Little Big Bad II

sico

sico

100 W
Joined
Jan 2, 2011
Messages
256
Location
Perth, Earth
Little Big Bad II

This is my experimental RC motor build. Its a Turnigy 8085 powered aluminium hardtail. The name comes from my old friends "Big Bad Orange" (compliance plate listed colour) Toyota Corolla, looking a bit like this one and nicknamed Little Big Bad:

View attachment 7

The bike is a big triangle Raleigh,


P1020800_800x600.jpg

I'm building up a gwhy! inspired reduction drive:

View attachment 5

Here is the motor mount so far.

P1020794_800x600.jpg

P1020802_800x600.jpg

P1020803_800x600.jpg

I hit a snag when I broke tap off in the motor plate:

P1020807_800x600.jpg

P1020808_800x600.jpg

I'm taking it in to work tomorow to try and get some nitric acid to dissolve out the old tap. I'm pretty sure it will work if I can just find the right person whose got access to the acid and is prepared to help. Otherwise I might have to make another mounting plate, which will be a pain.

Simon
 
Nice! Will be following this one :)

Very nasty about that tap. Had a similar situation once, needed to make the whole part again :(
 
The only way I've been able to get broken taps out in the past has been to break them up with a punch and hammer......or a plasma cutter. Probably easier to rebuild the part though in the long run.
 
Yep, little shocks work well, or a plasma will do it good too! Just remember to use Aluminum tapping fluid next time! The green stuff! it works wonders! Don't use WD40 or the like it actually can make it grab worse sometimes depending on the alloy...
 
I found a helpful chemist, and the part is currently sitting in a bath of 70% nitric acid, which the internet says will dissolve the tap leaving the ali unharmed, who am I to argue with the internet? The chemist wasn't entirely convinced, so its a chemist v internet smack down!
 
sico said:
I found a helpful chemist, and the part is currently sitting in a bath of 70% nitric acid, which the internet says will dissolve the tap leaving the ali unharmed, who am I to argue with the internet? The chemist wasn't entirely convinced, so its a chemist v internet smack down!
Click to expand...


The Aluminum forms a very heavy oxidation layer that most acids can't eat, the steel just rapidly dissolves away. That said, you will have SOME loss on the aluminum, it will be a bit like it was anodized.
 
We have lost Timma2500 to the frock...but gained another to the 'dark side' welcome
aboard Simon :mrgreen:

Breaking taps off is a pain in the ass, keen to hear how the acid works....

Be ready for the 7th of January? I'm thinking of a ride along the coast Freo
to Scabs and back...

KiM
 
Hi Kim, I doubt it will be ready for the 7th, but I should still be able to come with the frockie. Paul isn't getting rid of his man-bike is he? No harm having a couple of different systems for backup anyway.

I just went and checked on my part and no reaction has taken place part from a bit of yellowing of the acid (which the chemist says happens just by exposure to light/air). not sure if I misread something on the internet now. I'll leave it in there overnight and see if that makes any difference, but feeling pretty disappointed so far ... :|
 
liveforphysics said:
sico said:
I found a helpful chemist, and the part is currently sitting in a bath of 70% nitric acid, which the internet says will dissolve the tap leaving the ali unharmed, who am I to argue with the internet? The chemist wasn't entirely convinced, so its a chemist v internet smack down!
Click to expand...


The Aluminum forms a very heavy oxidation layer that most acids can't eat, the steel just rapidly dissolves away. That said, you will have SOME loss on the aluminum, it will be a bit like it was anodized.
Click to expand...

Well 3 hours of 70% (15 molar) and the ali and broken tap were both unharmed. From my research, the process you describe is called passivation http://en.wikipedia.org/wiki/Nitric_acid#Passivation This only occurs when the concentration is over a certain amount ... too weak and it will dissolve aluminium.

My suspicion is that the tool is also undergoing passivation, although Laura the friendly chemist says this is unlikely. If the tool is still unharmed tomorrow I don't think we can draw any other conclusion. There may be a balance point where the concentration is just right and will dissolve the tool, but not the part.

I will take some separated broken tap and ali in to her tomorrow and we will run a few scenarios hopefully.

What I realy need now is liveforchemistry, is he in the house? :p :wink: :D

Meantime I've started on a replacement part ... I'm not feeling that confident of a recovery and the second one is going much quicker.

Simon.
 
Here is the new part taking shape:

P1020816_800x600.jpg

I think this mark 2 plate will have clearance holes and lock nuts ... might not look as good but saves any risk of fuc<ing it.

P1020817_800x600.jpg

If the acid one comes good tomorrow I'll continue trying to tap it a bit more carefully (might drill out the pilot holes a bit). That one can be the show bracket. :)

Simon.

PS: The black shadow is Angus investigating the possibility of eating the new part.
 
sico said:
Little Big Bad II

This is my experimental RC motor build. Its a Turnigy 8085 powered aluminium hardtail. The name comes from my old friends "Big Bad Orange" (compliance plate listed colour) Toyota Corolla, looking a bit like this one and nicknamed Little Big Bad:
......................

Simon
Click to expand...

love the work mate. Do you have your own mill or one at work? if only I had the $$....
 
Nice parts. In my experience, I've had much better luck using 2 flute tools in aluminum.
 
Thanks for the complements lads. Snowy, I just brought the mill a few weeks ago, so still need plenty of practice :)

Well, the nitric acid worked, once I convinced the chemist to dilute it down. Note to googlers, 70% nitric acid will not dissolve a high carbon steel tap from ali, but 35% will :D

There was a fierce bubbling and clouds of brown smoke poured from the part and up into the fume cupboard. It took less than 20 minutes to turn the tap into brown sludge. Here is the part minus the tap:

P1020819_800x600.jpg

Thanks to my lack of patience I now have two of these:

P1020820_800x600.jpg

You can see the difference an acid bath makes to the ali.

I might find a use for the second one with a 6374 motor that I'm getting for chrissie.

Also, I tapped a few holes to get my eye back in, and found it to be very easy to avoid snapping taps, I was just having a brain fade and not paying attention, i.e. a lack of mindfulness, and when I kept the tap straight and did plenty of backward turns to clear the swarf, there was no issue. I may have got slightly better quality taps as well, but anyway live and learn.

Cheers,

Simon.
 
Nice going Simon, this build will put you in a different league, with regards to taping yes go back 1 to 2 clockwise or so, I like the turnigy motor I thought they were hard to come by, good luck in the future with the build

mark
 
sico said:
Thanks for the complements lads. Snowy, I just brought the mill a few weeks ago, so still need plenty of practice :)
....
Click to expand...


do you mind if I ask where you got it and the $$?

also, what's the weight of those alloy plates? im just starting on my own RC build using a 6374 to start, before upgrading to a 8085 or 80100... even with access to my uni's equipment im tempted to get a mill, looks like fun!
 
dingoEsride said:
Nice going Simon, this build will put you in a different league, with regards to taping yes go back 1 to 2 clockwise or so, I like the turnigy motor I thought they were hard to come by, good luck in the future with the build

mark
Click to expand...

Thanks Mark. I've had the Turnigy for over a year, before they stopped getting them at HK. The 80100's are hard to come by, but Leaders Hobbies showed there were 8085s avaiable last I looked. I don't know if that's a lie though, as it seems they are not above saying they are stocked to secure an order.

Snowy said:
do you mind if I ask where you got it and the $$?

also, what's the weight of those alloy plates? im just starting on my own RC build using a 6374 to start, before upgrading to a 8085 or 80100... even with access to my uni's equipment im tempted to get a mill, looks like fun!
Click to expand...

Hi mate, I brought it from Hare and Forbes machinery house for around $1700, then I paid about $800 for tooling and about $300 for a rotary table. Its far too easy to spend money on this stuff, but I'm pretty satisfied with this setup for now. It certainly is fun :)

In the next couple of years I'm planning to CNC the whole lot. 8)

Here are the CAD :wink: drawings, the plate is 10mm ali, so you can probably use some of your engineering skills to calculate the weight:

P1020824_800x600.jpg

P1020825_800x600.jpg

I can tell you that the weight of these mounts is quite a bit less than the weight of the motor, so I don't think its a big issue. Anyway, with the lightening holes the motor plate weighs next to nothing :wink: :D

Here is a mock up of the mount and jackshaft on the bike:

P1020822_800x600.jpg



I'm waiting for a few more parts now. My next task is probably to try putting hall sensors in the motor, though I'm not particularly looking forward to it. :?

Simon.
 
Ok, here is my experience with hall sensors in the 8085.

I got the ss4111a sensors from rs online.

I wired this one up to test with my high tech teting device (a magnet on a stick). The hall switches between 0 and 400mV when you move the magnet from one side of the hall to the other, so that's good:

P1020842_800x600.jpg

Threading the wires through:

View attachment 2

and blue-tacked into place for testing purposes:

View attachment 1

After testing a few combinations I found this one that works:

P1020853_800x600.jpg

But it has a few quirks, and I'd like to hear peoples opinions on.

The controller is a cellman 9 FET.

The first thing is that the motor only works in the first part of the throttle movement, when you go past a certain point it just stops.

The max amps unloaded before it it drops out is about 1.8-2A

I got my buddie to load it up by pressing a rag wrapped piece of wood against the side of it and we got it up to 4A.

It seems to be RPM rather than load related.

Could it be related to the programming of the controller?

Any advice would be great!

Cheers,

Simon
 
Sico,
armchair quaterbacking here, but i have some experiance with the xiechang controllers & the problems your experiancing.

#1) the throtle "cutting-out" issue is a well documented problem with these conrollers paired with high rpm/low resistance motors. its all discovered & reversed engineered in this thread:
http://endless-sphere.com/forums/viewtopic.php?f=2&t=16910

Bigmoose explains why such a circut is nessisary:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=18578&hilit=ohio+race+bike&start=105

#2) my 1st recomdation is solder a 1k resistor accross the C20 capcitor. This is the easyest way to beef up the cotroller's throttle responce without totaly dodging the current ratings your programed for.
next is get comfortable with flashing the software settings (i don't know if cellman provides a programing connection or not) I am a fan of the XPD programming stuff you'll find here:
http://endless-sphere.com/forums/viewtopic.php?f=2&t=27927

#3) Now for the bad news. I seriously doubt you are going to be satisfied with a 9fet controller. I blew 6fet controllers to smitherines with the 80/100's (then again I have vaporised 12 & 18 fet & castle hv160 controllers playing Rusian Routlett with them)

I am currently running 12fet units & they are good for about 5kw for a 15 minute run befor getting into thermal trouble (loaded with irfp3077 fet's same with 4110's) I just recieved a batch of 18fet kits from kewin to push to the next level.
I also find the cotrollers are far less tempermental on a wye terminated motor. but with carful set up Delta will work also.
you need to have the halls in the correct position for the rotation in delta. the internal set up has proven to be the most reliable in my experiance.

thats enough for now. Good Luck.
 
HI Thud, thanks for the detailed reply. :) I simultaneously stumbled on one of those links and realise the answer was already out there. I found this thread to have the answers at the front: http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=16910, so could be included in the new wiki if its not already there.

I'm actually only using this controller for testing the halls and plan to use my Lyen 12 fet on the actual bike, which I have a cable for and access to Lyens software, so that I can do:

"Selecting "EB212" instead of "EB206"",

which I don't currently understand but will have to figure out when the time comes.

At the moment the 12 fet is being used on my hubbie comuter. The 9C hubbie is coming unlaced from its wheel, one spoke at a time and at some point I will replace it with a Mac hubbie. The mac hubbie will be controlled by this 9 fet cellman controller and I'll be reprogramming the 12 fet to control the 8085.

So to cut a long story short, if this test confirms that the halls are good, I'll go ahead and glue them in and move on for the time being. 8)

Having said that, I do have a golden motor controller here so I reckon I'll try that and if it doesn't work, maybe I'll try one of the hardware fixes ...

Cheers,

Simon.
 
Scratch that, the Zhidong controller (supplied with my golden motor) just when phut, quite a loud and powerful sounding phut actually. I suppose that was an electolytic capacitor, I post pics of the carnage soon.
 
sico said:
Scratch that, the Zhidong controller (supplied with my golden motor) just when phut, quite a loud and powerful sounding phut actually. I suppose that was an electolytic capacitor, I post pics of the carnage soon.
Click to expand...

Thats the sound my 12fet made...3 times now it was the big 64v cap popping each time.
I'm with Thud you won't get fark all joy with a 6fet just when it starts getting fun ~5000watt
they shit themselves HAHA...i have 2 12fet Infineons here both farked but need only small things done to them all the fets are ok...i connected the battery leads back to front on one and blew the shunt as far as i can see visually
theres no other damage, perhaps take both with ya rob one two fix the other? Might do you till
you get something better? One has the 3077fets and the other the 4115 IIRC...I can swap parts if i know whats wrong but know clue how to test for what is blown and whats not....

KiM
 
Kim, thanks for the offer, I'll see how I go and get back to you. :) I have the same issue with electronics, although I worked as an electronic assembler for a while, so I'm pretty good at taking components in and out ... if you tell me which ones to do that to.

Here's the zhidong:

P1020857_800x600.jpg

Everything seems perfectly fine ...

P1020858_800x600.jpg

Until we turn it over ...

P1020859_800x600.jpg

The diode appears to have a large crack down the middle of it.



Now get out of the way of the cricket :wink: :|

Cheers,

Simon
 
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