Today I've been trying to get my self back in the groove of working on the go-kart; it's been very long days at work for the past several weeks.
This post is quite long, and I apologize for the lack of pretty pictures. My hands were so black that there was no way I was holding a camera!
I decided to take another stab at bleeding the front brakes I got from my pal Chris.
They were in a motorcycle accident so they look a little worse for wear, and I've been having a really hard time trying to get the slave cylinders to move.
It's tricky holding the master cylinder and the brake line, then squeezing the handle to pump some brake fluid with only two hands. Fortunately I have access to a vice that rotates, so I turned the jaws so they face the floor, and used them to grab onto the top edges of the reservoir, thus holding it upright (so the fluid doesn't all run on the floor - you have to do this with the reservoir open!)
So, I held the hose with one hand and pumped with the other. Of course the fluid must go somewhere, so I held the open end of the brake line over the reservoir! At first, mostly air will come out.
Once fluid starts coming out regularly, I found the trick was to hold the banjo in the reservoir, so that the fluid was covering the hole in the banjo (the end of the brake line).
This way, when you release the brake handle, instead of sucking air back down the brake line it sucks fluid instead. Pump many (a dozen at least) more times to ensure the air is out of the master cylinder and lines. I found that when I fully depressed the handle I would still get a little air pumping out of the banjo. This happened over 100 times so I'm certain there wasn't really air in the system, though I can't quite convince myself where it is coming from.
Anyways, bolt the banjo back on the slave cylinder assembly (brake assembly? - whatever it's called, the part with the pads in it) and continue bleeding by carefully following these steps in order:
1. Hold slave such that bleed valve is the highest point (so air heads towards it, very important)
2. Open bleed valve
3. Cover bleed valve with a rag (to not make a mess when fluid jets out)
4. Fully depress handle of master cylinder
5. Tighten bleed valve
6. Release handle
7. Repeat steps 2 to 6 until only fluid comes out, no air at all.
8. Do it once more for good measure.
9. Refill your master cylinder!
I would also recommend doing this procedure with something (screwdriver, etc) in the jaws of the calipers - preferably the brake disk you will be using, though that may or may not be the easiest way.
I finally managed to feel some resistance on the handle once I finished bleeding, but the pistons wouldn't move! I pushed a little harder and I saw they were really just stuck with black grime and brake dust.
Pushing them out with the master cylinder and forcing them back in with a screwdriver (by slooowly but forcefully prying between the piston and the steel side of one brake pad, NOT between both pads or you will wreck the brake pads) you can eventually work them loose.
I decided I needed to take the brake assembly apart to really clean the pistons as they were still sticky after working them back and forth a few times. Taking them apart was a snap, undo one bolt and tap the two pins out; both brake pads fall out and you can clean the pistons freely.
However I noticed something odd inside the housing! My brake assembly has two pistons. A flat steel spring inside the housing pushes the brake pads up and out of the housing (against the two pins) - but it was not symmetrical!
The left piston had a perfectly flat side of the spring, while the right side was folded nearly in half.
I judged that the bending was not intentional, and hammered it (sort of) flat so that each side acted on the brake pads symmetrically.
I cleaned up everything I could get a rag on, especially the two pins, and thew it all back together.
The pads are much more free to slide along the pins now, opening and closing as the pistons move.
Before they were binding so hard to the pins that I could barely move them by prying with a screwdriver; now they can be forced around, I'm guessing it's good now.
Secondly, Blogger troubles -
Today when I tried to log in to write a post, it only gave me the option to Publicly or Privately follow my own blog, no editing options like usual, no homepage, etc. Logging out and in several times, trying different accounts to log in with (google, yahoo, etc) finally it opened normally.
Now I am following my own blog - and since I am successfully logged in, I have no option to stop following it!
Hilarious but more frustrating when you just want to make a post.
Thursday, September 22, 2011
Sunday, July 10, 2011
Axle has arrived; upcoming plans
After a battle with a nasty 48 hour bug this week I managed to snap this photo of the new axle I bought from McMaster-Carr.
Axle
It is partially keyed - 14" on one side, 4" on the other. So, more then enough space for a wheel, drive sprocket and brake sprocket. It is made of 303 Stainless Steel - I'm darned happy because it is shiny, and it's going to stay that way. I would hate having a rusty steel axle and be fighting to remove all the sprockets from it in the future. The disadvantage is that the tensile strength is much lower, but still around 70,000lbs - It seems like a lot to me, but I'm sure the forces in this kind of system are intense.
For scale, the 1" bar in front is 12" long (30cm). The drive motor is properly aligned with the axle sprocket but perhaps too close together, I really need a frame to mock that up properly.
Frame
Speaking of frame, that's my task for this week, to go shopping at Metal Supermarkets, and to get a red flag or something to hang off the metal I'm sure will be sticking from the rear of my car. Thinking 1 1/2 square rather than 1 1/4 most (gas karts) use because of the extra weight I'll be lugging around in batteries.
Batteries
Still waiting for my contact at a certain battery company to get back to me. I have a contact who put me in touch with the sales manager, so I'm hoping to swing a great deal from them. It would cut a lot off the purchase price.
Interestingly I was also told to consider using NiMH - either industrial packs or sub-C cells - and making my own battery pack. Well that's the advantage of talking to people in the know, I would never have considered such a plan.
Apparently on Monster Garage they converted an old Bel Air to run on cordless drill batteries! Have to check that out some time.
Brakes
I've been reading a lot on www.diygokarts.com and a lot of people have been helpful there. A certain member who lives relatively close to me not only offered me advice and pictures of his experience, but also offered to sell me a set of working hydraulic brakes for a steal, only $60! Remember the bike shop earlier quoted $150 for the same exact deal - one set of used brake parts. Different models I am sure, but in both cases, just whatever was lying around.
I'm ecstatic! It might be a pain getting over to see him but totally worth it. I'm sure I will get a lot of sage advice too. Anyone else considering a similar project to this *really* needs to spend time on forums, there are some awesome people on the internet (i.e. in real life, that you can communicate with on the internet hehe)
Trailer
On a completely different note, I have been considering how to move this kart around when it's finished. Most people are settled and build these in their back yards... seeing as I am in an apartment this is a problem.
I have recently realized that my go kart has trailer tires, and the front (will have) actual trailer stub axles. So - get the kart licensed as a trailer, and tow it backwards! I'm thinking to build a pin into the steering mechanism to lock the steering straight for towing, and leaving a place to attach a long trailer hitch arm to the rear of the kart.
The Ontario website does not indicate much in the way of requirements for trailers so I think it should be relatively easy to get it plated.
Until next time...
Axle
It is partially keyed - 14" on one side, 4" on the other. So, more then enough space for a wheel, drive sprocket and brake sprocket. It is made of 303 Stainless Steel - I'm darned happy because it is shiny, and it's going to stay that way. I would hate having a rusty steel axle and be fighting to remove all the sprockets from it in the future. The disadvantage is that the tensile strength is much lower, but still around 70,000lbs - It seems like a lot to me, but I'm sure the forces in this kind of system are intense.
For scale, the 1" bar in front is 12" long (30cm). The drive motor is properly aligned with the axle sprocket but perhaps too close together, I really need a frame to mock that up properly.
Frame
Speaking of frame, that's my task for this week, to go shopping at Metal Supermarkets, and to get a red flag or something to hang off the metal I'm sure will be sticking from the rear of my car. Thinking 1 1/2 square rather than 1 1/4 most (gas karts) use because of the extra weight I'll be lugging around in batteries.
Batteries
Still waiting for my contact at a certain battery company to get back to me. I have a contact who put me in touch with the sales manager, so I'm hoping to swing a great deal from them. It would cut a lot off the purchase price.
Interestingly I was also told to consider using NiMH - either industrial packs or sub-C cells - and making my own battery pack. Well that's the advantage of talking to people in the know, I would never have considered such a plan.
Apparently on Monster Garage they converted an old Bel Air to run on cordless drill batteries! Have to check that out some time.
Brakes
I've been reading a lot on www.diygokarts.com and a lot of people have been helpful there. A certain member who lives relatively close to me not only offered me advice and pictures of his experience, but also offered to sell me a set of working hydraulic brakes for a steal, only $60! Remember the bike shop earlier quoted $150 for the same exact deal - one set of used brake parts. Different models I am sure, but in both cases, just whatever was lying around.
I'm ecstatic! It might be a pain getting over to see him but totally worth it. I'm sure I will get a lot of sage advice too. Anyone else considering a similar project to this *really* needs to spend time on forums, there are some awesome people on the internet (i.e. in real life, that you can communicate with on the internet hehe)
Trailer
On a completely different note, I have been considering how to move this kart around when it's finished. Most people are settled and build these in their back yards... seeing as I am in an apartment this is a problem.
I have recently realized that my go kart has trailer tires, and the front (will have) actual trailer stub axles. So - get the kart licensed as a trailer, and tow it backwards! I'm thinking to build a pin into the steering mechanism to lock the steering straight for towing, and leaving a place to attach a long trailer hitch arm to the rear of the kart.
The Ontario website does not indicate much in the way of requirements for trailers so I think it should be relatively easy to get it plated.
Until next time...
Sunday, July 3, 2011
Princess Auto shopping trip
This weekend I spent three hours (and several hundred dollars, sigh) on a bunch of mechanical parts for the project, and a little in the way of tools.
I ended up buying the tires that were on sale, they are Carlisle trailer tires, 16.5 inches diameter. Unfortunately they only had 3 in store, so I got a rain check and will have to go back to get the fourth.
I chose #50 chain and a 1" rear axle. Here are the rear sprocket and the motor sprocket, chosen for a gear ratio of about 2.5. I ended up with 48 and 18 teeth, for an actual ratio of 2.66.
All the sprockets I used are designed to be welded onto the hubs which are keyed to attach to the axle.
So here is the first real welding I have done in a few years, for the rim attachments.
It is fairly ugly, and was hard to take a picture of. A wire brushing would have helped, but I did bang off the slag with my welding hammer. The second hub went much better than the first, but still needs a some more improvement.
I then expanded the holes with 3/8 and 7/16 drills. The bolts I am using were designed for tire applications, to be hammered into the hub. Of course the dimensions are not handy; the threaded section is 1/2" but the flat area is 0.53" and the ridged area which provides the holding effort is about 0.55".
I had to use the mill here again to get the dimensions right; I don't know exactly how big the hole was but just over 0.53".
See the ridges don't quite fit? This is perfect. Now you have to beat the shit out of the bold head to drive it into this sprocket, which I swear is hardened steel. It was very difficult - if I made the holes larger it would have been easier, but there would have been less grip strength in rotation.
Hey, it fits!
Here's the bolt side.
You can't tell but the ridged area is too wide, so the nuts don't completely seat. I need to add spacers for a better fit. I should have used thicker sprockets instead.
Both sprockets together
Here's the posi-lube stub axle which I will be using for the front axles.
Both tires bolted to hubs and on the scrap 1" bar again.
Next I have to buy a 1" keyed axle, some keystock, locking collars, and a bunch of metal from Metal Supermarket.
Sunday, June 26, 2011
Welder plug installed, brakes make more sense now
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.
$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.
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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