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Best type of micro drill bits for metal

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    I see alot of micro sized bits being marketed for PCB or CNC  that have a short length of bit with 1/8" shaft and a colored plastic collar.  Are these any good for drilling metal or just for soft materials like wood or plastic?  For one thing most are listed as manufactured in China, so I'm a little skeptical of the quality.

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A number of years ago I bought a set of these.  They were supposedly carbide drills for manufacturing printed circuit boards.  For someone used to using steel twist drills, these were so brittle to be unusable.

 

Roger

 

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These carbide drills are for use only with a drill press. They are very sharp, very hard and will cleanly drill through any material. However, they are very brittle and the slightest bend, as when drilling with a hand held drill, will snap them immediately. Steel is much more forgiving and will bend without actually loosing its alignment permanently. Carbide drills much better though.

 

 I have a large collection of drills with all sizes duplicate in steel for hand drilling and carbide for use with the drill press.

 

Hope this helps

 

Vaddoc

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I use these drills almost exclusively, unless I am using a pin vise.  That includes free-handing with a Dremel.  You simply need a steady hand.  No problem drilling through brass strips but I have never tried using them on bar stock thicker than 1/8".  Take a peak at the offerings from Drill Bit City.  https://drillcity.stores.yahoo.net/index.html   They are in the Chicago area and I receive orders from them typically within 3 days.

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I think we had such a discussion before. There is actually no 'best' drill, only approriate ones, appropriate for the material and the conditions of application.

 

In industry drills are shaped for the materials they are supposed to drill. This concerns the cutting angles, secondary cutting angles, relief angles, the angle of the spiral, etc. However, unless you buy from an established manufacturer, you may not be able to get this information. This applies particularly to model supply houses and the hundreds of 'ebay shops' that are around today.

 

There seem to be two major supply streams for carbide drills into the secondary market theses days. One is that from 'seconds', meaning these are drills that did not pass the high quality standards of industrial sppliers, but that are still good enough for occasional use by people like us. The second stream are used ones that have been taken out of manufacturing processes in a scheduled way before they become dull and could spoil a work piece. Also these are good enough for us modellers. However, the traders rarely know the intended application of these drills, so you might get some from an aircraft factory intended for use with high-strenght aluminium alloys, or some from a printed circuit board plant, intended for use on glass-fibre reinforced epoxy resin.

 

As noted above by vaddoc, carbide is brittle and normally requires rigid machines and a rigid set-up for their use. They are unforgiving to wobbling in guiding the movement and to changes in feed. In drill depths that exceed 3xdiameter, I would use them only with a screw-feed, not with a lever feed.

 

Having said that, these carbide drills can be an economic option in sizes below 1 mm diameter due to their relatively low price and if you don't mind to bin a part from which you cannot extract a broken drill. HSS or SS (not recommended) drills in sizes below 1 mm can be quite pricey, particularly for sizes below 0.5 mm and those with thickened shafts (which are much better and easier to handle).

 

And: there are many different qualities of aluminium, brass and steel. Some are easy to drill and others are a pain. We modellers often seem to come across too soft qualities that catch drills. So a problem may not be a bad drill, but bad material.

 

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Posted (edited)

Carbide is the only way to go.  Lesser quality steel will become blunt quickly, they'll become more expensive than carbide soon.

 

Dave, the selection Toni showed is a wonderful collection.  The colored bands are only a reference to the coarseness of the individual bit.  Their individual usage is for the most part a matter of speed used and/or material that needs cutting/grinding.

 

For drilling holes, for instance in brass strips, a drill press or at least some kind of device that keeps the rotating instrument steady is a must in most cases.  Also, using the correct bit for the deed is good advice.  For instance, drilling small holes with a round bur does work, just the bur, even a carbide bur will dull soon.  Whereas a bit used only for drilling holes will last 5 times longer.

 

I've been acquainted with metal/carbide burs for 47 years.

 

Greetings,

Michael

 

PS:  I forgot to add, a wonderful source for every imaginable bit form/shape is from the dental industry.  Often, a dental depot will sell burs and bits less expensive than a hobby shop.  You might have to twist their arm to sell you some, but most will happily agree.

 

The plastic bands around the shaft are red = coarse, blue = middle, yellow = fine.  I believe there are also green bands, but I haven't a clue as to their usage, never had one.

Edited by Mickgee

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"Carbide is the only way to go.  Lesser quality steel will become blunt quickly, ...". Carbides are not steels. Carbides are composite materials made by sintering together hard particles of mostly tungsten carbide (WC) with a metal in powder form, mainly cobalt.

 

I would not dismiss HSS just like that. In fact, I found HSS much more forgiving even on my precision watchmaking machinery. Drilling deep holes below 0.5 mm with HSS is much safer than with cobalt due to the greater elasticity of the steel. When they become blunt depends on what you are doing with them and how often.

 

In industrial applications, where one can control very precisely the conditions, today carbide is the material of choice, of course.

 

What do you mean by coarsness with reference to colour coding ? I never use the colour coded ones, as the rings tend to obscure your view of what you are doing, but thought that the rings refer to the diameters.

 

Why would you want to drill a hole with a round burr ? The cutting edges of burrs tends to diminish to zero in the middle, hence 'diving' in with a burr is a very inefficient way of their use and will dull them indeed very quickly. Burrs are meant for side-cutting.

 

Hobby shops, indeed, are rarely a cost-effective source for tools. They only sell small quantities in comparison. Jewellery/watchmaking/dental supply houses are better sources with a wider range of choices. A new business area that has greatly expanded over the past ten years or so are manicure and pedicure supply houses - they supply the same kind of burrs and polishing tools to a much larger market and hence at lower prices.

 

I believe one should buy the tools one can afford. However, drill-bits and burrs fall (almost) into the category of consumables. There is also a considerable risk of breakage. Therefore, it tends to be more cost efficient to buy twice at half the price, if there is a chance that I break an expensive drill with double the life before it reaches the end of its normal useful life.

 

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I believe that you should buy the tools that with your work style will produce your required results.  Therefore a tool that one person relies on may not work at all for someone else.  I am naturally clumsy and my success rate using carbide drills Is very low.  On the other hand for me HSS drills enjoy a reasonable life.  

 

Roger

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Hello wefalck, a couple of your observations, especially concerning a quote, are incorrect.  For instance, I didn't state directly that carbide was a steel. 

 

Also, I didn't write to drill holes with a bur, I used this method as an example, later on writing that the proper bit is better suited for drilling holes.  This was used as an example, not to be taken as a method I'd prefer.  When a true drilling bit breaks, it's mainly because the initial mark was not indented to keep the bit on track, or too much pressure was applied, plus heat causes the material to break down.  I'm writing about drill bits of under 1mm diameter.

 

Color coding as written, pertains to how rough the cut will be, the better quality burs have an immovable color ring, it's painted on.  Concerning HSS, I rarely wasted time and expenses going this route as the material just dulled too quickly.  Also, the only time a carbide bur would break was when overheated while grinding or the sideward pressure applied was too great,  which would show that an improper technique was applied.  You may have noticed before some of these "carbides", or hardened steels are still magnetic, suggesting there would still be steel involved.  Sometimes the hardened heads are attached to steel shafts, not all of time though.  Again, depends on the quality and size.

 

Of course a modeler can choose whichever method he deems fit.  I chose with this reply to clear up a few of my points since you seemed to misrepresent or misunderstood what I'd previously written.  I try to make clear statements to keep things like this at a minimum, I'll try harder for the future.

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Very expensive though Vossiewulf!

 

I buy the cheap chinese carbides £3/set of 10, the better quality steel rolled or milled drills from ebay but for sizes smaller than 0.8 mm I buy Heller which are expensive but good. In such small sizes the very cheap ones are false ecomomy and cause frustration, even drilling wood.

 

Some times instead of silver colour drills I get black ones. I presume they are some kind of high carbon steel. These are always much sharper and rigid and drill better bur also they are quite brittle. I ve had a couple braking in the wood which indeed is a pain.

 

Regards

 

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Just chipping in on this subject as there are some very good comments here.  I use HSS "jobbing bits" as we call them in the UK on wood as they fly though without any issues and never really wear out due to the lack of friction and heat.  They are also easily sharpened when they go dull on a grinding wheel.  For brass, steel and stainless steel I use cobalt bits which are a little more expensive but not overly so.  They last for ages and just go through without any problems as long as they are lubricated if appropriate.  Anything else in modelling is just over kill unless you are using exotic metals which are particularly hard.

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On 5/3/2019 at 10:18 AM, Mickgee said:

ften, a dental depot will sell burs and bits less expensive than a hobby shop. 

When I asked my dentist how he disposed of his burs he said he threw them away. Then I asked was it possible to obtain any of them. He readily acceded but said he would have to sterilize or autoclave them first. Went back 3 days later and received a nice baggy of assorted burs over 50. Some had heavy use but cut threw wood like butter.

 

Had been going to him for over 30 yrs. so may not have been problematic for him. Free is nice.

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One other comment on drilling. One of the easiest ways to break a drill is to have it deflect, or “skate” then it makes contact with the workpiece.  To avoid this you can to punch a pilot hole at the location where you want to drill. The found two wars of doing this. The first is to make a small punch by grinding a point onto an old drill bit. You can chuck the blunt end of the bit into your drill press and then, while it’s rotating, us a grinding wheel in a rotary tool to grind a point on the end of the bit. The punch can (and should) be quite a bit larger than the hole you want to drill. You just want to make a small dimple for the drill bit to rid in. I put the punch in the press, lower tit down until it presses on the workpiece, then replace the punch with the drill bit for the hole I wNt to drill, angry to work.

 

the other approach is to use a center drill, which has a large, rigid     Drill body with a small spotting drill at the end. These come in various sizes.  The smallest that I have is a 5/0 drill, which has an 0.010 diameter spotting drill. These are particularly useful when drilling through a rod. The heavy body of the center drill prevents the spotting tip from skating on the rounded surface of the rod.

 

Vince

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Depending on the size of the hole, when cross-drilling round material or when drilling at an angle into surfaces, I start the hole with an end-mill that cuts across the centre. There is no risk of slipping with the point.

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And using a tungsten center punch or awl is never a bad idea even using a stiff centering drill when drilling curved stock if you can't do Wefalk's trick for some reason. I also have a very spiffy laser center finder that properly calibrated will mark the center within a couple thousandths of an inch, which is fine for anything but the most precise work. Very useful if one can fit in the budget.

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