Extruder Nozzle Variations
Split Heater Block
I found that glue can be a bit sticky to work with. You have to use special glue with high thermal rating which can also be hard to find. So I decided to come up with a glue-less alternative for the heater block.
Its simply an aluminium block, with a split (the thickness of a saw blade) cut down the middle. The hole that accepts the nozzle is then taped to M6 in the bottom half, and drilled out to a clearance hole in the top half. As you clamp the heater block onto the nozzle it closes the gap slightly and grips the power resistor nice and snug.
- No need for glue
- Looks like some kind of woodblock instrument
- Less material to conduct heat
- Looks like some kind of woodblock instrument
Its quite a delicate thing to make but can easily be made using the following technique. Start with a length of 3/4" square aluminium bar. Use the whole length of bar to your advantage and clamp it so that you can drill the hole in the right place at one end. Once the hole is drilled you can cut the split 4.5mm from the end of the bar, straight down the centre of the hole. I used a mitre saw to get my cut nice and square, but I am sure you could also do this with a junior hack saw, so long as you mark a line to follow. You don't want to make the split all the way through, so stop cutting a few mm before reach the other side. Finally cut the 9mm block of the end of the bar. The reason its easier to do it this way round is that its a lot harder to hold once you have cut it into a little block.
Rounded Support Block
I wanted to make a cheaper version of the support block so I decided to publish this design that uses PEEK rod instead of PEEK sheet. This is an alternative to crowd sourcing.
- Cheaper - more than ten times cheaper if you buy PEEK rod at £11.87 instead of PEEK sheet at £158.00
- Aesthetically pleasing - Although this is a matter of taste.
- Possibly harder to cut.
To make the rounded support block buy some 16mm dia PEEK rod. Cut a 42mm length of rod. Now cut two flats down the length of the rod. This can probably be done quite easily in a band saw, but I did it using a mitre saw and the following technique. Drill a 16mm hole into a scrap block of wood. Tap the PEEK rod into the hole in the wood. The wooden block acts as a destructible work piece clamp, now make a cut starting from the end of the rod, all the down and through the PEEK and also through the wood. Then repeat the process to get the other flat. The other holes are drilled in the same was as the original PEEK support block.
No Lathe - Variation
After seeing Adrian's Geared extruder nozzle I immediately liked it, but realized that it would be even harder to make than older designs. Reprap is supposed to be make-able in your garage, I don't even have a garage. So I offer this design as a compromise, that you can literally make in your front living room. Its similar in essence to Adrian's design. I admit its not completely lathe free since you still have to buy a nozzle. These however can be readily bought from from your fellow developers in places like the RepRap Marketplace, Makerbots, RepRapSource, and RepRapStores.
- Easier to make if you don't have access to a lathe.
- Still relies on some bought machined parts.
- PTFE buts up to barrel instead of being inside it.
To make this you will need to buy some 10mm PTFE and put a thread on it. Next you drill and tap some 16mm dia PTFE with an M10 internal thread. Screw the 10mm PTFE into the 16mm PTFE and you will have the completed PTFE insulator part shown bottom left. To make the middle part you use a piece of 16mm dia alu round bar, drill a 5mm hole all the way through the centre, then drill an 8.5mm hole to 8mm deep into one end. Tap the 5mm hole to M8 and 8.5mm hole to M10. Use the instructions for a rounded peek support block above to make the support block. The central hole in the block can be M6 threaded as shown if you prefer. The completed assembly is shown bottom right.
Inline Heater - Variation
This is my first contribution/attempt at the wiki. My Drawing is far from professional.
This design combines the Resistor Heater design in to one single Heater + Nozzle. It's more complicated to make than other heater designes and requires a lathe with a 4 Jaw chuck, as well as the knowledge and ability to use it.
I used Brass Bar, 10 mm x 20 mm x 35 mm long.
Mount the Brass in your 4 Jaw lathe Chuck 5 mm off center and turn it to 10 MM. Drill the Filament Hole 33 mm deep. Use the gague on the tail stock if you have one.
Drill and tap the M7 thread to accept the PTFE. Using the tail Stock to keep it Square, run an M10 Die down the 10 mm stub you created. This will screw in to the PEEK Insulator. Moving just 2 of the chuck Jaws turn the work around and turn the Nozzle to 6mm dia X 10 mm long. Drill the 0.5 mm hole before you put the 45 deg Angle on. Move the work over 12 mm then drill the hole for the resistor. I drilled the Thermister hole on a pillar drill.
The Peek support block has 1 change. Drill and Tap the Center hole to M10. You may also need to recess one of the support Nuts.
- 1 piece design.
- No thermal junction like the 'Block' Heater design = fast warm up.
- 6R8-resistor is Low Cost compared to Nichrome wire.
- Not easy to make and requires machine tools as well as the ability to use them.
- Thermister is still not as close to the Nozzle as I'd like.
Photos and Drawings
Now availiable from mendel-parts.com this variation uses a slightly more common M8 thread instead of the M7 thread, as well as some other slight tweaks
Retro (NiCr) variation
A kind of retro-variant for those who prefer NiCr and Chamois clay over a wire-wound resistor. Instead of the PEEK block a 30mm washer is used and three spacer bars. This version was originally built for a BfB gen2 RapMan.
Slide on the big washer and apply thin layer of fire-cement, or Chamois clay, to the nozzle. Let it dry (takes a few hours). Pre-wind the NiCr wire (6Ω) so it is more easily mounted on the clay base. Next close the wire up with clay and secure it with the brass-pipe section. The NiCr connections are isolated from the brass cover with a few mm of silicon tubing. The base washer is isolated with Kapton tape to prevent short circuit with a heater wire connection.
A thermocouple is used, kept between two small (15-18mm M6) washers and a half M6 nut. These washers can be isolated with Kapton tape to protect the thermocouple D/A IC in case of a heater short circuit. The NiCr is crimped to the connector wire with 0.5mm ferrules and heat shrunk as to protect from short circuit.
DIY Direct hot end (gas nozzle)
- uses a gas nozzle
- does not need any special machined parts (except the gas nozzle which needs to be purchased locally)
- interchangeable: heater block can be made so nozzles can be changed without dismantling anything else
Page link: DIY_Direct_hot_end
Alternative gas nozzle tutorial: Gas_nozzle_hot_end