# Enlarging a Hole in Stainless Steel Box



## 12-Gauge (Aug 28, 2009)

Any suggestions on how to best enlarge a conduit entrance hole in a SS box (without having to buy a KO Set)?

I don't want to scratch up the outside of the box and don't have a lot of room inside the box.

Does the "Hole Saw Inside a Hole Saw" trick work?


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## JohnR (Apr 12, 2010)

Uni-bits have always worked well for me. Step bit. etc.


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## Lz_69 (Nov 1, 2007)

If it's for 1" conduit or under a unibit will work, if that's no good and you don't want to buy one i would just borrow a ko set/punch from a coworker or employer.


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## erics37 (May 7, 2009)

Drilling through stainless with a hole saw would suck ass :blink:

Perhaps you can borrow a KO set, or maybe rent one? I dunno.


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## administr8tor (Mar 6, 2010)

erics37 said:


> Drilling through stainless with a hole saw would suck ass :blink:
> 
> Perhaps you can borrow a KO set, or maybe rent one? I dunno.


I only use a hole saw on stainless, dozens of holes later and i'm still using the same hole saw:thumbsup:


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## 12-Gauge (Aug 28, 2009)

*KO Set*

You're confirmining my feelings - I'll borrow a set from a buddy for the day.

Thanks all!


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## erics37 (May 7, 2009)

administr8tor said:


> I only use a hole saw on stainless, dozens of holes later and i'm still using the same hole saw:thumbsup:


I have a pile of cheapo "expendable" old small drill bits (1/4" or less) that I get the hole started with, then I use a step bit to open it up enough to get the KO ram through there. Even for small holes. I hate drilling stainless :laughing:


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## administr8tor (Mar 6, 2010)

erics37 said:


> I have a pile of cheapo "expendable" old small drill bits (1/4" or less) that I get the hole started with, then I use a step bit to open it up enough to get the KO ram through there. Even for small holes. I hate drilling stainless :laughing:


Stainless is easy to drill, when you know how:thumbsup:


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## erics37 (May 7, 2009)

administr8tor said:


> Stainless is easy to drill, when you know how:thumbsup:


I'm not patient enough to do it right


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## B4T (Feb 10, 2009)

If you can't afford to buy a KO set.. try renting from here..https://www.sunbeltrentals.com/locations/


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## nolabama (Oct 3, 2007)

Use those carbide cutters ideal makes. Get a C-clamp and put a couple four square lids on the box in the area in question. Use them as a guide for the cutter and you will have your fancy hole done. Might need two clamps.


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## Deepwater Horizon (Jan 29, 2013)

erics37 said:


> Drilling through stainless with a hole saw would suck ass :blink:
> 
> Perhaps you can borrow a KO set, or maybe rent one? I dunno.


I had to drill a bunch of stainless disconnects for a dishwasher in a commercial kitchen. I was handed some holesaws and a can of WD-40. It worked all right but was definitely not fun. :no:


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## sparky970 (Mar 19, 2008)

Drill the right size hole the first time and use the right tool for the job


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## erics37 (May 7, 2009)

sparky970 said:


> Drill the right size hole the first time and use the right tool for the job


That's what she said!

:clap:


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## Wirenuting (Sep 12, 2010)

Clamp a per drilled piece of plywood over the hole. 
Then just drill way.


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## NjSpark (Feb 14, 2013)

The hole saw inside of another hole saw trick works very well. The only thing is that you need an arbor in which the threaded piece is long enough to screw two hole saws onto it.

The 3/4" plywood trick also works well.


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## Deepwater Horizon (Jan 29, 2013)

NjSpark said:


> The hole saw inside of another hole saw trick works very well. The only thing is that you need an arbor in which the threaded piece is long enough to screw two hole saws onto it.
> 
> The 3/4" plywood trick also works well.


What is this "hole saw inside another hole saw" trick?


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## NjSpark (Feb 14, 2013)

Let's say you have a 3/4" KO and you ned to open it up to 2", but you don't have a KO set.

You take a 2" hole saw and thread it onto an arbor like usual. You then take a 3/4" hole saw and thread it inside of the 2" hole saw. As long as the threaded part of the arbor is long enough (some are, some aren't) this will work. You then drill out the hole using the 3/4" hole saw as the pilot bit to keep it centers.

This works very well when you have a large reel of wire with a small hole in it and the rigid pipe you are using as an axel won't fit thru it. Just drill out the holes with this method.


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## Deepwater Horizon (Jan 29, 2013)

NjSpark said:


> Let's say you have a 3/4" KO and you ned to open it up to 2", but you don't have a KO set.
> 
> You take a 2" hole saw and thread it onto an arbor like usual. You then take a 3/4" hole saw and thread it inside of the 2" hole saw. As long as the threaded part of the arbor is long enough (some are, some aren't) this will work. You then drill out the hole using the 3/4" hole saw as the pilot bit to keep it centers.
> 
> This works very well when you have a large reel of wire with a small hole in it and the rigid pipe you are using as an axel won't fit thru it. Just drill out the holes with this method.


Gotcha, thanks. I learned a new trick today. :thumbup:


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## erics37 (May 7, 2009)

Deepwater Horizon said:


> Gotcha, thanks. I learned a new trick today. :thumbup:


Me too. Of course it is moot because as soon as you enlarge the wire spool hole you'll accidentally drop the spool and the reel will blow into 8 pieces anyway.


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## NjSpark (Feb 14, 2013)

erics37 said:


> Me too. Of course it is moot because as soon as you enlarge the wire spool hole you'll accidentally drop the spool and the reel will blow into 8 pieces anyway.


Or maybe one of your drunken friends will break the spool in his underwear.


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## erics37 (May 7, 2009)

NjSpark said:


> Or maybe one of your drunken friends will break the spool in his underwear.


:laughing:


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## di11igaf (Jan 1, 2012)

erics37 said:


> Me too. Of course it is moot because as soon as you enlarge the wire spool hole you'll accidentally drop the spool and the reel will blow into 8 pieces anyway.


Yup, almost every reel of wire in my van no longer had sides. You could just set the reel down and pull the wire right off the side. Rack-a-tiers not needed.


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## Cletis (Aug 20, 2010)

You really need to invest in a nice KO set. It's one of the most basic things you will need all the time. Should be in every serious electricians truck


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## NjSpark (Feb 14, 2013)

Cletis said:


> You really need to invest in a nice KO set. It's one of the most basic things you will need all the time. Should be in every serious electricians truck


It depends. I did residential service for years with only a couple of holesaws.


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## randyr_124 (Jan 25, 2013)

Try to make a pilot hole and use the ideal carbide hole saws if you buy the small kit( 1/2, 3/4, 1") its a 100 bucks and works good


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## aDudeInPhx (Feb 20, 2012)

There is a hole saw arbor that's made for exactly what you're describing - trying to find a link. It's a carpenters tool for enlarging door handle holes where there is an existing hole but its a little too small. It's made to accept 2 hole saws.


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## sarness (Sep 14, 2010)

Oops arbor,

http://www.leevalley.com/US/wood/page.aspx?cat=1,180,42316&p=52518


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## aDudeInPhx (Feb 20, 2012)

sarness said:


> Oops arbor,
> 
> http://www.leevalley.com/US/wood/page.aspx?cat=1,180,42316&p=52518


I searched 'Goof arbor' & came up empty lol


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## sseivard (Apr 25, 2012)

nolabama said:


> Use those carbide cutters ideal makes. Get a C-clamp and put a couple four square lids on the box in the area in question. Use them as a guide for the cutter and you will have your fancy hole done. Might need two clamps.



Yep get some cutting oil press really hard and drill really slow. The fancy hole saws are a waste of money for stainless.


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## uconduit (Jun 6, 2012)

I like the fancy hole-saws for stainless but the methods are different than when using a cheaper hole-saws.

How to* ruin *a fancy hole saw cutting stainless:
1. Don't use a cooling liquid (water, cutting oil, etc), this gets that saw nice and hot (you know you're ruining it right when you see different colors of the rainbow in the shavings)
2. Use lots of pressure, this will not dull the carbide tips, it will crack them right off
3. Use the wrong RPM, too fast and it gets too hot, too slow and you become frustrated and resort to #2


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