Ruddy's Mini Mill

[ruddycrazy]

G'day Guy's,
                 After seeing a few guys on the forum making mini mills today for a bit of fun I started making mine today. I had a play in autocad to see if 200mm disks would be the right size and doing a count on the 16x13mm round N50 neo's I have left over from my 4kw motor conversion I have enough to do a 16/12 configuration



                The drum brake assembly I got for the 4kw conversion had the hub left over and a quick look found the bolt pcd is 100mm which will work purfect with the 200mm disks. I cut both disks out of some 4mm plate and in the morning I'll start counter boring the seats for the mag's. I did find with the countersunk holes on the 4kw kept the mag's seated nicely and with  21 of those N50's sitting all with the same pole up never moved once seated. As I'll be using 2 neo's per magnet pole the counter bores will hold each mag in place on the installation. As there is only 22.5 degrees between each north and south pole I'll use some stupid glue to hold each pole in place.

               Now I have seen other guys mag rotors where the corrosion starts on the base of the magnet where it touches the backing plate so for a novel idea I'm going to stamp out some of the motor rewind insulation and put one under each mag so the mag base will be insulated from direct contact with the steel but not interfere with the flux path.

               As this will be my first dual axial flux genny by going the 16/12 array I reckon I should get away with less turns per coil as there are 4 instead of 3 in each pole. In the autocad pic the coils are 30mm wide and as shown I could go a bit bigger.

              For the blades I'm going to make my first real job on my cnc I'm thinking of making a set of 600mm blades so the blades would be 1.2 metres diameter, but until I do the one coil test I won't know if 1.2 metre blades will too small as I reckon this little baby will be pushing out a bit more than 200 watts.

             Thats it for now and tomorrow I'll throw some pic's up of the work I have done so far.

Cheers Bryan

[bj]

   It's always nice to see leftovers put to work Bryan.  Sounds like you buy like I do, when the prices are right,
buy lots, as you never know.  Should be a sweet one.

[ruddycrazy]

G'day Guy's,
                  Bit of an update but no more pic's yet. Both magnet rotors have been countersunk and the front magnet disk has all the Neo's on, held in place by stupid glue. Went and priced up some fiberglass resin today and $25 for a litre is way out there so time to hunt around for some at a cheaper price. For the blade mount I found and old shaft stub so this week after work I'm machining it down and I'll use the same taper lock system I have on my 1.5kw motor conversion this will bolted on the front disk. Now I find using the 4mm plate there is no magnetism on the rear side so that is a good sign.

               I did ask the Q in the IRC about using polyester fiberglass resin for the stator and read on the otherpower site Dan used to use it so for this small stator I reckon it should be OK. There are 4 tapped holes right behind the hub on the old rear brake mount so they will be purfect for bolt the stator mount. With the magnet rotors I put a 19mm SS band around but with the magnets only 13mm high and the plate 4mm thick that left 2mm protruding on rear of the disks. So I'll use some caulk around it to ensure it is totally sealed so no moisyure can get in.

             Hopefully by this weekend I'll be doing the one wire test and as there are 4 coils in series it will be a guess at what turns to use to suit a 24 volt system. If I can get the space I'll use 14awg wire and get the ohm's right down so this mini can make some real power.

Cheers Bryan

[artv]

Hi Bryan,...like bj said nice to see using whats available..
"Both magnet rotors have been countersunk".....curious as what that means exactly??
looking forward to your progress.........artv

[dave ames]

Sounds like shes gonna be a beaut there Bryan! We will be following along with the progress.

The idea of the insulating between the magnets and steel rotors has to be a step in the right direction..should be invisible to the magnetic flux i should think and stop any electrical circulation to help ward off the galvanic reaction that may be the cause of the corrosion we have seen start under the magnet poles.

Good stuff! That's a lot of magnet there for a mini..we predict a very low turn count and super low resistance

it's all good fun!
cheers, dave

[ruddycrazy]

G'day Guy's,
                 Art what I meant by 'counterbore' is I put each magnet plate on the rotary table and used a 5/8" slot drill and sunk the cutter in about 0.4mm. This gives a register where the mag has to sit and holds it in place. With 32 of those small magnets on such a small disk the placement will be critical to insure they are in the right place or the whole project could be a big stuffup.

               Dave in the end I didn't worry about using the insulation as I just decided to spray some cold gal on the disk then seat and glue the mags. The magnets will be fully covered by the resin and as I will have a 2mm ridge from the SS strip I'll caulk it and that will make sure no moisture can get into the mags.

              Tonight I started roughing down the blade mount and I'll wait until this weekend to put the other mags on the rear disk as I will have some resin by then and I can pot both at the same time. I'll borrow the jig saw from work and cutout some islands for the molds out of some plastic I scored from work. Once I get the blade mount finished machined I'll make a start on making the coil winder. As I reduced the PCD for the M10 studs to 76mm I'll have plenty of room for making the coils and really I can't wait to get the one coil test underway as this really proving to be a fun project.

Cheers Bryan

P.S. Man am I getting nagged by the missus over this project and she's saying we don't need a bloody wind generator. But like all women once it's in place making power I'm sure the tone will change......

[ruddycrazy]

G'day Guy's,
                 Last weekend I tried using epoxy to pot a mag rotor in but after 3 days the epoxy still hadn't gone off so I ripped it all out and started afresh with some fiberglass resin. Had a bit of leakage and ended up using a full kg of resin on both plates but this morning on a quick check it has set nicely. The wooden island is some 16mm thick MDF board and I painted it with some motor varnish I have here to fully seal it. Then I fully greased it so it should pop out easily ( inserts Hopefully).



As the neo magnets are 13mm thick I have enough machining allowance to face the resin so it will run true. I will leave both plates for a few days so the resin can fully cure and todays jobby is making up the coil winder and working on the hub for the stator mounting plate. If I get time i'll also make the mould for the stator and hopefully in a few weeks it will be close to finished.

Cheers Bryan

[rossw]

               Dave in the end I didn't worry about using the insulation as I just decided to spray some cold gal on the disk then seat and glue the mags. The magnets will be fully covered by the resin and as I will have a 2mm ridge from the SS strip I'll caulk it and that will make sure no moisture can get into the mags.

Bryan, I wish you luck with that. In the past, I've had less than wonderful results with anything over the top of cold-gal. It's great as a top coat to slow down rusting, but it doesn't stick very well to the base metal - I'd be concerned that the resin will stick to the cold-gal better than the cold-gal sticks to the steel.

YMMV.

[artv]

Hi Bryan,...Looking good so far. In reply #2 you said you were going to do the "one wire test"....I seen in one of Zubblys' postes where he does this with a motor rewind....but how would you do this with dual mag plates??....I haven't seen any postes describing this test.....their probably out there just haven't found them yet..maybe when you get to that stage you could document it here..
thanks for the update, waiting for more....artv

[ruddycrazy]

G'day Artv,
               It does seem the so called guru's of this forum are taking the back door on this thread so yea a one wire test on a dual axial will be needed to test how many turns are needed. I will be using 1mm wire for the first test and as I will have 4 coils in series  I'll try 40 turns. If it works out I can get less turns then I'll go 14awg 1.6mm wire. It would be nice to get a word in from the so-called guru's on this forum but if there heads are that far up their ass then they will smell their own farts.

              It does seem us small guy's do a heap but go under the window of the main stream....

              Well if this was a well run forum one wouldn't get that screen saying contact the adim as we have an error


Go figure.......

 Anyway my mini mill project will go ahead and if any member feels abused by my post go talk with Helen Wait

[TomW]

              Well if this was a well run forum one wouldn't get that screen saying contact the adim as we have an error


Go figure.......

As with any odd behavior on a web page did you try removing all your forum centric cookies?

You expect too much I guess on responses to threads. Not everyone cares to explain things for the 7,000th time I guess.

Maybe if you said "one coil" we would not have to explain what you mean?

Just from here.

Tom

[jlt]

I think you have a great little alt. And it is nice to see that you posted about  building it . I had to use a conversion table to get an idea of the size of it. never did understand metrics.I think you could use a larger blades Say 2 meters. or 6 ft.
   I am not a wind guru . But i have quite a bit of Experience With rust prevention .I was in the auto body trade for many years .

[artv]

Hi jlt ,...yeah metric they taught me feet and inches through all my years in school , then they switch it up on me after I'm done ..go figure???
Bryan,... I consider you to be, one of the gurus' thats probably why none of the others are responding.....you're doing the job quite well..
TomW,... I can understand your frustration with the same question being asked over and over again, but people who are new here may not know how to search or are frustrated with the search function.......I use the search all the time but , it seldom gives me what I'm looking for ....It usually ends up with me reading stuff I wasn't even looking for ,it's all _good info_ but it didn't answer my question
There's a wealth of information here,...It takes along time to find it searching..........asking a question ,might get you instant results
still looking forward to more updates......thanks.........artv

[dave ames]

Hey Bryan,

Still tuned in and following along..Looks nice so far 

We oughtn't let a perceived lack of interest cause a boilup..Lots of views (650) so far so folks are definitely watching...and not too many complaints. So looks like a win so far.

I bet if you try doing something silly with the build the thread would come alive with warnings.

How it looks from here anyway.

Cheers, dave

[ruddycrazy]

G'day Guy's,
            Well I canned using the drum brake hub as while chatting in irc I did say I had a 750 kg trailer hub here. Anyway I went and checked it against my magnet rotors and I only needed to machine the outer casting on the front bearing to the rear rotor. While I was there I machined down the OD to just under where the holes were so it's nice and compact.

           I cut the extra off the 45mm square butt on the stub and I have some 40mm solid square bar here so I'm going to cut a length and set it up @ 45 degrees to give me more tower clearance. I cut 4 off 25x10mm lengths of flat bar for the stator mounts and tapped M16 holes in them for the stator. I will be using M16 grade 8 all thread for holding the stator which should hole the stator in place when the brakes are applied. Under my bench was a 355 mm OD MDF disk so I marked out the pcd then bolted all 4 struts then welded them onto the stub. This ensured that all the holes were lined up and each strut was welded nice and square.

         I went over to my pile of hydraulic pipe and found some heavy walled pipe that is a neat sliding fit so that solved my drama's on how to make the final genny mount. Tomorrow I'll cut the pipe and that 40mm square bar and get the genny mount all finished then it's time to make a start on the coil winder.

 I've made the stator mold and marked out a sheet of drafting paper so when I place it down in the mold where I marked out and drew the magnets I can see thru the film and check the placement of the coils which is handy. I did the sums to get the maximum wire in the stator and it does look like I can go atleast 2 in hand. I'm going to use 1mm wire 2 in hand for the first coil test and I might even try a 1.6mm 2 in hand coil too. Depending on the turns I need for 24 volts I am hoping to use the 1.6mm wire to get the Ohm's right down.

      
       Anyway the batteries on the camera are flat and tomorrow I'll get some new ones and take a few to show my progress on this mini genny.

Cheers Bryan

[wooferhound]

people who are new here may not know how to search or are frustrated with the search function.......I use the search all the time but , it seldom gives me what I'm looking for ....It usually ends up with me reading stuff I wasn't even looking for ,it's all _good info_ but it didn't answer my question
There's a wealth of information here,...It takes along time to find it searching..........asking a question ,might get you instant results
still looking forward to more updates......thanks.........artv

I guess that not everybody knows that we have 2 search functions here on FieldLines.Com

One of them is in the little navigation menu at the top left of every page.
The second is a Google search of the forum at the bottom of the Home Page only

There is a third search [text input window] that appears on the top right of all the pages but I think it only searches the topic category that you are currently viewing.

You can get very different results with these different search methods

[ruddycrazy]

G'day Guy's,
                 Got a bit of time this morning so I welded up the genny mount. The pipe is 60mm with a 5.5mm wall thickness and the inner pipe has about 0.035" clearance. The offset from the centre is just over 5" and I put a 6 degree up slope on so the blades will have plenty of clearance.



Here is a pic of the finished front magnet rotor



And here's a pic of the 750 kg trailer hub I machined down



Getting there.....

Cheers Bryan

[bj]

   Getting there indeed.  Looks good, nice and robust.

[artv]

Hi Woofer,...Your description of the board doesn't match what I have?? The search I have is in the top left, a box you can type in,or advance search, which lets you pic area, user's and subject....theres so much info here ,that the search function can be frustrating,..

Hi Bryan ,looks good so far ,I've noticed that all the rotors when cast are always flat on the surface like yours.
Since heat is a concern ,couldn't you cast fins between the poles ,acting like a cooling fan for the stator??
Just something I was wondering about....Still looking forward to that one wire test......thanks......artv

[ruddycrazy]

G'day guy's,
                    Well got the genny assembled ready for the single coil test and making the coil winder is next on the list. This morning I cut the old tail of my old F&P genny and it's just the right size to re-use.



         The steel spool on the end is for holding the blades and I'll use a conlock like I did with my 1.5Kw motor conversion. With a bit of tweaking I got the shaft running within 0.003" too which I was very happy with.

Now for the yaw bearing I used a sealed ball bearing and made the top plate with a 3mm shoulder to locate the bearing then machine a 2 mm shoulder so it will contact the inner race. I welded it on the pipe and the genny mount swings nice and freely and when I grease the tube it will also run nice and silent. Not shown is the O-ring groove I machine in lower part of the main pipe, not only hold hold the grease in but also to help keep the pipe square for the bearing.





hopefully this afternoon I can get a coil made up and finally start doing some tests.

Regards Bryan

[ruddycrazy]

G'day Guys,
                Anyway I made up a test coil using 18awg 40 turns 2 in hand mainly to check on the size to fit. I checked the ohms with my fluke 865 and it came up 0.24 omhs. Now take off the 0.16 ohms of the leads and that gave 0.09 ohms for the coil. Rather then put a heap of pic's in here I uploaded some scope views on my irc gallery so here is the link.

http://www.anotherpower.com/gallery/album129

For the setup I just used my 50 volt DC motor with a jaw coupling on and made a crude belt out some plastic pipe then joined it with some 18awg wire. Now as the rpm kept changing all the time due to belt slip I should be able to work the rpm off the Hz. But this is where the grey matter took over and left me in the dark. Hopefully one of the guru's on this forum can look at those scope pic's and let me know if those 40 turns are right.

Regards Bryan

P.S. Later I'll go and take a pic of my crude testing method

P.P.S. Ok so with 16 poles on each magnet for the Hz count it is (count/(X * 16). I had to ask one of my Electronic mates to answer that question and it did equate to my smiths guage on my crude method of testing rpm.

[dave ames]

Hey Bryan,

Hooley dooley! What a robust little machine you have worked up. Some MAD fabrication skills you have there, thanks for the look.

Hope we can get some more experienced eyes to have a look at those sillyscope readings..but for now I can offer some observations from the cheap seats to get things started?

I was looking at your gallery within the past hour and question photo numbers 4,5 and 7 of 11?..not sure what we had there? perhaps over sampling. The rest looked reasonable enough to back each other up.

Not sure what your friend was on about with his frequency to rpm conversions. " (count/(X * 16). "
I make it to be 375 rpm @ 50Hz....50/8(16 poles 8 pole pairs)*60 seconds = 375 rpm
Looks like we had 2.51VAC @ 51Hz (382 rpm) giving us a star voltage of 24 VDC at that speed. (before line loss and rectifier drop)

sure do have an ubber low resistance winding planned..is there such a thing as too low? That is sure to be one stiff machine! and may find the need to add some line resistance in (not such a bad thing) to loosen it up enough to run a smallish prop?

Looks like the internal resistance for power transfer in a battery system might come in at 0.93 ohm..(0.09*4*2*1.3)

And internal resistance for stator heating at 0.72 ohm (0.09*4*2)

Fun stuff !! Hope we get some more input on these numbers..
Looking forward to the next instalment.

cheers, dave

EDIT: I can't seem to access those O'scope pics now?

[ruddycrazy]

G'day Dave,
                  I deleted those pic's from gallery as today I made up new test coils and spent most of the day trying to sort it out. After searching this forum for hours last I finally found Hugh's formula and worked out 27 turns so I made a straight oval coil and a wedged coil. The wedge coil had a 0.5 volt better result over the oval so that is the way I will go. Anyway with 27 turns the cutin was close to 700 rpm which was way too high so in the end I wound a coil out of some 0.7mm wire @ 60 turns. Soon after I turned on the motor I was seeing 6.2 volts and it didn't look to going that quick. Anyway with my ultra crude setup I could get the genny spinning upto 1100 rpm once the belt took up. Now with 60 turns I worked a cutin of close to 300 rpm so I am thinking a 2.5 metre diameter blase set should suit.

Now details of my ultra crude setup

50 volt DC motor with a jaw coupling

Belt made out of some flexible plastic hose tied together with some 1mm magnet wire and too keep the tension on the belt I used the 4Kw motor conversion motor body to keep the DC motor in place.

          For the test coils I made up a plexiglass holder and just used some GG ( Ghurd Glue) to hold each coil in place.

Anyway time for a couple of pic's......



this is my ultra crude setup that worked a treat......



This is how I got the test coil in place...


The coil jig is just some MDF board and I put the jig in my toolroom lathe and manually counted the turns. In orderto keep the coil in place I put 2 off short lengths of 1mm wire in and twisted them tight once the coil was wound. I just used a screwdriver to gently prise the coil out of the former then taped the coil tight with some insulation tape. I originally had the airgap set to 17 mm so I took out some washers and set it to 15mm and got 0.5 volts more on the same test using the 27 turn wedge coil. I originally planned to make the stator 14mm thick but now i'm going to go  10mm (3/8") so I can get the airgap that much closer. Now with the wedge coils I made they were bigger than the magnets so tomorrow i'm going to make a smaller jig and hopefully I can get 60 turns using 18awg wire to fit.

Cheers Bryan


Edit: Yes Dave it is really a shame this project of mine goes past the mainstream.

[bj]

   Ultra crude only applies if it doesn't work.  You got the answers you needed, so it is innovative.

[ruddycrazy]

G'day Guy's,
                 Well made a new coil this morning out of the 18awg wire with 45 turns and it tested nicely. Below is the results I got and I did double check them so I do feel they are reasonably accurate.



The next pic is of the coil sitting on the markout I did for the coils and it does look like the coil is just the right size. I'll be going for a 10mm thick stator so I will need to make a new mold as the one I originally made was 14mm thick.



I need to get a new length of M10 allthread and I'll go for grade 8.8 so there's no chance of the all thread stretching. The test were done with a 15mm airgap and on the final assembly I should be able to get it down to 13mm.

Regards Bryan

[Bruce S]

Bryan;
I'm not sure about the rest of the "mill" people, BUT I'm not missing any of what you're doing. Past logging in to see if I need to nuke some new offender this IS usually the first post I check on for updates.
Can't really comment on this unit, you're building ability and notes on testing are too complete.

Cheers;
Bruce S

[GoVertical]

Hi, what does the H2 stand for?

[TomW]

Hi, what does the H2 stand for?

I think it is "HZ" with a rounded Z so I say "hertz"

Tom

[mab]

Bryan,

I too am very interested in you mill - I'm building a 'mini' mill (when work allows) as my first attempt (actually more mini than yours), and your results are more relevant to me than some of the 'monster' mills that appear on here.

Thank you for sharing.

mab

[artv]

Hi Bryan ,...so a one wire test is juat a test coil??.........I was sure Zubbly had just one strand of wire in his motor conversion,  for a test..........confused again ....
I don't understand using hertz readings.....at 450rpm you were at 60HZ ,but only (I think) 3.2 VAC ,would 120VAC be better?
So at 60HZ with all 12 coils you would be at 38.4 VAC??
Is 60HZ at 120 VAC what we should be shooting for???....since that is what most grid power is??
Sorry for all the questions.......artv

[ruddycrazy]

Hi Bryan ,...so a one wire test is juat a test coil??.........I was sure Zubbly had just one strand of wire in his motor conversion,  for a test..........confused again ....
I don't understand using hertz readings.....at 450rpm you were at 60HZ ,but only (I think) 3.2 VAC ,would 120VAC be better?
So at 60HZ with all 12 coils you would be at 38.4 VAC??
Is 60HZ at 120 VAC what we should be shooting for???....since that is what most grid power is??
Sorry for all the questions.......artv

G'day Artv,
                I'm really not sure what page your on here, for a start I'm off the grid, the grid here is 240V not 120V. Not that it has anything to do with this mini mill. The whole point behind winding a test coil is to check the cutin voltage at the intended RPM. This is the first dual axial I've made and IT ISN'T a motor conversion. So far I've wound 6 test coils, then after reading Dave's post I went and made that 45 turn test coil. The above results do show a cutin for a 24 volt array around 300 rpm which is my intended rpm cutin. As I do intend to make 2.5 metre diameter blades the rpm will need to up there so it won't bog down at cutin.

            Anyway last night I wound some more coils and cut the former down so the inner of the coil is a tad smaller. Today I need to de spool some more 1mm of the broken spool so I can finish winding the rest of the coils. Yesterday I went searching for some M10 all thread but could only find the gal type and I will need to run a die nut down as due to the gal standard nuts won't wind on. With a bit of luck I'll be casting the stator this weekend and making a start on the tower which aint a small job.

Hope that cleared your questions up

Regards Bryan

[dave ames]

Cheers Bryan,

   Looking nice buddy. Regarding that 300 rpm..seems we are still a tad over that? This "mini" is turning out to be a hair bigger than you first planed...2.5 meters (8.2 feet) 

  For the benefit of those following along and others looking for information in the future, hope it's OK to go into the easy maths we are using here to figure cut-in?

  Using our test results above we can take a reading..lets use the 450 rpm (that one cross references very nicely with some of the others as well as with the projected Hz reading).

  We see a reading of 3.2VAC at 450 rpm..that will let us get a very good idea of what a finished machine might do.

3.2 VAC X 4 coils in series =12.8 VAC
12.8 VAC X 1.73 (star connected 1 WYE stator) = 22.14 VAC
22.14 VAC X 1.4 (AC RMS to DC conversion) = 31 VDC
we can take that 31 VDC and divide by 450 rpm and find we get 0.0688 volts per rpm.
on this machine Bryan is looking to charge a 24 volt bank of batteries.
A lowish battery bank on a 24v nominal system might be about 25 volts.
For cut-in we need 25 volts plus 1.4 volts rectifier voltage drop = 26.4 volts to start charging.
26.4/0.0688 = 383 rpm cut-in with the above 45 turns at the airgap tested.

Hope that sounds reasonable.
cheers, dave

[ruddycrazy]

G'day Guy's,
                 Well I finally got some fiberglass resin today 4 litres of industrial grade stuff $54 but now I'm wondering I have made the coils and mold but that 385 rpm cutin has me a bit worried. I do have a heap of 0.6 or 0.7mm wire here so I'm thinking it might pay to wind a new single coil to target a 190rpm cutin. Sure it going to mean a heap more turns with thinner wire but eh lets faces it this mini isn't going to be a multi Kw generator.

                As my 1.5Kw motor conversion has proved to be a good 300-500 watt genny I do want to take it down and do a re-wire so I can make it a 1-2Kw genny.

              Well why I am asking this we do live in a gully and my 4kw conversion which will happen in the new year (just gotta buy some epoxy to finish the rotor) this mini mill will be on my test tower beside my shed to replace the 1.5Kw motor converion which cuts in around 110 rpm.

             My master plan is to put all but one genny up ontop of the hill and this mini will be my shed genny. That vawt I made years ago and tested on the back of my ute scared me as with little wind it was spinning at 450 rpm so imagine what a hawt will do ontop of the hill.

           So the question do I go with this coil set and make blades that will scream at cutin or go for a lower cutin with new coils. I do think I should start again but guys your thoughts please.

Regards Bryan

P.S. and may that rock near you wish you a safe time off work....