Compact Mk5 Extruder Heater Core
Description
I am adapting the extruder head to fit to a CNC mill to increase the accuracy and build envelope available to me, so whilst I've had my extruder running on the bench, I'm still working on adapting the extruder controller to allow it to be driven by the CNC controller (Siemens Sinumerik)
UPDATE: I've got my TechZone Extruder controller re-coded and running my extruder nozzle now. I've measured a warm-up cycle at 3'44", with the heater running a continuous 28W. Some of my theoretical power has disappeared somehow - not sure why
Instructions
The resistors are glued into the core using a calcium carbonate-filled epoxy resin mix.
I had some spare CPU paste, so I used it when installing the nozzle to increase the heat transfer properties. I also counter-bored the block to allow some insulation around the filament tube to reduce heat transfer up the tube - I'm not sure whether this is worthwhile to do though...
After installing the thermistor, the resistor leads are poked through short lengths of insulation tape each side and the remainder is wrapped in a length of tape running the other axis with a hole punched in it to allow the nozzle to poke through. All the tape is held on with Kapton tape.
The resistor wires are brought together and soldered to the power supply cables on the outside of the insulation. This has the advantage that the solder connections are not subject to as much temperature as on the original design.
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Nice thinking Andy...
But have you tried it...
Is it not a bit ......... slow..?
How long does it take to heat it up to... 220 °C...?
These resistors have a capacity of 7Watts each ..? a max of 28 watts total....?? i use 45 watts...on 2 25watts resistors....heats up to 235°C in 10 minutes...
And i i see your res
istors have a max of 200°C.... i don`t think they will last long.... but i may be wrong..
God luck anyway... if them resistors don`t last long maybe it exists resistors in the same size with better specifications...
And again... good idea... i have been thinking of something like this too... on
ly using heat elements from some solder irons.... haven`t tried it yet tho..... ;)
I had a test resistor epoxied into an aluminium block and ran that to 265
°C at which point the epoxy started to smoke a bit, but the resistor still works OK.
On the heater block as built, it takes me about 3mins to reach 210°C or so from cold (18-20°C). I have four 10ohm resistors in parallel, which gives a total resistance of 2.5ohms - that's nearly 60W power! Th
e 7W spec is for the resistors in "normal use" - i.e. allowing for their normal heat rejection to the surrounding air as if it were populated on a PCB.
We shall see how long it lasts...
Correct me if I'm wrong... but is not the wattage rating on resistors a rating for thermal disapation, not power consumption?
We are generally abusing the resistors we use anyway, and the top end of the thermal rating is typically a time limited rating (and short enough to be less than we use). The normal MK5 resistors are 10w are they not? (mines all wrapped in insulation). The main requirement is that the resistance is low enough that we can jam enough current through.
I think that vitrious enamel resistors might be a better bet as they have far higher thermal ratings. If I had a drill press I'd be all over this!
Maybe I need to make that dremel mount I have been thinking about for so long... see how long my dremel bits last!
Mmmm.. cupcake making upgrade parts
is always cool!
License
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I like that you are having a crack at the problem. There's a lot of experience to draw from in the thingiverse world, and this project encourages discussion from all quarters. Just what's needed. ;)