Health and Safety Gone Mad…

[SillyOldDufferModerator @sillyoldduffer]

Well I've read about it and even had a few mild grabs before, but the real thing was still a shock. A shim being made from a bit of surplus electrical brass needed two 4mm holes in it. First hole no problem, but then the drill snatched violently in the second. In a less than blink the brass strip wrapped itself around the drill, the machine vice leapt into the air, and the bench-drill stalled, clunk.

Then I had to use pliers to get my twist drill out of the tightly wound brass strip's death grip.

My bench-drill is only 1/3 HP.

I've learned a bit more about metal-working and confirm that no Model Engineers were injured during the making of these pictures.

Regards,

Dave

[SillyOldDufferModerator @sillyoldduffer]

Drilling Sheet Metal

[Steve WithnellParticipant @stevewithnell34426]

Good thing it was in a vice and not between your fingers!

[Roger Provins 2Participant @rogerprovins2]

View this YouTube…

 

Edited By JasonB on 06/01/2016 20:16:32

[Anonymous]

Easier and quicker to have used the vice and a hand drill.

Stoning the edges of drills has never worked all that well for me. I now use slow spiral jobbers drills specifically designed for short chipping materials such as brass. Or for larger sizes a slot drill often has a slower spiral than a normal twist drill.

Andrew

[Neil WyattModerator @neilwyatt]

I bought a cheap 'mole grip' with square-shaped jaws that makes it very easy and quick to clamp down the drilling vice.

Neil

[Ady1Participant @ady1]

The vice needs to be clamped to the bed of the milling machine, multiple vices are best, then you can use one for each machine

[SillyOldDufferModerator @sillyoldduffer]

"Easier and quicker to have used the vice and a hand drill. " – now he tells me!

I wish I had a good reason for using a power tool but truth is I did it thoughtlessly. Very likely my thinking head was skiving-off, again.

Thanks Andrew.

I tried stoning a drill once and just spoiled the drill. Thanks to Roger's video link I now know what I was doing wrong!

Cheers,

Dave

[Roger Provins 2Participant @rogerprovins2]

I bought a small cased set of twist drill bits from Irwin 1.5-10mm and modified them all (except the two smallest) for brass. Took just s few minutes and now drilling brass is a pleasure.

[Joe PageParticipant @joepage27051]

Same thing happened to me when I were about 13, I got my first drill press, exactly same vice too and it was on brass, luckily the belt was loose. At the time I never knew about this problem with brass as schools used to give you a hand vice and give you a hole to drill, I always assumed it was ok as it's what I were taught at school, probably why they don't teach metal work in schools anymore.

Andrew- I used to machine plastic seals which couldn't be clamped most of the time and had to be held by hand, I used to use only slot drills as even the slow spiral drills were unusable. I admit I had many accidents on the miller at work, no emergency stop on machines either, it was a case of deal with it, this was the kind of place where you given an interlock key to over-ride CNC machine doors so you could catch the parts as they come off, one of the reasons I left.

Maybe someone should start a near miss thread,

[V8EngParticipant @v8eng]

Posted by Joe Page on 06/01/2016 21:57:00:

Maybe someone should start a near miss thread,

 

I do not think that is a good idea, because all sorts of people might get the wrong idea about home workshop activities.

Do not forget that this forum is readily accessible online by search engines.

Edited By V8Eng on 06/01/2016 23:13:15

Edited By V8Eng on 06/01/2016 23:14:04

[Mike PooleParticipant @mikepoole82104]

I think I would have clamped material as thin as that between something thicker and drilled through the lot. Drilling thin material is always a problem when you break through and the hole usually finishes up triangular. On this occasion I think the material thickness contributed more to the problem than being brass but I would always adjust the rake on a drill or as mentioned above, use a slow helix drill for brass.

Mike

[BazyleParticipant @bazyle]

About 25 years ago MEX was full of these drilling machine mole grips. One of the best small tools I ever got at a show. Always there not lost as it is part of the machine but you do have to get the right sixe for the table.. Link is to first picture in search engine not a recommendation at that price.

[Peter KroghParticipant @peterkrogh76576]

Drilling plastics like acrylic need the drill treated as for brass, but I have found that a larger 'flat' is needed to work well all the time on plastics.

Pete

[Ady1Participant @ady1]

Squishing tin stuff between wood makes things easier

A good storm or two tends to give us lots of sacrificial material

[JasonBModerator @jasonb]

I'll make a note of this for the next time the tab breaks off a tin of cornbeef

[HopperParticipant @hopper]

If you are drilling holes in thin sheet, it helps to use a drill bit sharpened like an old time woodworkers' drill:

It cuts much like a holesaw or trepanning tool. The centre "tit" provides a stable centre of rotation and the two outer points then cut around the OD until a nice circular disc pops out. No need for sandwiching with this bit, but still need to have the sheet firmly secured somehow, and a piece of flat wood below the sheet for the tip of the drill to run into.

[JAParticipant @ja]

An alternative is to use a punch. A hardened and tempered silver steel rod with squared end, sharp corner, into a close fitting hole would easily do the job. You can make it as complex as you like.

But, I suppose, the obvious ease and speed of using a drill always wins.

JA

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Michael Poole on 06/01/2016 23:18:53:

I think I would have clamped material as thin as that between something thicker and drilled through the lot.

That's fine if you don't have to locate the hole accurately. I'm not sure how you would pick up on a punch mark.

Russell.

[egaParticipant @ega]

Bazyle:

Those drilling machine clamps are excellent as long as one can be bothered to use them. I found the ring nut rather slow in use and have recently substituted a quick nut which makes installation and removal much quicker and removes the temptation to take a chance.

Apart from its tendency to grab brass can also work harden which accentuates the problem.

[egaParticipant @ega]

PS I meant to upload a couple of pics of the quick nut – my first attempt at making one of these – but the website was again proving difficult. I have now succeeded:

The second photo shows the thread machined away at an angle to allow the nut to slide on the bolt; half a turn then locks it.

[AjohnwParticipant @ajohnw51620]

Posted by Michael Poole on 06/01/2016 23:18:53:

I think I would have clamped material as thin as that between something thicker and drilled through the lot. Drilling thin material is always a problem when you break through and the hole usually finishes up triangular. On this occasion I think the material thickness contributed more to the problem than being brass

Mike

Put something on top of it that is held by the vice and drill through that. The stuff underneath needn't be held tight.

So much trouble you probably wouldn't have done it in the first place and made the part from a decent sized sheet.

John

=

[Ian S CParticipant @iansc]

When I did my aircraft engineering apprenticeship, some was done at the NAC(National Airways Corporation) Training school, and we were taught to grind drills as Hopper shows. I think they were first used for aircraft skins in the USA during WW2.

Ian S C

[egaParticipant @ega]

Russell Eberhardt:

Sheet metal punches have a central pip which I assume is intended for location.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by ega on 07/01/2016 10:49:46:

Russell Eberhardt:

Sheet metal punches have a central pip which I assume is intended for location.

Agreed but I was referring to the suggestion of clamping the part between two thicker pieces.

Russell

[Author]

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