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I've never heard the term "series drill" before. Google suggests that it's a contraction of "Long series drill", but I've not heard that term either.
Walking down my street this morning I passed a Telephone "Engineer" drilling a hole for a cable through a stone wall. So far so good.
He was just starting the hole and was using a series drill which I estimate was 10mm x 700-ish mm and it was wobbling all over the place and flexing alarmingly along its length. Protective clothing? One baseball cap.
I don't know the outcome of this exercise: I walked home a different way to avoid possible scenes of carnage and bloodshed. Back in the day, I was taught to use a series of ever-longer series drills so that the really long ones were suported by the hole they were drilling. Please don't tell me that doing it this way is considered okay nowadays? In a public space? With people (me) walking by?
Nick snipped-for-privacy@yahoo.ca
Well, Virgin, many moons ago put my cable in first drilling a smaller hole with longer and longer drills, then one very long big one through the wall. After the cable came in they seemed to fill up the rather jagged hole with some kind of sealant or foam and then sliced it off to the wall. I never saw any protective clothing, he said the speed was slow so nothing bad could happen... I thought, yes, until one day it does"! Brian
Never had a problem with a snapped drill
Yes, but have you ever waved a thin and flexible 700mm long bit around on the end of an electric drill rotating at -say- 800RPM?
Nick snipped-for-privacy@yahoo.ca
700 seems an odd length - 400 or perhaps 600 being more common. Was this a SDS bit or a normal one?
The longest "thin" SDS I have is a 400mm long 8 mm drill. That is easy enough to start a hole with...
Can't see there being much risk on a 400mm bit - a 1m one would be easier to start with a shorter one.
I do recall seeing someone trying to drill a 2" core into a concrete wall of a multi-storey car park. The hole was very low down on the wall, close to the floor. He was sitting on the floor in a position that suggested that if the core were to snag, the drill handle was going to hit him right in the nuts!
I don't know the answer to either question. Woodworking drills are more my style and I was just walking by! Measuring it out on my desk, it can't have been less than 500mm and it certainly flexed a lot.
Ive done worse than that with an AMCO 35 diesel engine. Ripped my fingers to shreds when starting.
But surely even you wouldn't be stupid enough to have a long and flexible drill not actually in contact with the stonework before you pressed go...
Likely not a problem. The first time I needed to core drill a 5" hole in my wall, I invested in an SDS drill. My normal drill was perfectly capable of doing it, but the SDS drill came with a built-in safety clutch, so that if the bit snagged, it would release and not twist my wrist off. On snagging, it hardly moves.
Don't ask me how stupid you'd have to be, ask his employer. It's a sub-contractor to CityFibre who, according to the Telegraph yesterday, doubled their losses this year to over GBP200m. (Although to be fair, that's a drop in the ocean to them.)
Nick snipped-for-privacy@yahoo.ca
He was not using a SDS or a proper core drill - so no guarantee it had a clutch.
Done that on the top of 3m ladders.
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