Classic cars forum & vehicle restoration.

[ukdave2002]

This is a gripe I have had for several years !!!

Cordless drills are great for building work, but in my experience most of them are very poor when used for drilling steel, at first I was blaming drill bits, but the same bits cut like a hot knife through butter when used in the drill press or lathe, so I though it must be me not keeping the drill steady.. after a bit of experimentation I found that of the 5 cordless drills I own; 2 Dewalt and 3 Makita, only one of the Dewalt actually drills reasonably true likewise as does my right angle Makita, but neither perfect

I put the inaccuracy down to wear and abuse!.....a few of weeks ago I mentioned this to a mate who owns a plumbing business, he spends a fortune on tools and arranged via his supplier for my to try a new, Dewalt, Hitachi and Makita....none of them were much good for anything less than 10mm They just wander too much.
So I now suspect it's down to the lack of case rigidity ? And there is not much we can can do, except use an air drill (all steel body)

Has anyone else had the same problem and like me blamed the drill bit?

Dave

[47Jag]

Dave,

I tend to agree with you but I reckon the problem is chuck speed. The best drill that I have had for all round work was a Performance from B&Q. It has a speed of 850RPM. The others that have replaced it over the years were all slower, not by a great amount when you look at the numbers but they never performed as well as the old B&Q. I would like to see a standardisation of the batteries as after a seemingly short time you can't get replacement batteries anymore (that's my gripe/whinge)

Art

[Peter_L]

Having worked at companies involved in precision engineering, drilling holes was a subject of frequent discussion. 100%, round can only be achieved by a reamer type bit, twist bits, by their design, always produce a slightly elliptical hole. To obtain the best accuracy in a robust drill press, the drill should be as below.

CUTTING LIPS
The cutting lips must be of equal length. Even though the point angle is equal on both sides, if the cutting lips are not equal in length the chisel edge will not be centered, and the drill will cut oversize. A scale should be used to check the lengths of the cutting lips.

In a hand held drill, it is impossible to prevent the machine from moving so even with a perfect bit the drilling machine will move because the holding force is not the same throughout one rotation of the bit.

The slower the drill speed, the more exaggerated the ellipse.

Add to this a drill bit that has been re-sharpened and has either a slight bend or the shank is burred or worn and the drill will have a "built in" ellipse pattern regardless of being used in a hand drill or drill press.

Keyless chucks on hand machines are a modern curse, drill chuck jaw pressure can never be as high as with a keyed chuck. Add to that low quality steel for the jaws and the whole drilling thing is on a one way trip to producing an oval. All of this doesn't even include any bearing wear.

To get an idea of how good or bad a hand machine is, put it in a vice, add a bit and rig up a pointer placed close to the tip, rotate the drill by hand and see the run out on the tip, this run out will force the machine to move in an elliptical pattern.

There were/are several devices designed to hold hand machines, for applications where using a drill press is not an option.

I was taught how to sharpen a drill bit in school metalwork class, our teacher used to work at an aircraft factory. Later in life I worked alongside "drillers" whose sole task was to drill holes, they had a range of drill bit sharpening techniques, often fearlessly debated during tea breaks.

Drill bits with a Morse taper were always the tool of choice.

Who would think creating a humble hole could be so involved and how, as kids, did we ever make a wooden cart with nothing more than a piece of red hot bar and some old pram wheels.

Not sure if this is common knowledge, but DeWalt (for example) produce tools of differing quality. Same for Henkle kitchen knives.

[kevin2306]

Ive given up on using my battery drill pretty much and always use my old school 240v drill or even better the pillar drill.
Having been a tradesman many years ago, in my eyes the battery drills are nothing more than a lazy screwdriver.
My Dewalt 18v has given up the ghost now anyways, doubt it will get replaced

kev

[Peter_L]

What would be useful, (and I haven't done much research so there may be one). are battery powered tools that also have a facility that allows one to plug in a power cord that will run the tool at full power and also charge the battery.

We now have a large house,(renovation project) with outbuildings and a lot of land, so battery power can make life easier, but putting up with battery drain was a pain. The answer is an inverter/power pack charged from the ATV workhorse, which also has a mounting to carry our generator, if we need to use the big table saw.

[colwyn500]

Over the years, my instinct to distrust cordless has changed by positive experience. batteries have got better as has weight and controllability. When drilling metals I have always found that lower revs work best and the cordless scores high with its variable speed.

I'm guessing that Dave's problem relates more to the weight of the drill. I have a cheap bur very heavy 240volt SDS drill. It powers through masonry that my cordless hammer drill will hardly make a mark on. That's why the pillar-drill is so useful as you are going very slowly but applying a huge point load,

[ukdave2002]

I think in my original rant I wasn't clear about the issue; most cordless drills just don't run true, if you put a clock on the drill bit and measure the deflection it becomes obvious why the bit will struggle to cut, the smaller the bit the more relative the problem is.

I suspect the reason why the drills are more effective at lower speeds in steel is that the deflection can be absorbed somewhat in the operators hand at slow speeds, allowing the bit to run truer.

Ironically for drilling brick and the like I almost universally use the same 18V Dewalt drill that is so rubbish at drilling steel as it has a hammer function and its brilliant although 90% of what I do with masonry is 7mm holes for brown plugs !

Dave

[Rdover]

I discovered another advantage of my bosch cordless over the 240v one - it avoids breaking your wrist.

I was drilling an 11mm hole ready for tapping an M12 thread in a 10mm steel plate and the cordless ran out of power after the first of 2 holes. I had drilled a pilot hole at 7.5mm (the sharpest/least used bit I have) and then used the 11mm to widen it out. As I got to the last 1mm the bit would grab and have to back it off and then 'dab' it in gently to finish the hole off.

When I switched to the 240v drill instead of stalling out as the cordless did, it grabbed, spun the drill out my hands braking the drill bit and nearly breaking my wrist - I had to hold my pint in my left hand for 3 days!

I know I should have used my press drill but it was a very large piece of steel!
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Richard

[Bitumen Boy]

Not a cordless story, but I was trying to drill some steel the other day and wondering why progress was so slow. The drill has an awkward reversing switch, and it took me a while to realise I was running it in reverse... Once that was corrected the job was done in no time at all

[heathelect]

I use cordless tools on a daily basis, I am an electrician, I use a bosch 36v for general brick/block fixings up to 25mm, and HSS bits up to 10mm for steel and it performs perfectly, albeit battery life does reduce after a number of years. I also have the smaller 10.5v bosch drill which is good for smaller metal drilling, and a bosch 10.5v impact screwdriver which is used all the time for screws These tools are great if you dont need accurate drilling.
Definately would not be without any of these.

[L5Foye]

I used to moan about cordless drills until I bought a Hilti one-great power, great battery life. I have also found a vast variation in the quality of drill bits.
You might think Makita drill bits would be good-in fact they are rubbish
compared to Dormer and the like.

[ka]

My experience shows that there is a direct relationship between price and quality. I have used a Tesco/Lidl cordless, and fond them really handy as screwdrivers, for drilling holes, try amanita/Bosch etc, these really do work.
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KA

Better three than four.