I'm sure that a drill's electric brake is designed for only the very short lived pressure of the shaft/bit coming to a stop. So I'm wondering, would there be any problem with the prolonged back pressure that will occur when the skateboard/scooter/whatever is coming to a stop?
How come a scooter DC motor controller has a big heatsink, but there is no apparent heatsink in a powerful cordless drill system? If I'm not mistaken, drills are used continuously long enough to overheat anything if it were possible, like when drilling through 1/2" steel. Modern cordless drills are extremely powerful, the one I just bought has 560 inch pounds of maximum rotational torque. Milwaukee produces a 28 V right angle drill that has over 1000 inch pounds of maximum rotational torque (real torque, not instantaneous hammer drill torque).
I'm probably going to try this anyway but I'm curious (and the drill is expensive).
Thank you.
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if you have concerns about using a cordless drill as a modular
drive for a skateboard or scooter, I\'ve put significant thought into
the idea and will appreciate your input, but I haven\'t actually
built the thing yet
Yeah... maybe because a scooter has that carrying capacity. My cordless drill comes with two 18 V, 3 amp hour batteries, that's about the same total power capacity as Razor's e300 scooter battery.
"Carrying capacity", is why the scooter is an order of magnatude higher in power draw. You can go ahead and use your drill motor, but may get much less speed/range.
And what is your scooter's output torque? I've researched the issue but haven't found much for an answer. One site seems to suggest that a cordless drill motor at 400 inch pounds of torque is enough.
My cordless drill is 18 V. Milwaukee's V28 right angle drill is 28 V at 1080 inch pounds of maximum rotational torque. And there's still no sign of a big heatsink like there is on a scooter's 24 V DC motor controller.
As any woodworker will tell you, clearly the reason why is user fatigue. You don't have the same limitation with a scooter.
John Doe wrote in news:jiYKg.6091$ snipped-for-privacy@newssvr14.news.prodigy.com:
But they are not made for -continuous duty-. "drill hole,PAUSE,drill next hole;repeat." And that torque is derived from the planetary gear multiplication;the motor doesn't have that torque.
No heatsink at all on my scooter;it uses a relay to switch in the current.It has a circuit where you have to push off before the relay will energize. The motor is also a LOT bigger than any cordless drill's motor. It will run cooler than a drill motor. I don't know it's torque rating,though.
(some scooters use a 12 V motor and use 24V of battery for more start torque,with a pulse control for speed.Mine doesn't.Pulse control may give longer battery endurance.)
One other thing to consider is the loads on the motor's bearings;a drill is designed for axial thrust loading on the bearings,not radial load like a scooter motor gets.
Well,you seem fixed on using the drill motor,so go right ahead. For a small child,it should not matter much,although they would be disappointed at the short run time.
BTW,I *HAVE* a scooter,and have used it personally for two years,(EXPERIENCE) and I weigh 175 lbs. (it's a bit bigger than any dinky toy Razor) Rated up to 200 lbs.
I'm not sure I agree with that idea, frequent starting and stopping is hard on a motor, but of course overheating is a concern. It depends on the drill, some are more rugged than others.
As far as I know, torque is given per speed range, and the gearing is a part of that, just like a scooter's belt or chain.
Or maybe you are only familiar with cheap little cordless drills.
I think that's part of your abstinence. You realize this is potentially a very good reason to buy a powerful shiny new cordless drill, so you are attempting to keep this thread fresh with off-the-wall comments, hopefully providing you with some good arguments. I appreciate that.
Of course that depends on the drill.
Apparently modern high quality drills output much higher wattage than your scooter.
Yes, and the PWM helps keep motor parts from being fried.
Again you appear to be limiting your experience to your cheap little cordless drill. My drill uses ball bearings. I'm considering direct drive. If not direct drive, that concern can be eliminated using ball bearings on the external shaft. By the looks of it, my drill uses the same bearings my in-line skates use. If they are easily replaceable, even a radial load will be a non-issue here.
The primary function of a drill is to twist a rod. Twisting a rod really hard is precisely what they are made for. The parallel application is obvious to me.
And, as I explained after your other (group) reply about the subject, a modern drill includes some nifty attributes/features for this application.
You appear to be fixated on throwing out whatever counter ideas that pop into your head without attempting to answer my original questions.
I think my cordless drill is more powerful then your scooter motor, and an auxiliary battery can be supplied if 6 amp hours of 18 V isn't enough.
Apparently you are shooting from the hip (for example, Razor scooters are in fact sturdier and more powerful than yours). But I do appreciate you apparently helping me fish for answers.
My cordless drills have centrifugal fans near the back, presumably attached to the shaft directly. A scooter can't guarantee anything like that kind of airflow.
If a scooter motor has to be waterproof (and cheap), maybe that's why it doesn't have a fan and requires a PWM.
My cordless drill has a fan too, apparently right next to the brushes.
So what does a cordless drill use for speed control? Apparently it's in the trigger box, used for varying speed and reversing direction. Doesn't that have to supply a tremendous amount of current? So where are the huge resisters and heat sinks?!
The thing that is being missed about the difference in cooling, is stored energy in the 'system', when slowing. With the drill, the maximum amount of energy that needs to be dissipated to stop, is just the energy stored in the rotating drill/chuck etc.. With the scooter, if you have climbed a hill, and then go down the other side, you have the potential energy of the rider/scooter, descending possibly hundreds of feet. It is this that the scooter controller has to dump, when it is used as a braking system.
Or when you just release the throttle on level ground. If they can't economically send that energy back into the battery (I know it's possible, for a high price), maybe they should put that energy into a brake light.
X-Mailer: Mozilla 4.78 [en]C-CCK-MCD (Win98; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: sci.electronics.design Subject: Re: OT: cordless drill to drive a skateboard or scooter? References:
Why, yes you are! Thank you for admitting it to the entire newsgroup. You post under an ignorant alias from a '50s bubble gum wrapper and you don't listen to what people say. I've been on this group for about eight years now, and used my real name.
So what if you can copy headers? Is that your only other trick? How about this? Your ISP reports that
IP: 66.136.51.2 Country: United States City: San Antonio, Texas or Plano Texas area
Country Code: US Currency: USD [United States Dollars] Private IP? No Known Proxy? No
NetType: Reassigned
which means you're a cheap bastard who uses dialup. Another sign of a troll.
This still applies. This has nothing to do with electronic design. It is a mechanical problem. I've repaired a bunch of cordless drills from a time that just having one in your car would have you locked up and charged with possession of burglary tools, and I've never seen one with a brake like you describe. They all had a high gear reduction drive train which caused the braking effect. The gear reduction is so high that you can break the output shaft where the chuck screws on and not damage the motor or gears. I just took a pair of defective, new 18 V drills apart and repaired one. It had a loose wire to the forward/reverse switch. The other had the output shaft sheared off in the gearbox. So I have one good free drill and seven battery packs along with almost any part to repair the drill just for picking them up from a friend's thrift store. There is no way the cordless drill motors would be heavy enough for what you wand to do the pair of motors in my power chair are a lot larger, and its only rated for someone who weighs under 250 pounds.
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shows the size of the motors, which use regenerative braking.
Abusing power tools belongs on rec.crafts.metalworking but they would tear you a new asshole just for the hell of it if you cop the same attitude there.
--
Service to my country? Been there, Done that, and I\'ve got my DD214 to
prove it.
Member of DAV #85.
Michael A. Terrell
Central Florida
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