Powering 115v tools without a heavy transformer?

Agile

Agile

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I recently discovered a used 115v 90 degree angled drill which is very useful for drilling horizontal holes through floor joists in situ. I had bought this a few years ago and put it somewhere safe and then forgot I had it.

However, these are usually powered from a heavy isolating transformer for outdoor work where you do not want mains voltages.

However for indoor work where mains voltages are not a problem, is there any good reason NOT to use an SCR or TRIAC controller?
 
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Agile said:
is there any good reason NOT to use an SCR or TRIAC controller?
Click to expand...

The wave form from a SCR / TRIAC power controller is not a sine wave and this may not be suitable for the motor which will be expecting a sine wave.

The motor may appear to operate normally as regards speed and torque but may over heat.
 
Yes, but it weighs 6.5 kilos which is why I would like to use an SCR controller which would be about 0.1 kilo!
 
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Startup load? A motor potentially draws a lot more power at startup, especially an older hard start one, so would your proposed controller be able to handle the load fluctuation?

In reality the reason we us transformers is that they are generally very reliable in what are often very poor conditions (water, debris, etc) - that and they are cheap
 
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What make is it? Many bigger manufacturers make 2 versions.
If you could find a spare parts book you may be able to swap parts over. At a cost.

Might be cheaper to buy another tool. I have a right angle screwdriver and have only used it ten or so times in as many years
 
An SCR controller can easily handle a very high start up current and can be turned up from zero at start up.

Transformers are relative expensive compared with simple electronics. And heavy!
 
Tigercubrider said:
I have a right angle screwdriver and have only used it ten or so times in as many years
Click to expand...

Yes, but on the few occasions that you use a right angled power tool it is probably the only way to do the job.

For example how else could you drill a horizontal hole for a pipe in a floor joist without a right angle power tool?
 
A right angled adaptor would effectively turn the power tool into a right angled tool.

But I have never seen one which is capable of anything apart from very light work.
 
Agreed. For joist doubling, a fairly common task in older building refurbs, you generally need a dedicated need a purpose made corded angle drill. Until recently there hasn't been a cordless tool up to the task (Makita, Milwaukee and deWalt all do one now). Adaptors generally don't have chucks on them and in any case just can't handle the torque associated with a 12 to 16mm auger bit with a tendency to disintegrate fairly quickly
 
Agile said:
Yes, but on the few occasions that you use a right angled power tool it is probably the only way to do the job.

For example how else could you drill a horizontal hole for a pipe in a floor joist without a right angle power tool?
Click to expand...
You can use a 3D bit, allows rolling the drill into right angle as it cuts .
 
They don't work in thickedr joists (e.g 3in), they struggle in old hard timbers or even .modern C24 and they don't stay sharp all that long. Also no good if you need a curate straight holes, such as you do for joist doubling...
 
Agile said:
Yes, but it weighs 6.5 kilos which is why I would like to use an SCR controller which would be about 0.1 kilo!
Click to expand...
Just put a longer flex on the tool so you don't have to move the transformer about as much.
 
As mentioned transformers provide full sinewave outputs (minised distortions due to magnetic saturation) but also can handle significant current loads, as you would have with sustained power tool use. A transformer doesn't overheat easily, usually just warms up a bit at high current as the magnetic core warms up. A key safety feature is complete isolation of input voltage from output voltage, protecting the equipment and user from 240v or 400v mains in event of a fault. Advances in power electronics over the last 30 years have seen the rise of switching power conversion systems, they basically switch on for half the sine wave, then off, dropping the peak voltage. There are many advantages of this system however, power electronics heat up a lot! Have hard current/voltage limits and do not provide clean sine wave outputs. More importantly there is no isolation between mains input and output. I also find them to be less robust, having fried a couple lol. You might make it work for you, but be aware you might end up frying you kit under heavy load, while a step down transformer will keep ticking for years. Also be very wary of build quality, it is frankly shocking on a lot of electronics from China, when I fry something I also take it apart and to be frank I am amazed a lot of it lasted as long as it did. It is not usual for components to be soldered together to avoid using a PCB, minimal or no heatsinks, substandard wiring that melts under full load, no fuses etc.
 
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