MiniBnz's Triple extruder
by MiniBnz, published
Description
three spring loaded arms apply grip to the filaments as a camshaft releases each arm at 90' intervals.
more of a write up here
minibnzreprap.blogspot.com/
Recent Comments
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i have a block of peek plastic about 15mm's thick that the nozzles screw into, as the pinch rollers are a fair way up from this peek block i found that the 3mm filament would bow out the front, so i installed three brass tubes that is 3mm ID this fixed two problems it stopped the plastic from bowing or bending out the front and it also stopped the plastic from getting warm, i noticed that the whole extruder was getting rather warm so i installed an extra fan to keep the aluminum cold this also keeps the plastic from getting warm too... the brass tubes are press fit into the peek block they are pressed as far in as they will go but not to touch the top of the nozzle, if it touches it will conduct too much heat and the plastic melts above the nozzle.
keep the questions coming people I need the feedback 8-)
I was wondering how there could be so little spacing between the 3 hot-ends but reading this it makes sense.
So there is no thermal barrier between the hot-end and this extruder?
How do you keep this printed extruder-block from melting or at least from getting soft due to the heat coming up from the 3 hot-ends?
added the edrawings to here for convenience and front and side views this should give you a little more info.
basically the way it works is the tension arms pivot to apply pressure to the hobbed bolt and the camshaft regulates this movement. you could shorten it but you will end up with less movement between the idle rollers and the hobbed bolt, you need to find the sweet spot between enough grip, enough
release travel distance to suit your camshaft, using a lager diameter camshaft would make this easier to work out. i used 8mm bolt as camshaft so that gives me 4mm of travel at the camshaft for the tension arms this works out to be about 0.75mm of travel at the idle rollers, this also amplifies the
amount of tension that is applied to the filament, if you shorten the height this multiplication is reduced and harder springs will be needed, if you do that the load on the camshaft is also increased, so the sizes that you see there are a compromise of all the factors.
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i have added the Edrawings to my blog, they are standalone files viewable on windows.
at the moment this extruder is not designed to fit to a standard printer, i have a repstrap that i build a dove tail slot onto the X axis so its removable.
Nice. Can you add some images of your design, because i don't have Solid works and i want to make something similar in Openscad? Btw, don't forget to add tags.
I agree.
Also some questions:
* what printer(s) does this mount to? Repman, Mendel, ToM/Cupcake, Darwin,...?
* what hot-ends are you using?
added the edrawings to here for convenience and front and side views this should give you a little more info.
basically the way it works is the tension arms pivot to apply pressure to the hobbed bolt and the camshaft regulates this movement. you could shorten it but you will end up with less movement between the idle rollers and the hobbed bolt, you need to find the sweet spot between enough grip, enough
release travel distance to suit your camshaft, using a lager diameter camshaft would make this easier to work out. i used 8mm bolt as camshaft so that gives me 4mm of travel at the camshaft for the tension arms this works out to be about 0.75mm of travel at the idle rollers, this also amplifies the
amount of tension that is applied to the filament, if you shorten the height this multiplication is reduced and harder springs will be needed, if you do that the load on the camshaft is also increased, so the sizes that you see there are a compromise of all the factors.