Very Different Extruder in action

A short clip of the VDE-100 in action on a delta, using the original heatsink to keep variables to a dull roar.
[www.youtube.com]

... looks good! - congrats!

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Well done. I look forward to more reports on how it is working.

Very nice, it looks exceptionally light as well. What is the black line around one of the rollers?

Mike

Very nice! Can you post photos of the finished print? Does retraction work?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Mike, the extruder itself (motor, drive mechanism, and groove mount adapter) weighs 100 grams. 70 grams of that is the motor. A NEMA14 or 11 would also work, but I don't see them in a "pancake" format.

For those who have been following this exercize, I started out with a three bearing "Rohlix" design, with the intent of texturing the bearings. Many iterations later, the "final" prototype has two "pressure" rollers, which just add support to the filament, and one "drive" roller. The drive roller has a single sharp edge on its circumference. It looks exactly like the cutting roller in a plumber's tubing cutter. In fact I bought several replacement cutters from the local hardware store just to study their design and angles.

Various iterations with multiple threaded rollers worked, but introduced the issue of having multiple thread starts on the filament, so there was a lot of scuffing and repeatability problems, especially during retraction. Having just one drive roller, with just one concentric edge, makes that all go away. So the black line that you mention is the drive edge on the drive roller.

All of the rollers are mounted at an angle of 15 degrees to the filament axis. Varying that angle determines the drive rate per revolution.

I think my next step would be to make the drive roller out of two flanged bearings, mounted with the flanges together. I would then grind the drive edge in to the mated flanges. I would also mount the drive roller on an eccentric axle, so that it's "bite" is adjustable. Currently I have to print a new bearing carrier each time I want to vary the bearing center distances, although it's not particularly critical.

One interesting artifact of this design is that it drives smaller diameter filament faster than fatter filament, because the smaller filament engages more with a greater "pitch diameter" on the drive roller. It tends to :auto-correct" for filament diameter variation.

Yes, retraction works well, and was part of what drove me to the single drive roller design. Having a single thread start on the filament is critical, and the drive roller is allowed to "float" axially to ensure that it will always re-engage with the previously cut groove in the filament during retraction.

I did have to reduce the retraction amount and the acceleration. The acceleration I can understand (motor dependent, as I'm driving a 1 amp stepper at about 0.2 amp). The reduction in amount of retraction has me somewhat confused, but there it is. It will be interesting to see what happens when I install the custom heatsink and heatbreak back on the unit, but I used the originals just to avoid uncontrolled variables like these.

The test cube and benchy are PLA at 195C, 60C bed, 0.1mm layers, 60mm/sec, 100% part cooling fan.

Edited 1 time(s). Last edit at 07/15/2021 01:27PM by rq3.

Very cool and elegant design. Needs a better name though! VDE-100 is just too generic and is lost in the internet of searches.

... my own designs are named something like "RollRing..." for the German name ... maybe something with "...spin..." or "...spinner..."?

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Give it a catchy name like...

"The Twister"
"Spiralizer"
"SpinStruder"

corny but memorable

+1 for "twister" and "spinstruder"

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I like "spinstruder", or maybe "screwstruder". God knows I'm no marketing whiz, but there is actually a method to my madess. The first three letters are an acronym that describes (at least to me) the function of the product. VDE=Very Different Extruder. TAP=Totally Accurate Piezo. The following three digits are a revison number, like software. The first pass at the idea gets assigned 100.

Edited 1 time(s). Last edit at 07/16/2021 06:13PM by rq3.

Take a look at this thread at Duet forums, then look at your prints- do you see any of the "woodgrain" or vertical banding in your prints?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

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the_digital_dentist
Take a look at this thread at Duet forums, then look at your prints- do you see any of the "woodgrain" or vertical banding in your prints?

Woodgrain, no. Vertical banding yes, no matter what extruder I'm using. I've always attributed it to improper acceleration and/or jerk settings, but its never bothered me enough to spend time on. I probably will now that I have to play with those settings anyway for the screwstruder. The effect is visible on the corner of the test cube I posted earler, but as I said, its always been there.

Edited 1 time(s). Last edit at 07/17/2021 10:53AM by rq3.

That looks like ringing, caused by flexibility in the mechanism and the moving mass of the extruder carriage, not the vertical banding that people think is coming from the gears in the BondTech extruders.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Is the edged roller you are using custom cut on a lathe or something off the shelf you bought?

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obelisk79
Is the edged roller you are using custom cut on a lathe or something off the shelf you bought?

It's custom cut out of 10mm bar stock, bored either for 8mm bearings, or 4mm for the shoulder screw as a "bearing" during development. I then make one pass with a 60 degree single point threading tool, reverse the stock, and make another pass until I get a knfe edge around the diameter. The whole process takes about 10 minutes. You could also do it with the stock in a drill press, and a steady hand with a dremel tool and miniature grinding disc.

I used the second basic technique for a simpler drive wheel (edged roller), except in my lathe rather than the drill press. I fixtured two bearings with 10.3mm diameter flanges, with the flanges face to face, then used the dremel to grind the mated flanges to a sharp edge 10mm in dianeter. Easy to do, uses stock parts, and bearing steel is VERY hard so should last quite a while even with abrasive filament. Plus you get the benefit of ball bearings, with a noticable reduction in torque on the filament.

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the_digital_dentist
That looks like ringing, caused by flexibility in the mechanism and the moving mass of the extruder carriage, not the vertical banding that people think is coming from the gears in the BondTech extruders.

I agree, but as I say I haven't pursued the root cause. I guess I could start by doing an extremely slow print and see if there is any effect. I just don't want to start introducing too many variables, while still keeping this printer usefully functional ;-)

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VDX
... my own designs are named something like "RollRing..." for the German name ... maybe something with "...spin..." or "...spinner..."?

I have a small woodworking tool known as a "gimlet", basically an auger with a screw point, driven like a screwdriver, used for making tapered holes for wood screws. In German it's called a "schnekenbohrer", or something like that, meaning drilling snail (in reference to the twisted auger part looking like a snail's shell).

So maybe "shnekenstruder"? Now that I say it, it sounds like a yummy German pastry! Schnekenstrudel? Extruded snail pastry? I'm getting hungry. Or Hungary. Time for some chicken paprikash.

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Viktor
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Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

I really like Schneckstruder as the name.

Now the question: How can engineering-challenged people like me get one?

I have been corresponding with rq3 about the VDE extruder for some time now. I have just released a video about a version I have made using simple tools.

Clever solution to the difficulty of grinding the underside of the flange, using two opposing single-ground bearings on different posts. And nice to see that the thin walled hollow posts are strong enough in plastic. That's how I wanted to eliminate the need for expensive shoulder screws, but I figured it would have to be made out of metal or they'd just break off. And you just left the spring washers off entirely? I suppose I should have tried that before messing with split lock washers Coarse thread/self-tapping screws would probably work even better. In my experience machine threads in PLA wear out pretty quickly, and thus are generally looser and more likely to wiggle free without spring washers. You could even vary the hole diameter so the threads don't have to cut very deep in the thin walled post and risk cracking it, but do have a nice tight fit once they get down into the solid base.

I'll try making one in this style and see how it goes Maybe another attempt at my outrunner version, and just make the shaft supporting section much longer this time to hopefully eliminate the rotor tilting/magnet rubbing problem I had before.

The screws do become loose in the posts over time as you predicted. So far I have managed this by ignoring it! When extruding, the bearings are pushed into the carrier so the screws are mainly there to stop the bearings dropping off due to gravity.

I also have in mind that printing a new carrier is cheap and quick and replacing it is trivial. So I'd be happy to see it as a consumable. Always have a spare ready to fit.

The other function of the screws is to strengthen the posts. They protrude a little into the base of the carrier. This may be overkill, though, because, again the main force is into the carrier.

It may also be, as you suggest, that self tapping screws are better. Something to try perhaps.

Since the carrier is printed, there is no ned for the spring washers. The posts just have a chamfer where they connect to the carrier, which presses against the inner race but leaves the outer race free to rotate. And as long as the screw head is small enough, it presses against the other end of the inner race without pressing against the rest of the bearing.

The shoulder screw solution is very satisfying from the perspective of good engineering but it does require high grade machining in the carrier and spring washers.

"Genius is 1% inspiration, and 99% perspiration": Thomas A. Edison

This looks impressive, good work! But the sound is strange.
tracking employee productivity site

Edited 1 time(s). Last edit at 10/05/2022 03:59AM by Janeer.

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Janeer
This looks impressive, good work! But the sound is strange.
tracking employee productivity site

The extruder itself is silent. The delta printer is another story.