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Melanie De Castro Pugh
11-03-2012, 12:28 AM
Hi chaps, I have yet another problem and would welcome any advice!

I am making a bangle from 2mm copper sheet and want 1mm holes drilled every half centimetre or so around the edge. I have got a fair few done using my Dremel as a pillar drill but when the inevitable happens and a bit breaks, I'm having a heck of a job getting the broken tip out of the semi drilled hole. Some I've managed to retrieve by using a centre punch on the reverse and bashing it back through but this only works when the hole is deep enough that I can see a dimple forming on the other side.

I've been using HSS bits and also carbide microdrills, I seem to get the same levels of breakage with both so go with the cheaper HSS ones in a multichuck rather than the expensive ones on a 3.2mm shank. I've tried drilling speeds of 5000-15000 rpm.

So if anyone has any solutions, I'd be so grateful! Thank you x


Melanie

http://www.spinysharklythings.com

Kwant
11-03-2012, 08:42 AM
I have used with remarkable success, alum dissolved in hot water to remove broken drill bits in silver, they just dissolve away, I am unsure what the effect on copper would be so you would have to try it first on some scrap to make sure it did not dissolve the copper too.

I used a saturated solution of alum and kept it warm in a hot water bath, the last time it happened it took about a half hour for the drill bit to be gone, with a bit of occasional stirring and poking. You can get alum at the chemists.

I also use burr saver when drilling and that drastically reduces the number of breakages in the first place.


A quick check on google would suggest the copper will be safe and unaffected.

ps_bond
11-03-2012, 08:51 AM
Dissolve the bit out either with an overnight soak in some pickle and then a jaunt in an ultrasonic or use alum. You're bound to have some copper dissolve, but it shouldn't be too bad. Test first, As Kwant suggests!

As to why you're getting breakage, run the Dremel as slow as possible (slower than they can manage is better - you want the same linear speed as larger bits, but the small diameter means you get that at lower rpms if that makes sense), have the minimum amount of bit protruding (but don't grip the flutes in the chuck), don't put too much pressure on the bit and do not side load it. The bog standard jobber HSS 1mm bits I use will cope with that job, but I do run them slow. And yes, do use burr life, beeswax or a drop of oil as a cutting lubricant.

Melanie De Castro Pugh
11-03-2012, 09:53 AM
Thank you both, why didn't I think of dissolving them in pickle.... Duh! I'll do that at the end as it's flat at the moment and won't fit in my bath, but after I've curved it should do the trick. I can finish the offending holes by hand then.

I have beeswax, so will give it a whirl (quite literally!) with that :-)


Melanie

http://www.spinysharklythings.com

ps_bond
11-03-2012, 10:31 AM
I've always used old pickle to do it and not put it back in the main pot, BTW.

Wallace
11-03-2012, 10:37 AM
I use wd40 instead of beeswax now (it comes in a pen type applicator too) I dab a little on a small lid and dip the drill and burrs into it. Very slowly, as Peter mentions, is indeed the key to reducing the breakages.

Dennis
11-03-2012, 05:48 PM
For years I drilled happily with hardly a breakage, using Busch mounted drills on 2.35 shanks (Cooksons 972040-150) . Then I tried the HSS version and had repeated problems until I gave them up. I think you will find HSS just too brittle below about 1.5mm. There also seems to be more of a problem with copper which feels sticky to drill. Dennis.

Melanie De Castro Pugh
12-03-2012, 08:45 AM
Sticky... That describes it perfectly! Well thanks to all your tips and help I drilled the last third of the holes on just one bit! It needed fresh beeswax for each hole, and sometimes two or three applications. While I had a bit of a grumpy five minutes that it made for a very staccato work flow, it saved more time than repeatedly changing drills! The pickle method worked a treat too, just need to give it a blast in the ultrasonic now :-)


Melanie

http://www.spinysharklythings.com

kiwikiwi
24-10-2013, 05:02 AM
Great answers. I have had the same problem as well. Thanks

kiwikiwi
24-10-2013, 05:10 AM
Will just normal candel wax work as a lubricant

Wallace
24-10-2013, 07:06 AM
Yes, as will most oils. Ensure the piece is thoroughly cleaned afterwards.

pearlescence
24-10-2013, 07:30 AM
Hi. I use 0.7mm and 1mm bits all the time. Your bits are probably breaking because you are using a dremel and bending them. Try using a big household drill, a normal drill for putting up shelves. You will find it much easier to hold it straight because any movement is much easier to perceive. You probably don't think you are but even a tiny i degree bend is enough to break such thin bits
Keep the drill bit very short in the chuck too - leaving it long also allows it to distort.
Also change bits regularly. a blunt bit is more likely to break. And those bits go blunt in a strong wind, never mind actually going through something.

Dennis
24-10-2013, 10:32 AM
May I just add that it is not necessary to discard blunt drill bits. All you need is a medium or fine diamond disk mounted on a mandrel to sharpen them.

You need to find a way to rest your handpiece in a horizontal position, so that you can lightly touch the bits against the disk in two places as indicated by the previous facets. The angle is not very critical, but the drill is sharp if you feel it bite your skin when turned by hand.

As a result all my drill bits vary in length, but last for years. Dennis.

ps_bond
24-10-2013, 11:24 AM
The blue diamond impregnated rubber wheels that are now available in the UK are very good for sharpening drill bits too. Magnification helps to see the angles (and no, I don't just mean a scope!).

If you really want to get silly, you can grind a used carbide burr to make your own short twist drills using a diamond disc to set up the angles & carve the flutes, then sharpen it. Still not entirely convinced it's a good use of time, but it does work well.

Patstone
24-10-2013, 11:55 AM
Now you are getting really silly. Good idea sharpening drill bits though, I will have a go at that. Peter I know you like different tools but have you had any dealings with the ring stretchers that you hammer the top of, it looks like a mandrel with steps on, because I was thinking of getting one, cant afford the £150 jobbies, couldnt justify having one of them really.

ps_bond
24-10-2013, 12:03 PM
Now you are getting really silly.

I'll have to post a picture of one :)


Good idea sharpening drill bits though, I will have a go at that. Peter I know you like different tools but have you had any dealings with the ring stretchers that you hammer the top of, it looks like a mandrel with steps on, because I was thinking of getting one, cant afford the £150 jobbies, couldnt justify having one of them really.

Honestly? Never used one, the verdict from people I know who have is that they're pretty uncontrollable. I use a ring mandrel and a mallet or planishing hammer.

caroleallen
24-10-2013, 04:37 PM
Waste of money Pat. If you get a proper one, it'll revolutionise your work. Christmas is coming!

pearlescence
24-10-2013, 07:21 PM
One Tahitian top quality pearl £50. one 0.7mm drill bit 30p

ps_bond
24-10-2013, 07:57 PM
1 carbide short drill bit around £7...

Dennis
24-10-2013, 08:43 PM
One Tahitian top quality pearl £50. one 0.7mm drill bit 30p

It seems to make sense put like that Wendy, but I use mounted drills for my handpiece and they cost £2.28 inc. VAT. I am just too mean to fund my suppliers sending their daughters to finishing school in Switzerland, so I sharpen them. Regards, Dennis.

pearlescence
24-10-2013, 08:45 PM
That's in a specialist pearl drill or in my hand held which is a normal put up shelves domestic black and decker

Tabby66
25-10-2013, 03:31 AM
Funny, the cost of saw blades and drill bits has really been grating lately,......though I can't do anything about the blades once broken, I am going to have a go at sharpening my drill bits!!

Can anyone post a link to the discs you mean.......please tell me they aren't these at £17+ http://www.cooksongold.com/Jewellery-Tools/Diamond-Burr-Thin-Disc-22mm-With-Mandrel-prcode-999-1877

ps_bond
25-10-2013, 05:39 AM
The ones I use are diamond all the way across, not just a narrow band. They do last well though.
The rubber wheels are £25 each...

Dennis
25-10-2013, 11:43 AM
I have had mine for about twenty years, Tabby, so I have not looked recently, but both Sutton tools and HS Walsh list some for less. Dennis.