Hi I need to drill 1.5 - 2.0mm diameter holes to a depth of about 8mm in very soft alloys / lead. Using a small model maker's drill of unknown rpm only seems to get to about
2mm easily. The workpiece warms up (actually, quite hot) and it seems that drilling stops. Is there a technique for drilling this type of material? High rpm or slow? Ta.
SLOW! I'd use a hand drill.
I suspect your drill is simply getting clogged and so is unable to cut any further in. The trick with soft materials, especially something like lead, is a very slow drill speed, and I mean really slow. Drill a little way in, and lift up to allow swarf removal. Repeat a few times until you're at the required depth.
seems that
I expect that the flutes of the drill are getting clogged with the relatively soft swarf. Use a 'pecking' action - drill in a short way, withdraw to clear the drill flutes then start again. The smaller the drill the faster you need it to turn. See here for a chart:
And thanks for the link to that chart.
The message from Grunff contains these words:
And experiment with the angle of the cutting edge of the drill. Too sharp may cause problems if it's trying to remove too much material at a time.
If dimensions are not critical, I'd start by trying a hammer and nail.
You should find that quick spiral drills work better than ordinary jobber drills.
Colin Bignell
pull the drill and swarf out and try again.
The soft swarf clogs it,.
Lubrication and a low drill speed works best.
From my apprentice days I seem to recall that Turpentine was the recommended lubricant for lead. Paraffin would also probably work - I always used that for machining aluminium.
Thanks. What do you call low speed (in rpm) for a 2mm bit?
Hand drill speed - 100-300rpm tops.
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