Hi Chris,

Drilling very small holes with a normal size drill press is difficult as youdo not get the feel of the pressure on the drill bit due to the strength of the return spring. I made a drill stand to hold a small Minicraft drill (I do not think these are still available.) for drilling small holes in printed circuit boards. It uses part of the print head slide from an old printer to give a very smooth action with a long tension spring which only just supports the weight of the drill. Arc Euro Trade do a "Micro Drill Adaptor" (Item number 040-015-00400 for £9.99) This is basically a sliding spring loaded sleeve to take a small chuck which can be used in the lathe or pillar drill. There is a collar which you hold to apply the drilling pressure. Threre is no picture of this item on their webpage so I will try to attach pictures from the catalogue.

One of these may be the solution to your problem. You could probably make one yourself if you are in a hurry. There was a thread recently on removing broken taps. This may help you to remove the broken drill.

Les.

Edited By Les Jones 1 on 18/03/2012 12:25:48

Hi Chris,

Stewart's and Les's advice is very good but I would add that a drop of good cutting oil helps greatly, as does clearing off the chips frequently from the drill with a miniature wire brush. Also, there are drills and there are drills. It pays to buy the best quality drills you can from an industrial supply house. Even the best drills are not that expensive, relatively speaking. In North America I buy mine from http://www.kbctools.com, Precision Twist Drill brand. Better steel, better grind, and keep an edge much longer than bargain shop/hardware store drills.

JD

This is a good tool. We used it at a company that I work in and drilled a 0.4mm hole with it.

Andy.

Terry,

I have found that Dormer PS2 pointed drills are the best at centering and holding centre. Greenwood tools supply these. They are four facet ground drills.

K

Hi Chris,

I've just rechecked my plans for Elmer's tiny and there are 2 versions. The original quotes #57 drill (0.043) for the port holes but the later amended drawings call for 0.063 holes.

This might make your task a little easier. I would support all the earlier advice and perhaps note that the small hole to the tapped inlet should be drilled before the tapped hole and so avoid breaking through on a curved surface with the smallest drill.

Bob D

Respectfully, Terry, and just curious, but was there a particular reason that you did – rather then creating a separate thread?

1) Because I thought that it would not be a good idea to have two threads out of 10 on show with such a similar theme and;

2) that readers with the same problem as me may turn to this thread looking for a solution – as I did due to it's title;

3) Others are still answering the original problem anyway and;

4) it will not be the first thread to be 'hijacked' and at least the problem I highlighted is related to the original unlike many 'hijacks'.

Best regards

T

Edited By Terryd on 19/03/2012 03:13:10

One of the problems with drilling holes in castings is that the rough unmachined surface will very probably deflect the drill point off course as it enters the surface. Not sure whether that is applicable here, but it may be the case with others.

The possible solutions are (1) to use a stiffer drill bit – a stub drill will typically deflect a quarter as much as a normal length drill bit (2) start the hole with a centre drill – these are very much stiffer as most of the shank has several times the diameter of the pointy bit (3) start the hole with a slot drill – these will plunge cut quite well (which end mills won't) and as they cut on the side as well as the end they won't be deflected; when you have a good start you can switch to a normal drill bit. For this use only, you can safely ignore the stricture that milling cutters must not be used in a drill chuck; there is no significant sideways pressure here.

One case which will always cause problems is if the surface you are drilling is not exactly normal (i.e. at 90 degrees) to the drill axis. This is guaranteed to cause deflection with any normal drill bit, and the only practicable solution is (3) above – start with a slot drill. If you use a slot drill exactly the same diameter as the drill bit this will give the best support to the normal drill bit when you switch to it.

When drilling a long hole it is particularly important to have bit with exactly equal shoulders, and to back out to remove swarf very frequently. Neglect either of these and you hole will wander (and your drill bit is likely to break). Use of a chuck with the smallest possible runout is also important.

David

Hi Cornish Jack

This is an easy job.

I covered this in a Workshop Special.

I will try to find the relevant pages.

regards David

DC1

Many thanks for the offer but I already have the publication. Bought it on the assumption that it would ease the build but, sad to say, it didn't. The myriad photo's are far too small for my decrepit old eyes (even with magnifiers) and the machining detail was very difficult to interpret. I should, perhaps, have copied your jigs and fixtures but I suspect that your expertise and equipment far outweighs my ML7/Dore-Westbury!!

Will keep on 'keeping-on' and make sure the waste bin is handy!!

Rgds

Bill

I have a cheap Clarke pillar drill (the bottom of the range one) and I have used it with drills down to at least number 65, if not a bit smaller.

Make sure you have it on the highest speed, clamp the work and go very gently. Have a centre pop to make sure the drill doesn't wander, or use a smallest size centre drill to peck a tiny mark for it to start in. And make sure you are perfecty lined up on where you want the hole.

Neil

Hi Cornish Jack

Email not received.

regards David