Spring loaded extruder for Leapfrog Creatr
Description
After a few different ideas, the Mk7 minimalistic replacement extruder seemed a nice design to start with and here is the result.
Now changing colors is actually a fun thing to do ;)
Update: I found that the pressure on the filament was not always enough so I moved the spring and compressed it a bit more resulting in more pressure on the spring. I've tested this for > 100 hours with ABS, Taulman Nylon and PLA and had no problems at all.
Also added a longer filament guide towards the hobbed wheel, making a filament change a bit easier.
note: photos with the light green parts are v1, red parts are v1
Instructions
N.b: the instructions are still for v1 but v2 is almost the same (except for the washers when mounting the stepper motor).
You do not need to remove any wiring or cut or change original parts. Everything can be restored to its original state if needed.
Besides the printed parts (and some tools) you will also need:
- about 12 3mm washers
- 2x 3mm nylon washers (I prefer those for lower friction)
- 2x M3x25 screws
- 1x M4x15 screw
- 1x M4 nut
- 1x spring (25mm x OD 10mm)
I used a spring from reprapworld.com (http://reprapworld.com/?products_details&products_id=228&cPath=16160), the same type is available from different shops.
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I'm having trouble getting mine to feed correctly. Is the spring you used really stiff? I found a pretty stiff one at Lowes (Bi Folding Door Replacement Hardware) that I cut to size. The spring is strong enough that it is difficult to assemble. Without filament, the drive roll spins the idler bearing, but with filament the bearing does not turn. It may be that I need to clean my hot zone, as it is fairly difficult to manually push the filament in.
I love the design though, I hope I can get it working!
just measured my spring. Uncompressed it is 25mm long and 10mm wide. When I compress the spring to about 16mm (that;s approximately how long the spring is when compressed in the extruder) it develops about 1.5 kg force.
I just measured this by placing the spring on my kitchen scales and then pushing it until it is about 16mm long. The scale now shows 1500 grams.
And that actually is a bit on the low side. I currently have the spring compressed a bit more to develop about 2 kg force.
you should be able to push the filament in with a bit of pressure. Keep in mind that different colors have different pigments and they may need different pressures to be pushed through. My white and black ABS go in very easily, green takes more force and orange is in between those.
Are you using ABS or PLA ?
License
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Hi Rob
I have tried both the first and second versions on my Creatr and the design keeps getting better.
I
find with both designs, especially with the stiffer springs I prefer,
that I get jammed or curled filament escaping out of the extruder area.
When
I tried the the thing-o-matic drive block (thing 72215) I found it fits
the leapfrog with some spacers, and solves the issue of filament
squirming out of the side of the extruder by having a small guiding
section beneath the idler/pulley, but it's not such a strong build or
good fit as your design.
Maybe a hybrid of the two might be perfect?
Art,
thanks for the hint. Is this "squirming out" occurring during printing or only when feeding a new filament ?
I am currently working on something like 72215 but for a different reason. I have no problems printing ABS, PLA or Taulman Nylon but the Arnitel (aka Flex PolyEster or FPE) is too flexible and needs some extra guidance.
I am hoping to have a new base-plate next week that does the job for me.