I does slightly depend upon the grade of stainless steel. However, what is usually important is that the drill is not allowed to dwell during the feed. That quickly causes local hardening of the steel, which blunts your drill.
Ideally, use a powered feed, having first looked up the speed and feed speed in one of the many available charts. If you have that option, use solid carbide drills and flood the work with lubricant.
Failing that, use a pillar drill, use a good lubricant and keep a steady pressure on from start until break through. Trying to drill most stainless steels with a hand held drill is simply asking for problems.
It's a boom for a ham radio antenna. I need holes. The holes are on both sides to support the insulated elements. I need the pilot holes on one side to make sure everything is in line before using the pillar drill. I'm using a small hobbyist power drill to do the pilot holes ;it struggles a bit.
The material is 15mm BS4127 Stainless Steel Permatube. I've a few surplus 3m lengths. Normally I'd use aluminium, but I thought I'd try this as it's a bit stronger for the wall thickness.
Agreed, pillar drill is a far better bet. I've always been impressed with the new cobalt drills. For 4.5 mm, fairly low speed and firm pressure. 3-in-1 should work, or Toolstation do an aerosol cutting and tapping fluid.
eBay item 183034379363 is £2-75 for 4.5mm. I'd buy two or three to be on the safe side (although I reckon you should get 30 holes out of one).
Wrong geometry, a sharp masonry drill would do better (but still not well).
If it's just a one-off job and the HSS bit is working OK until it blunts, I'd probably just deal with sharpening it a few times. If that was too tedious or otherwise unsuitable I'd order a couple of cobalt bits.
formatting link
used to be competitive and quick, I've not used them recently.
The other thing if you have to sharpen them is to try different angles from the ones classically set up for drilling thick steel. I don't know the science or the names of the angles, but if you make the drill more pointy, and shift the plane of the ground face into the flutes so there is more clearance at the back of the cut then it may rip its way through thin tubes quicker, perhaps at the cost of slight raggedness. Well worth a try, especially if the holes are not going to be visible. Just do it by hand, there is no point in using a jig if you are trying arbitrary angles, at least for small drill. But don't let it get too hot.
Twist drills are designed for steel as a compromise between jamming risk, breakage risk & cut speed. If you steepen the angles it will cut faster but be a lot keener to jam & break. Fine on wood, but trouble on SS.
A big impediment to drilling speed is the blunt zone in the centre. If you thin that down, a twist drill drills everything a good bit faster.
This is one of the "points" about high speed steel (as well as cobalt and solid tungsten carbide). These materials retain their hardness at red heat, at which temperature most steels have the mechanical properties of lead. So you get frictional heating in the centre which softens the target material here while allowing the cutting edges to do their thing just away from the soft zone with much less local heating.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.