Here is a little public service announcement for all of you who shop online...just in time for holiday shopping! I found a website called retailmenot.com. You can go to that site and search for any online retailer and it will list a whole bunch of coupon codes for that store...free shipping, xx% off, $x off your order, etc, etc. They also allow you to provide feedback about whether the code worked for you or not, so each listed code says how frequently it worked for other people.
There is even a Firefox extension available that will automatically inform you if online coupons are available at retailmenot.com for the store whose page you are currently on. Nifty!
I have used codes from this site twice now (once at Macy's and once at PetSmart) and both times it worked out great! Happy shopping!
Showing posts with label how-to. Show all posts
Showing posts with label how-to. Show all posts
Saturday, November 01, 2008
Sunday, May 18, 2008
Ouch, crap! My finger!
After Ashley's Graduation, Michael went home and I stayed behind to spend some extra time with my family and to help my mom with some home improvement projects. During the past week, we managed to install a hardwood floor in the living room. Here it is...a work in progress:
This was achieved by hand nailing the boards rather than by using a pneumatic cleat nailer, which might have been smarter given the injuries to our left index fingers that occurred during the course of the project (more on that in a minute). They make a manual cleat nailer, but it's almost impossible to use and the pneumatic ones are prohibitively expensive to buy. You can rent them for approximately $70/24 hours, but it probably still would have taken us several days to lay the floor, so we would have spent quite a lot to rent one, too. A lot of our time was spent finding just the right boards to complete a row...it's a lot like a puzzle. They come in random lengths, and it's important that your seams not match up exactly with those on the previous row or two, so you can imagine that you could spend a fair bit of time finding just the right combination of boards to complete a row. You can cut them to fit, but then you end up wasting wood, which we were loath to do. Because we were so frugal with our wood, we probably have almost enough left to do the next room, too (yay!), so our plan is to lay out most of our rows ahead of time and then go rent the cleat nailer and just nail, nail, nail. That way we can get the most out of our 24 hours.
As I mentioned, there were some injuries during the laying of the floor. My mom managed to drive a nail set into her left index finger. My major injury occurred when I was holding a board in place while nailing it and I missed the nail and hit my finger, which drove the edge of the board into the pad of my index finger. OUCH. Both of these injuries bled profusely and, although we each dripped blood all the way to the sink we managed to not bleed on the new floorboards. Kudos to us.
Anyway, here is the finished product:
Isn't it pretty? I'm so excited that it's done! Let's not talk about the other, larger room that we haven't started on. Today I am clean and dressed and I have makeup and jewelry on and I'm not covered in splinters and sawdust. I'll think about THAT tomorrow, just like Scarlett.
This was achieved by hand nailing the boards rather than by using a pneumatic cleat nailer, which might have been smarter given the injuries to our left index fingers that occurred during the course of the project (more on that in a minute). They make a manual cleat nailer, but it's almost impossible to use and the pneumatic ones are prohibitively expensive to buy. You can rent them for approximately $70/24 hours, but it probably still would have taken us several days to lay the floor, so we would have spent quite a lot to rent one, too. A lot of our time was spent finding just the right boards to complete a row...it's a lot like a puzzle. They come in random lengths, and it's important that your seams not match up exactly with those on the previous row or two, so you can imagine that you could spend a fair bit of time finding just the right combination of boards to complete a row. You can cut them to fit, but then you end up wasting wood, which we were loath to do. Because we were so frugal with our wood, we probably have almost enough left to do the next room, too (yay!), so our plan is to lay out most of our rows ahead of time and then go rent the cleat nailer and just nail, nail, nail. That way we can get the most out of our 24 hours.
As I mentioned, there were some injuries during the laying of the floor. My mom managed to drive a nail set into her left index finger. My major injury occurred when I was holding a board in place while nailing it and I missed the nail and hit my finger, which drove the edge of the board into the pad of my index finger. OUCH. Both of these injuries bled profusely and, although we each dripped blood all the way to the sink we managed to not bleed on the new floorboards. Kudos to us.
Anyway, here is the finished product:
Isn't it pretty? I'm so excited that it's done! Let's not talk about the other, larger room that we haven't started on. Today I am clean and dressed and I have makeup and jewelry on and I'm not covered in splinters and sawdust. I'll think about THAT tomorrow, just like Scarlett.
Thursday, December 06, 2007
How-To: Fix Bunching, Moving Floor Mats
My floor mats have been driving me crazy! Perhaps a little explanation is in order. The driver's floor mat in my old-enough-to-drive-itself 1991 Honda CRX has always bunched up and moved around. Maybe my clutch-depressing technique is unusual. Maybe my tiny feet and stumpy legs are the problem. Whatevs. The point is, this issue has plagued me for all of the 11 years I've owned the vehicle. I was recently inspired the fix the problem by a post of the CRX Community forum. Here's how you, too, can have smooth, stationary floor mats.
Cut apart an old wire hanger. (Joan Crawford and my own mommie dearest would be proud.) Then straighten the 2 "shoulder" pieces as much as possible:
Next, bend them to an angle approximately matching the footwell of your car, probably about 45 degrees:
Place the mat over the edge of a coach or what have you to approximate the correct curvature and use duct tape to fasten the ends of the wires to the mat. It's important to get the bend in the correct location.
Add more duct tape to keep the hanger parts in place:
You may not have copious amount of adhesive hook-and-loop (Velcro) closures in your home liek I do---Take that!---but you can buy a box of a meter or so for a few bucks. Cut the hook side into 2 to 4 strips, whatever works best for the geometry of your mat, then stick them firmly to the underside of the mat. Be aware that you may have some kind of rubber mat built into your car's floor carpeting. You need to ensure that the Velcro will land on your carpet and not that built-in mat.
Take the mat out to the car, position it carefully over the spot where you want it, and press it down into the carpet. You may need to press on the curved area to put the correct bend into the wires.
I've had this hacked---ahem, customized---floor mat in my Rex for 2 weeks, and it hasn't bunched, moved, squirmed, or otherwise irritated me. I consider this little project a success.
Cut apart an old wire hanger. (Joan Crawford and my own mommie dearest would be proud.) Then straighten the 2 "shoulder" pieces as much as possible:
Next, bend them to an angle approximately matching the footwell of your car, probably about 45 degrees:
Place the mat over the edge of a coach or what have you to approximate the correct curvature and use duct tape to fasten the ends of the wires to the mat. It's important to get the bend in the correct location.
Add more duct tape to keep the hanger parts in place:
You may not have copious amount of adhesive hook-and-loop (Velcro) closures in your home liek I do---Take that!---but you can buy a box of a meter or so for a few bucks. Cut the hook side into 2 to 4 strips, whatever works best for the geometry of your mat, then stick them firmly to the underside of the mat. Be aware that you may have some kind of rubber mat built into your car's floor carpeting. You need to ensure that the Velcro will land on your carpet and not that built-in mat.
Take the mat out to the car, position it carefully over the spot where you want it, and press it down into the carpet. You may need to press on the curved area to put the correct bend into the wires.
I've had this hacked---ahem, customized---floor mat in my Rex for 2 weeks, and it hasn't bunched, moved, squirmed, or otherwise irritated me. I consider this little project a success.
Tuesday, October 30, 2007
How-To: Nitro-to-Brushless Conversion: Part 6
Part 5 can be found here.
OK, this post isn't so much a how-to as an update on a previous how-to, but I feel that keeping the title consistent is important.
I've been quite happy with the performance of my brushless-powered Losi 8IGHT, but I couldn't resist tweaking it a bit. Below is a list of some of the changes I've made since my last post, several of which were predicted therein. Most of these changes are clearly visible in the photos that follow the list.
OK, this post isn't so much a how-to as an update on a previous how-to, but I feel that keeping the title consistent is important.
I've been quite happy with the performance of my brushless-powered Losi 8IGHT, but I couldn't resist tweaking it a bit. Below is a list of some of the changes I've made since my last post, several of which were predicted therein. Most of these changes are clearly visible in the photos that follow the list.
- I successfully tamed the motor braking. The car still stops quickly, but it's more controllable, and now I don't feel like I'm going to damage the motor every time I slow down. I really would have liked to use the disk brakes that came with the kit, but there just wasn't room for the servo required to operate them.
- I've replaced the batteries and speed-control's Dean's connectors with 5.5-mm bullet connectors. The bullets will have lower resistance at high currents. This higher conductance is important, since I expect to draw close to 200 amps for short periods.
- I added a second temperature sensor, this one is thermal-epoxied directly to the motor. Now I can monitor the temps of both the motor controller and the motor. I've found that both temperatures mostly stay below 130 degrees F, which makes me feel confident that I'm damaging neither component.
- I've replaced the single battery tray with 2 smaller ones, which allows me to hold 2 6300-mAh 2-series LiPo batteries. I've soldered the batts together in series, giving me a 4-series LiPo with 26% more capacity than my single 5000-mAh batt. This change should not only give me longer runtimes, but also higher currents and thus more power. Additionally, the new setup creates an almost perfect left-right weight balance. As a bonus, the new battery configuration also fills previously unused space on the left side of the car, making it look a little more efficiently laid out..
- I've mounted some Pro-Line Moab tires on orange Kyosho 10-spoke wheels, which are visible in the first pic. The tread on these tires has a good multi-purpose pattern, useful for on- and off-road driving. Additionally, these tires have transverse ribs on the inside, which helps prevent them from ballooning at high wheel speeds. Not only will these ribs keep more tire in contact with the ground, but they will also keep the tires glued to the rims. The wheels, by the way, are probably my favorite 1/8th buggy wheels; they are both well made and attractive.
- Speaking of tires, I also found some GRP Rally tires, which I mounted on orange Kyosho 5-slot dish wheels. These wheels and tires are visible in the second pic. In addition to being made of a surprisingly sticky compound, these tires have an extremely low profile, which not only keeps them from ballooning, but also reduces side-wall flex during corning. They don't absorb jump-landing impact as well as higher-profile tires, but that seems like a good trade-off, given that they are intended for on-road use. The major downfall of the tires is their outside diameter; they not only look too small on the vehicle, they also necessitate a significant gearing change. I'd really prefer tires with the same profile mounted on wheels about 10 mm larger in diameter. The wheels, meanwhile, aren't as attractive as the 10-spokers, in my opinion, but they do give the car a somewhat futuristic look, which I find pleasing. I think they certainly look better than the stock dish wheels. (These wheels actually look quite a lot like the wheels that come stock on the Honda Civic Hybrid, which, being a hybrid, is meant to look all future-y.)
- Gearing is, of course, determined by terrain, but I've been running mostly 15/39 on the road and 14/39 or 13/39 off. It's much easier to change the pinion gear (mounted on the motor shaft) than the spur gear (mounted on the center differential and holding the viscous silicone fluid therein at bay).
- Since my electrified car is heavier than the stock nitro version, especially with the larger batts, I've stiffened the suspension, cranking up the front and rear spring rate by 14% and 19%, respectively. I also increased the damping concomitantly. The suspension is now set to something much closer to the truggy version of my buggy.
- I've replaced the stock plastic steering knuckles (axle carriers), servo-saver arm, and servo arm, with their hard-anodized aluminum counterparts. This change should rigidify the entire steering system, resulting in better steering in high-speed situations with only a slight weight penalty. Several other hard-ano aluminum parts are available for the 8IGHT, but I'm not convinced that they offer improved performance or that, if they do, said improvement justifies the additional weight and cost. Incidentally, only the servo arm is visible in the first photo.
- I've also purchased a Pro-Line Crowd Pleazer 2.0 body, which I've painted almost identically to its stock counterpart. I don't think I like the CP2 as well as I do the stock body. I'll put up a pic later and let you be the judge.
- I haven't had a chance to measure the top speed of the vehicle to see if the larger battery and taller gearing had an effect. Certainly the car seems fast enough, and the acceleration is more than sufficient for my purposes.
Monday, September 10, 2007
How-To: Mod a Nerf Revolver: Part 2
My last post demonstrated how to modify the Nerf Maverick revolver to let the cylinder swing all the way out and spin freely. This post will show you how to mod the "weapon" to shoot slightly farther.
First, disassemble the gun as a I described last time. Then pull the cylinder out. Pry off the orange plug pressed onto the end of the axle, which will allows you to pull the axle out.
The cylinder is made of two parts. Unscrew and remove the back part, and you will see the orange spikes onto which the darts, which are hollow, slide.
Pull the spikes out, and you will find a spring and flow limiter behind each one.
Discard all 6 of the flow limiters and 5 of the springs. Put the spikes back in place and reassemble the cylinder, but don't put it back on its axle yet. This omission of the limiters and the springs will allow more air to flow to the darts.
Slide the reserved spring onto the axle. Then slide on the cylinder. The spring will help keep the cylinder pressed up against the plunger mechanism, thus preventing air from escaping between the plunger mechanism and the cylinder.
Now reassemble the revolver and unleash your fury upon your spouse. Or on a smooth, flat surface. Your choice.
In our testing, Team Grondul found that a gun with the cylinder mod from the last post and the mod describe herein fired, on average, about 5 or 6 feet further than a gun with only the cylinder mod, when all 6 darts were discharged from each gun while it was held at an angle of about 30 degrees.
First, disassemble the gun as a I described last time. Then pull the cylinder out. Pry off the orange plug pressed onto the end of the axle, which will allows you to pull the axle out.
The cylinder is made of two parts. Unscrew and remove the back part, and you will see the orange spikes onto which the darts, which are hollow, slide.
Pull the spikes out, and you will find a spring and flow limiter behind each one.
Discard all 6 of the flow limiters and 5 of the springs. Put the spikes back in place and reassemble the cylinder, but don't put it back on its axle yet. This omission of the limiters and the springs will allow more air to flow to the darts.
Slide the reserved spring onto the axle. Then slide on the cylinder. The spring will help keep the cylinder pressed up against the plunger mechanism, thus preventing air from escaping between the plunger mechanism and the cylinder.
Now reassemble the revolver and unleash your fury upon your spouse. Or on a smooth, flat surface. Your choice.
In our testing, Team Grondul found that a gun with the cylinder mod from the last post and the mod describe herein fired, on average, about 5 or 6 feet further than a gun with only the cylinder mod, when all 6 darts were discharged from each gun while it was held at an angle of about 30 degrees.
How-To: Mod a Nerf Revolver: Part 1
A long time ago in a blog very nearby, I reviewed the Nerf Maverick revolver and promised to post a how-to on the mods I've made to it. Here, finally, is the first of them:
In stock form, the Maverick's cylinder only swings out about 20 or 30 degrees, just far enough to load a couple of darts at a time. Additionally, the cylinder doesn't spin continuously; its rotation is quantized into increments 360/6 = 60 degrees. These 2 shortcomings make reloading in the heat of a harmless, foam shoot-out time-consuming and frustrating. This post will show how to mod your Maverick's cylinder to swing out about 90 degrees and spin more freely, increasing both the reload speed and the all-important coolness factor.
Place the "weapon" down on its left side. Remove the 3 screws holding the slide together. Remove the slide.
Remove the remaining 8 or so screws holding the right half of the frame to the left.
Lift out the cylinder, along with the gray front and rear arms that support it.
Examine the front support arm, and you will find a nub that prevents the arm from swinging out of the frame.
Use a utility knife to cut off the offending nub.
You are now halfway done. Examine the left frame, just to the rear of where the cylinder would sit. You will find another nub, this one preventing the rear arm from swinging out freely.
Cut that nub off, too.
Now reassemble the gun.
The cylinder will now swing out all the way and spin easily, enabling quick reloading and fun, nontoxic Russian roulette.
Your newly modified Maverick can now be used to rain brightly colored, suction-cup-tipped terror down upon your young nieces and nephews. But not your dog; that's just mean.
The second modification can be found here.
In stock form, the Maverick's cylinder only swings out about 20 or 30 degrees, just far enough to load a couple of darts at a time. Additionally, the cylinder doesn't spin continuously; its rotation is quantized into increments 360/6 = 60 degrees. These 2 shortcomings make reloading in the heat of a harmless, foam shoot-out time-consuming and frustrating. This post will show how to mod your Maverick's cylinder to swing out about 90 degrees and spin more freely, increasing both the reload speed and the all-important coolness factor.
Place the "weapon" down on its left side. Remove the 3 screws holding the slide together. Remove the slide.
Remove the remaining 8 or so screws holding the right half of the frame to the left.
Lift out the cylinder, along with the gray front and rear arms that support it.
Examine the front support arm, and you will find a nub that prevents the arm from swinging out of the frame.
Use a utility knife to cut off the offending nub.
You are now halfway done. Examine the left frame, just to the rear of where the cylinder would sit. You will find another nub, this one preventing the rear arm from swinging out freely.
Cut that nub off, too.
Now reassemble the gun.
The cylinder will now swing out all the way and spin easily, enabling quick reloading and fun, nontoxic Russian roulette.
Your newly modified Maverick can now be used to rain brightly colored, suction-cup-tipped terror down upon your young nieces and nephews. But not your dog; that's just mean.
The second modification can be found here.
Thursday, August 30, 2007
How-To: Resurrect a Dead Trimmer
I own a small beard/sideburn/other trimmer that I get quite a bit of use out of. I don't use it to cut my hair evey 3 or 4 weeks; I have another one for that. Instead, I use it to make my sideburns the desired length and angle, to trim the hair around my ears---which lets me go another week between haircuts---and to trim the hair around the back of my neck after a haircut.* The particular model I own has several different-sized detachable cutting heads, which fact makes it extra useful.
Anyway, the thing started acting up on me not too long ago; it just wouldn't hold a charge. I suspected that the batteries were at fault, especially since consumer electronics containing rechargeable batteries often use low-quality batteries, and said batteries often loose their capacity after comparatively few charge cycles.
Not wanting to lay out the cash for a new trimmer when I could probably fix mine, I pried open the case, revealing guts of the device:
As you can see, it uses standard AA-sized cells. If I'd been more careful with my camera, photo below would show that the particular batteries in this model have a nominal capacity of 600-mA-hr.** That stated capacity isn't great, and I can assure you that the batteries were doing much worse than that in practice. I happened to have 12 rechargable double-As in the house at the time, all of which were rated with higher capacities. I wanted to reserve 2 sets of 4 for my RC transmitter, which left me with twice as many as I needed to fix this problem. Groovy.
There was just one very minor wrinkle. Despite the blurriness of the pic, you can see that the two AAs were permanently wired in series by a thin metal---steel?---strip. I duplicated this arrangement with my new cells using a short length of fine-gauge wire:
I inserted the new double-As into the trimmer, snapped the case closed, and charged it up. Guess what? No luck. Crap. And here I thought I was being soooo smart.
I realized, after cracking open the case and tracing the trimmer's wires more carefully, that I had put the batteries in wrong orientation, left-to-right. I repositioned them, reclosed the case, and recharged the batteries. It worked this time. Ta-daaa!
So, the take-home message is this: Don't let The Man keep you down by buying new consumer products when they stop functioning; reach for your tools instead.
* Actually, I usually get Alison to do that last part. Ah, the joys of marriage.
** Or mAh, if you prefer.
Anyway, the thing started acting up on me not too long ago; it just wouldn't hold a charge. I suspected that the batteries were at fault, especially since consumer electronics containing rechargeable batteries often use low-quality batteries, and said batteries often loose their capacity after comparatively few charge cycles.
Not wanting to lay out the cash for a new trimmer when I could probably fix mine, I pried open the case, revealing guts of the device:
As you can see, it uses standard AA-sized cells. If I'd been more careful with my camera, photo below would show that the particular batteries in this model have a nominal capacity of 600-mA-hr.** That stated capacity isn't great, and I can assure you that the batteries were doing much worse than that in practice. I happened to have 12 rechargable double-As in the house at the time, all of which were rated with higher capacities. I wanted to reserve 2 sets of 4 for my RC transmitter, which left me with twice as many as I needed to fix this problem. Groovy.
There was just one very minor wrinkle. Despite the blurriness of the pic, you can see that the two AAs were permanently wired in series by a thin metal---steel?---strip. I duplicated this arrangement with my new cells using a short length of fine-gauge wire:
I inserted the new double-As into the trimmer, snapped the case closed, and charged it up. Guess what? No luck. Crap. And here I thought I was being soooo smart.
I realized, after cracking open the case and tracing the trimmer's wires more carefully, that I had put the batteries in wrong orientation, left-to-right. I repositioned them, reclosed the case, and recharged the batteries. It worked this time. Ta-daaa!
So, the take-home message is this: Don't let The Man keep you down by buying new consumer products when they stop functioning; reach for your tools instead.
* Actually, I usually get Alison to do that last part. Ah, the joys of marriage.
** Or mAh, if you prefer.
Wednesday, July 18, 2007
How-To: Nitro-to-Brushless Conversion: Part 5
Part 4 can be found here.
We have finally arrived at perhaps the most interesting part of this how-to on the conversion of a Losi 8IGHT 1/8th-scale buggy from nitro to brushless/LiPo power: the installation of the motor, battery, ESC, and supporting components.
Here are a pair photos of the completed car without the body or battery:
This photo shows the 5000-mA-hr battery in place:
You can see a few important aspect of the car's construction from these pics:
Next: some shots of the car with road tires---Pro-Line Road Rages---mounted in place of the dirt-track tires---Pro-Line Crime Fighters1 ---shown above. I also purchased some extra-knobby all-terrain tires---Pro-Line Badlands---for more rugged surfaces.
This last photograph shows how I measured the weight distribution. Yes, those are season box sets of Star Trek: Deep Space Nine. And yes, that is the second Trek reference in this post, but I'm not some kind of raging Trekkie; these boxes were the first objects I could find that are all the same thickness, and very close to the thickness of the scale.
At this point, the conversion is done, and I'm quite please with the way it turned out. The car accelerates like nobody's business. The acceleration is far better than a nitro-powered buggy can produce, since nitro engines' torque peaks at many thousands of RPM, while the motor in my buggy produces full torque at zero speed. The vehicle also hits remarkably high speeds. I used Alisons GPS receiver2 to measure the top speed to be 41.8 mi/hr with a 14/48 pinon/spur and the road tires. (This test was done on a straight, nearly flat strip of asphalt with nearly no wind.) Additionally, the buggy remains flat---doesn't roll---in corners, and it can be slid very dramatically on smooth pavement.
I only plan minor tweaks from here on out. Here are some of the changes I'd like to make, in approximate order of precedence:
Your comments and suggestions are welcome.
1 Pro-Line's tire names, especially those designed for off-road racing, have a criminal theme to them. I addition to the aforementioned Road Rage and Crime Fighter models, there are also the Cell Block, Mugshot, Inside Job, and Dirty Harry. It not clear to me whether the Knuckles model counts.
2 We have named the device Garmin Tanzarian.
Part 6 can be found here.
We have finally arrived at perhaps the most interesting part of this how-to on the conversion of a Losi 8IGHT 1/8th-scale buggy from nitro to brushless/LiPo power: the installation of the motor, battery, ESC, and supporting components.
Here are a pair photos of the completed car without the body or battery:
This photo shows the 5000-mA-hr battery in place:
You can see a few important aspect of the car's construction from these pics:
- I've put everything except the battery on the right side of the car or along the centerline. Id did so because, as I said, the battery is quite heavy. With the 5-A-hr battery shown, the weight is distributed slightly to the right, but with the larger 8-A-hr battery, the left tires carry more weight so I think my arrangement is a pretty fair compromise.
- You may also be able to make out the custom speed-control mount/heatsink that I bent and cut out of 5052 (bendable) aluminum. I'm quite pleased with it; it places the ESC near the centerline of the vehicle and keeps the ESC running cool.
- The little circuit board thermal-epoxied to the top of the ESC is a temperature sensor. I plan to put another on the motor. Since the transceiver and servo run off a 5-V voltage regulator, I added a voltage sensor---really just a pair of wires with a Rx/servo connector on the end to the setup. You can see the leads disapearing into the ESC's input connectors in the photos.
- I've dispensed with the front and read disc brakes, which normally sit just ahead of and just behind the center differential. Instead, I'm relying on motor braking. It seems to me that disk brakes are more efficient, from a current-draw standpoint, but I just didn't have room for the servo that would actuate them.
- As I mentioned last time, I had to grind the motor/diff mount down to fit under the body. (The part was actually made to fit the Losi 8IGHT-T truggy.)
- Those of you who know me are aware of the significance of the number I've chosen to place on the wing.
Next: some shots of the car with road tires---Pro-Line Road Rages---mounted in place of the dirt-track tires---Pro-Line Crime Fighters1 ---shown above. I also purchased some extra-knobby all-terrain tires---Pro-Line Badlands---for more rugged surfaces.
This last photograph shows how I measured the weight distribution. Yes, those are season box sets of Star Trek: Deep Space Nine. And yes, that is the second Trek reference in this post, but I'm not some kind of raging Trekkie; these boxes were the first objects I could find that are all the same thickness, and very close to the thickness of the scale.
At this point, the conversion is done, and I'm quite please with the way it turned out. The car accelerates like nobody's business. The acceleration is far better than a nitro-powered buggy can produce, since nitro engines' torque peaks at many thousands of RPM, while the motor in my buggy produces full torque at zero speed. The vehicle also hits remarkably high speeds. I used Alisons GPS receiver2 to measure the top speed to be 41.8 mi/hr with a 14/48 pinon/spur and the road tires. (This test was done on a straight, nearly flat strip of asphalt with nearly no wind.) Additionally, the buggy remains flat---doesn't roll---in corners, and it can be slid very dramatically on smooth pavement.
I only plan minor tweaks from here on out. Here are some of the changes I'd like to make, in approximate order of precedence:
- Adjust the motor braking. It's way too aggressive at the moment.
- Add a second temperature sensor to monitor the motor itself.
- Add another strap (or some other component) to the battery tray to hold the larger, 8000-mA-hr batteries in place securely and cleanly.
- Replace the Deans Ultra Plugs I have on the batteries and the input to the ESC with 5.5-mm bullet connectors, like I have on the motor and the ouput of the ESC. Deans aren't really meant to be used over 50 amperes, while the 5.5-mm bullets can be run up to 200 amps.
- Experiment with gearing. A simple pinion change to 15/48 should put the vehicle just under 45 mi/hr. If that doesn't hurt the low-end acceleration, I might go to 15/47. I suspect 15/48 will be close to the ideal gearing, though.
- Experiment with the suspension parameters. The setup suggested by the manual is pretty good, but I think I should stiffen it up a bit, since the car is a bit heavier than the nitro version.
- Possibly solder the ESC directly to the motor to reduce loss and improve reliability. I'm not sure if that step will be necessary.
Your comments and suggestions are welcome.
1 Pro-Line's tire names, especially those designed for off-road racing, have a criminal theme to them. I addition to the aforementioned Road Rage and Crime Fighter models, there are also the Cell Block, Mugshot, Inside Job, and Dirty Harry. It not clear to me whether the Knuckles model counts.
2 We have named the device Garmin Tanzarian.
Part 6 can be found here.
Tuesday, July 17, 2007
How-To: Nitro-to-Brushless Conversion: Part 4
Part 3 can be found here.
After a couple-month-long hiatus, during which I pursued some of my other hobbies, I recently returned to working on the brushless conversion of my Losi 8IGHT 1/8th-scale buggy. And to posting about it on Industrial-Strength Science. This part of my how-to concerns selection of the electronics and associated parts for the vehicle.
The motive force for the car, and indeed the centerpiece of the conversion, will be a NeuMotors 1512/2.5D. All Neu's 1512 motors are rated at 1200 W of continuous power and 2500 W for 30 seconds. This particular motor has a Kv rating of 2000 RPM/V, which means that, with the nominal 14.8-V potential difference supplied by my batteries, it should spin up to 29,600 RPM. That should be fine, because the 1512s aren't meant to spin above 60,000 RPM. The manufacture claims that this motor is "86+" percent efficient. I'm not sure how they measure that---it seems to me the efficiency will vary strongly with voltage/current/speed---but the point is this motor is much more efficient than any brushed motor. Here's a photo of the Neu:
As I think I said before, a brushless motor running off a lithium-polymer battery is truly 2 great tastes that taste great together. The high efficiency of the BL motor combines with the high current capacity and low load-induced voltage drop of the LiPos to deliver lots of power to the wheels, propeller, or what have you. For now, I'll be running a MaxAmps pack consisting of 4 LiPo cells in series. Each cell has a nominal voltage of 3.7 V and a capacity of 5000 mA-hr, so this so-called 4s pack has nominal voltage of 14.8 V and a capacity of 5000 mA-hr; the capacities do not add. This pack is claimed to be capable of putting out constant currents of 20 C---that's 100 amps-for a 5-A-hr battery---and burst currents of 50 C---250 amps for 5-A-hr. The downside to this pack is that, even though LiPo cells have much higher specific capacity than nickel-cadmium or nickel-metal-hydride cells, this battery is just plane huge. You can't determine the size from this photo, but it will be apparent when I show it in place in the vehicle:
Because brushless motors have electronic, rather than mechanical comutation, a brushless-specific electronic speed control is required. I've chosen a Quark 125-B Monster Pro, which is claimed to be capable of sustained currents of 125 A and 10-second bursts of 180 A. Here's a pic:
The Quark ESC has a built-in "battery-eliminator circuit," which is simply a voltage regulator that allows you to pick off 5 or 6 V from the supplied higher voltage to run the receiver and servo, rather than including a small "receiver pack" battery to provide that lower voltage. This BEC is resistive and thus inefficient. In order to reduce power consumption, I'll be using a transitor-base switching regulator, which is more efficient. Here's a shot of this external BEC:
To disable the ESC's BEC, I simply cut the positive power lead coming off of it; since that BEC is resistive, I believe that mod should prevent it from sucking up current. I should point out that Nick taught me that resistive power supplies are less noisy than switching types, but, since I'm not trying to build a fiber laser for optical metrology---at least not today---I'm more worried about efficiency than noise.
The only part I bought that was specificly---more or less---made for this project is a motor/differential mount I purchased from Mike Cronin at RC Monster. This mount replaces one of the diff mounts and allows the motor and its pinion gear to mesh with the spur gear on the diff. I said "more-or-less" because the part was actually made for converting the Losi 8IGHT-T, the truggy1 version of my buggy. Since the buggy body is "skin-tight," while the truggy's encloses a lot of unused volume, I found that the mount rubbed on my beautifully painted body. So, I had to grind off the upper outboard edge of the mount. Here's a photo of the unmodified motor/diff mount; the modified version will be visible on the completed car:
To hold that ginormous battery in place, I also purchased a machined plastic battery tray from RC Monster. I modified this part as well, which I'll show you later.
I also custom made a mount for the ESC that places the speed control near the centerline of the vehicle. I don't have any photos of that mount, although I'm Brian with the overhead projector about it.
I mentioned before that I'll be using a Nomadio Sensor radio, which has several nice features, including telemetry and noise insensitivity. Here's a photo of the transmitter:
Part 5 can be found here.
1 A truggy, at least in the world of RC, is a "truck" that is really a modified buggy. Typically, a truggy has these features:
After a couple-month-long hiatus, during which I pursued some of my other hobbies, I recently returned to working on the brushless conversion of my Losi 8IGHT 1/8th-scale buggy. And to posting about it on Industrial-Strength Science. This part of my how-to concerns selection of the electronics and associated parts for the vehicle.
The motive force for the car, and indeed the centerpiece of the conversion, will be a NeuMotors 1512/2.5D. All Neu's 1512 motors are rated at 1200 W of continuous power and 2500 W for 30 seconds. This particular motor has a Kv rating of 2000 RPM/V, which means that, with the nominal 14.8-V potential difference supplied by my batteries, it should spin up to 29,600 RPM. That should be fine, because the 1512s aren't meant to spin above 60,000 RPM. The manufacture claims that this motor is "86+" percent efficient. I'm not sure how they measure that---it seems to me the efficiency will vary strongly with voltage/current/speed---but the point is this motor is much more efficient than any brushed motor. Here's a photo of the Neu:
As I think I said before, a brushless motor running off a lithium-polymer battery is truly 2 great tastes that taste great together. The high efficiency of the BL motor combines with the high current capacity and low load-induced voltage drop of the LiPos to deliver lots of power to the wheels, propeller, or what have you. For now, I'll be running a MaxAmps pack consisting of 4 LiPo cells in series. Each cell has a nominal voltage of 3.7 V and a capacity of 5000 mA-hr, so this so-called 4s pack has nominal voltage of 14.8 V and a capacity of 5000 mA-hr; the capacities do not add. This pack is claimed to be capable of putting out constant currents of 20 C---that's 100 amps-for a 5-A-hr battery---and burst currents of 50 C---250 amps for 5-A-hr. The downside to this pack is that, even though LiPo cells have much higher specific capacity than nickel-cadmium or nickel-metal-hydride cells, this battery is just plane huge. You can't determine the size from this photo, but it will be apparent when I show it in place in the vehicle:
Because brushless motors have electronic, rather than mechanical comutation, a brushless-specific electronic speed control is required. I've chosen a Quark 125-B Monster Pro, which is claimed to be capable of sustained currents of 125 A and 10-second bursts of 180 A. Here's a pic:
The Quark ESC has a built-in "battery-eliminator circuit," which is simply a voltage regulator that allows you to pick off 5 or 6 V from the supplied higher voltage to run the receiver and servo, rather than including a small "receiver pack" battery to provide that lower voltage. This BEC is resistive and thus inefficient. In order to reduce power consumption, I'll be using a transitor-base switching regulator, which is more efficient. Here's a shot of this external BEC:
To disable the ESC's BEC, I simply cut the positive power lead coming off of it; since that BEC is resistive, I believe that mod should prevent it from sucking up current. I should point out that Nick taught me that resistive power supplies are less noisy than switching types, but, since I'm not trying to build a fiber laser for optical metrology---at least not today---I'm more worried about efficiency than noise.
The only part I bought that was specificly---more or less---made for this project is a motor/differential mount I purchased from Mike Cronin at RC Monster. This mount replaces one of the diff mounts and allows the motor and its pinion gear to mesh with the spur gear on the diff. I said "more-or-less" because the part was actually made for converting the Losi 8IGHT-T, the truggy1 version of my buggy. Since the buggy body is "skin-tight," while the truggy's encloses a lot of unused volume, I found that the mount rubbed on my beautifully painted body. So, I had to grind off the upper outboard edge of the mount. Here's a photo of the unmodified motor/diff mount; the modified version will be visible on the completed car:
To hold that ginormous battery in place, I also purchased a machined plastic battery tray from RC Monster. I modified this part as well, which I'll show you later.
I also custom made a mount for the ESC that places the speed control near the centerline of the vehicle. I don't have any photos of that mount, although I'm Brian with the overhead projector about it.
I mentioned before that I'll be using a Nomadio Sensor radio, which has several nice features, including telemetry and noise insensitivity. Here's a photo of the transmitter:
Part 5 can be found here.
1 A truggy, at least in the world of RC, is a "truck" that is really a modified buggy. Typically, a truggy has these features:
- The chassis is a slightly lengthened version of a buggy's pan chassis.
- The suspension ams linking the wheel to the chassis are lengthened.
- The wheels arnd tires are truck components.
- The body is similar to the stylized "stadium truck" body found at the 1/10th scale.
Friday, April 27, 2007
How-To: Nitro-to-Brushless Conversion: Part 3
Part 2 can be found here.
Part 3 of the brushless buggy project was painting and decaling the body that came with the kit. As I've said, and as many of you have noticed, I'm very concerned with appearances and other superficial matters, so this part was great fun for me. Additionally, I must say that the stcok Losi 8IGHT body is more attractive, to my eye, than the aftermarket bodies available from Pro-Line or JConcepts. Here're a couple of good shots of the mounted body:
Yet another reason for going electric is that I won't need to cut one hole in the body to allow the engine's cooling head to protrude and another to allow me to fill the tank. Not only does the vehicle look cleaner this way, but the aerodynamic drag should be lower as well. For a comparison with the stock, nitro 8IGHT, check out this photo.
I'm Brain with the overhead projector about how the paint came out; there are a few flaws in my masking, but you can't resolve them in these photos. I'm also quite happy with how the black and white of the body contrasts well with the orange1 of the wheels, wing, antenna tube, and body-clip retainers.
For scale, here's a photo with my Associated RC18B,2 which some of you have seen:
Also for scale, here's a shot with everyone's favorite Bichon, Newton:
My plan now is to report on the real guts of this project---the brushless/Lipo power system---once I get that done, whenever that turns out to be.
1 I've chosen orange as my signature color in the world of RC.
2 I converted this thing from an RC18T, which conversion basically consisted of attaching some wing-mounting hardware and a new body.
Part 3 of the brushless buggy project was painting and decaling the body that came with the kit. As I've said, and as many of you have noticed, I'm very concerned with appearances and other superficial matters, so this part was great fun for me. Additionally, I must say that the stcok Losi 8IGHT body is more attractive, to my eye, than the aftermarket bodies available from Pro-Line or JConcepts. Here're a couple of good shots of the mounted body:
Yet another reason for going electric is that I won't need to cut one hole in the body to allow the engine's cooling head to protrude and another to allow me to fill the tank. Not only does the vehicle look cleaner this way, but the aerodynamic drag should be lower as well. For a comparison with the stock, nitro 8IGHT, check out this photo.
I'm Brain with the overhead projector about how the paint came out; there are a few flaws in my masking, but you can't resolve them in these photos. I'm also quite happy with how the black and white of the body contrasts well with the orange1 of the wheels, wing, antenna tube, and body-clip retainers.
For scale, here's a photo with my Associated RC18B,2 which some of you have seen:
Also for scale, here's a shot with everyone's favorite Bichon, Newton:
My plan now is to report on the real guts of this project---the brushless/Lipo power system---once I get that done, whenever that turns out to be.
1 I've chosen orange as my signature color in the world of RC.
2 I converted this thing from an RC18T, which conversion basically consisted of attaching some wing-mounting hardware and a new body.
How-To: Nitro-to-Brushless Conversion: Part 2
Part 1 can be found here.
The second part of my brushless buggy project was assembly of the non-nitro-specific portion of the Losi 8IGHT kit. First, I assembled all of the mechanical components that required no modification. Doing so entailed putting about 200 parts (plus screws) together, which wasn't so bad, since the manual is quite clear. The hardest parts were filling the diffs and especially the shocks with silicone oil of the appropriate viscosities; getting all the air bubbles out can be challenging. Here's a photo showing the car at this point in the construction; it also illustrates just how off-center the center diff is.
Next, I modified the electronics box by cutting off the portions designed to house the receiver pack and brake servo. I'll be powering the Rx and the servos using a voltage regulator---called a battery-eliminator circuit in the RC world---running off the main battery. Additionally, I'll be using the motor to provide braking, which will eliminate the ability to adjust front/rear brake bias, but also save a lot of weight, room, and complexity. Here's a photo of the car with the modified electronics box, Rx, and steering servo installed:
Note that I have only a very short length of antenna oriented vertically and potentially projecting out of the body. (The antenna is housed inside the orange antenna tube at the right front of the car.) I can do this because my radio system, the Nomadio Sensor, uses the same 2.4-GHz band that cellular phones employ. Between this high frequency and the spread spectrum1 modulation that Nomadio radios use, the transmitter-receiver link should be very resist to noise. (Come to think of it, noise is another reason to go electric; all those moving metal-on-metal interfaces in a nitro engine put out a lot of radio static.) I should also mention that the link is bidirectional; the receiver---really a transceiver---cames with temperature, voltage, and speed sensors, and it can send telemetry back to the transmitter---also really a transmitter. I'll try to post photos of the transmitter later.
By the way, in the above the photo, you can see the body I painted for the 8IGHT. That will be the subject of my next post on this project.
Part 3 can be found here.
1 Frequency-hopping spread spectrum,2 if you must know. Nomadio claims this is superior to direct-sequence spread spectrum, but I would think the opposite would be true.
2 I should point out that actress Hedy Lamarr contributed significantly to the development of spread spectrum.
The second part of my brushless buggy project was assembly of the non-nitro-specific portion of the Losi 8IGHT kit. First, I assembled all of the mechanical components that required no modification. Doing so entailed putting about 200 parts (plus screws) together, which wasn't so bad, since the manual is quite clear. The hardest parts were filling the diffs and especially the shocks with silicone oil of the appropriate viscosities; getting all the air bubbles out can be challenging. Here's a photo showing the car at this point in the construction; it also illustrates just how off-center the center diff is.
Next, I modified the electronics box by cutting off the portions designed to house the receiver pack and brake servo. I'll be powering the Rx and the servos using a voltage regulator---called a battery-eliminator circuit in the RC world---running off the main battery. Additionally, I'll be using the motor to provide braking, which will eliminate the ability to adjust front/rear brake bias, but also save a lot of weight, room, and complexity. Here's a photo of the car with the modified electronics box, Rx, and steering servo installed:
Note that I have only a very short length of antenna oriented vertically and potentially projecting out of the body. (The antenna is housed inside the orange antenna tube at the right front of the car.) I can do this because my radio system, the Nomadio Sensor, uses the same 2.4-GHz band that cellular phones employ. Between this high frequency and the spread spectrum1 modulation that Nomadio radios use, the transmitter-receiver link should be very resist to noise. (Come to think of it, noise is another reason to go electric; all those moving metal-on-metal interfaces in a nitro engine put out a lot of radio static.) I should also mention that the link is bidirectional; the receiver---really a transceiver---cames with temperature, voltage, and speed sensors, and it can send telemetry back to the transmitter---also really a transmitter. I'll try to post photos of the transmitter later.
By the way, in the above the photo, you can see the body I painted for the 8IGHT. That will be the subject of my next post on this project.
Part 3 can be found here.
1 Frequency-hopping spread spectrum,2 if you must know. Nomadio claims this is superior to direct-sequence spread spectrum, but I would think the opposite would be true.
2 I should point out that actress Hedy Lamarr contributed significantly to the development of spread spectrum.
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