Example as a model.) text text text text text text text text.
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Text text text text New Example. Another Example text text text text text text text text.
Files and Parts
Sub Assemblies and Related
Text text text text Example/SubAssembly and Related Example text text text text text text text text text text text text text text text.
Downloads
- File:Uploaded files example.zip
- File:Even more example files.zip
- File:Example part.stl
- File:Other example part.stl
Photos and Drawings
Captioned
Links can be put in captions.
More Examples
Huge Image
