Making holes in 316 plate

[Jonathan Webb]

Hello,
I need to make 10 x 1", 4 x 3/4" and 4 x 1/2" (or near metric equivalents 26,19 & 13 will do) in 10mm 316 stainless plate/bar. (in pieces vaguely the size of playing cards - they're load-spreading washers.)

I've come across Starrett CTD holesaws, which seem suitable but they don't go smaller than 15mm so only good for the larger sizes.

Dormer's A108 13mm stainless drilling bit is ca £45

I have a decent handheld drill, but was presuming to use my Tauco bench drill.

I could take them to an engineer - any chance 4 holes would be less than the cost of the drill bit? (FWIW, I've had quotes to laser/water cut the plates and they're £300ish, which is way outside my budget)

As a last resort, I wondered about the possibility of making rough holes with either my Javac Avalon 40 plasma cutter (hey, it works), or possibly arc gouging, then grinding out the resulting holes with dremel-type tool to 13mm. They won't be seen, so neatness isn't an issue, but function is. And this is a hobby, so time-cost doesn't come into it too much.

Ideally can anyone recommend a not-too expensive drill bit that will last for 4 holes (or 4 cheap ones?)
Many thanks.

 

[cianh91]

I use standard hss bits on stainless keep the speed down and pressure reasonable. Get some cutting paste itl make more difference than a fancy bit

 

[cianh91]

https://www.amazon.co.uk/Rocol-5302...vlocphy=20481&hvtargid=pla-422560609818&psc=1

 

[Hood]

Any half decent HSS drill bit will manage that no problem. People think you need something fancy for drilling stainless, you don't. Slow speed and a fair bit of pressure is what you need. Let it rub and it will work harden and then carbide will be the only way.

 

[Hood]

BTW definitely use the bench drill on a slow speed, a battery hand drill can also be used but you need to put your weight on it to keep it cutting. A normal corded hand drill will be too fast or potentially too fast and cause you to work harden the stainless.

 

[slim_boy_fat]

https://www.google.com/search?q=13m...hWllFwKHXeFBZEQ_AUoAXoECAsQAw&biw=998&bih=484 + as @Hood said.

 

[Ruffian]

For those diameters I would be using generic hole saws in a pillar/bench drill.

Especially if you got a decent roundtable vice.

 

[Hood]

For those diameters I would be using generic hole saws in a pillar/bench drill.

Especially if you got a decent roundtable vice.

In sheet I would agree but don't fancy doing 10mm thick stainless with a hole saw, too easy to let it rub a bit too much.

 

[Paul.]

Without a decent drilling machine you will struggle, cheap bench drills usually run too fast and lack power to drill decent sized hole in stainless, you will also need some decent cutting oil such as Rocol RTD which is not cheap, I usually just get stuff like this laser cut, it comes in just needing a deburr with a flap disc and is ready to use,

 

[m_c]

3/4" and 1" is not in the territory of your typical pillar drill, which is where the big problem will be.
I know I've done 16mm in my Clarke pillar drill, but I wouldn't want to go any bigger.

If the drill goes slow enough (just done a quick search, and Starrett recommends around 170rpm for their hole saws in stainless/tool steel, although 316 you probably want to got a bit slower than that), then suitable hole saws for the 3/4" and 1" make sense.


Regardless of what you use, as Hood says, you always want to be cutting. The moment things rub, and the 316 heats up, it's pretty much game over for anything non-carbide.

 

[mike os]

Rotabroach for the 1 and 3/4, decent hss or hssc for the 1/2 , rocol and pressure are a must

 

[Richard.]

I wouldn’t be using a hole saw on a gage like that. 316 drills surprisingly nice and your standard drill bits will chomp away at it no problem at all.
id get a few sizes ran through to about 10mm. Make sure she’s clamped down really well and open her up with a blacksmiths drill bit to get your size. Keep the speed really low and enough pressure to see it cutting. Don’t go mad on the pressure.

carbide will be the only way.

You can reinstate it easy enough by annealing

 

[WorkshopChris]

Blacksmiths drills nice and slow with good cutting oil or compound.

 

[Brad93]

Don’t bother with fancy drill bits.
Standard HSS, nice and sharp.
Cobalt is just a waste of money. Better to have 4 sharp HSS drills for the same price on stainless.

If you want decent drills at realistic prices look at Sherwood (Cromwell or Zoro stock them). Good quality and not silly prices like dormer.

As said, Rocal RTD Cutting Compound is a must.

For the 3/4 and 1” holes I’d use a rotabroach but it depends if you are going to be able to clamp to the part.

Holesaw will end in tears.

Honestly I’d mark it out. Centre dot it, and drop it to the local machine shop.

 

[Hitch]

Drop it in somewhere with a Geka/Kingsland type punch. 5 Minutes work.
Drill the 13mm ones. Just need a sharp half decent bit and a dab of oil.

 

[Brad93]

Drop it in somewhere with a Geka/Kingsland type punch. 5 Minutes work.
Drill the 13mm ones. Just need a sharp half decent bit and a dab of oil.

I always forget about the punch.

You’re right my kings land would do that in seconds.

 

[sako243]

Have you spoken with Dave @ Cirrus Laser? I'd have thought he might be able to tack that on the side of another job if you're willing to wait a bit for an opportunity.

 

[Jonathan Webb]

Don’t bother with fancy drill bits.
Standard HSS, nice and sharp.
Cobalt is just a waste of money. Better to have 4 sharp HSS drills for the same price on stainless.

If you want decent drills at realistic prices look at Sherwood (Cromwell or Zoro stock them). Good quality and not silly prices like dormer.

As said, Rocal RTD Cutting Compound is a must.

For the 3/4 and 1” holes I’d use a rotabroach but it depends if you are going to be able to clamp to the part.

Holesaw will end in tears.

Honestly I’d mark it out. Centre dot it, and drop it to the local machine shop.

My local machine shop (who's doing making my 1" studs and some other machining) recommended getting them laser cut, but I've been quoted £300+ and can't afford that. Maybe I'll see if he'll drill them for me, rather than make them up completely. I'll investigate rotabroach.

 

[Richard.]

It’s only 18 holes in 10mm plate.
Why are we handling jobs out nowadays because they pose a bit of a challenge.
I bought a set of Bsmiths for jobs like this and banged many a 1” hole in thick plate. My little ml10 with her 2/3hp motor would happily put a 25mm bore down a 13mm pilot if I was taking it nice and steady.
A machine shop might do it in seconds but what’s wrong with the op doing it himself in a couple of hours.
Welding and engineering forum here not hand it to someone else forum.

 

[Brad93]

It’s only 18 holes in 10mm plate.
Why are we handling jobs out nowadays because they pose a bit of a challenge.
I bought a set of Bsmiths for jobs like this and banged many a 1” hole in thick plate. My little ml10 with her 2/3hp motor would happily put a 25mm bore down a 13mm pilot if I was taking it nice and steady.
A machine shop might do it in seconds but what’s wrong with the op doing it himself in a couple of hours.
Welding and engineering forum here not hand it to someone else forum.

Sounds like the guy isn’t set up for it to be honest Richard. Why spend £100 tooling up when quite frankly if that came through the door I’d do it for £40.