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Reprapping Engines

Posted by Ian Woollard 
Re: Reprapping Engines
November 07, 2007 09:54PM
Hey, you got a thread to two pages. So, it digressed a bit, they all do. Welcome to the RepRap project, where ideas won't stay in the box.

P.S. Victor Dirks has described a complete power train. Motor, (the four solenoids operating in chase light fashion,) "transmission", (the pump,) and driveshaft/differential, (the tube solenoids.)

Again, welcome to RepRap.

Edited 1 time(s). Last edit at 11/07/2007 10:05PM by Sean Roach.
Re: Reprapping Engines
November 09, 2007 06:15PM
Interesting idea for the air pump, Viktor. Have you actually built one? How much pressure can it apply? It doesn't look like it would apply much, I'm afraid. And the MRF pump, is that a scale model? Because I should think that with that large of a gap between the electromagnets seem large enough that it would just sequentially solidify sections of the tuby, not actually drag fluid. Maybe I'm just not acquainted well enough with MRFs.

Re: Reprapping Engines
November 09, 2007 06:41PM
The pump doesn't work; pumps move air from a low pressure to a high. This 'concept' moves air from a high pressure to a low, like an engine, except that both air pumps and engines need to vary the volume and/or speed of the gas to work.
Re: Reprapping Engines
November 10, 2007 02:41AM
... the ferrofluid-pump works from low- to high-pressure as good as in the opposite - the red arrows didn't show the active pressure, but the flowing direction, when i turn the weel.

The magnets are surrounded with so much ferrofluid, that it fills the gap between the magnets, and the stator-walls completely and acts as sealing.

Between the magnets are cavities, which wanders with turning the weel.

All media in the cavities (air or not ferrofluid-soluble fluids) will be transported, as the ferrofluid in the gap acts as barrier.

To extract the media i have the three magnets at the outer side, which 'compress' the cavities with their settled feroofluid, so it can't flow back to the inlet ...

Say this barriers can withstand 0,4 bar (in tests 0,3 to 0,5 bar, dependant of the gap-width, magnet-strength and ff-type), so with the sketched setup i should be able to output until differences of nearly 1 bar (the length, magnet-count and gapwidth at the 'compressing block') - with bigger wheels and/or more magnets even more ...

Look at the image beneath, here i have a prototype of a helical air-pump with another principle, but the same ferrofluid-sealing ...

To the MRF-engine: - the (elastic) hose between the solenoids can be from millimetres to nearly a centimeter, depends of the solenoid-size and -strength.

The MRF should stiffen completely in the gap! - it works as sealing, to prevent backflow from high to low pressure.

When i activate a solenoid, then the MRF stiffens in some microseconds, but in this time the solenoids sucks a bit additive MRF from the sides in the centre, until the MRF stiffens completely, so the hose forms a small 'bulb' (for this is the elasticity!)

When i activate a neigbour-solenoid, so this 'sucking from the sides' is blocked from the already stiffened gap and it sucks only MRF from the free side.

With traveling this 'stiffing-and-sucking' over the sequece it moves small amounts of MRF in the opposite direction of the switching sequence.

To hold the pressure i have to activate one or more solenids at the same time, so every time one stiffed MRF-block (or two) seals the pressure - for this ther could be even 5 or more solenoids in the sequence, but 4 are a minimal optimum ...

open | download - FF-Pumpe.jpg (194.1 KB)
Re: Reprapping Engines
November 12, 2007 10:04PM
No, the pump would generate only miniscule pressure, it's a totally useless pump.

The 'MRF-Engine' is (more or less) an existing pump (Einstein-Szilard electromagnetic pump) that's used to pump mercury around. It's used in nuclear power stations because it has no seals or moving parts to break, but other than that, it's a fairly horrible design also.
Re: Reprapping Engines
November 13, 2007 06:24AM
Hi Ian,

... if every 'ferrofluid-tooth' can withstand 0,3 bar, then with a sequence of 10 'ff-teeth' in a row i can pump 3 bar difference!

If i need 10 bar pressure, then my pump must have 31 free 'teeth-cavities' and 30 'blocking-teeth' (also nearly 60 tooth-magnets in the wheel) for defining the pressure-difference in the radial pump, what's a bit scary ...

For this reason i evaluated the Helix-FF-pump (see the image = 3 complete thread-windings and so with the 4 linear magnets nearly 12 separate cavities for 1 bar end-pressure), here i have 0,3 bar per winding/thread, so the length of the tube and the thread-count defines the transportable pressure - for example 50 cm tube-length with 20 windings for 6 bar end-pressure!

For the MRF-pump - main difference: in the Einstein-Szillard-pump the medium is transported through magnetic forces, so a traveling magnetic setup moves the medium with it.

With my method the medium stiffens/blocks completely in the gap, so no real flow is performed, but with the activating-pulses int the elastic hose a kind of peristaltic micro-transporting per solenoid-gap is running against the activating sequence.

With this setup i can transport very-very-low volumes with extremely high precision, so call this type of pump better a 'Nano-pump', where the pressure can be accumulated too with the counts of solenoids (nearly 2 bar per solenoid) ...

For bigger volumes i have some different types, where i combine the stiffing/blocking effect with oszillating moving of tubes, so i have a kind of virtually activated and released pistons, where the MRF is transported medium and sealing/piston in the same time ...

Re: Reprapping Engines
November 13, 2007 11:54AM
It's not an engine, and it's junk anyway.

What's the point of a forum where people spam completely off-topic stuff, and the moderators ignore it?


This forum is a waste of time, you're a total waste of space Viktor.
Re: Reprapping Engines
November 13, 2007 01:02PM
I don't think these forums are moderated but if anything wants moderating around here I think it's you being rude to people. Many dictionary definitions count something that converts some other form of energy to movement as an engine, so Victor's pump could be considered one. They even call LED car light clusters "light engines" these days!

I think Victor posts some of the most interesting stuff around here and the fact that he backs it up with photos and videos is evidence that his ideas work. More valuable IMHO than a lot of the speculation that goes on by people that have not tried anything.

Re: Reprapping Engines
November 13, 2007 01:04PM

I agree with nophead. If anyone is spamming the forum it's you with your malcontent. Grow up.

Re: Reprapping Engines
November 13, 2007 02:23PM
Hi Ian,

... excuse me, i didn't want to offend you - english isn't so easy for me, so maybe i was a bit of ignorant?

What pushed the thread-size was your declining of my setups as 'engines' and my explaining, that it's one indeed and that's good for 'powering' of pneumatic- and hydromechanics or 'artificial muscles'.

So it was for me a legal 'engine'-definition - i think when i can perform moving and power-ups, then it's not essential, if it's a steaming and firing combustion-engine, or some current-driven morphing structure ...

Re: Reprapping Engines
November 13, 2007 02:40PM
Ian, please try and keep it civil here.

I got your flagged post, and I ignored it because Viktor is by no means spamming. He's putting forth valuable information that is inline with the topic at hand. If you have technical critiques of his ideas, then by all means present them (ideally with evidence to back them up.) otherwise, please refrain from personal attacks.

viktor, dont worry. i think everyone else here really enjoys the stuff you post. i certainly do.
Re: Reprapping Engines
November 13, 2007 03:59PM
Hi Zach,

... i didn't want to start a flame-war - if Ian is right and i consume to much 'forum-space', then i can reduce the amount of my posts ...

For me the forum is very interesting because of exchanging ideas and evolving some fuzzy thoughts with a backup from other enthusiasts.

My biggest 'problem' is maybe the sheer amount of possible interesting stuff and concepts, which accumulated over the last 30 years of my playing around with different ideas of home-fabbing and 'home-brew-nanotech' ...

Re: Reprapping Engines
November 13, 2007 06:14PM

Ian was speaking inappropriately. We're interested in your ideas and thoughts.
To put it tactfully, if Ian is not, he should apply his energies more productively.

Re: Reprapping Engines
November 13, 2007 06:15PM
You don't consume too much "forum-space" IMHO. It isn't exactly a failing commodity.

Re: Reprapping Engines
November 13, 2007 06:38PM
I find your presence, and your contribution, to be desirable. I find Ian's insistence that this thread stay on the very narrow topic of ...thermic engines to be foolish.
I find the fact that, currently, nine of the ten posts made by Ian have been in this thread, with the other in the "oil bath" thread, (where did state something helpful,) to be a bit telling.
Personally, I'm getting tired of the argument. If I could relabel this thread "Ian's ego thread", I might. I already have in my own mind.

As for your post count. You produce some of the most useful posts. I don't think you've "wasted" a single post. Please don't slow down.

As for your english, you're use of "engine" is certainly in line with my understanding of the term. I've had no trouble understanding what you've said, and I speak not a word of german that wasn't borrowed into the english vernacular.
Re: Reprapping Engines
November 13, 2007 07:24PM
Now that we've discussed this matter at length, back to the fun stuff.

Anyone ever tinker with electroactive polymers? I'm surprised this didn't come up in the artificial muscles thread:

I imagine in some ways these will surplant some of the small and large electric motors out there. Unfortunately, (from casual reading), many of these are thin-film based and may be difficult to fabricate in situ. (Still applicapable for drop-in fabrication.)
Re: Reprapping Engines
November 14, 2007 01:59AM
Hi Sebastien,

... my experience with electrostatic flex-systems weren't so good, that i tried further - i partially filled elastic polymers with graphite and applied voltage (eventually until 2kV!) to expand or bend the structures.

The behaviour was similar to SMA's with much lower forces, but much faster activating speed.

So if we find a better material-combination which generates higher forces with <60Volts (for safety!), it's worth a new try ...

Another point: - i have some samples of a Magnetic-Shape-Memory-Alloy from NiMnGa, which changes in a magnetic field until 10% of its length-factor, apply the same forces (Newtons to kilo-Newtons), as piezo-actors and reacts in kHz-range!
But unfortunatelly the company, from which i've got my samples, went down in 2006, so it's an empty trace ...

Re: Reprapping Engines
November 15, 2007 11:15PM
Can you print out real working engines? Yes you can.

Especially if you had a Electron Beam Melting type fabber.(more about EBM here [en.wikipedia.org])

With EBM you might be able to print out a working V8 engine or at least the parts for one. Heck, you might even be able to print out all the parts for a car. Only problem with EBM is that it takes a long time.
Re: Reprapping Engines
November 16, 2007 09:32AM
Hi gene hacker,

... another problem with the EBM is the vacuum you need and maybe the cost, if you weren't wealthy enough ...

SLS (Selective Laser Sintering) is better fitting - i'm playing around with 1Watts- and 8Watts-diode-lasers and some metall-powders with different viscous fluids as paste, what seems to work very well.

With the 8W-laser (used power ~4Watt, spotsize ~80 microns) i worked with gold-powder+dexpanthenol+water, dispensed small droplets on pads and melted them to solid gold (another project, no SLS-fabbing, but i'm on the way).

Actually i ordered two green DPSS-laserpointers for further testing in lowcost-area (one pointer is only 30 Euros).

DPSS means DiodePumpedSolidState-laser - here a IR-laserdiode with output power between 500mW and 1Watt activates a NeodymYag-solidstate-laserrod, and the output is converted to green with an frequency-doubbler, what is in the 1mW-range.

I'm not interested in the weak (but very bright, yeah! - for this is the second pointer winking smiley ) green solidstate-laser, but in the much stronger IR-diodelaser.

As mentioned in some laserfreak-forums, when you salvage a modern DVD-writer, you can extract two diode-lasers - a red one and an IR-type with nearly 220 mW.

They show in videos, that even the red laserdiode can unfocussed cut through a plastic-sheet, the IR-diodelaser is even stronger, so for us much better useable.

But if the IR-diodelaser in the green Pointer is 3 to 4 times stronger and cheaper too (100-200 Euros against 30!), then i know exactly where to go winking smiley

Re: Reprapping Engines
November 25, 2007 12:20PM
Was gonna post a separate thread for this, but after searching the forums for ultrasonic and piezo motors/engines I found this line of thought which seemed more appropriate.

Have any of you looked into ultrasonic or traveling-wave motors? They are used in cameras and such. They exist in both linear and stepper forms. More info here:

The advantage here is very high degrees of precision in their operation. Could be mounted between the extruder head and the main drive to increase the degrees of control, maybe?
Re: Reprapping Engines
November 25, 2007 12:35PM
... i used the Piezomotor-drives ( [www.piezomotor.se] ) and developed 1- to 3-Axis-Micropositioning Stages at Gerwah Mikrotechnik (see MPL-3 [www.gerwahmikro.de] ).

The motor have an accuracy of nearly 150 nanometers per step, but it's depending on the load, vertical orientation an friction, so you hev to implement a precise encoder for error-correction.

The travel-lenght is 25 millimeters, the maximal payload/stall-force lays between 4 and 6 Newtons (400 - 600 gramms), so you can't move so powerfull, as with steppers (or you by the much more expensive motors from PI).

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