Homemade Multi Drill

[ClydeCrashKop]

Search for gang drills & multi-spindle drills.

 

[Cosmosus]

That might cope with one chuck, but even then it would drill very slowly.
A typical power drill is rated at a few hundred Watts, so I don't think a 24V 10A supply would be enough, particularly bearing in mind that ratings for some online products tend to be 'optimistic' (to put it politely ).

If you look at the table in this dc motor description, it says 160mA current, when 24V supply is connected. Wouldn't that be enough for this project's purpose?
And how big of a amperage power supply should I then get? If one motor has 160mA, then sure 10A supply is enough isn't it?

https://www.banggood.com/775-Gear-M...tail-top-buytogether-auto__2&cur_warehouse=CN

 

[be80be]

use a old psu from a computer you'll have more then a enough to stall 6 of them motors
The 775 is a strong motor there is a 555 good for small bits but the 755 is a power house there lots of plans using it for drilling and routing with 1/4 inch or smaller bits 10mm I guess
The 555 is good to 4mm bit's

 

[MaxHeadRoom78]

Btw, why are these so cheap?

Because when they fail running such as motors, they sell more!!
Max.

 

[ronsimpson]

Btw, why are these so cheap?

Factory workers make very little money No unions,.
No safety standards. Who cares if a worker dies on the job.
The profit is lower.
Less middle men.

 

[hydrochad]

If you look at the table in this dc motor description, it says 160mA current, when 24V supply is connected. Wouldn't that be enough for this project's purpose?
And how big of a amperage power supply should I then get? If one motor has 160mA, then sure 10A supply is enough isn't it?

https://www.banggood.com/775-Gear-M...tail-top-buytogether-auto__2&cur_warehouse=CN

Max speed for drilling wood:
0 to 1/4 inch 3800 to 4000 RPM
1/4 to 1/2 inch 3100 to 3800 RPM

from specs 3500 RPM obtained with a 12 V supply pulling 0.14 amps or 1.68 Watt.
To put this in prospective, 1/8 horsepower is 95 Watts.

 

[gophert]

Max speed for drilling wood:
0 to 1/4 inch 3800 to 4000 RPM
1/4 to 1/2 inch 3100 to 3800 RPM

from specs 3500 RPM obtained with a 12 V supply pulling 0.14 amps or 1.68 Watt.
To put this in prospective, 1/8 horsepower is 95 Watts.

3500 RPM with no load would likely be 0.14 amps. Now, if I tell you the type of bit, bit diameter, the feed rate and the type of wood, can you also tell us the current draw. For example, my Bosch 18V can draw 10 amps from a lithium battery when I use a quarter inch bit into a wet railroad tie feeding about 3 mm per second with a twist bit. That is 180 amps. 1/4 HP.

 

[hydrochad]

3500 RPM with no load would likely be 0.14 amps. Now, if I tell you the type of bit, bit diameter, the feed rate and the type of wood, can you also tell us the current draw. For example, my Bosch 18V can draw 10 amps from a lithium battery when I use a quarter inch bit into a wet railroad tie feeding about 3 mm per second with a twist bit. That is 180 amps. 1/4 HP.

How does "Bosch 18V can draw 10 amps" equate to 180 amps? I know, I know you meant to say 180 Watts - to error is human ... .
Is the rating on you Bosch no load or full load? Where on the specs for this 8 dollar motor specify horsepower? torque?
As we know horse power is not measured but calculated. "Large torque high power" is not a specification, it's
an advertisement. Where does the spec sheet specify the current rating is "no load"; additional, of what value is a
"no load" rating? You really intend to compare your north of $100 Bosch to a $8 motor? Additionally, there are
formula to calculate torque requirements of drilling and milling taking into account materials, depth of cut, feed rate, etc
but you obviously know that. You're either an engineer, machinist, or home shop machinist - good talking to you.

 

[Nigel Goodwin]

Where does the spec sheet specify the current rating is "no load"; additional, of what value is a
"no load" rating?

As it's such a low figure it's obviously got to be no-load - they use such ratings because it's easily testable, and it makes the motor 'look good'.

If you believe that's a loaded figure you're going to be sorely disappointed

 

[be80be]

Come on here lets see most of these drills are at most 3 to 8 amp loaded
And 100 to 140 mA doing nothing 6 motors 18 to 48 amps at most
use a car battery

 

[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

 

[Nigel Goodwin]

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.

That's only the idle current, and not drilling - once you drill the current will increase a LOT!!!.

A 2.08A PSU is far too small for one motor, never mind six of them - as far as current goes the motors will only take what they need, and only then if the PSU can supply it (other wise the motors will slow, stall completely, and the PSU may die).

 

[alec_t]

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?

Most power supplies similar to that have a trimmer which you adjust to set the output voltage. The higher the voltage, the lower the maximum current the supply can provide. If you know the power (Wattage) of the supply you can calculate the available current by dividing the power rating by the output voltage. That said, it is not a good idea to draw the maximum rated power from a power supply of unknown quality. Go for 70-80% of the rated power. I agree with Nigel's assessment of that specific supply.

 

[hydrochad]

As it's such a low figure it's obviously got to be no-load - they use such ratings because it's easily testable, and it makes the motor 'look good'.

If you believe that's a loaded figure you're going to be sorely disappointed

The fact is, I would not be looking at that motor for any project I am planning.

 

[Cosmosus]

What about this one: https://www.alibaba.com/product-det...?spm=a2700.7724838.2017115.104.b3c83ab4kVNWnq

Output Power:
75W
Input Voltage:
110V/220V
Output Voltage:
5~48V
Output Current:
1.6~15A



I think the motor is more than enough for what I'm trying to achieve, I'm just not sure these two (supply and DC motor) are compatible.

Edit: https://www.alibaba.com/product-det...l?spm=a2700.7724838.2017115.66.7c7246ac4qRpUU
45A

 

[MaxHeadRoom78]

For a transformer-rectifier, the transformer will need to be something from 15V to 18V depending on ratings and quality - that will give around 24V after rectification and smoothing. You need a reasonably well smoothed supply otherwise the motor load and power will be very uneven and the gearboxes are likely to wear rather faster..

A transformer with 24vdc secondary and a bridge will give you close enough to 24vdc, no filter required for inductive/motor devices.
But after ignoring advice across 3 forums, I suggest the OP go for the SMPS supply he is bent on using and see if it stands up.
Max.

 

[gophert]

A transformer with 24vdc secondary and a bridge will give you close enough to 24vdc, no filter required for inductive/motor devices.
But after ignoring advice across 3 forums, I suggest the OP go for the SMPS supply he is bent on using and see if it stands up.
Max.

I must be banned from the other two sites - but I agree that lessons learned from a failed experiment are usually pretty good lessons and are not soon forgotten nor repeated.

 

[rjenkinsgb]

I'm set on this DC motor: https://www.banggood.com/775-Gear-M...tail-top-buytogether-auto__2&cur_warehouse=CN

Two problems here:

1: No gearbox - any drill has gearbox to give reasonable speeds at vastly higher torque than the bare motor gives.

2: The stall current rating on that motor is 43 Amps. Full load continuous is probably around a third to half of that.
eg. 12V @ 15A =

That's why I suggested higher voltage (24V means half current and lower losses) and a 1000W power unit, to run just a few motors:

That same motor from a supplier that gives slight better specifications:
**broken link removed**

Edit - interrupted by a phone call & lost track..
12V * 15A = 180W estimated per motor @ around full load.

(And yes, the 24V I mention relates to some 24V geared motors I posted a link to earlier on).

 

[Nigel Goodwin]

That's why I suggested higher voltage (24V means half current and lower losses) and a 1000W power unit, to run just a few motors:

I presume you mean for an entirely different motor?, driving the same motor at twice the voltage means it will take more current.

I must say I liked post #21. I've never seen or heard of such a thing.

 

[Cosmosus]

I agree, maybe I was a little fast to jump the gun
It's just so much conflicting information that I can't really decide, but thank to everyone who has replied.

Things I extracted from all discussions:
- motors draw a lot more current when they work connected than when idle
- if the current drawn from motors exceeds power supply output current, power supply will burn out
- same for voltage, if more voltage than motors are made for is applied, motors will burn out

Since quite a few people have been telling me not to use power supplies I provided link for, I started looking for transformer, like this https://www.alibaba.com/product-det...l?spm=a2700.7724838.2017115.47.50fd7486e4UQlw

Then I must find one Bridge motor controller that has about 20A (?) outout and then 24V * 20A = 480Watt. Is that a reasonable thinking? Maybe even soft start driver? like L-298
Or find a different motor, I guess it's more important that it has high torque and gears.. But still I didn't really extrapolate if it NEEDS gears or not, atleast for this project. Mind, low budget

edit: why not use a rectifier, something like this: https://www.alibaba.com/product-det...l?spm=a2700.7724838.2017115.62.69126323Zcck7C
35Amperes should be enough right?
or even this one: **broken link removed**