New delta drive

Thews made a new extruder drive last week. I've been testing it and it works great!







Best part about this drive is the quick release setup and being able to clean ground filament off the spur drive without having to disassemble anything.

The whole idea of suspending the extruder like that is to reduce the length of the bowden tube. Like this I only need 2.1mm retracts and I don't get any blobbing or stringing anymore.


The stepper motor is a Nema11 with a 27:1 ratio gearbox on it. Can be bought here or from many other places: [www.omc-stepperonline.com]

STL files are attached but its on thingiverse too: [www.thingiverse.com]

With a nema 11 motor and the 27 to 1 box would your torque be about 36 Nm? Do you think that is enough for longer bowden tubes?

Awesome, simple, clean design!

27:1 gearing is very high. What retraction speed and acceleration are you able to achieve? Although I guess that with a short Bowden tube on a flying extruder, fast retraction is less important.

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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].

Quote
dc42
27:1 gearing is very high. What retraction speed and acceleration are you able to achieve? Although I guess that with a short Bowden tube on a flying extruder, fast retraction is less important.

I have both the 5:1 version of that motor and the 27:1. Either fit my extruder which is direct. I did not find the 27:1 to be any improvement, if anything it was slightly worse.

Depends on the voltage. With 12v you can do 12mm/s or 28.86mm^3/s at 3500mm/s^2 accel without any real concerns on 1.75mm filament. With 24v you can go up up to 20mm/s with the same accel, but you'll want to limit the unretract or prime to about 12mm/s still. I can extrude at about 19.2 cubic mm / s with completely even sheen, but if I push it beyond 24 cubic mm it will have some shiny spots at the end of accel and look matte on the rest.

This started off with the insane volumetric rate before I dropped it down. That's at 2mm width I think.

no retraction issues with normal printing


Edited 3 time(s). Last edit at 06/07/2016 12:11PM by thews.

Quote
DC42
What retraction speed and acceleration are you able to achieve?

I had to set microstepping to 2x to be able to get fast enough retracts on my RAMPS 1.4. I was able to go up to 20mm/s but use 10mm/s because 20mm/s retracts weren't always reliable.
The 3mm filament I use is really stiff so if you run thinner filament I'm sure you could use a higher speed. It works beautifully! I'm retracting 2.1mm and coasting 0.3mm before doing retracts.

Quote
BuildAThing
With a nema 11 motor and the 27 to 1 box would your torque be about 36 Nm? Do you think that is enough for longer bowden tubes?

It has loads of torque, easily enough torque for a longer bowden tube.

Hey TTN,

Couldn't you shorten that Bowden tube further? Not sure how long your arms are but there seems like plenty of leeway to suspend the extruder lower down.

Very tempted to print one and try.

I'm down to 1.2mm retracts on my set up with a 200mm Bowden tube from the flying extruder on 674mm long arms

I could probably shorten it a bit. If it was too short it would have to move around with the hotend too much while printing, though there is definitely room for shortening yes.

Nice and simple.

What is the total weight of the extruder?

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Lykle
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Co-creator of the Zesty Nimble, worlds lightest Direct Drive extruder.
[zesty.tech]

Sorry, coming in late on this...

Who/what is 'Thews'? Something to do with thews-wo_ ?

I'm curious about the thinking behind a NEMA11 + 27:1 gearbox... they're quite pricey. Why not (say) a NEMA17 or NEMA14 pancake motor? Is it that you can't get the torque for the low weight?

According to the website, the holding torque = 1.3Nm (cf 0.43Nm for a 48mm NEMA17 direct drive).

Thews is a user on IRC in #bigdelta on freenode.net aka thews-wo or thews-work
If you can get the torque, why not use it. The point of the nema11 was to reduce weight, while still being able to do the extruding functions.

He's made a newer fully parametric version of the filament drive: [cad.onshape.com]
Since I run 3mm filament I had to resize some parts and thicken them.

Whats the total mass of your extruder+motor/gearbox? I only say this as I am using a flying e3d titan and 20mm nema 17 and its 250g, and the results are stunning.

A part I recently printed for someone with 150 micron layers until the top section with 100micron layers.

Edited 1 time(s). Last edit at 08/11/2016 09:32AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

The assembly weights 220grams all up.