why do I keep snapping drills

ok I'm not really heavy handed and I can manage most noob things but why do I keep breaking drills (usually <2.5mm) I am as gentle as I can be with the feed, I use oiley stuff to lubricate and I drill a bit, withdraw and clear the swarf but I still snap the little buggers. the material seems irrevant I did it today in a bit of softy Aluminium. Its got that much of scary thing I would rather part something off !!! Should I use the slow motion drive thing rather than the big handle on my SX2 ? (I've a feeling I just answered my own question )

PS got one of them de-burring tools this week... advice to other new chaps GET ONE they are cheap and really save a lot of messing about

Sorry SX2 means nothing to me is a lathe or mill or drill ? Either way, if your drills are less than 2.5mm then,in my experience, I think you need to "feel" the pressure you are putting on the drill - try a sensitive drilling attachment - and run the machine fast, withdraw frequently to clear the chips. Oh yes and buy a stock of small drills!

Our friends at ARC have a neat sensitive attachment

Regards

Norman

I am sure you will have done this but I thought it might be worth saying. Have you checked your speed? I have broke one or two small drills when the speed has been too slow. The other thing I have noted is the poor quality of the drill sets that are around at the moment. I bought a 1 to 6mm with 0.1mm increments and about 1 in 6 of the drills are either bent or blunt!!!

Norman - that attachment looks like it might be worth buying.

Phil H

Hi Dismaldunc,

Drills of that size are best run fast, 3000 rpm would not be out of the way. Aluminium is a chewy, sticky metal a drill can jamb easily, use kerosine to lubricate when machining this.

Hope this helps.

Peter.

hi chaps, many thanks to Norman, Phil and Peter,

1, gonna get the drill thingy

2, yup drills from a cheap set

3, was drilling the ally at about 1200 rev

Seems you peeps have nailed it once more, its a good job you all are so helpful, i'm on a scottish isle so without y'all I would be REALLY stuck

Hi yes the Arc attachment looks good but you should not need for 2.5mm drills unless you machine is VERY unsensitive! I have drilled lots of 0.015" holes in the past on a jig borer and for this made a sensitive feed but down to 1/32 [.0315"] it was not necessary to use this.

As peter says ally can be difficult if it is the soft type alloy most others drill easily and parrafin is a good lube. Your speed is way to low.

Buy good quality drills , Dormer, Hertel, or similar high quality European made drills, yes they are expensive but cheaper in the long run because they work! try Rotagrip, J&L now MSC supplies or your local engineering supply house

good luck. John

Others said it before but I'm sure the problem is your drills. I just drilled 300 axial holes of 1.5 mm in stainless steel screws; about 11 mm deep, all with the same drill (with a couple of regrinds when the drill starts to squeal, though). But I had to try a couple of different drills before I found one suitable for this task. It's not one from China! (well I think...)

Greetings, Hansrudolf

Hi there, Dunc,

I don't know what an SX2 is either but if it's a lathe I presume you're drilling from the tailstock.

Have you made sure that your tailstock is properly in line with your mandrel? (aka headstock spindle)

Best regards,

Swarf, Mostly!

Although my eyes are fine for most purposes those 5 quid a pair glasses from garages, Lidl etc are really handy for inspecting and working with small drill tips, they go up to about 3x magnification

The smaller the drill, the faster it should go, A slow small drill pushed hard will buckle and snap or even unwind if of poor quality and are usually soft just where the flutes end at the parallel shank.

It pays to buy good quality drills, cutting angle relief and equal length lips are very important also that the drill is not bent. Roll it across a flat surface and see if it lifts at the cutting end. Drills from an unknown source are no good at all, buy premium quality drills if you can.

I view the cutting end with a magnifying glass and its amazing what you see even on new drills.

Make a 4 Facet drill sharpening jig for smaller drills and invest in a decent drill sharpening jig for bigger ones.

Clive

It`s best to stop frequently and clear the swarf out of the hole you are drilling especially with small drills, and as Norman said you have to feel the pressure you are putting on the drill.

Andy

For those that have lived a sheltered life "SX2" is a "Super X2" mill/drill, 2500max rpm and plenty sensative for anything down to 0.5mm

Surprized no one has asked if the work is held firm and how the Punch? mark is being located. If the drill is not perfectly above the starting point this will also make it wander and snap.

You don't need to use the fine feed on the quill, the three lever handle on the side will be OK and a lot easier for peck drilling than winding the drill back out.

J

Edited By JasonB on 21/08/2012 08:16:51

hi chaps, as Jason says the machine in question is a super SX mill drill (must remember to be more specific!) and the work was clamped tight and the punch mark set using a pointy ended wobbler thingy, I had another crack at it and top revs (2500) whistled through it with the help of a wee drop of heating oil from next doors tank . thanks again everyone

Well  - speed, as they say, WAS of the essence!

Now then - heating oil from next doors tank? That does sound like a good idea........Hmmmm I must investigate!

Glad you are sorted now.

Regards

Norman

Edited By NJH on 21/08/2012 09:34:59

I've found that starting with a center dril helps a lot with small drills, I guess it gives less chance of the point running out and bending.

There are some totally useless cheap drills being sold in markets,I've tried some that were so poor that they twisted to the shape of a corkscrew attempting to drill wood. If a small drill does not cut into metal easily don't use it! It will break. Make sure you buy only HSS drills; dont use carbon steel.If any drill appears to rub instead of cutting cleanly stop immediately and sharpen or replace it. Don't hope it will do "just this one hole" Colin

Hi, the twist drill quality will make a lot of difference. The sensitivity of the drilling machine shouldn't be too great an issue for that size of twist drill, IMO, provided your not using a "Bill Massive" machine. A good quality bench drill of the 1/2" type should be able to be used quite successively, while using suitable coolant/lubrication.

Many years ago I used to get an annual major maintenance job which entailed making up 144 5/16" mild steel rods, where each end had a 3/32" hole drilled for a split pin. I used to cut all the rods to length and dress the ends. I had a piece of square bar which was drilled down the end by about 1/2" to fit the rods snugly and a 3/32" hole was drilled cross-ways through the hole at the distance the holes had to be drilled in from the ends of the rods. This square bar was case hardened and was set up in the drill vice with the 3/32" cross hole lined up with twist drill in the chuck. All the rod ends were then spotted to the width of the drill in this square jig. The jig was then removed and the vice jaws set far enough apart to allow the twist drill to have the same clearance each side, but close enough to support the rods. Each rod end was then held by hand on the vice jaws and were drilled. A little soluble cutting oil mix was squirted on each one from a washing up liquid bottle to help cutting and the drill was withdrawn frequently to clear the swarf.

I could drill all these rods both ends using only one twist drill and without re-sharping it, and that was a total of 288 holes, and still had the twist drill to drill more holes in other things. We used Dormer twist drills at that time FWIW.

Regards Nick.