#garfield Logs

Jun 04 2012

00:07 katsmeow-afk http://designerthinking.com/images/pancake/IMG_1762m.jpg <<== the winding jig with one pass on it , the motor will have 4 green passes, 4 red passes, and 4 "natural" passes
00:07 katsmeow-afk er
00:07 katsmeow-afk no passes on that
00:07 katsmeow-afk just pins
00:08 katsmeow-afk http://designerthinking.com/images/pancake/IMG_1765m.jpg <<== the winding jig with one pass on it , the motor will have 4 green passes, 4 red passes, and 4 "natural" passes
00:08 rue_mohr hmm
00:08 e_mohr mentally calculates the field pat
00:09 katsmeow-afk http://designerthinking.com/images/pancake/IMG_1766m.jpg <<== with un-magnetted disc laying over it to show wire placement relative to the magnets
00:09 rue_mohr interesting
00:10 rue_mohr it solves the magnetic path problem
00:10 katsmeow-afk <curtsey>
00:10 katsmeow-afk solves the gigantic assembly issues too
00:10 rue_mohr especially if the rotor on the other side has a phase difference
00:10 katsmeow-afk it will, the poles alternate
00:10 rue_mohr hmm, amp-turns
00:11 katsmeow-afk #18 wire , 4 wires per phase , 3 phases , two sides , i'll let you do the math, please
00:11 rue_mohr make it into an epoxy-resin disk, and give it ferrite reluctance reducers
00:11 katsmeow-afk give it a whowhat?
00:12 rue_mohr ferrite in between there to reduce the resistance of the magnetic path
00:13 rue_mohr one phase per plate, hmmm
00:13 katsmeow-afk in between where and where?
00:13 rue_mohr in between the...
00:13 rue_mohr spokes
00:13 katsmeow-afk "one phase per plate" ?
00:13 katsmeow-afk what spokes?
00:13 rue_mohr each plate would be a phase
00:13 katsmeow-afk why??
00:13 rue_mohr so to make a 5 phase motor, you would stack 5 plates
00:14 katsmeow-afk if you make each disc one phase, 2/3 of the time 2/3 of the plates will be mostly idle!
00:14 katsmeow-afk this is a one-disc motor
00:14 rue_mohr no, you can push and pull on plates
00:14 katsmeow-afk you are not seeing the entire motor yet
00:14 katsmeow-afk you can push and pull on one disc too
00:15 katsmeow-afk none of those pics show a working motor, just pieces
00:15 katsmeow-afk that 1/4 steel plate with the pins is not part of the motor
00:15 rue_mohr I know
00:17 rue_mohr katsmeow-afk, was your design influenced by a floppy drive at all?
00:17 rue_mohr oh damn, its passed bedtime
00:17 katsmeow-afk no
00:18 katsmeow-afk hold on. i'll wind another color and post it's pic
00:25 katsmeow-afk uploading
00:26 katsmeow-afk http://designerthinking.com/images/pancake/IMG_1767m.jpg
00:27 katsmeow-afk they aren't held in proper place, i didn't build that jig yet
00:27 katsmeow-afk they sprung a lil too, they aren't even the finished size
00:28 katsmeow-afk there's some spaces just not right, where the drill bit wandered even tho i transfer punched the steel first
00:29 katsmeow-afk they are even slightly dish shaped
00:35 katsmeow-afk i see now my drill bit placement tolerance is so bad, i'll need to make dentical starting point for every winding
00:39 katsmeow-afk ok, got 2 red and 2 green done for the first layer, i am going to need the hold-down jig in 10 minutes, and tomorrow the jig for the 2nd layer
01:27 rue_mohr hmmm
01:29 katsmeow-afk hmm?
01:47 rue_mohr I want to see more
01:47 rue_mohr but its waaay past bedtime
01:47 katsmeow-afk hold your eyes more open!
01:47 katsmeow-afk more of what?
01:53 katsmeow-afk damned isp
01:53 katsmeow-afk [01:37] <katsmeow-afk> more of what?
01:53 katsmeow-afk [01:40] *** Disconnected
02:04 katsmeow-afk http://designerthinking.com/pancake.html
03:35 Tom_itx those outer pins on the jig aren't evenly spaced are they? they look like they are spaced in pairs. not knowing the offset or diameters used, i can't make a jig
03:36 Tom_itx looks like you did a fine job anyway
03:38 katsmeow-afk the small bit wandered, even tho i punched the locations,,,, in the hi-res images the rought surface of the steel is amazing
03:39 katsmeow-afk the spacing is way off, it's going to make assembly of the coils difficult
03:40 Tom_itx i wonder why Fr4 couldn't be used to actually hold the wire. drill 3 sets of od holes offsetting each winding and weave them like shoelaces
03:41 Tom_itx and even if you used 3 slightly different OD for the outter wire
03:41 katsmeow-afk because the wire over the magnets is supposed to be fairly solid block of copper, i don't know where you'd have fr4 with holes?
03:41 katsmeow-afk you mean make a donut of fr4?
03:41 katsmeow-afk same problem
03:41 Tom_itx well i didn't think of that but..
03:42 Tom_itx so each set of wire will touch side by side
03:42 Tom_itx ?
03:42 katsmeow-afk http://designerthinking.com/images/pancake/IMG_1766m.jpg
03:42 katsmeow-afk yeas
03:42 Tom_itx forming a solid piece
03:42 katsmeow-afk a layerof 6 side by side, then anotehr layer same way
03:42 katsmeow-afk yeas
03:42 Tom_itx oh not just one layer?
03:43 katsmeow-afk i found 3 layers worked *much* better than one, but atm i don't know if that was because of density or amp-truns
03:43 katsmeow-afk amp-turns
03:44 Tom_itx how about 6 different inner and outer diameters with holes the wire size? would it matter if they are offset a bit?
03:44 Tom_itx i'm not sure that would work either
03:44 Tom_itx may make it too flimzy
03:45 Tom_itx what's the wire diameter?
03:45 katsmeow-afk ~.043
03:45 Tom_itx see what i'm thinking is the inner and outer diameters would be on the botom with the spokes on top
03:46 katsmeow-afk so 6 passes fits tween the magnet-center-to-center nicely at this design
03:46 Tom_itx offset using 3 or 6 different diameters
03:46 katsmeow-afk i am not seeing what you are seeing
03:47 katsmeow-afk or thinking
03:47 Tom_itx because the wire on the outside and inside running parallel to the diameter doesn't matter so much as the spokes
03:47 katsmeow-afk right, the wire at the magnet radius is what matters most
03:47 Tom_itx the 'spokes' would lay flat on the fr4. and you would weave it thru the inner and outer diameter sets of holes
03:48 Tom_itx offsetting each set of wires by the wire diameter
03:48 Tom_itx and matching holes
03:48 Tom_itx think indexing wheel
03:48 katsmeow-afk staggering the hole patterns so you don't get a slot
03:48 Tom_itx uh huh
03:48 katsmeow-afk can you drill me one?
03:48 Tom_itx they could zig zag for that matter
03:48 katsmeow-afk i'll be glad to weave it and see
03:48 Tom_itx i can if we can figure out a good layout
03:49 katsmeow-afk it would be the same layouot as if you did the layout on a double-side pcb with plated vias
03:49 Tom_itx draw something up like ou did for your template and lemme see. i can't fully visualize it myself either. it was just a 3am thought
03:50 Tom_itx the holes would need to be far enough apart on the sets so it wouldn't break apart the fr4
03:51 Tom_itx or wood or whatever
03:51 katsmeow-afk this is #18 wire, it's pretty stiff
03:51 Tom_itx that is thick
03:52 Tom_itx i used stranded 18 on my stepper wiring
03:52 katsmeow-afk i was aiming for very few turns of high current and real low voltage
03:52 Tom_itx what did slot car motors use for wire size?
03:52 Tom_itx i forget
03:52 katsmeow-afk 6v-12v , 100amp surge
03:53 Tom_itx you could check on that
03:53 Tom_itx that would be a very similar app for voltage
03:53 katsmeow-afk slot cars i nkow of used 28 and smaller
03:53 Tom_itx for the high powered ones?
03:53 Tom_itx used neo magnets?
03:53 katsmeow-afk a 2 inch long slot car?
03:53 Tom_itx mmm, maybe 4 or 5"
03:54 Tom_itx on the big tracks you went and rented
03:54 Tom_itx it was big in the 60's?
03:54 Tom_itx maybe a bit later than that
03:54 katsmeow-afk oh, i don't know them,, but this is not the same game, remember i want huge surge capacity for hopping robots, or similar
03:55 katsmeow-afk i never knew abut renting slot cars at big tracks'
03:55 Tom_itx these were high current motors
03:55 Tom_itx at probably 12v
03:55 katsmeow-afk you sat in them?
03:55 Tom_itx like 13 windings
03:55 Tom_itx no
03:55 katsmeow-afk i dunno
03:55 Tom_itx armature was like 1/2" diameter
03:56 katsmeow-afk that's tiney
03:56 Tom_itx 13 rounds of wire would fill it iirc
03:56 Tom_itx maybe less
03:57 Tom_itx http://en.wikipedia.org/wiki/Slot_car_racing
03:58 Tom_itx 1:32 scale or 1/32, cars are smaller and more suited to home-sized race courses but they are also widely raced on commercial tracks, in hobby shops or in clubs. A 1:32 car averages 5 to 6 inches (13�15 cm).
03:59 katsmeow-afk would it cost me more than $5 to build the motor?
03:59 Tom_itx http://en.wikipedia.org/wiki/Pancake_%28slot_car%29
04:00 Tom_itx it would be just like what you have
04:00 katsmeow-afk i canot afford to buy what i have
04:00 Tom_itx just wound on fr4 etc. how were you planning to hold the windings?
04:01 Tom_itx my idea is your design wound on fr4
04:01 katsmeow-afk afaik, those were not true pancakes, they were larger dia but shorter normal motors
04:01 Tom_itx no they weren't
04:01 Tom_itx i was using those as a wire size comparison
04:02 Tom_itx for current
04:02 Tom_itx many a controller was smoked using them
04:02 Tom_itx alot of the controllers were just a on off switch inside a hand trigger
04:02 katsmeow-afk 2.^ Haydon Switch & Instrument Inc (2001). "Pancake motor/gear train. (Designer's Corner: useful technology for your idea file)". Global Design News. http://findarticles.com/p/articles/mi_hb4736/is_200110/ai_n17306025. Retrieved 2007-08-16. [dead link]
04:03 Tom_itx i didn't know if you were sure of the wire size or not
04:03 Tom_itx i'm not
04:03 katsmeow-afk http://www.hoslotcarracing.com/image/Aurora/AuroraT-Jet.gif <<== "pancake" is not a true pancake
04:04 Tom_itx those were the tiny ones
04:04 Tom_itx i has a track with those as a kid
04:04 Tom_itx these motors were similar but bigger
04:04 katsmeow-afk http://www.hoslotcarracing.com/History.html , lotsa pics
04:04 Tom_itx i was just using that as an example of motor current draw, not for their motor design
04:05 Tom_itx the ones i'm thinking of used a more normal motor armature with big wire
04:06 Tom_itx i just don't know how big
04:06 katsmeow-afk i dunno
04:06 Tom_itx i like your design
04:07 katsmeow-afk thanks
04:07 Tom_itx i just couldn't figure how you were gonna hold the wires
04:07 katsmeow-afk i had a much easier way to wind the wire, but it would have permanently encased the rotor
04:08 Tom_itx are you gonna put wires on both sides of the magnets?
04:09 Tom_itx top and bottom
04:09 katsmeow-afk so far, all i can come up with is the same way i built the boat ribs, but with tracing paper and epoxy
04:09 katsmeow-afk yeas
04:10 Tom_itx i'll try to make a jig if you want one. think about it a bit and so will i.
04:10 Tom_itx i'm gonna go sit in the chair now
04:11 katsmeow-afk according to the math, if i can get just 3 ounces of push out of each magnet, i get 36 lbs of push at the tangent to the axle, as if it were pulling on a cable
04:12 katsmeow-afk on zhanx's octopod, that's 300lbs of lift for all 8 legs
04:12 katsmeow-afk and, with the pancake's huge acceleration
04:14 katsmeow-afk same for a robot paw, the accel isn't needed, but another 4x geardown would give 120lbs pull on each finger tendon, which sounds like a lot, but there's a lot of friction in the tendon getting to the finger, and 30% leverage loss at the finger
04:15 katsmeow-afk unless i can do more about the winding extending past the rotor, this motor is going to be almost 4 inches dia :-(
04:15 katsmeow-afk but only 1/2 inch thick
04:31 katsmeow-afk possible current draw specs if operated as 6-phase: 7amps per phase, 5 phases being on at all times, 35amps , voltage unknown ,,, but you can see, acceleration can be incredible, since the rotor weighs almost nothing
04:34 katsmeow-afk AHHA!
05:54 tsmeow-afk is going to get pounded : http://classic.wunderground.com/radar/radblast.asp?ID=BMX
05:55 katsmeow-afk http://www.intellicast.com/National/Radar/Summary.aspx?location=USGA0132
06:41 katsmeow-afk �"Where a calculator on the ENIAC is equipped with 18,000 vacuum tubes and weighs 30 tons, computers of the future may have only 1,000 vacuum tubes and perhaps weigh 1� tons." - Popular Mechanics, March 1949
06:42 katsmeow-afk �"When they say they want to put somebody on Mars, I'm certain of it. Mars is, of course, already red, so that could work well for Chinese marketing and public relations." - Neil deGrasse Tyson
06:51 katsmeow-afk http://classic.wunderground.com/radar/radblast.asp?ID=BMX
06:56 katsmeow-afk ok, epoxy still sticks to paper that's been saturated with silicone spray
07:05 katsmeow-afk this is going to be a bad storm, my ears just popped
22:23 Tom_itx http://designerthinking.com/pancake.html
22:23 Tom_itx rue_mohr, take a look
22:23 rue_mohr oooo
22:24 Tom_itx 6 phases is the plan
22:24 rue_mohr lots of poles, that'll be pretty torquie
22:25 Tom_itx i think she said 18ga
22:25 Tom_itx i can't remember
22:25 Tom_itx i've had my head up cnc last few days
23:24 katsmeow-afk i wanna take a break from the motor tonite
23:25 katsmeow-afk i figured how to secure the windings differently, shorten the amount of wire needed, and wind the way i set out to, without permanently enclosing the rotor in wire
23:26 katsmeow-afk my paws need a break, let the blood blister absorb now, when it will quickly, rather than make it worse