Zero Force Motor Replication Project

[DMANN]

Yaro,
Are you using the Doctor's bipolar schematic? If so what ratings are you using on the components? I have used reed switching on my window motor. To big of a trigger magnet can equal to much on time and you will have trouble getting it to the resonant point where it speeds up where it produces less heat on the components/coils. The trigger rotors that I design for the file are fairly easy to twist on the shaft until you find the spot you want where you can permanently mount them. They are set up with small .125 diameter magnets. Without a build of this design I may be pissing on the floor in the dark. I'm feeling motivated to get a start on this.

DMann

[Yaro1776]

Hello DMANN and Dave B.,

Welcome to this thread - I was becoming a bit concerned that there were few out there interested in the ZFM - glad to have you both here showing your designs and thoughts. Excellent!

DMANN - interesting to see the progression of your 3D design and how it comes together. The coils in the ZFM demo unit are elliptical or egg shaped and wound around the plastic 4 inch pipe section that is approximately 1/2" wide and 1/4" thick. When the #20 wire wrap is completed it works out to be about 1 1/2" wide and 1 1/4" thick over the 90 degree segment, at least in the Proto ZFM that I have built.

The ZFM Proto design was put together with 3/4 x 1/4 Neo's on an Al rotor and it performed reasonably well, but without much usable torque. I have the Al original rotor being re-machined to accept thicker 3/8 inch Neo's and intend to reassemble and run to obtain more comparison data. The iron core and shaft are also being machined and it remains to be seen which one is done first.

Dave B. emphasized the difficulty of getting the timing correct, or at least close, with the reed switches. I agree, however I found that by using a short plastic cylinder, in this case a 2 inch PVC coupling, with reed mounting holes spaced 90 degrees apart, seemed to reduce the amount of work. The reeds were positioned inside the coupling lengthwise and the coupling mounted on a wooden track - this method allowed the reed coupling assembly to be moved to and from the timing rotor face, additional the assembly could be rotated to adjust the angular position of the firing angle. This could be done while the motor was in operation to immediately observe the impact of the changes in firing. The reed switches can also be adjusted in or out in the radial direction for fine tuning.

If need be a short video can be put together of the mounting system.

The ZFM demo timing rotor is acrylic and has two sets of two (probably) 1/4 D x .100 or .125T Neo's spaced 180 degrees apart. With the ZFM Proto I played with various Neo configurations and found that a single Neo (using 0.100 inch thick) in each hole yields about a 45 degree firing duration. Changing the number of Neo's by progressively double stacking increases the total firing duration to about 70 odd degrees or more. The best RPM (2700) with the ZFM Proto was achieved with the greatest firing duration, but the coils heated up rapidly to 135 F. High coil temps for prolonged periods are not good for PVC!

Best to all,
Yaro

[DMANN]

The rotor is an easy adjustment in cad. Its probably going to be best for one to fab there own rotor with the metal backing like Dave suggested though. There is plenty of space to fit most any size magnet though. Nevertheless I will add a rotor with any size magnet. The rotor I have listeted uses a 1/2" diameter. I will add rotors with 3/4" and 1" slots. If anyone wants metric stuff pm me and I will see what I can do. My cad program is set up for imperial and I generally have to change my parts to metric before I convert to stl.

DMann

[ZPDM]

[ATTACH=CONFIG]5663[/ATTACH]

If anyone sees any issues or has suggestions please comment.
http://www.thingiverse.com/thing:1940207

Thanks
DMann

DMann,

Thanks for doing this. In looking at the conference machine, the magnets have a length equal to half the core length. I'm looking forward to Dr. Lindemann's paper on all this, but given Peter and John I doubt it was just happenstance that these were the dimensions they demonstrated. I go back and forth with thinking I understand this machine well or not at all. I could mumble stuff for a page or two but basically I think whatever is happening to the outgoing magnet is exactly cancelled by the incoming magnet, this will happen if the magnets aren't correctly spaced but it would "hitch" between the two. Also, if we think of the lines of force as a rope that we are grabbing to pull on than the more the magnetic field is distributed the more hands on the rope. I think this may be part of the reason for the ferromagnetic center. So, my guess, while it will still run fine, is that your magnets are too narrow for that wide of cores.

Got new magnets yesterday or day before and will start building soon, need to run to the skate shop in the mall for skateboard bearings, whew, yea rebels, hey great nose ring. I ran the Mk II with the NS facing tangentially not radially, I don't think that is what was done on the conference machine but it worked well and the concepts seem close maybe the same. If as I hope and suspect I get further improvement with the stronger magnets for the Mk III I'll tear down the M II and rebuild it with the magnets radially to see what I get.

[DMANN]

12/08/2016 With some encouragement I decided to add this version which seems to be closer to Peter's replication. The coils take up two 90 degree sections of 360 degrees. The rotor here is 2.25" inches radius. The magnet sizes, shaft, bearing, and bolts are the same as version one. This print will be more difficult. You will need to use support on the coil piece.

You can use my plastic rotor file supplied or you can fabricate your own metal rotor like Dave mentioned above. The maximum diameter of the rotor should be no more than 2.25" with this one. This design also offers horizontal stackability. I posted to the same Thingiverse page. There are five files with this V2. You will have to print two bearing holders (one for each side). If you need a source to print anything I would recommend contacting Teslagenex. The size of this motor is slightly larger than the first motor. It is roughly about 4.5" square.

If anyone sees any issues or has suggestions please comment.
http://www.thingiverse.com/thing:1940207

Thanks
DMann

[David Bowling]

I also have a 3D printer, but to follow John's design for this motor, you need the steel piece in the center to back the magnetic field of the magnets, so a plastic rotor will not work, except as a proof of concept, OR to give you the shape you need to reduce air friction with the correct pieces embedded into it. You also need the commutator to follow the curve of the rotor to use your coils to their full effect. I am in AZ right now, and my machine is 12 hours away, so you won't see any pictures from me any time soon. Sorry about that. I have had a couple phone conversations with Peter L in the last month or so, and am pretty sure there are some specific things you need to have to get the MOST out of this design. I just wanted to show a simple way that most folks could replicate it without having to have parts machined.

Dave

[DMANN]

Hey Dave. It works really good for me to see pictures or videos so that I can better visualize what you are talking about here. I am excited to be able to join in on the discussion of this thread. I hope to be able to put one together myself at some point and discuss it with my own experience. My replication efforts will be closer to John's 3D printed ZFM like in this video.

I can certainly agree that you will never get the accuracy from a 3 axis machine for a rotor like you will from a good lathe? This little $400 3D printer has paid for itself X3 since I bought it in May. It is a great prototyping machine for this type of work.

DMann

[David Bowling]

I built a simple replication of this motor using a four sided nut (3/4") you can purchase at most places that specialize in nuts and bolts. I had a plastic piece with a hole in it that I pounded into the center and epoxied in place. The plastic stuck out BOTH SIDES of the nut, but that was fine with me, because in helped stabilize the nut better. You can find plastic pieces at Lowes or Home Depot that will fit right inside the nut, if you get the correct size. I drilled the plastic piece out for my shaft, and epoxied the shaft to the plastic piece. I used four 1"x 1"x 1/2" neos with holes in them that I bolted to the nut by drilling and tapping holes and using brass screws fixed in place with local tight. It has an 8mm brass shaft that rests in two ceramic bearings. The stator is formed from the coupler that goes on 4" black pic sewer pipe. I wanted a bit larger size, since my square nut is a bit larger than the block of steel Peter used. The coupler has a larger ID than the pipe itself. The PVC is 1" wide, exposing as much surface are of the wire as possible to the rotating magnetic field.

I spent a LOT OF TIME. A LOT OF TIME. A LOT OF TIME setting the rotor in specific places, and then firing the coil by hand so I could see WHEN to turn the coil on, and WHEN to turn the coil off. Starting the rotor in a SPECIFIC place and providing the coil with voltage for a SPECIFIC amount of time gives best resupts. You want to know that in order to get the right timing. It also taught me a LOT about how this machine operates that you will never understand if you just hook it up and run it. Yes, you will know HOW to make it run, but you may never know WHY it does what it does.

This is the simplest ACCURATE representation of John's machine I can build without a machine shop to fabricate parts. Hope that was useful information.
Dave

[DMANN]

12/05/2016 at 11:07 AM est: added two more rotor options with corresponding reed/hall switching rotors. The magnets for the rotors are 1/2" X 1/4" disc magnets. The reed/hall magnets are 1/8" X 1/4"D cylinder magnets. I cut pieces of 1/4" inch tube to use as bearing stand-offs. Once you determine which set-up that you want to use permanently you can lightly sand the shaft and apply a minimum amount of Gorilla Glue to secure the rotor.

http://www.thingiverse.com/thing:1940207

Enjoy!!
DMann

[DMANN]

I put a file together for anyone that may be interested in a small build. It is about 4 inches square. It is here: http://www.thingiverse.com/thing:1940207 I have started here with a two magnet rotor. If someone wants a rotor with more magnets just let me know. I do not have any plans to build this until after March 2017.

DMann

[Yaro1776]

ZFM Proposed Rotor Material Spec

Researching the the material spec for the rotor iron has been a fun exercise wading through all the ferromagnetic metals available in the market place. The most likely and appropriate candidate for the rotor is a low carbon 99.5% or 99.8% Cartech Electrical Iron that can be obtained from Carpenter Technologies' distributors. If you wish to obtain this material contact a reliable metal supplier to see if they have access to the round and bar stock. There are other major metal mills that, undoubtedly, have a similar material.

If you wish to do your own research into this, go to CarTech.com and search magnetic alloys/metals - prepare to be overwhelmed with 58 possible choices.

Update on Supplier and material spec. Material can be obtained from http://www.cmispecialty.com/ and iron conforms to CMI-C Magnetic Core Iron Cold Drawn Rod and Bar per ASTM A-848-01

The magnetic properties of parts machined from this material can be enhanced by proper heat treatment, but in this instance the parts probably can be used, as is, for proof of concept.

I intend to initiate the machining process of the Iron ZFM rotor as soon as the machine shop can fit this little project into its schedule and obtain the material. With the holidays rapidly approaching, it may be wishful thinking to see the parts before the New Year, but it may happen.

The intention here is to put together a simple design rotor for a start, and gluing the Neo's to the rotor with the magnets properly positioned by a shallow counter bore on each side of the rotor. The glue (Loctite 334) is high strength and designed specifically for secure magnet applications. The assembly will be reinforced with the recommended tape wraps. More importantly, the rpm will be limited to well below 10,000 rpm by utilizing the principles (operating voltage and timing) learned from the ZFM Proto with the Aluminum rotor. Anticipate that a 4,000 rpm maximum will be a comfortable speed zone to do the necessary testing and still be in a safe speed zone. It will be interesting to see if that milepost speed can be achieved.

Once the above is proofed and deemed worthy, I may post the machining schematic design for the shaft and rotor if requested, or some form of this procedure.

If anyone has relevant suggestions and other options for a rotor material spec that will suit this application do not hesitate to post your recommendations.

Chomping at the bit here,
Yaro

[Ed_Morbus]

Thank you peter.

[ZPDM]

Paul,

The bi-polar switching is required in the design I am talking about because the coils are used to actuate both North and South magnets on the rotor. It is not, however, required in all designs that John demonstrated over the years. Single-sided switching can be used for any coil that actuates only one pole (North or South) of a magnet.

I hope that answers your question.

Also, I have now uploaded the image for the timing of the motor in Post #88, so that should complete all of the details people will need for successful replications.

Peter

Hi Peter,

Appreciate your answering my question and all the very worthwhile information provided. Will try and order parts tomorrow. I begin to think this machine has some layers like an onion, will have lots of permutations to look at. When I first started experimenting with this I was pretty stunned when I realized there is no direct correlation/feedback with B field strength. As John said it runs on the "A Field" and the magnetism is contained. I don't fully understand the machine but I have to guess it is closer to a Faraday motor than a conventional AC or DC motor. I'll shut up on theory because it seems like half the time when I don't all the changes I make based from my "theory" make things worse and/or I realize the next day I am 180 degrees off. I am certainly curious though to see whether I can improve my last go around.

Paul

[Retep]

Gyula,

Thanks for catching that typo. There are definitely 4 strands on each side. All strands in series, so replications can just fill the area with a single #20 wire if that is easier. I have fixed the reference in Post #99 so that now reads correctly. N40 was probably pretty close for Neos purchased in 2002. In general, the specific strength of the magnet is not critical, other than to note that "the stronger the better."

Good luck, guys.

Peter

Dear Peter,

In your post #99 you wrote about 3 strands of wire while in the close-up pictures taken at the conference 4 strands of wire can be seen (2 green and 2 red) the ends of which were brought out to the terminal blocks for the series connection. Could you address this? (I know what difference the 3 or 4 strands may cause.)

One more thing: someone wrote the Neo magnet grades on the rotor in your prototype was N40 if I am not mistaken, is this okay or maybe stronger rotor magnets could also be used?
If you think these are irrelevant details, then ok...

Thanks,
Gyula

[Gyula]

Dear Peter,

In your post #99 you wrote about 3 strands of wire while in the close-up pictures taken at the conference 4 strands of wire can be seen (2 green and 2 red) the ends of which were brought out to the terminal blocks for the series connection. Could you address this? (I know what difference the 3 or 4 strands may cause.)

One more thing: someone wrote the Neo magnet grades on the rotor in your prototype was N40 if I am not mistaken, is this okay or maybe stronger rotor magnets could also be used?
If you think these are irrelevant details, then ok...

Thanks,
Gyula