Hubba Hubba – a Power Wheels Fairy tale

A long time ago (last summer) in a place far far away (Detroit, New York or something) there was a power wheels race car called Red Lotus, crying alone in the pits.

IMG_20130824_110122
Red Lotus

All of the sudden, out of nowhere with a screech of tires and a puff of tire smoke appeared the Fairy Godfather (after all, Fairy Godmother wants “nothing to do with that dangerous racing stuff.”)

The Fairy Godfather asked Red Lotus “What’s the matter little race car?”

Blown tires

“Well Fairy Godfather, every time I try to catch up with the other cars my tires just pop!”

“Well little car, what you need are magic tires! and please call me FGF – all my drinking buddies laugh when someone calls me ‘Fairy’ ”

And with a wave if his enchanted tire iron POOF! a magical tire appeared!

New tire

“Really?” said Red Lotus “That rim won’t hold up for 20 seconds on a power wheels track.”

“Hey!” exclaimed FGF “You get a magical tire, you can figure out the rim yourself!”

Old hub

And so Red Lotus did figure out the rim herself. Thus was born the Quad Bolt, Flange Welded, Wood Spaced, super rim!

And all the rest of the season Red Lotus didn’t pop a single tire – at least not a rear tire…

Then one day when all the races for the season were over, once again Red Lotus was sitting alone in the pits crying.

With a squeal of tires and more blue smoke FGF appeared!

“What are you bawling about now? Didn’t I give you magic tires? Didn’t they last the entire season with out popping?”

“yes, they are wonderful” sobbed Red Lotus “but” (there’s always a ‘but’) “my front tires keep popping and the hubs I made suck.”

FGF thought for a minute and said “so why don’t you buy some real tires and make your own hubs to hold them?” “Here, I’ll show you how:”

Foam and tube

With a wave of his magic Tire Iron POOF pieces started to appear!

“Yum!” squealed Red Lotus “Pink frosted doughnuts!”

Bit foam

—- CRUNCH —-

“These are awful doughnuts, they taste like Styrofoam!”

—- SMACK —-

FGF knocks the doughnut out of Red Lotus’s mouth. “Those aren’t doughnuts, they’re hub patterns!”

Assembled pattern crop

“Put them on the tube like this”
“Pack it in sand”
“And pour molten aluminum all over it”

Casting

“And you get something like this”

Raw Casting

“Ewww” said Red Lotus “That’s gross!”
“Well its not done yet, you need a little time turning it on a lathe to turn it into something beautiful”

Turned casting

“Now you have your solid aluminum, hand cast, personally machined unbreakable super hub!”

And with a hearty belch FGF vanished leaving Red Lotus to do a whole bunch of work.

Tune in next time for the story of the PPPBBB – Pronounced:

Jake and the motor stack – the story of the largest motor in PPPRS racing

A long time ago (about 3 years) in a land far far away (my garage) some would be members of a Makerspace decided to build a few Power Wheels cars for the PPPRS race in Detroit.

One of the cars they selected was a plucky dump truck called Big Jake.

Big Jake ready for its 1st race

Big Jake ready for its 1st race

Well the first thing we did was pull out the stock motors (1 and 2) so we could install a surplus motor we had laying around (motor 3).

Jake's Original Motors

Jake’s Original Motors

(Sorry, we didn’t save any pictures of Motor 3)

Too bad this motor burned up – it was an odd motor anywaty, the commutator was a disk not a cylinder and the brushes were triangular – we found this out when we took the burned motor apart, doesn’t everyone take the thinks they break apart?

So we put in motor #4, a starter motor from a small gas engine, and it burned up – noticing a pattern here?

Jakes Motor #4

Jakes Motor #4

I think Fisher Price did as well – a recall about burning motors:

http://www.cpsc.gov/en/Recalls/1999/CPSC-Fisher-Price-Announce-Recall-to-Repair-Power-Wheels-Ride-On-Battery-Powered-Vehicles/

Then we installed a 1000W scooter motor and controller bought on-line and it was… ok.

Jakes 1000W scooter motor

Jakes 1000W scooter motor

We drilled holes in the motor and added a fan so it didn’t burn up.

But it wasn’t power full enough.

Then the big crash between Big Jake and the Yellow Escalade happened. And when the pieces were put back together – Jake N’ Stein was born.

(insert dramatic music here)

And of course such a majestic car need an equally majestic motor – so in went with a 4.5hp winch motor (#5)

4.5HP Winch Motor

4.5HP Winch Motor

Then it melted. So we took the motor from Little Pink Trike and put in on (motor #6) until we could rebuild motor #5 and put it back on (does that make it motor #7?)

Little Pink Trike's Motor

Little Pink Trike’s Motor

And it burned up.

Well we decided this wasn’t working so we did the only reasonable thing: bought a bigger winch motor! (#6/8) and it was good until it burned up.

6HP Winch Motor

6HP Winch Motor

So we re-installed the rebuilt 4.5hp motor (#5 or 9 depending on how you are counting) and added some gear reduction and it was fast until it burned up.

So back went the larger winch motor (#6/10) and added a water cooling system with some vent holes and it worked great, until we forgot to inject the water and siezed the bearings and melted the comutator – and almost got black flagged for being on fire, it was only steam!

So it came to pass, we looked around for the biggest motor we could find (too bad it was in a home brew electric car – 15″ diameter and about 200lbs) and decided to put a slightly smaller one in.

15 inch motor

15 inch motor

So motor 7/11 (lucky numbers right?) is

Jake's new MotorJake’s new Motor

Just how big is Jake N’ Stein’s new motor?

Well is 11″ long, 7.5″ in diameter and weighs around 80 pounds.

But how powerful is it?

Well, it used to haul around 6000 pounds of stuff in a warehouse all day long.

But how may horse power is it?

I don’t know, but Jake runs really nice :-)

5 of Jake's Motors

5 of Jake’s Motors

Power Wheels 1 Weekend Build

So the plan is to build a power wheels racer in 1 weekend. We started Friday night July 13th with the best of plans.

Here’s what happened:

So I got started Friday at 6pm…..

Ok, so it was dinner time so we broke to eat…..

7pm: Time so Start….

Hmm, there’s not room to do the build, I guess we should clean up and organize a bit.

9pm: Plenty of room, lets begin….

Now where did we put all those parts when we were cleaning up…..

Saturday 10am – slept in, aren’t Saturdays great?

Saturday 11:30am – found the rest of the parts, got them set up along with the camera and some “before shots”

Saturday 12:00pm – Lunch time!

Saturday 1pm, what were we going to do again?

Oh, yea – time to start building! 2 helpers!

Saturday 3pm – other commitments mean everyone quit – 6 man hours invested, front steering is rebuilt with heaver axels for the new tires, the body is off the donor car, rear axle is out of the car and marked for modifications.

Saturday 9pm – lathe time! 2 hours on the lathe modifying the rear axle and sprocket to fit.

Sunday 10am – Damn, its good to sleep in on weekends :-)

Sunday 11:30am – ready to start, Whats that? You’re hungry, ok lets get some lunch….

Sunday 1pm – 5 more man hours.

Installed rear axle, cut key ways in the sprocket, wheel hub, and axle. Tucked in batteries, wired batteries, controller, safety disconnect, fuse and cut throttle cable. Zip tied everything in place – took it for its first test drive at 6:10pm Sunday.

So far we have 11 man hours invested and a driving chassis.

Sunday 6:30 PM – Time for a test drive

Still needed:

Tune steering

Shift motor and seat further back to make some leg room

Raise steering column

Attach body

June 22 Update:

One weekend build! (Ok so, 2 weekends and a few evenings)

I put in another 9 hours during the week and on Saturday and 8 more on Sunday and we have a finished (almost) car!

I want to tweak the steering for tighter turns and add a reverse switch.

Some cosmetics and it’s ready for Detroit!

MMS Eclipse watching party

Although poorly attended (only one full and one future member) everyone had a great time observing the 98% solar Eclipse.

Using the official MMS pinhole card:

 

 

 

 

Too bad the eclipse image is so poor, what a minute – whats that on the building next door?

 

Openings between the leaves of trees are acting as pin hole cameras and giving hundreds of images of the eclipse, we felt a little silly looking at the tiny ones the card was making for the first half hour :-)

You can also see some on the leaf in the foreground (I’m writing this on an old netbook so I can’t tell how the pictures are coming out, so I didn’t clip or tweak them)

And just so you don’t think its some other effect, here’s a shot at the max we witnessed, notice the arc is at the top instead of the side:

I’m still not sure why we had such a poor turnout, after all its only a 36 hour drive to San Francisco!

 

 

My neverending quest for quick turnaround prototype PCBs

For years I have dreamed of a fast way to prototype PCB for projects I am designing.

20 years ago I was using rub on drafting tape and stencils – slow and spotty results.

I tried to modify a plotter to plot resist directly to a PCB – no luck.

Magic markers – I’m no artist.

5 years ago I hacked a laminate router by tapping into the stepper controllers and adding a better Z axis – It can rout boards ok, but takes some tweaking.  It only does fairly wide traces.  But its great at drilling holes!

2 years ago I tried the inkjet printing systems – lots of smeared wet ink and poor registration, not very effective.

I opened up a laser printer and tried to get a board to go through it – almost worked, but the fuser was to narrow to take the board.

Although I haven’t found a fast system yet, I get by with the PNP Blue material and a good laminator.  Although I am regularly disappointed when dust, not quite clean boards, minor wrinkles and other issues leave gaps in traces that need touching up.

Which brings us to the latest attempt:

Now that the maker space has a small laser cutter I am trying to find something I can coat a board with and either burn away or melt onto the board to act as an etch resist.

Early attempts with paint had moderate results – our laser cutters on only 25W so it didn’t burn it cleanly.  I have heard that using flat black paint and a more powerful laser works.

Paste wax and markup fluid weren’t dark enough for the laser to vaporize (thinking of trying black crayons)

The latest attempt uses laser printer toner (just like the PNP only skipping the printing and iron on steps.)

The problem is how to get an even coat on a board without it blowing around.  Static electricity has potential (just like what they do inside a laser printer) but I don’t like the idea of a 5KV power supply exposed and handling powered toner is an automatic mess.

So for the first attempt I mixed the toner with rubbing alcohol (30% water).

Messy stuff!

I painted it on with the tongue depressor but it seemed to coat evenly and took only a few minutes to dry:

It mixes well and paints on fairly easily, here are some sample prints I did at various power and speed settings.  I cleaned the board fairly aggressively with paper towel and rubbing alcohol.

None are quite clean enough to become PCBs but they are getting close.

Although the toner paint looked dry, it may still have had some water in it.  I plan on trying a batch with denatured alcohol (100% – no water) and see if it works better.

 

2/16/2012

Updated progress

I have been trying a number of materials and methods to make my fast turn circuit boards.

I’ve decided that last toner is too messy and there are too many variables to create a repeatable process.  So now I’m trying various other masking materials:

 

Black and white spray paint – it works ok, but the ash left behind by the laser resists the etchant and leaves you with a poor etch.

I also tried tape:  Painters tape, electrical tape, clear and brown box tape.  The masking tape worked ok until the etch was slow and the tape started to dissolve.

I held a few of the boards up to the light so you can see how it etched:

 

 

 

 

 

 

One of the other members of the space found someone who had made the black paint work.  The process is to do 2 passes with the laser – the first burns off the paint, the second burns off the ash!  Then you wipe the board down with rubbing alcohol to clean off any residue.   Here is a set of 3 projects I lasered and etched at once:

This board turned out rather well, I had some trouble with the etchant taking for ever so lost some of the detail on the lettering, but the boards came out nicely.  I should get even better results on the next project.

In an attempt to speed the entire process up I tried to drill holes with the laser cutter from the back of the board:

   Not very good results!  After about 6 passes it still didn’t cut through thin PCB material and stunk and smoked the whole time!

 

 

 

 

 

 

So instead, I used the laser to cut wholes in a small piece of acrylic to use as drill guide:

 

 

 

This gives you a pattern to follow using a Dremel and the holes wind up in the right places and nicely lined up.  I drilled 2 holes in opposite corners of the board and used the leads from resistor to line up the template and board and hold them together while drilling.

 

 

 

This image shows the template attached to the board and about half the holes drilled.  This worked very nicely!  The only problems was small disks of acrylic getting stuck to the drill bit (you can see little craters on the left side of the board where these came from)  I had to clean the drill bit twice to drill the whole thing.  Either bigger holes or a different plastic might fix this.

 

This is first of the 3 boards I put together and it works just fine.  It is a level translator for the encoder you see in the holder.  The encoder will be attached to the drive motor in my electric car and feed back motor position to the controller.  The encoder is 5V and the controller wants a 15V signal.  The test bed uses a 15V power supply and LEDs on the 4 quaderature outputs.

Encoder test video

Rotary Encoder – built into motor for Electric Car

My electric Dodge neon uses an AC motor and an industrial motor controller.  I upgraded from m 1984 motor controller to one less than 25 years old (actually less than 5.)

The new controller does much more than the old one and has the ability to do some fancy tricks.  At the moment I am running it in “sense vector” mode.  The controller senses the position of the armature by monitoring the current in the field coils.  This works great…   as long as the motor is spinning.  From a stop it tends to get out of sync, but there is a cure!

The controller can use a quaderature encoder so the encoder can read the position of the armature at any speed.

To add an encoder to the motor I decided to try a chip amde by Austrial Microsystem AS5040.  This chip senses a magnet near the chip and calculates the position of the magnet and can generate multiple output:  PWM, binary via I2C, and quadurature!

I bought a few of the chips and built a surface mount board to hold the chip and a few LEDs to display the output.  The first two version had a few problems but the 3rd time was the charm.

 

 

Thanks to Royce for working out the process for surface mount PCBs.

 

The final version had to be small enough to fit in a depression in the end of the motor cap.  The sensor centered and the whole board insulated (clear enamel)  since this is a grease pocket

for the rear motor bearing.

 

 

 

 

The magnet is mounted to a bolt that is threaded into a tapped hole in the back end of the armature.  It took a while to the position right (it needs to be within a few millimeters of the sensor) hence the nuts and washers.

 

The cable is brought out of the motor through a small threaded hole (it was an alternate location for the grease fitting.)  The hole is filled with epoxy and the wires go to a DB9 connector.   I built a small test board that shows the quadurature signals (4 round LEDs) and the status outputs from the chip (the two rectangular LEDs)

 

 

 

 

 

The motor controller puts out 15V to power an encoder and wants A and B as well as inverted A and B signals.  The circuit includes some NPN transistors along with a voltage regulator and a few capacitors to tie it all together.  I put the schematic for both the sensor and test board on one schematic so I could make both boards at the same time.

I installed it in the car today, but still need to put a few more parts together to run it.

 

 

 

DOH!

It doesn’t work!

Ok, so the electronics work fine, it talks to the controller.

But it tops out at 256 pulses per revolution and the controller needs 1024.  It was a minor confusion between terminology.  The sensor detects 1024 positions, but to generate quaderature it uses 4 positions per pulse output.

Back to the drawing board.

 

I picked up a commercial shaft encoder on ebay for 50 that outputs 1024 PPR but it only works at 5V, so I’ll need a level shifter board and connector adapter.

Oh, yea, and I need to put the motor again, take out the old encoder, bring a shaft extension through the back grease pocket, add a grease seal and couple it to the encoder.

 

 

 

 

Solid Wood computer desk for less than a Wallmart flat pack!

David (high school student) member of the space needs a new computer desk and wants to build it himself.

He drew up a design that is small (he lives in an apartment), can hold his new computer and monitor (big gamer case and wide screen monitor), and something he could customize.

His design is similar to what you can buy as flat pack furniture from places like Walmart for under $100:

http://www.walmart.com/ip/Orion-Computer-Desk-With-Hutch-Oak-Black/9854984

But we want to build something that will last, something he can take to college, something strong and useful.

Here is David’s original design:

So the question is what to make it out of.

Since the desk is only 24″ deep, we could make it out of 1×12 oak boards, except that would cost over $300 for the wood!

We could make it out of plywood then go back and trim the edges with solid oak, At $40 per sheet plus the banding its going to be around $100.

Then it hit me, the desk worked out to about 55 square feet and flooring is sold by the square foot!

You can buy unfinished oak flooring for under $1.50 on sale!

After thinking about it for a while I realized the following:

Not much waste -  since you only build the boards where you need them, not cut them out of a 4×8 sheet.

Mortise and Tenon construction – just leave a board long for a tenon and a gap between planks for a mortise.

Artistic potential – you can create opening and patterns just be leaving gaps in the planks.

A visit to a few local hard wood flooring suppliers and we found a left over batch of prefinished hickory for $0.50 per square foot!

Total cost for the wood:  $28!

We picked up the wood the week before Xmas and got started Xmas eve.

Less than a week later we had the first 3 panels cut and glued and they fit together the first time!

Will it go round in circles….

What do you do when you need pictures of a 300lb power wheels car from multiple angles so that someone can create a 3D model?

You build a turn table, a rather big turn table.

But what if I don’t have a really big bearing, you ask.

Well, you use a bunch of little ones – preferably in casters!

This is a metal base with 4 casters from some old equipment that was trash, I drilled a hole in the center and welded a 1/2″ nut to the bottom.

 

 

 

 

Take 4×4 sheet of plywood, drill a hole in the center.  Just because its a quick and dirty project I put a 1/4″ thick washer under the board and figured the weight of the rig would hold it in place

 

 

 

 

Put it all together and you have a turn table that can support the Little Pink Trike and we are ready for the photo shoot!

 

 

 

 

 

 

\

 

 

 

 

Spinning Little Pink Trike Video on Flickr

 

 

 

Library of Images of the Little Pink Trike on Flickr

 

 

 

Electric Neon – home brew Electric car

I have been working on building an electric car for the past year.  The car is on the road and drivable.  I am starting this blog a little late so I will spend some time trying to walk through some of the early decisionis and processes. 

You can find a number of videos on youtube:

I have wanted to build my own electric car for over 20 years, it has taken that long for me to accumulate the knowledge and skills to attempt the project.  It also took a little luck to get me started.

I wanted to something a little different than what most people do, I also didn’t want to build an electric car with $20,000 worth of parts.  The original ideal was to build a car using off the shelf industrial parts:  An AC motor, an inverter (AC Drive) and available batteries.

You can find AC motors of almost any size at surplus outlets, auctions and junk yards.

The controllers are a little harder but still available and getting cheaper.

Most people use DC motors and high currents.  Using an AC motor and a battery pack that runs the equivelent of 240V AC (340V DC) means the current , and wire size, will be smaller.

What finally kicked off the project was a load of batteries showed up at work and were mine to play with.  they were C&D 12-270  UPS batteries rated at 12V  75AH.  These are rather small for a DC car (you usually want something over 200AH) but ideal to make a high voltage AC Car (12V batteries mean half as many batteries as with 6V)

I got 18 of the batteries and decided it was time to build a car.  I started out with some initial test using a 5HP motor, 5HP AC Drive and 9 13AH 12V batteries I had from the battle bots I built to see if I could run an AC motor from a battery pack.  It worked great!

Now I needed a car.  I didn’t have anything in mind so I started doing some reading and looking around.  Lighter is definitely better for electric cars, but you also need enough room and strength to hold the extra weight of the batteries (and the driver – I’m 6’4″ tall)

I have a PT Cruiser and though it would make a good electric until I saw the curb weight (over 3000 lb) but that started me looking at the Neons (built on the same chassis.)

I soon found out that the 1st generation Neons tended to be lighter (2400 lb curb weight) and they have a version with beefed up suspension  the ACR.  The ACR is a stripped down car – no extras, has 4 wheel disk brakes (all the better to stop all those batteries) and stronger suspension.  The ideal car for an electric conversion.

I found a 1999 Dodge Neon ACR on craigs list for $1200, when I went to pick it up there were 8 other Neons in the driveway!  The seller was a neon nut (I mean that in the nicest of terms) and was interested in my plan, he even bought the engine back later along with the other parts I didn’t need and has been invaluable with advice and parts, thanks Barry!