Extruder for Large Kossel

I have a large Kossel from Think3dprint3d which has been working fine but recently the extruder gear started skipping in one spot, it was only very occationally to start and didn't effect the prints but has now gotten to the point I need to replace it. It is basically the standard Extruder for their mini Kossel


I have asked them for a price for the gears to fix the issue but I want to replace this with something more robust and if I am doing that I thought an upgrade to a flying extruder might be in order. I am looking for recommendation, an extruder which can use some of the current parts would be good, particularly the NEMA17 40N.cm 1.8deg stepper motor and maybe the 8mm hobbed insert which you can see at the right of this image.


Once I get the replacement gears I plan on printing the replacement extruder parts but if you know of where I can purchase the parts and they are cheap enough I might consider it.

I had a similar problem with my Mini Kossel extruder. I ended up replacing it with a modified Ormerod extruder. The printed parts are here [www.thingiverse.com] and [www.thingiverse.com]. It uses the same hobbed insert. See [reprappro.com] for the assembly instructions, except that the spring loaded version needs two extra M3 screws and a strong spring (e.g. from a handwash dispenser). Unlike the one supplied with the MiniKossel kit, it doesn't need any superglue, so it is easier to take apart if you need to.

If I were replacing that extruder now, I would probably try the E3D Titan.

If you want to fly the extruder then I suggest a smaller motor because of the weight. I suggest a 34mm long motor with a torque of about 22Ncm, which I find sufficient for 3:1 geared extruders.

Edited 1 time(s). Last edit at 04/19/2016 03:34AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I've used the MK8 extruder on two flying extruders, they work quite well with a few simple mods. I think that if you're using 1.75mm (as I am) then you don't need the complications of gears.

You can get just the extruder frame (without the motor) quite easily on ebay, such as here:
[www.ebay.com]

Here's a simple way to fly your extruder if it uses a Nema17:
[www.thingiverse.com]

Good luck, flying extruders are the only way to go. Once you've tried it you won't go back.

I replaced the extruder on my T3P3 mini kossel over the weekend - with the new E3D Titan - although mounted on the frame rather than as a flying setup - and so far, I've been very pleased.

You should be able to reuse the motor you have with the titan (I didn't personally do this, I wanted to keep the T3P3 extruder intact as a spare or for future use if I go dual-nozzle in the future) - the only thing to note is that the gearing on the titan turns the other way, so you'll need to set the reverse flag in the config.g file.

Edited 1 time(s). Last edit at 04/19/2016 05:54AM by codiourso.

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Current Printer: T3P3 Kossel (modified with E3D Titan and lighting)

My 3d Printing Blog - [codiourso.wordpress.com]

Thanks all, I will have a proper look at these when I get home.

This geared extruder was designed to reuse rePrapPro parts with the M3 hobbed insert, initially for the Fisher. There is a variety of mounts, but not yet anything for Flying extruder.
There is an option to use same bearings as other RRP extruders (MR93).
The RepRapPro stepper being relatively light, this is a good option for flying extruder.

[rouzeau.net]
[github.com]




The gears are thicker than RepRapPro gears (they are widened Ormerod Extruder gear), but what makes them more durable is that they are printed in PETG. I don't recommend PETG inside an enclosed printer, but for an open machine, this is the best option for mechanical parts.

It does have a quite good grip, better than MK8 hobbed insert based extruder and with a 3.3 gear ratio and current at 1.2A the stepper skip step without grinding filament. Overall, it is better than my direct drive extruder.
Extruder accelerations adjusted at 2000 mm/s^2 and 420 steps/mm (like Ormerod).

The spring is the one used on the Fisher beta (same on Fisher 1 ?), so you may have to order it separately.

Edited 2 time(s). Last edit at 04/19/2016 01:31PM by PRZ.

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Pierre

- Safety [reprap.org]
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DC42, how did you attach the Ormerod extruder to your printer? It looks as though it was made to clip on the Ormerod.

Quote
MightyMouth
DC42, how did you attach the Ormerod extruder to your printer? It looks as though it was made to clip on the Ormerod.

I printed this mounting plate [www.thingiverse.com] and used it to attach the back of the stepper motor to one of the vertical extrusions.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Great thanks for the fast reply.

DC42, can you advise what length crews I need to attach the extruder to the motor? Is it the same as for the ormerod extruder, M3x12mm countersunk socket screws, would these ones do?

Edited 2 time(s). Last edit at 05/11/2016 12:26PM by MightyMouth.

The extruder is basically the same as the standard Ormerod extruder, so use the same screws listed by RRP in their Ormerod build instructions, plus another one for the hinge and another for the pressure adjustment. You will need two additional long screws to attach the back of the motor to the mounting plate, see the instructions on Thingiverse.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks, I assumed that was correct but wanted to be sure, I just need the screws to mount the extruder to the motor, I already have everything else put together.