1.1mm hole in brass

I have to drill and tap 3/32" brass rods on both ends. I've gone with M1.4 x 0.3 thread as the suggested 0-80 taps/dies are rarer than a rare thing, so I need to drill a 1.1mm tapping hole.

What speed? These are available 840/490/280/145/85/48

What feed? Constant push or pecking?

Edited By pgk pgk on 15/07/2018 09:40:23

Fastest speed possible and peck. Best done with sensitive drill but you get little feed back anyway at this diameter. I have no trouble with 1mm holes. If you are getting new drills get ones to suit brass, standard flute drills can grab in brass.

Don't use ANY "speed", just tap by hand....put the brass rod(s) in the chuck or collet, put tap in good tailstock chuck, put your finger behind the (unlocked) tailstock and turn the headstock by hand using, preferably, a hand crank mounted in the lathe spindle by expanding mandrel.....allow the tap to do it's own thing and make sure you use lots of back turns to free the cuts......

An alternative method that works well with small taps is to hold the tap in a pin vice and just use both hands to GENTLY cut the thread by turning the work against the hand held tap which you can then 'feel' into the cut thread.

.

Good advice re. tapping, Bob

But the question was about drilling the holes.

MichaelG.

Thanks gents, looks like I have a couple of tools to make first as finesse with the tailstock wheel is not my strongpoint yet. I'll be making a few of these miniature engines so the tools will come in very handy.

Paul,

The 'Micro Drill Adapter' that Jason mentioned on an earlier thread would be a good investment, I think.

**LINK**

https://www.model-engineer.co.uk/forums/postings.asp?th=136679&p=1

MichaelG.

i have one of the micro drill adaptors & have found it very useful for 'feedback' with tiny drills. Drill with drill bits made for brass, but at that size I would take the edge of the cutting lip with a stone or diamond lap, doesn't need much, a couple of strokes would suffice otherwise you'll have a pile of broken drills. Use a loupe or other means to look at the cutting edge, as soon as you detect a shiny edge that's it dulled enough. Use the fastest speed you can & peck away at it. When I use drills for brass I keep them in a separate box ( with divider compartments for ea. size. ) for future use.
Happy drilling...

George.

.

Excellent advice, George

MichaelG.

I drilled many dozens of 1/32" holes for Southam in an ordinary cheap bench drill mostly in brass plate but a many in tinplate and some in steel.

OK I broke about 8 drills, but that was because I found myself drilling into partly assembled bodywork through existing holes.

Very easy to drill into solid brass at sub-millimetre sizes if you take it gently and clear the drill regularly.

Neil

That micro adapter looks the business, probably save me more in drill bits, 7 down already.

I have just finished a job in PB102 bronze on my Myford and in which I needed to tap 39 (thirty nine) M1.4 holes 3/16" deep. To be honest, it is not as difficult as it sounds. The most important thing is to start by centring lightly with a No.0 centre drill and use a new, high quality HSS drill. 1.1mm dia. is good for brass over a short length but, despite what the book says, you can get away with using a 1.2mm drill instead of 1.1mm for bronze. There will not be quite as much thread but they are strong enough for purpose. I have been told that 75% thread depth is still 95% efficient, so you are not losing much strength anyway.

It is also much better to never cut dry, always use a cutting oil and "3-in-1" with added PTFE will do the job for you. I drilled at about 800 rpm, with light cuts, relieving the drill frequently and tapped by hand, relieving the tap every two turns.

I have never tapped this small a size before but did all 39 holes with the same drill and the same tap and don't think you will have any problems either.

Kind regards,

Leszek

No sympathy from me - your excavations are all whoppers by my standards. (I'm currently struggling to make a 0.3mm diameter hole 10mm through brass.)

Down to 0.5mm diameter, easy peasy. Below that I'm finding life gets tricky with drills less than 0.5mm. I think the reason is because the strength of a drill is proportional to the square root of its diameter.

A 1.1mm drill is 14 times stronger than a 0.3mm drill allowing much more room for clumsiness. A 0.5mm drill is three times stronger and even I have a chance of not breaking one.

Diameters illustrated  are 1.1, 1.0, 0.8, 0.5 and 0.3mm:

Putting it another way, you can squeeze thirteen 0.3mm diameter holes inside a 1.1mm diameter rod. Now that's a challenge!

Dave

Edited By SillyOldDuffer on 15/07/2018 16:18:40

Mr Duffer,

what are u making that needs drill's that small.......?

very interested to find out.......a clock or better yet a wristwatch.....?.

ps ....my/ur lathe clutch works a treat, thank u....

Apart from winding up the speed a bit I don't do anything special for that size drill in any metal. Last steam engine I did had about 20 M1.6 holes for which I drilled 1.2mm in a mixture of steel, iron, aluminium, brass and bronze and a couple of 0.8mm cross holes in steel pins for 1/32" split pins.

Don't think I have ever stoned a bit for brass/bronze just use the same I would for anything else.

If you have already broken that many drills there is something seriously wrong with your methods or the drill bits you are using. Try a decent bit such as Dormer A002 split points or the shorter A022 Stub Length ones.

Long story cut short I'm making:

A Pendulum Clock Analyser:

That needs a pendulum clock thingy to test it:

The test clock has a standard steel bob and I'm experimenting with different materials for the rod. I started with polyester cotton thread, then 1mm carbon fibre rod, currently testing 0.5mm carbon fibre rod, and I have 0.3mm diameter carbon ready for the day I manage to drill a couple matching holes:

Another reason I may be in trouble drilling tiny holes in brass could be work hardening? It's likely that out of fear of breaking drills I'm pecking too softly, rubbing rather than cutting, and thereby toughening up the brass such that the tiny drill isn't strong enough to push through. Quite a lot of bother in my workshop is caused by poor technique.

Dave

Probably guilty on both counts, I've done two bars out of the four and I'll wait for the adapter and new drills before continuing

.

Who is this clot? You can only drill nine 0.3mm diameter holes inside a 1.1mm circle. Thirteen would overlap.

Ho hum...

Albion Alloys make micro brass and nickel silver tubing with a 0.1mm wall. You can get it from Chronos and others.

They make a 0.5 OD x 0.3 ID - three foot long lengths for 6 quid. This isn't even their smallest! They also sell selection bags of telescoping sizes.

Could you use it as bushing for your existing 0.5 holes?

I've used this stuff in all different sizes as bushes etc.

Going for less than 100% thread will reduce cutting forces on the tap.