Anyone know how to convert a cordless drill to corded?

I was checking out Glen's (worntorn's) thread on a homemade welding positioner, and he's using a corded drill to power the thing. Eureka!!! I have a similar project and I need a way to power it, I also have a couple of old cordless drills. one is a 14.4 volt makeeta with dead batterys. but the thing had enough torque and most important a really prercise trigger. the speed control was better than any cordless tool that I have ever had. so the plan is to rig thing up to the crank on my positioner and use some kind of cables to control the trigger and direction by foot. (this is a new idea to me, so haven't quite got those details worked out) What I'm wondering is if anyone on this forum would know how to wire up one of these little motors to run off something else like a transformer or even a lawn tractor battery. If I used a battery i couild build a battery tender into the setup and i cant imagine efer having to use it long enough at 1 time to ever kill the battery. problem is that a cordless tool battery has extra terminals on it that ihave no idea what they do. please put in your 2 cents especially if you know how thesae batterys work. os a mbetter idea on how to spin this thing pics to come tomorrow

I would skip the cordless drill thingee and just ust an ordinary 110 volt cheap drill with a router speed control, the router speed controls will let you plug in any thing like that and let you dial your speed. Others have use household dimmer switches on old drills and that works also.

You would need a DC converter to change the AC current from the wall socket to the DC current the drill motor is going to need. Shouldn't be difficult at all, just make sure you find one with the proper voltage rating or you'll fry something. I believe radio shack has one that can be switched between different voltage outputs. As for the connection on the drill, there should only be a positive and negative terminal and it won't matter which one you connect to the pos or neg wires to. If you hook it up with the wrong polarity the motor will just run in reverse.

I've used "wall wart" AC to DC converters, usually from a kids toy, to supply DC power in various applications. (For instance, my Mom was visiting and brought the car charger to her mobile phone, instead of the wall charger. I used a 12 volt wall wart to supply DC to the car charger and charged her phone for the plane trip home.) You *might* rig up something similar, but another consideration is the amperage: wall worts usually deliver less than 1 amp and your drill will require more. I've seen DIY projects that will convert a computer power supply to 12 volts / 12 amps (http://www.wikihow.com/Convert-a-Com...b-Power-Supply), which may be closer to what you need. PC power supplies can be had for nothing if you pull one from a throw-away PC.

Like you I've got a couple cordless drills where the batteries have gone south. It's expensive to rebuild the batteries and expensive to buy new or rebuilt batts- almost as much as a new higher powered drill. My son is young enough that he thinks it's REALLY cool to have a drill "just like Daddy's" even though technically it doesn't work for more than a few seconds.

Quote:

---

Originally Posted by Mikeymetal

I was checking out Glen's (worntorn's) thread on a homemade welding positioner, and ha's using a cordless drill to power the thing. Eureka!!! I have a similar project and I need a way to power it, I also have a couple of old cordless drills. one is a 14.4 volt makeeta with dead batterys. but the thing had enough torque and most important a really prercise trigger. the speed control was better than any cordless tool that I have ever had. so the plan is to rig thing up to the crank on my positioner and use some kind of cables to control the trigger and direction by foot. (this is a new idea to me, so haven't quite got those details worked out) What I'm wondering is if anyone on this forum would know how to wire up one of these little motors to run off something else like a transformer or even a lawn tractor battery. If I used a battery i couild build a battery tender into the setup and i cant imagine efer having to use it long enough at 1 time to ever kill the battery. problem is that a cordless tool battery has extra terminals on it that ihave no idea what they do. please put in your 2 cents especially if you know how thesae batterys work. os a mbetter idea on how to spin this thing pics to come tomorrow

---

One of the challenges with operating a high torque dc motor off of a dc power supply is that the current demands can be very dynamic and many supplies that are designed to run electronics or resistive loads will puke when you use them on a motor. That being said, your Makita likely has a very nice PWM based speed controller that will smooth that out somewhat but you will still need lots of power if you want lots of torque. You could cobble together a simple supply with a transformer and a rectifier with some bigA$$ capacitors (they will act like the battery as far as supplying big current when needed. Your idea to just use a 12V battery would resolve all that, as the battery can, and will source large amounts of current. The speed control will only have two wires, the battery has many contacts to carry lots of current, internally they should be summed together before heading to the speed control. I can sketch up a schematic if you want to go the power supply route. let me know.

Try an old PC power supply. Cheap, plentiful and good output power.

Thurmond

If ya got an old car batt or motorcycle batt sitting around use that and just throw a float charger on it. Personally though I'd just go to HF and get a cheap 110 and router controller. That way you have 2 different places to vary the speed and overall will probably be one of the cheapest ways to go without having to worry about changing out batteries

I've got a couple PC power supplies with 12V DC regulated output, one should be good for 7 amps 12VDC, and another is rated for 13 amps. If you have a very powerful cordless drill motor, I don't know that it would be enough to fully power it and I can't say whether the power supply would be damaged or not. I hear the worst case load on a cordless drill battery is if you completely stall the motor with the trigger fully depressed. But if you are using it to just spin a welding positioner it might not take all that much load on the drill to do that; I don't know. I would think 12V DC would work fine for a 14.4V drill motor, since a Ni-Cad battery voltage drops considerably in normal use, (I'd bet well below 12V.)

Let me know if you could use one; the only reason I have them kicking around is in case a project such as this requiring DC regulated voltage should come up. They are a metal box weighing probably 2-3 lbs, with a cooling fan built into them.

You might be able to bet by with a battery charger and a filter capacitor.

This is getting good. What is a filter capacitor and what does it do? I guess the main concern id that if you feel the torque that any decent cordless tool has, it's quite substantiel. I don't know if a pc power supply would do the trick, but im no electrician(not in my wildest dreams.) I think the 12 voplt batt will be the forst thing I try, but I still don't know what function the xtra terminal(s) on a cordless battery perform. Are they like the extra leg on a 3 phase motor, or do they have something to do with charging? or maybe with signalling the tool that it's about to die? A lomg tome ago I cut tha outside case off one of these things and besodes tha pile of little cells in there was a little resistor type part. It was small and I ahve no Idea what it was supposed to do. could have been the mysrerious xtra terminal?

Quote:

---

Originally Posted by Mikeymetal

This is getting good. What is a filter capacitor and what does it do? I guess the main concern id that if you feel the torque that any decent cordless tool has, it's quite substantiel. I don't know if a pc power supply would do the trick, but im no electrician(not in my wildest dreams.) I think the 12 voplt batt will be the forst thing I try, but I still don't know what function the xtra terminal(s) on a cordless battery perform. Are they like the extra leg on a 3 phase motor, or do they have something to do with charging? or maybe with signalling the tool that it's about to die? A lomg tome ago I cut tha outside case off one of these things and besodes tha pile of little cells in there was a little resistor type part. It was small and I ahve no Idea what it was supposed to do. could have been the mysrerious xtra terminal?

---

Generally the 3rd leg is for charging and is connected to a thermal cut off to keep the charger from overheating the battery. should have just 2 terminals on the drill, unless..

Filter cap is large electrolytic capacitor to smooth out the power, look in the car stereo department at Wall Mart, should be some fairly cheap there.

A few months ago, I "hotrodded" my Hitachi 18V worklight from incandescent to high power LED. (Total custom job. ;) ) So I had to figure out how the battery worked of course, and happen to have this photo of the battery terminals.
Attachment 1824

Now from memory... i believe that the only terminals used by the drill (as well as the worklight) are the "-", the "+", and I believe also the "LD". The charger I believe does use the other terminals ("C+", "T", "V", "LS") somehow, but they are not used by the drill or the light.

The "LD" terminal, IIRC, is a signal to the drill motor (or worklight) to automatically turn off when the battery is getting too low, to prevent overdischarge of the lithium ion battery. I don't think Nickel-Cadmium drill battery designs used this feature, because you can't overdischarge a Ni-Cad. (Whereas an overdischarged Li-Ion battery apparently becomes no longer chargeable, and useless.)

I'm not sure that it is worth the effort to convert a cordless drill to run off wall current. I used a 14.4 Volt Makita cordless for the weld positioner because I had one with a couple of good batteries to go with it. Also, it has a really nice variable speed.

For the bead roller power conversion http://www.everlastgenerators.com/fo...ead.php?t=1256 I used a Harbor Freight drill which came in a pile of stuff I got off Ebay. I paid just $19 for the entire pile . It included a good 1/2hp bench grinder with worklight, an 18 volt cordless drill, a 7" Polisher with several discs and polishing heads and a 1/2" heavy duty variable,reversible corded drill. All of the items were new return items. The only flaw I could find in the whole bunch was a bent work support on the bench grinder, took about a minute to fix.

I used the 1/2" corded drill for the bead roller because the cordless drill would not have enough torque to do the job.

I would head for HF tools and get a cheap drill. Not worth the effort. Download a 20% coupon before you head there. I have all the stuff here (caps, PS, etc) to do it and would still run out and pick one up. :D

They are on sale right not at the store for $14.99, normally $19.99 3/8" variable speed and reverse.

if it were just a getrdone thing, the harber freight idea would doubtless be the way to go. but this is garage logic-that is-figuring out what you CAN dowith what you have. in other words it has now bercome just as important to me to learn how to do the conversion as to get the positioner done:D:D

Then it is simple. You will need to a power supply that match the drill (volts and amps). And hook it up. Problem is, the power supply will probably cost what the new drill will run you. You can charge the battery pack and run on the batteries too.

Quote:

---

Originally Posted by jakeru

I "hotrodded" my Hitachi 18V worklight from incandescent to high power LED. (Total custom job. ;)

---

I think you may have voided your warranty. (How many times have you heard THAT one?!)

Quote:

---

Originally Posted by Mikeymetal

if it were just a getrdone thing, the harber freight idea would doubtless be the way to go. but this is garage logic-that is-figuring out what you CAN dowith what you have. in other words it has now bercome just as important to me to learn how to do the conversion as to get the positioner done:D:D

---

You are right Mikey,
There may be a shorter, faster, cheaper path to victory but when you value the journey as much or more than the destination you are on the TRUE path to happiness. I will effort to bring some technical info to light, such that you can make intelligent decisions as you wander the wasteland.

Fundamentally, there are two types of DC supplies. Linear (heavy, durable, not particularly efficient) and switching (Low cost, efficient, not particularly robust). That being said these are regulated supplies that tightly control the voltage and often, but NOT always limit current, well they will limit current when the weakest component fails, not very helpful for your purposes. PC supplies are switchers, THEY ARE NOT good supplies for running a high torque motor. They are designed to CHEAPLY provide stable voltages at largely steady state currents. Some may say "Well a PC has disk drives and they have motors" and yes they in fact do, however they are minuscule compared to the job you have in mind.

So this brings us to our old friend the linear supply. Now for your task we don't need all the fancy regulation and filtering because its just a DC motor and the battery voltage is all over the place as you use the drill anyway. So in the end we need a cheap, robust non-regulated DC supply. You can achieve this by A). Getting a big honkin AC transformer 115AC in ~10VAC out @ say 4 Amps or better and then get or make a full wave bridge rectifier (its just four of the same diodes hooked together that will magically transform the AC output of the transformer into DC). Next a couple of big capacitors in parallel on the output (They sort of act like current "tanks", if you will, to handle those situations when the motor is getting ready to stall and needs more umph). Now this setup will be ideal from a maintenance stand point and should last a real long time if carefully built.

B). Just get a lawn tractor battery (Used will be fine) and a battery maintainer (Battery Tender is a great choice) and wire that sucker to the speed control inputs of your Makita drill.

Obviously you will learn more on one of these paths than the other, and if you need a schematic, or guidance along the path, I can, and will help you anyway I can.

Attachment 1866Attachment 1867

Wruehl, I think that as interesting as option 1 sounds, option 2 fits the spirit of my intent perfectly. thanks all for the awesome info, and i will post the results. To further compilcate matters, I just came across a power window motor in tha trash being disposed of due to a broken cable. it says siemens on it. now if i could only figure out how to..........

Quote:

---

Originally Posted by Mikeymetal

Wruehl, I think that as interesting as option 1 sounds, option 2 fits the spirit of my intent perfectly. thanks all for the awesome info, and i will post the results. To further compilcate matters, I just came across a power window motor in tha trash being disposed of due to a broken cable. it says siemens on it. now if i could only figure out how to..........

---

There used to be a TON of Saturn windshield wiper motors on the surplus market. My students used two of them to drive a 50lb nuclear waste recovery robot they built for a design contest. These motors cost less than $20, had three speeds built in, and their robot had power to spare, think monster truck crazy power.

The Saturn (made by Trico) units seem to all be gone, but this place has crazy deals on the stuff:

http://monsterguts.com/index.php?act...od&productId=4

Your diodes/rectifier will need to handle the current of the drill or motor. And it will not hurt to go larger. But no signal diodes. The inductive motor will require a regulator as long as T1 (not labeled) is close to you battery voltage.