Welder:
$110 later, I have a 40A circuit hooked up for my welder. Plugged her in, and she welded first try.
Of course I checked voltages with a meter first :) I'm just glad the 240 to 208 conversion I did last week worked properly.
Brakes:
In other news, I've been bugging people on the forum diygokarts.com and I've gotten some great help in the hydraulic brakes area. More specifically, how to take hand brakes from a motorcycle, removing the hand lever and replacing it with a different lever, cable-driven by the brake pedal. Perfect!
Now I definitely know what I want to do, I just have to buy some brakes. The person who helped me out might also sell me some, or eBay has a decent selection.
Tires:
Still fuzzy in the tire selection arena. I only have a week left on that Princess Auto sale. Someone on the forum is using that particular kind of tire, but they installed tubes in the tubeless trailer tire, so that he could run a low pressure setup, compensating for having no suspension. According to him, these tires are capable of bending the go kart frame when off-roading at the recommended inflation pressure. Crazy! I have asked for clarification, we'll see what he says.
Sunday, June 26, 2011
Tuesday, June 21, 2011
Work proceeding slowly
So I was home on the weekend for Fathers day, it was a great rib fest - all ten of us!
While I was there I borrowed some of my Dad's tools and picked up some of my own.
Now I know what you're thinking, stealing from my Dad on Fathers day, right? The thing is, he has all the tools he needs up at the cottage right now, the rest were in 'storage' not being used. Except the chop saw my sister and her husband were using.. sorry guys!
Anyways, I have picked up:
Lincoln Electric 'Mig Pak 15' welder
Bosch chop saw
Mikita angle grinder
Welding mask, tool boxes, misc.
Even more electronics junk
Welding to do:
Now I have to get my new 'shop' (read: workplace - thanks for letting me build this at work guys) set up to weld.
Of course the welder is set up for single phase 220, and work has three phase 208, so today I opened the guts of the welder, and swapped over the terminals.
While I was in there, I disconnected the gas solenoid - I use innershield flux-cored welding wire rather than solid wire with CO2 gas. No point in running the solenoid all the time if I never use it!
Now I have to go buy 18 feet of 8AWG four-conductor wire - preferably armoured but I don't think I'm going to spend that much money for something temporary (and in a zero-traffic environment). Also need a two-pole 30A breaker and a box for the receptacle (that I already have)
I hope finding the breaker won't be difficult - it's not a standard home-type breaker with the little metal peg at the bottom, it has a slot that the breaker box pushes inside (so female instead of male). A Cutler-Hammer unit.
Princess auto trip
I live in Toronto, Ontario right now. There are three Princess Auto stores relatively nearby to me. Wouldn't you know that all three stores are equally distant, 36, 36, and 37 minutes travel time - in different directions. Could be worse.
They have some trailer-tire assemblies on sale right now for $50 for tire+rim.
The tire is 16.5 x 6.50-8
PA: 8227175
Of course you should *never* use a trailer tire for a drive or steering wheel on a car - but the go-kart will weight much less than a car, so (at least I'm hoping) the load on the tire isn't too high, and the tire gets a sufficiently good grip on the pavement. They should also ride a little softer than car tires - most trailers have minimal suspension like my kart will, so they have softer sidewalls to compensate.
Other tire alternative:
I'm looking at a wrecking yard close to home in Scarborough, and another much further away. With any luck I'll be able to get a set of used tires from a small crappy car, with rims also already attached. If I'm desperate/lucky I can ever steal the steering knuckle and repurpose it.
Axle attachment:
For the front wheels I'm thinking of getting a trailer stub axle from Princess Auto or the wreckers.
PA: 8217242 1,000lb Posi-Lube Stub-Axle. Has a 4x4" bolt pattern to match the PA tires I was looking at.
For the rear axle, I'm thinking of using the same type of weld-on hub that I'm using for the sprockets
PA: 3845351
then welding a disc onto the hub, turning it down with the lathe, etc. I'm also debating saving time (read: lazy) by using an actual sprocket designed for these hubs, and just drilling holes in it to bolt to the hub, just ignoring the sprocket teeth. That eliminates a lot of machining time - the hub and spocket have pretty small tolerances where they mate.
So that's four weld-on hubs.
Motor sprocket (18 teeth)
Axle sprocket (60 teeth)
2x tire rims (however many teeth I need to get a size large enough to drill holes through the sprocket and small enough the teeth don't hit the curved part of the rim. Going to decide in-store)
Still need a 1" axle and pillow blocks to go with that.
And a brake!
Brake hunt:
Princess Auto carries cable-powered disc brakes, but they are very expensive for the whole kit.
eBay sellers carry the same thing for half the price or less.
The current alternative I'm pursuing is a hydraulic brake assembly from a motorcycle. I'm hoping to snag the whole thing from a motorcycle wrecker in one piece, so I don't even have to bleed the system. Just have to figure out how to attach the master cylinder to the brake pedal instead of of the brake handle.
Electronics junk:
I brought up my 4x20 character LCD screen so I can have a display for the go kart. RPM, heatsink temperature, current, that kind of thing. The controller board that I'm using (which I designed for work) has a lot of flexibility, including a ribbon cable connector designed for a - you guessed it - LCD screen and some buttons. Note: This was a requirement of the design spec for the board, not something I added on for my own purpose to a work project!
So I'm going to get a ribbon and make up a little board with the LCD, and tack it into the software.
The great part is this ribbon cable has everything, power, I/O and even a PWM output so I can dim the backlight of the LCD screen effortlessly. Gosh I am happy about that.
I need to pick up some metal enclosure for the electronics - the logic board, main contactor, aux relay, precharge resistor, and 18V linear supply. It'd be nice to have this protected from the elements, at least somewhat. I would seal it in a weatherproof plastic box but the linear supply has to dissapate (probably worst case) 10V*0.1A = 1W. Alternatively, just stick 14g of aluminum on the linear supply and it will heat up by 100°C after 20 minutes of runtime too. I kind of hate having to do that twice, the kettle is bad enough. Metal enclosure means I have no time limit here :)
The IGBTs on the aluminum block will have to remain exposed, maybe a small rain/mud shield.
Kettle design:
As I said in the video, the IGBTs will need water cooling. This project does not call for the complexity of a pump, radiator, etc. so I have decided to use boiling-water cooling. For a current of 200A, 1.5V, 15 minutes that is a grand total of 270kJ.
From the thermal enthalpy of vapourization of water, that equates to 0.12kg of water boiled, or 120mL. 30cm of 1" diameter copper pipe is long enough to contain enough liquid; I will solder the copper pipe to a copper sheet, which is in turn bolted to the back of the aluminum block.
You have to add more pipe than optimally required, since the soldering will involve flattening most of the copper pipe.
I will add a shutoff valves at the bottom of the kettle. This will allow me to drain excess water when I am done driving. To keep bugs out of the kettle during storage, I will either use metal screening to cover the hole, or insert a stopper of some kind.
Summary:
I've been doing a lot of thinking an research for the project, but haven't been posting regularly enough. I'll try to post more often so I don't generate these unreadable walls of text.
For this I am truly sorry.
William
While I was there I borrowed some of my Dad's tools and picked up some of my own.
Now I know what you're thinking, stealing from my Dad on Fathers day, right? The thing is, he has all the tools he needs up at the cottage right now, the rest were in 'storage' not being used. Except the chop saw my sister and her husband were using.. sorry guys!
Anyways, I have picked up:
Lincoln Electric 'Mig Pak 15' welder
Bosch chop saw
Mikita angle grinder
Welding mask, tool boxes, misc.
Even more electronics junk
Welding to do:
Now I have to get my new 'shop' (read: workplace - thanks for letting me build this at work guys) set up to weld.
Of course the welder is set up for single phase 220, and work has three phase 208, so today I opened the guts of the welder, and swapped over the terminals.
While I was in there, I disconnected the gas solenoid - I use innershield flux-cored welding wire rather than solid wire with CO2 gas. No point in running the solenoid all the time if I never use it!
Now I have to go buy 18 feet of 8AWG four-conductor wire - preferably armoured but I don't think I'm going to spend that much money for something temporary (and in a zero-traffic environment). Also need a two-pole 30A breaker and a box for the receptacle (that I already have)
I hope finding the breaker won't be difficult - it's not a standard home-type breaker with the little metal peg at the bottom, it has a slot that the breaker box pushes inside (so female instead of male). A Cutler-Hammer unit.
Princess auto trip
I live in Toronto, Ontario right now. There are three Princess Auto stores relatively nearby to me. Wouldn't you know that all three stores are equally distant, 36, 36, and 37 minutes travel time - in different directions. Could be worse.
They have some trailer-tire assemblies on sale right now for $50 for tire+rim.
The tire is 16.5 x 6.50-8
PA: 8227175
Of course you should *never* use a trailer tire for a drive or steering wheel on a car - but the go-kart will weight much less than a car, so (at least I'm hoping) the load on the tire isn't too high, and the tire gets a sufficiently good grip on the pavement. They should also ride a little softer than car tires - most trailers have minimal suspension like my kart will, so they have softer sidewalls to compensate.
Other tire alternative:
I'm looking at a wrecking yard close to home in Scarborough, and another much further away. With any luck I'll be able to get a set of used tires from a small crappy car, with rims also already attached. If I'm desperate/lucky I can ever steal the steering knuckle and repurpose it.
Axle attachment:
For the front wheels I'm thinking of getting a trailer stub axle from Princess Auto or the wreckers.
PA: 8217242 1,000lb Posi-Lube Stub-Axle. Has a 4x4" bolt pattern to match the PA tires I was looking at.
For the rear axle, I'm thinking of using the same type of weld-on hub that I'm using for the sprockets
PA: 3845351
then welding a disc onto the hub, turning it down with the lathe, etc. I'm also debating saving time (read: lazy) by using an actual sprocket designed for these hubs, and just drilling holes in it to bolt to the hub, just ignoring the sprocket teeth. That eliminates a lot of machining time - the hub and spocket have pretty small tolerances where they mate.
So that's four weld-on hubs.
Motor sprocket (18 teeth)
Axle sprocket (60 teeth)
2x tire rims (however many teeth I need to get a size large enough to drill holes through the sprocket and small enough the teeth don't hit the curved part of the rim. Going to decide in-store)
Still need a 1" axle and pillow blocks to go with that.
And a brake!
Brake hunt:
Princess Auto carries cable-powered disc brakes, but they are very expensive for the whole kit.
eBay sellers carry the same thing for half the price or less.
The current alternative I'm pursuing is a hydraulic brake assembly from a motorcycle. I'm hoping to snag the whole thing from a motorcycle wrecker in one piece, so I don't even have to bleed the system. Just have to figure out how to attach the master cylinder to the brake pedal instead of of the brake handle.
Electronics junk:
I brought up my 4x20 character LCD screen so I can have a display for the go kart. RPM, heatsink temperature, current, that kind of thing. The controller board that I'm using (which I designed for work) has a lot of flexibility, including a ribbon cable connector designed for a - you guessed it - LCD screen and some buttons. Note: This was a requirement of the design spec for the board, not something I added on for my own purpose to a work project!
So I'm going to get a ribbon and make up a little board with the LCD, and tack it into the software.
The great part is this ribbon cable has everything, power, I/O and even a PWM output so I can dim the backlight of the LCD screen effortlessly. Gosh I am happy about that.
I need to pick up some metal enclosure for the electronics - the logic board, main contactor, aux relay, precharge resistor, and 18V linear supply. It'd be nice to have this protected from the elements, at least somewhat. I would seal it in a weatherproof plastic box but the linear supply has to dissapate (probably worst case) 10V*0.1A = 1W. Alternatively, just stick 14g of aluminum on the linear supply and it will heat up by 100°C after 20 minutes of runtime too. I kind of hate having to do that twice, the kettle is bad enough. Metal enclosure means I have no time limit here :)
The IGBTs on the aluminum block will have to remain exposed, maybe a small rain/mud shield.
Kettle design:
As I said in the video, the IGBTs will need water cooling. This project does not call for the complexity of a pump, radiator, etc. so I have decided to use boiling-water cooling. For a current of 200A, 1.5V, 15 minutes that is a grand total of 270kJ.
From the thermal enthalpy of vapourization of water, that equates to 0.12kg of water boiled, or 120mL. 30cm of 1" diameter copper pipe is long enough to contain enough liquid; I will solder the copper pipe to a copper sheet, which is in turn bolted to the back of the aluminum block.
You have to add more pipe than optimally required, since the soldering will involve flattening most of the copper pipe.
I will add a shutoff valves at the bottom of the kettle. This will allow me to drain excess water when I am done driving. To keep bugs out of the kettle during storage, I will either use metal screening to cover the hole, or insert a stopper of some kind.
Summary:
I've been doing a lot of thinking an research for the project, but haven't been posting regularly enough. I'll try to post more often so I don't generate these unreadable walls of text.
For this I am truly sorry.
William
Friday, June 17, 2011
Photo/Video Update
Hi all;
Here are some more photos, but most importantly the video I've promised.
IGBT Motor Controller - Youtube
IGBT Controller with Capacitor bank and wiring
Here are some more photos, but most importantly the video I've promised.
IGBT Motor Controller - Youtube
IGBT Controller with Capacitor bank and wiring
IGBT Controller gate drive circuitry.
Friday, June 3, 2011
Motor upgrade ($$$ ouch!)
A picture is worth a thousand words.. so I'll show you the upgrade first
As a reminder, the old motor on the right was the car starter from the 1999 Sunfire.
The previously-loved motor on the left is from a place in Brampton Ontario.
Anyways, she's a 10" long 7" diameter 24V, 1725RPM motor.
Not quite the beast I was hoping for, but I'm planning on overvolting to 36 to get a higher locked-rotor torque. I think I'll have to be careful to limit the RPM somehow, I don't know if she will survive wide-open-throttle on flat ground (The armature expands and slams into the stator. Poof goes your money.)
Apparently though, everyone in the go-kart hobby arena overvolts their motors - it's just a question of how long you want the motor to last...
I've tested her on 12V using the IGBT controller I haven't even posted on my blog yet. I really need to put batteries in my video camera and actually do some filming.
On 12V the motor doesn't do anything all that interesting.. It's "slow" even at full speed, and doesn't have enough starting torque to even jump a little when I go from 0% to 100% throttle instantly.
Since it is a series-wound motor I'm sure she'll take off with a higher voltage, but I still was hoping for more... These things are supposed to wind up like crazy in a no-load situation.
Onwards!
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