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Author Topic: DC Motor's from drillmachine  (Read 1409 times)

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Offline BumboltTopic starter

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DC Motor's from drillmachine
« on: October 08, 2011, 01:17:00 PM »
I watched the ep40 DIY Combat robot from Systm @ Revision3

No there was a tips for low budget to use motor's from drilling machines. Now i need 2 since i want to make a cleaning robot as my first. Now i he told in the vid that it's best to use 18V motors for that kind of robot.

The robot will be around 50cm x 50cm (Should be around 19.68 inches)
On the weight i'm not sure, I was planning to keep it under 15kg (30-35 pound) As the video was for a 30pound robot.

Now my question is will this motors do:

Einhill BT-CD 18 (http://www.einhell.nl/ps/4513340_01017.pdf)

Technical Data
 Battery: 18 V, 1,300 mAh
 Idle speed: 0 - 550 min
-1
 Torque setting: 21 + 1
 Charging time: approx. 3 - 5 hour


I'll be using 2 of them.
On the product i have 2 batteries (4 in total) and a charger (2 in total) wich comes in handy. Since the robot will be a automated house cleaning device.

I know that those aren't the best motors to use since they are cheap and bla bla bla.. but i just haven't got the money to spend 1000$/€ on a robot. I was thinking about keeping it under 300€

Offline Soeren

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Re: DC Motor's from drillmachine
« Reply #1 on: October 11, 2011, 06:39:26 PM »
Hi,

[...] i want to make a cleaning robot as my first. Now i he told in the vid that it's best to use 18V motors for that kind of robot.
Higher voltage means lower current for the same amount of power which equates to lower voltage drop in the wires, but for your purpose, just get the cheapest, the difference will be hard to see.
A given (physical) size of battery shell can hold roughly the same amount of power whether it's 14V, 18V or something different, assuming the shell is filled to the same amount.


The robot will be around 50cm x 50cm (Should be around 19.68 inches)
On the weight i'm not sure, I was planning to keep it under 15kg (30-35 pound) As the video was for a 30pound robot.
15kg sounds like a lot, but I'm not certain if your term "cleaning robot" involves washing and hence carrying around a "bucket" of water?

Robots like the Trilobite and Roomba that just vacuums the floors are much lighter.


Now my question is will this motors do:

Einhill BT-CD 18 (http://www.einhell.nl/ps/4513340_01017.pdf)

Technical Data
 Battery: 18 V, 1,300 mAh
 Idle speed: 0 - 550 min
-1
 Torque setting: 21 + 1
 Charging time: approx. 3 - 5 hour
The "Torque setting: 21+1" doesn't deserve to be called technical data, as it just describes how many clicks are on the "torque selector" and nothing in the data tells you the torque of the motors, but they should be able to move your 'bot - it's just impossible to say how fast exactly, as the torque data is missing. The weight is an important parameter in calculating this as well.


I'll be using 2 of them.
On the product i have 2 batteries (4 in total) and a charger (2 in total) wich comes in handy. Since the robot will be a automated house cleaning device.
While the basic chargers that comes with power drills do work, they don't work very well (they cook the batteries). For longevity of the batteries, get (or make) a real charger with dV/dT charge termination.

One up for an automated 'bot... Add thermo sensors to the battery shells (and terminals to connect to) and make a charger that it connects to automatically at the end of a run.


I know that those aren't the best motors to use since they are cheap and bla bla bla.. but i just haven't got the money to spend 1000$/€ on a robot. I was thinking about keeping it under 300€
Cheap is good  ;D
While I cannot vouch for a product I don't know (power drills comes in very different qualities and Economy Brand-X is bound to be worse than eg. Makita or Bosch), there are more than a few 'bots driven by power drills and I have a pair of large power drills (Brand-worse-than-X) that I got very cheap for the exact purpose and another pair of power screw drivers (3.6V) bought for a smaller 'bot.
With a power drill, you get both a relatively strong motor, a (planetary) gearbox and batteries at a price much lower than if you bought the parts "loose".

I have even seen a guy using the speed controller from the drill, by pushing the button with a servo - a bit too ghetto for my taste, like a duct taped car ;D but it goes to show that you get a lot of value for your hard earned when using power drills.


Free power drills can be found in dumpsters now and then (although rarely as a pair), when their previous owners cooked their batteris with cheap chargers and discovered that a new battery costs more than a new drill with a battery (or two).
« Last Edit: October 11, 2011, 06:41:04 PM by Soeren »
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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