Drilling Stainless

Lakesailor

Lakesailor

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Engineering types only need apply. :D

I may need to drill an extra hole in my stemhead fitting to gain enough clearance to fit a furling drum.
It's a fabricated stainless steel flange. Not very thick, perhaps 3mm.
In view of the fact I will be using a Makita battery drill with a spare battery, what is the most efficient way to drill stainless?

In the past I have drilled s/s and it's taken ages.
Do I need a special drill bit? What is the best speed to use, fast or slow?
 
That will be slow speed and a SHARP HSS drill, lots of pressure and some lube. Fast will tend to harden it. Any screeching indicates hardening. 3mm isn't any big deal.
A
 
KE, cobalt are nice but I wonder if worth the difference. Also I use, for large holes, a single pilot of, say, 5mm for a final hole of 10/12mm.Keeping the edge good is V important. Stepping up in stages tends to put a high load on a small part of the cutting edge of each drill. No tech data to back this up, just it works for me.
I had to cut 50 odd 50mm holes in 8mm bar for a project. I have a commercial pilar drill that I rerigged to 1/2 the slowest speed on the pulleys for that.
Lakey's hole can't be bigger than 6mm, so all a bit irrelevent.
A
 
Cobalt drills BUT if in an doubt or problem the gold-tipped DeWalt drills if not actually cobalt are a bloody sight harder and last infinitely longer than standard HSS bits. They're also readily available.

Those are what I use for stainless.
 
On smaller sized holes say up to 12mm the pilot drill only needs to be big enough to produce a hole big enough for the dead centre to pass through. Then it is dependant upon how work is clamped, drill speed, holding for the drill bit etc. The important bit is the diameter hole you are going to drill with regard to speed. I imagine you are drilling something around the 6 - 8 - 10mm size if so the speed that you probably want to drill at is around 200 rpm, with plenty of power so you can push hard and maintain cutting. As has been sad if it slips/screaches etc and it hardens you are in for some trouble.

I had to do a similar job and did not use the 14.4V 3 speed dewalt drill but borrowed a mechanical 2 speed electric drill with electronic control and a bit over a 1000W. Do able but hard work.
 
Corded drills bit tricky on swinging mooring.
Just checked and the hole is 5mm so an 1/8th pilot (never went metric) and the finished size at a slow speed should do the trick.
 
Drilling the forestay fitting

Hi Phil Any drill bit will be fine provided it is sharp. Look at the tip of the bit under a magnifying glass. You can sharpen 6mm drill by putting the drill bit in a vice facing upward and us an oil stone to carefully grind the shoulders so sharpening the cutting edge. Yes you could use a power emery wheel or even an angle grinder in a vice but these take off too much metal too quickly. (and get it too hot) Or buy a new bit.

Use the battery powered drill on low speed. Put oil on the bit and job. if there is any sign of smoking it is too hot. Use as much pressure as you can muster and just drill for a short time then stop and recover your strength. You should be getting a metal swathe off the bit at all times. I imagine it will be a horrible job but if you must do it in situ that is all you can do. Find some strong youth to do it for you. Of course if you can remove the bow fitting it will be an easy job in a drill press. (pedestal drill) good luck olewill
 
SS Drilling.

As everyone says, use a centrepoint to start with and then drill as slow as you can, with as much pressure to keep the drill cutting.

With a 3 MM, have spare drill bit ready, as I'm sure, you'll break a few.
 
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