Hmm, I was pretty sure I posted here before on some of the questions, but must have failed to do it properly.
what should we call this class of extruders? Something like "remote direct drive"?
, that is exactly what we were calling it before we picked the Nimble. Remote Direct Drive, aka RDD. We also had DoubleD but RDD is better.
What makes it different from the flex3drive?
As Michael mentioned, we are lighter, and a lot more flexible. Flexible in the sense of positioning, applications and add-ons.
Not only are we a lot lighter, now 28 grams, the breech loading system makes filament loading easier than ever. You open it up, see the whole filament path down to the hot end, slide the filament in and close the breech block with a click.
Our shape makes it possible for planned add-ons. Like a filament sensor (together with David Crocker), a brush to clean the hobbed wheel, a little bracket to make a "reverse bowden" to the filament spool. Those kind of things.
The 30:1 is relevant, as it allows a greater extrusion speed. We found that some boards were struggling to deliver the steps needed, especially with a Volcano 1.2 mm nozzle on 1.75 mm filament. We tested from 20:1 to 50:1 and found the best combination of response and speed in 30:1.
The 30:1 gear set is custom made for us, as we have a very tight space requirement. Also, the fact that the thing is ambidextrous, creates some special needs for the worm wheel. It needs to be symmetrical in every way, so you don't have to open up the unit and flip the worm over to use it upside down. Or the Australian way as I like to call it.
Of course we looked at off the shelf components, but with each of them there was an issue. Too long, or the wrong diameter, or the gear was to thin, things like that.
Absolutely but even a geared stepper at 5:1 has plenty of torque.
Correct. We can generate about 5 kg of pushing force. (6 kg in static tests, but let's play it safe) So we do not reach the heights of Bondtech, but normally there is no need. The average pressure needed to good flow and clean extrusion is between 2 to 3.5 kg. I have seen a spike to 4 when the hot end was a bit too cold, but that also impacted negatively on the layer quality.
Can the flexible drive cable be trimmed to length? What length comes with the kit?
The standard length we supply is 95 cm. This is a compromise that works best on a lot of printers. My Delta is 1 meter tall and it is perfect for that.
It can be trimmed, but that creates issues. The trick with this cable is that all the layers inside the cable need to be connected very well. It is vital. It is not easy to guarantee that if you cut the cable.
Having said that, if you require a different cable length, we will supply a different cable length. Simple.
stock max will require a longer cable and if that increases the rotational twist.
I don't think you will require a longer cable. As I said, my Delta is 1 meter tall and it looks as if the Max is about the same. The flex does increase a little, of course it does. But looking at the numbers, we will need about 2.5 meters of length to increase the flex far enough to make the retraction go from 1.2 as it is now to 2.2 mm.
If your Delta is 2 meters tall, mount the stepper a little below the middle of a column, and the 95 cm cable is still long enough.
How much hysteresis do you get with the metal cable in the Bowden tube
I have not noticed any. As I said, my retraction is 1.2 mm. I don't set an Extra Restart Distance in S3D.
We clamp the sleeve on both ends to handle torquing effects, but let the sleeve form a natural curve to the effector. Friction is there, but is low.
Finally, the only extra thing I would like to point out is that we recently updated the Nimble (even before we finished the Kickstarter campaign) and it is now smaller, lighter and even easier to use, with a complete new breech system.
Also, we added filament shavings handling. We built in a garbage chute, and a way to empty the garbage without opening up the Nimble. Nifty yes? There are 2 holes in the design, one on top and one at the bottom (preserving the ambidextrous nature of the beast). Blow canned air in at the top and all the shavings come shooting out the bottom.
(Why is it, that the spell checker has an issue with shute, is that the wrong word?) Edit! Found the answer thanks to Mac the Knife. Chute!
OK, give me more questions please.