Mag drill woes.

[Tony K]

Afternoon all. 

I have used hired mag drills successfully before, but run into an odd problem recently. 

 

I hired the drill, and used a 12mm cutter bit I had from a previous episode. I attached the drill to an exposed steel beam and proceeded to drill 30 of the 36 holes I require. During hole 31 the cutter bit broke. I replaced it with a new one, but it won't cut the steel despite apparently being the correct tool for the job. Whenever I turn the handle to push the drill down into the steel, it won't cut and then ultimately the mag drill lifts off of the steel if I apply full force. 

 

I have tried various other places along the beam and the same thing happens. I have tried a third, final cutter bit but it just snapped upon contact with the steel. 

 

I'm baffled. Even if the steel has a particularly tough spot (as can happen with timber) the fact that the drill won't puncture the steel anywhere anymore seems to rule out the idea of a localised obstacle. 

 

At the same time, there is power to the drill. Everything works fine until the bit contacts the steel. 

 

Anyone ever experienced this before?! 

[Nickfromwales]

It can only be the bits AFAIC?

 

Drills defo not been inadvertently put in reverse has it?

[Tony K]

1 minute ago, Nickfromwales said:

It can only be the bits AFAIC?

 

Drills defo not been inadvertently put in reverse has it?

 

Not aware of any reverse option on the drill, so I doubt it. I will double check though, thanks. 

 

The hire shop has tested the drill today and say it works fine (which it certainly did for me right up until it didn't), and are offering to lend me a drill bit to try again. 

 

Very weird though. 

[Nickfromwales]

5 minutes ago, Tony K said:

and are offering to lend me a drill bit to try again. 

Run there, gallop back! Lets see if it was a duff batch of bits?

[Tony K]

9 minutes ago, Nickfromwales said:

Run there, gallop back! Lets see if it was a duff batch of bits?

 

I shall do so in the morning!

 

I can understand one drill bit snapping, but for the second one to then not work, and the third to snap as well when all three were from different places suggest some dark magic at work. Perhaps.

 

I've only got six more holes to bloody drill! Getting through the steel with a standard drill is a bloody nightmare though, so fingers crossed for the mag drill. 

[Temp]

I've never broken a drill bit that wasn't already halfway through drilling a hole or was tiny (like 2mm). I'd be drilling a 6 or 8mm pilot hole first then the 12mm. Put some oil on it?

 

 

[markc]

If you break an annular cutter spend some time getting any broken bits out of the hole or better still finish the hole from the other side. Also a dull cutter can heat up the material and cause local hardening so a new cutter then won’t bite without giving it a harsh bump to break the surface and get the teeth to start

[Tosh]

There's no way that drill should lift from the metal with the mag on. How hard are you pulling on the handle?? That alone could indicate its f*****d to me. Sounds like it may have got overheated along the line somewhere. Plus pulling hard on the handle will put too much pressure and snap a bit.

Theragain what bits r u using - annular or twist.

[Tony K]

1 hour ago, Tosh said:

There's no way that drill should lift from the metal with the mag on. How hard are you pulling on the handle?? That alone could indicate its f*****d to me. Sounds like it may have got overheated along the line somewhere. Plus pulling hard on the handle will put too much pressure and snap a bit.

Theragain what bits r u using - annular or twist.

 

Not exactly this one, but pretty much... 

 

https://www.orbitalfasteners.co.uk/products/18mm-rotabroach-mag-drill-cutter-short-series-raptor-rap180

 

 

[Tony K]

I returned to the task this morning with a new (used) drill bit provided by the hire shop. Initial signs were not promising but eventually I got it done, drilling all remaining holes with the exception of one. The drill bit did not have a pilot through the centre today, and I found that after every cut the next would only work if I hollowed out the bit, removing the top-hat-shaped excess that had formed inside. 

 

The bottom right hole as shown in my original photo remains unfinished. The drill simply wouldn't do it, again lifting off the steel rather than puncturing the beam. As @markc mentioned, I think p[perhaps some localised hardening took place during failed attempts to drill that spot.

 

Anyway, hope that is useful to someone, one day. Thanks, as ever, for the advice.

[Canski]

In the past I have tek screwed 1000’s of ties to steelwork and I can confirm that the steel does vary. Some fly in and others take ages,  multiple screws and the really nasty ones need to be pilot drilled. And this can happen in the same section of steel. 

[saveasteading]

I don't think steel has hard bits in it except where heated or hammered. It could be affected by the drilling as markc says.

Perhaps use a small pilot hole and then a conical cutter / step drill to get to size.

 

[Roys]

I did my apprenticeship at the start of the 80’s 1st year of which covered a broad range of skills including arc welding,  I was fairly decent at it.

Fast forward 20 years I bought a welder, got a lump of scrap steel and away I went, my welding was rubbish, spoke to welder to ask what I was doing wrong, and he echoed what was being said on thread. Steel ain’t what it used to be, gone are the days of top quality British Steel, mostly from China now with all sorts of strange lumps in it. He gave me a couple bits of decent steel and my welding was much better.

[saveasteading]

10 minutes ago, Roys said:

gone are the days of top quality British Steel

That was some time ago. There are still standards though and perhaps these steels have slipped through. There was a while that Mexican steel was coming in and not meeting standards, but still being sold.  Strength though, not bits in it.

Having seen a steel mill in action, I'd be surprised if there are lumps in it. Something you do properly or not at all I would think.