Homemade Multi-Drill

[Cosmosus]

Hi,
I'm thinking of making a multi drill for wood drilling, that uses anywhere from 6 to 9 9V or 12V DC motors. These motors would be wired in parallel, with one battery source. I'd mount a drill chuck on each of the motors shafts for a drill bit. Now, I need a little bit of help from you. Do any of you have an experience in doing such a project?
My main concerns are drilling torque so that I could drill holes effortlessly in about 5 centimeter thick wood frames. Also, Another concern is battery life and how many volt batteries should I get? With same voltage as the motors? Are DC motors prone to overheating by working close to their full potential? My goal is to have reliable and long-lasting contraption for drilling.

Thank you very much, I wish you all a good day!

 

[KlausST]

Hi,

My main concerns are drilling torque so that I could drill holes effortlessly in about 5 centimeter thick wood frames.

It surely depends on drill diameter, type of wood, forward speed....

Also, Another concern is battery life and how many volt batteries should I get?

Battery Lifetime depends on the power the motors draw and the energy stored in the battery.
Battery voltage: same as motor. If you want speed control, then I recommend battery voltage same or higher than motor voltage.
I don´t know about the used power, but I recommend rather 24V than 12V. Currents will be lower, thinner wires, higher efficiency, higher torque.

Are DC motors prone to overheating by working close to their full potential?

You need to go through datasheets. They tel you about RPM, torque, heating, cooling...

Klaus

 

[asdf44]

Wouldn't an actual drill be the best basis for this? Cordless DC drills are cheap and would be easy to take a part and modify for your needs. And it would be easy to gauge the power of the entire set-up for a drilling application before you buy it.

Some modern higher end lithium drills will have microprocessors that get in your way but many don't (Ryobi for example). So you could remove the internals of multiple drills and power them from your own DC source.

 

[Cosmosus]

Thank you for your message.

I was thinking anywhere from 6-8 drills, spaced about 5 centimeters apart. I would like to be able to use smaller aswell as bigger drill bits, like 10 mm.
Maybe batteries are more of a hassle than I thought. After more thinking about this project, the best option would be 220V power supply rather than battery, since this machine would only be needed in garage. In this case, a transformator should be wired before the circuit (motors). Would I need anything else, like voltage regulator? My main goal with this project is being as straightforward and simple as possible, with enough DC motor torque to drill thicker pieces of wood and without motors overheating.

Here's a circuit of what I'm trying to achieve:

 

[c_mitra]

Depends on how much power the motor can deliver. Small 12V motors can deliver 24W or so easily but please see the power ratings of the motor to be used for this.

1 mm drill bit can drill in wood about 1-2-3 cm but you want 5 cm; you will need about 5mm dia drill bits. You may get stuck with insufficient power.

You need to specify both torque and speed and the power.

 

[BradtheRad]

Drills commonly have step-down gears between the motor and the chuck. This allows using a motor which is smaller, weaker, faster and less expensive.
Rather than have you fabricate precision metal parts, it is easier for you to buy complete drills at the store, ready to use.

Then construct several gripping jigs, using straps or belts. It is possible to drill multiple holes a couple inches from each other. All drills must be perfectly aligned together, if you don't want broken drill bits.

Also consider the duty cycle of usage. Example, my cheap electric drill (Black & Decker) heats up after a few minutes of continual use. Then it's almost too hot for my hand to grip.

As an alternative, you might mount several hand-crank drills in a row. With a lot of work you may contrive a way to drive them simultaneously from a single long rotating shaft, driven by a single motor. The gear train needs to be slow and powerful. Slow speeds are less likely to overheat drill bits. Slow speed is forgiving if you move the work as you start drilling.

 

[Relayer]

Hello Cosmosus,
This is not quite on track with what you're asking, but just last year I removed the batteries
on one of my 12V cordless drills and converted it to take power from an old PC power supply
whitch gave me heaps of torque. Though I had to adjust the clutch on it as it was wanting to
strip the screw heads it was that powerful.
Sorry the above isn't really on point, but I thought I'd suggest it just in case you were needing
a good source of power.
Regards,
Relayer

 

[Cosmosus]

Thank everyone for help.
I'm looking for the cheapest option I can get away with, but still provided with good drilling power and not worrying about motors overheating.This "machine" is used for drilling multiple holes at the same time, evenly spaced.It is used for making holes in hive frames. Don't know exactly why, but there is a demand in my area, so I thought I could begin with this project.
The requirement thickness of drill bits is 5mm maximum.
All the mechanical parts I can get for free, laser cut, even stainless steel.
I concluded that power from outlet is better option, since it doesn't require batteries and people use this machine in a garage anyways. So if I use 220V i would need transformer and some kind of bridge rectifier right?
Here are pictures of what I'm trying to accomplish:

 

[asdf44]

Yes you could have a large 60hz step down transformer, rectifier and cap bank hower that final solution is going to be heavy and poorly regulated

I think you're better off buying a bulk 12V DC supply. On quick search I see 12V/30A/360W for $20 on Amazon.

 

[Kajunbee]

In case you are not aware of it you can find DC motors with the drill chucks already mounted on eBay. They may cost more than your wanting to spend but they might give you and idea of what size motor to look for.

 

[Cosmosus]

Thanks to all of you for helping,
after prolonged research, I'm set on this DC motor: https://www.banggood.com/775-Gear-M...tail-top-buytogether-auto__2&cur_warehouse=CN
This one is used in most battery powered drills, usually on 24V.
I'll be using 6 of these motors, so if they are connected to 24V one motor draws 0.16A, then 5x0.16=0.8A with a deviation of a few Amperes.
Onward, I've been looking and have been recommended this power supply: https://www.alibaba.com/product-det...pm=a2700.7724838.2017115.1.b3c83ab4qLUWpu&s=p
Now this supply has output current 2.08A, is this maximum current? What if I connect these 6 motors, where there is 0.8A, can power supply go that low with providing less than it is made for?
I've got another question; if power supply has for example output voltage 9-40V, does this mean that if I buy the motors (link), where voltage is 12-36V, that power station will fry the motors with full voltage or does it regulate it?

Thank you,
L

 

[Kajunbee]

It doesn't specify whether the current is no load or full load. I did some looking around and came across a YouTube vid named " 775 motor from banggood - are the specs correct". No way to know how accurate his ampmeter is but I think the measurements are more realistic than the datasheet. In any case you might want to verify yourself before you order a power supply that might not handle the load.

- - - Updated - - -

The power supply is rated for 100 watts output. It can supply 4.5 amps at 24 volts. You will want to allow some headroom. You also need to consider the starting amperage which can be several times higher for a brief amount of time.

 

[Kajunbee]

I didn't see it at first but the same fellow made a follow up video on the 775. I won't try to explain his findings but you should probably check it out. Search YouTube for " more about 775 motors - will they work as generators.

 

[KlausST]

Hi,

24V x 0.16A = 4W
This sounds way too low fir a good drilling machine.

I expext at least 50 ... 200W.

Klaus

 

[c_mitra]

You need to remember the following points:

1. Cutting speed depends on the speed (RPM) and the diameter of the drill (in fact, the cutting is done by the edge and the rate of cutting is related to the linear velocity at the cutting edge)

2. The torque is dependent on the power output of the motor

3. The whole energy goes into producing the wood chips cut by the drill bit; total amount of chips produced per unit time is directly related to the power

4. Small power drills are not really very useful for reliable work.