# New to electronics. Need help with a student project involving a motor pulling an object with weight

#### MrSoftware

Joined Oct 29, 2013
2,006
Low speed torque of electric drills aint all that great, I'd question it's ability to pull the skin of custard at low speed, even more so if it doesn't have a hi or low gear option.
This depends entirely on the drill. I've used heavy duty drills to cut large holes in wood that would spin me around if I didn't brace myself.

I like the drill idea myself. Cheap, plenty of power, variable speed and it plugs right in the wall. There are even commercially available drill powered winches, if you want to jump right to the finished product:

https://www.amazon.com/910500-Drill-Winch-500lb-capacity/dp/B00SF70SN4

But if you want to get your hands dirty and start from scratch, here is a source of gear reduction motors to look through. You'll need a lot of reduction and a lot of mechanical advantage (block and tackle with multiple pulleys):

http://www.kr4.us/search.asp?keyword=gear+motor&sortby=0&page=2&catid=85

Joined Jul 18, 2013
22,630
Actually a PSC with identical winding's are just as easy, if not easier, to reverse than DC.
Most of the G.D. openers in N.A. are Chamberlain or relabeled, and these predominantly use PSC motors.
Max.

#### shortbus

Joined Sep 30, 2009
8,429
Personally since this teacher doesn't seem to know any more than the students about this, I'd go another route. Instead of starting with a motor, start by using ropes and pulleys to show how the mechanical advantage of them works. Like just pulling the rope, then adding a "snatch block" pulley at the anchor point. And then make the pulleys multiple, like a block and tackle to show that mechanical advantage doesn't need to mean electric power. That's something the kids will remember . And less chance of any injury.

#### KeepItSimpleStupid

Joined Mar 4, 2014
4,554
How about ropes, pulleys and cranks? And maybe a torque wrench substituted for the crank.

#### ClassOfZero

Joined Dec 28, 2016
114
This depends entirely on the drill. I've used heavy duty drills to cut large holes in wood that would spin me around if I didn't brace myself.

I like the drill idea myself. Cheap, plenty of power, variable speed and it plugs right in the wall. There are even commercially available drill powered winches, if you want to jump right to the finished product:

https://www.amazon.com/910500-Drill-Winch-500lb-capacity/dp/B00SF70SN4

But if you want to get your hands dirty and start from scratch, here is a source of gear reduction motors to look through. You'll need a lot of reduction and a lot of mechanical advantage (block and tackle with multiple pulleys):

http://www.kr4.us/search.asp?keyword=gear+motor&sortby=0&page=2&catid=85

Like I said unless the drill has a hi-lo gear the low speed torque of these of these drills is basically useless. A good quality cordless drill generally has more torque size for size. A good quality drill is going to cost big $$, something I can't see the OP spending for a lesson. This comes from a good 25 years working on site. Yeah I remember some of the early model cordless drills. #### shortbus Joined Sep 30, 2009 8,429 Around the "white ribbon" must have different drills than in the real world. #### ClassOfZero Joined Dec 28, 2016 114 Around the "white ribbon" must have different drills than in the real world. Thank you for playing, I was waiting for someone to take the bait. Least it was bit better than a comment about 'shrooms. Anyways enough posturing, I'll give this round to you. Grab a power drill out of your tool kit, hold the chuck and you'll see at the low speed setting how easy it is to prevent the chuck from turning, don't try it at high speed and definitely not with a jacobs chuck, one would not want to mince ones hands. Anyways the actual speed control doesn't have a great range of control. Yeah it seems pretty silly but the current models of battery drills have a %^*load of torque. Apart from being more convenient to use, 9 times out of 10 I'd reach for a cordless drill based on the greater torque at low speeds and better speed control, when driving in bugle or tek screws the clutch is also a bonus. I do have a larger drill with good low speed torque and a little better speed control but that's for SDS bits, it also cost big$$$, as I said not an item I'd suggest buying for a teaching exercise. #### DNA Robotics Joined Jun 13, 2014 599 I bought this Drill Sunday just because it was cheap & I didn't have a hammer drill. Less than$30.00 with coupon.
http://www.harborfreight.com/12-in-Heavy-Duty-Variable-Speed-Reversible-Hammer-Drill-68169.html
After all of Zero's negativity I decided to test it. I clamped a cord to a 1/2 " shaft & tied it to a 5 gallon bucket full of water. 40 pounds, right? Squeezing the trigger as little as I could, it slowly lifted that 40 pounds of water. That should be harder than moving 60 pounds on wheels, right?
Never mind with a block & tackle that would slow things down to a crawl & increase the power exponentially.

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#### ClassOfZero

Joined Dec 28, 2016
114
I'm sorry if my 25+ years experience on the tools doesn't agree with your ideas. Tho it is good you did the experiment, just because i disagree with you does not mean I think any less of you or feel the need to vocalise any assumptions I may have of you (not that I have any since this appears to be our only interaction that I can recall).

Maybe there is a mechanical engineer that could convert these values into a torque figure. These figures may indicate with an appropriate gear reduction & wheel diameter the drill in question may be suitable.

On the dodgy Aussie version of top gear they managed to power a Suzuki Might Boy (if memory serves me correct) with 4 to 5 cordless drills connected via a planetary gearbox. It was a shame the gearbox failed cos they were onto something.

#### BobTPH

Joined Jun 5, 2013
2,993
Not a mechanical engineer, but 40lb lift via a 1/2in shaft, r = 0.25 f = 40lb t = 10 in lb

Bob

#### DNA Robotics

Joined Jun 13, 2014
599

#### Tonyr1084

Joined Sep 24, 2015
5,802
Problem solved. Argument finished.

Oh, and I hate this music!

#### Picbuster

Joined Dec 2, 2013
1,026
My students want to create a pulley system that pulls a wooden dolly that will have someone standing on it. They want to use a motor to make the pulley pull the dolly with the student on it. The student weighs 60 pounds. The dolly just needs to move between 2 and 4 feet from the original location. Speed is not a factor. They are new to motors and after researching them, they see that it will have to connected to a power source.

What type of electrical or dc motors should they be looking at to do the required work?
Can electrical motors be connected to a wall socket? If so how would that be done?

I hope I provided enough information and have posted in the correct area. This area is new to me and my students. If more info is needed please let me know. Thanks for any help that can be provided.
736Watt is needed to lift a mass of 75 Kg one meter in one second. (= one Hp)
Here you are; formulae given.
Define the process time and the theoretical power needed is produced.
The real power needed should corrected with all losses in the mechanical and electrical system.
Calculate for 30% energy loss in electro motor.
Rush in current is the next thing you have to calculate.( motor depended look in the spec's of the selected motors)
Picbuster

#### shortbus

Joined Sep 30, 2009
8,429
I'm sorry if my 25+ years experience on the tools doesn't agree with your ideas.
Wow things must work different down under. And my 55+ years of tool experience does differ from yours.