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Advice on a Mini Drill please

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LARNE CABIN
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Hi all,

I am seeking advice on the most appropriate mini drill. I purchased a small hand drill, but failed miserably when I tried to drill a 0.5mm hole in a resin kit! The bit snapped immediately. I need something suitable for working with resin kits and also brass etch such as MSE Signal Kits where I would need to drill cast whitemetal posts. Any advice greatly appreciate.

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The answer is it depends! Have you tried an Archimedes drill? Dremel etc are good but really need to be in a stand for work like that. Am assuming you have dimpled the work piece first, and are using lubricant ?

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HI,

I use various sizes of pin vice that hold bits from 0.3mm up to 3mm. 

Drill bits I use are from Expo tools and they last me around 8-12 months with the cutting edge becoming blunt after that but then I use then a lot and once blunt I still keep them for drilling in to softer materials and for applying glue etc. I also have a set of PCB drills to do anything in plastic as that seam to work better than anything else.

One of the issue is that unless you are using a pillar drill as you drill by hand the dill bit flexes due to the movment of your hand. When using the samller dill bits I only have a few mm of the drill bit sticking out of the bottom of the chuck it try and give it a bit of strength whilst drilling. Also dont press down as you drill let the drill cut at its own pace as this also helps to prevent breakages.

Lubrication wise, I don't on anything other than white metal and for white metal I use a bit of spit as it works better tha anything else.

Thanks

Simon

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If by 'hand drill', you mean this sort of thing, then a 0.5mm drill bit will struggle with the side-loads from the handle, however short it is mounted. The Archimedean drills are much safer, with fine bits, the driving force is along the drill axis, rather than across it.

Mini Hand Drill (2464) | Bromley Craft

These may have their uses, but they require care when using fine bits.

You can pick up sets of carbide drills at reasonable prices - sometimes.

http://www.fortex.co.uk/wp-content/uploads/2015/09/2.jpg

If you're using collets, rather than a chuck, they do have the advantage of a common shank size - but, that also stops you 'hanging' the bit very short.

Swings and roundabouts...

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One thing that helps is to make sure you are using HSS bits (I prefer the shanked variety) and not the tungsten carbide bits widely (and cheaply) available on ebay and other outlets

The tungsten carbide bits are very brittle and aggressively fluted so break really easy.

The HSS ones are more flexible and more tolerant of use and abuse.

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1 hour ago, Angus said:

One thing that helps is to make sure you are using HSS bits (I prefer the shanked variety) and not the tungsten carbide bits widely (and cheaply) available on ebay and other outlets

The tungsten carbide bits are very brittle and aggressively fluted so break really easy.

The HSS ones are more flexible and more tolerant of use and abuse.

Yes, the carbide ones are really intended to cope with the glass fibres in printed circuit boards, etc., and they can often be 'used' and a little dull, too - but they have their uses in softer materials - HSS is definitely better for all-round use and, particularly, use in metal materials.

The smaller carbide drills are very prone to mishandling when hand-held, and the potential for small, sharp pieces to fly about does need to be taken seriously.

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5 hours ago, LARNE CABIN said:

Hi all,

I am seeking advice on the most appropriate mini drill. I purchased a small hand drill, but failed miserably when I tried to drill a 0.5mm hole in a resin kit! The bit snapped immediately. I need something suitable for working with resin kits and also brass etch such as MSE Signal Kits where I would need to drill cast whitemetal posts. Any advice greatly appreciate.

If one is using HSS drill bits from the 'Microbox' that Expo and craft shops sell - the small bits are as blunt as the chuck end! Expo do replacement drill bits in packs of 10 for the small sizes and these are sharp.

The tungsten carbide bits are for high speed drilling and can only be used in pillar drills or CNC machines, as said above hand use is a no, hand use is to slow and snags causing side force will break them, these work best with a 'peck' drilling action only and not constant force drilling.

Candle wax- preferably paraffin wax candles is the best lube for all materials, I find.

Eoin

 

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Also, a lot of people will be drilling brass and the "standard" angles on most HSS drills are not ideal for that, there can be a tendency to pull into the material, with subsequent snapping problems, particularly on small drill.

There are "actual brass drills" around, but they will be very hard to find and unlikely to be cheap, especially in small sizes.

On 'manageable' sizes, people often just remove the positive rake at the actual cutting edge, but that will be a difficult task on a 0.5mm drill...

Drilling brass - The Home Machinist!

 

And you would need to keep modified drills separately.

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Posted (edited)

Impossible to get small size brass drill bits now, and even more impossible to make them yourself under .6mm, it's just to small to focus on even with magnifiers!! Though I did get a book 'Miniature Injectors Inside and Out' by D.A.G. Brown by TEE publishing, in which Mr Brown's last chapter 'Sharpening Small Drill Bits' discusses the difficulty and supplies drawings for a jig to do the job on a diamond lap - I bought the lap but not made the jig yet!!

Eoin

Edited by murrayec
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40 minutes ago, murrayec said:

Impossible to get small size brass drill bits now, and even more impossible to make them yourself under .6mm, it's just to small to focus on even with magnifiers!! Though I did get a book 'Miniature Injectors Inside and Out' by D.A.G. Brown by TEE publishing, in which Mr Brown's last chapter 'Sharpening Small Drill Bits' discusses the difficulty and supplies drawings for a jig to do the job on a diamond lap - I bought the lap but not made the jig yet!!

Eoin

Yeah, I wouldn't fancy making a reasonable job by hand under 1mm.

 

I have a few genuine brass drills - but never the right size, of course.

 

For occasional small sizes, there could be a case for having just a few sizes prepared, then drilling small, opening up to size carefully with a pentagonal broach, especially in thin sheet. You can 'ease' the size to suit and the surface finish should be better, too - with the penalty of additional time being required, of course.

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0.5mm shanked drills are available from Proxxon at reasonable prices and also quality German and Swiss 0.5mm drills can also be found via the Jewellery tool supplier Cousins UK and Cookson Gold.

I have some Seiko drills in the 0.2 to 0.3mm range that appear on Ebay from time to time price is around £25 for a box of ten.

Other than that there are plenty of straight shanked drills available, I just find handling them a bit of a pain once they get down to the smaller diameters. You also need a decent quality pin chuck to hold them.

I also use some three side micro broaches from Bergeon for adjusting very small holes to size

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