Drilling a hole in a stainless steel worktop.

[ProDave]

Todays job that I had to abort and re group when i have worked out how to do it.

Mobile catering trailer, wants an extra socket. The entire worktop is stainless steel sheet on a wooden (block board?) backing.

To get the new socket where they want, I need a 20mm hole through the stainless steel worktop and through the wooden board underneath it. the hole will be very close to the wall (normal conduit standoff distance, just a few mm)

So I can drill a pilot hole with a sharp HSS drill bit, but I only had a few small drill bits with me. So how to open that up to 20mm?  My cordless drill will only go up to 13mm, so even if I had a full set of drill bits, that's the largest I could go with that. I don't think my stepped cone cutter would do it, that struggles on mild steel.

All I can think is a new, non stepped cone cutter?

How would you do it?

 

[Andy™]

i would probably use a step drill, or a q-max if there was nothing under it, but you said there was wood so that wouldnt work

 

[Tony S]

Use a cone cutter with plenty of cutting fluid. Normal drill sizes get yourself a set of titanium drills there’re not much dearer than HSS.

 

[steptoe]

I done a kitchen a while back and just used a normal hole saw, plenty of cutting paste, and go slow, you show get 3 or 4 holes from a new one, 

 

[Sidewinder]

Normal hole saw slow speed high feed, keep it cold, use cutting compound.

 

[SLIPSHOD & SLAPDASH]

As others have said, use a normal hole saw with plenty of lube

 

[Rob_the_rich]

can the worktop be unscrewed and pulled forward a foot. Could then cut a notch with angle grinder, drill and chisel the wood first else might be smoky/dusty in there.

Then use trunking.

 

[ProDave]

No worktop is well and truly fixed.

The owner is going to have a go at drilling the hole, so I might not have to after all. I'll wait and see how he gets on before I buy an new drill bits or hole saws.

 

[Andy™]

No worktop is well and truly fixed.

The owner is going to have a go at drilling the hole,

best take some 110mm soil pipe for the cable then...

 

[Blue Duck]

:slap

 

[ProDave]

best take some 110mm soil pipe for the cable then...

That might be tricky to terminate to the back box.

 

[apprentice87]

Hi all,

People think stainless steel is super hard and difficult to machine/drill. The usual grades you will come across are quite soft and easy to cut, but you want a sharp cutter and slow speeds. Do like Paul said, high feed and slow speed. Reason is, it work hardens to a very high degree, and very readily too, so let the cutter rub without cutting, or try to use a blunt cutter, and you will be doomed within seconds....

With sharp tools, it is actually very nice to machine...

john...

 

[Blue Duck]

I'd go from underneath with a flat wood bit til the point makes a little protrusion then gently knock it back down and use it as a pilot for a hole saw, use a blunt one with no lube it will be fine, nothing to worry about, like john says it's probably quite soft metal.

 

[Marvo]

One of these  in a cordless drill as mentioned at slow cutting speed with a bit of oil. Once you're through the s/steel and into the wood change to a spade type wood bit. It's something we do regularly and I don't see you'll have any problems in stainless that's under 2mm thick.

 

[Evans Electric]

What make is that Marvo ?    Its different to what we normally see here.

 

[Marvo]

My local wholesalers sell a brand called 'Waco'. Waco do everything from light fittings to tools, the hole cutters shown above are disposable and are cheap as chips (around ZAR30.00 or about one quid fifty for a 20mm) and they're actually pretty good. http://www.wacoelec.co.za/general-products-(1).html#!itemdetails/id=10B4770B-8A26-43C1-87F4-88149815353D

 

[Evans Electric]

Ah !   Not come across that brand in the UK  .

 

[OnOff]

+1 with apprentice, have no fear of stainless!

I've drilled 70mm holes in 6mm thick stainless before with a standard Starrett hole saw without much issue (still got the waste "washers" somewhere for future use on something). If drilling a good few then as said above a standard one will do. If drilling a lot then I can thoroughly recommend Morse brand "Master Cobalt" hole saws. Had a big job drilling 140mm OD stainless tubes with a 3mm wall a while back. Got the 25mm ones I have from WF. Again keep dipping into Temaxol or Rocol RTD.

http://www.mkmorse.com/products/index.aspx?product=15

I'd drill a small hole on the "X" with a 3mm cobalt drill, then go through with the Starrett pilot first with the hole saw removed just to limit any chance of it going through suddenly and wandering/ scratching around where the hole's going to go. 

If it's that close to the wall, right angled drill adapter. Mine isn't much bigger diameter wise than a 20mm Starrett and gets closer than the proper right angled drill:

https://www.machinemart.co.uk/p/rad-1-right-angle-drill-attachment/

How thick is the wood under the stainless top, a bit of deft tube work if doing in galv tube with a coupler either side maybe?

(Saying that the bevel gears on my Clarke adapter have just gone t!ts up so it's going in the scrap. Has been brilliant until then. There s a little threaded collar behind the chuck that really needs Loctite on it from new. Will get a another when passing M'mart. Did the other day buy a couple of cheapo adapters from Dyas on a whim: http://www.robertdyas.co.uk/right-angle-drill-attachment OK as fall backs. The drive is just round rather than hex like on the Clark one. Body's plastic and where the handle screws in, LH or RH it's just tapped into the plastic).