knockout size holesaw or?

[jdsac]

Can anyone point me to a knockout size holesaw? I need to add to a 10x 10 junction box & can't find one small enough. Other ways to do it? Greenlee punches are expensive for a one time use.

Thank You!

 

[Terry D]

What size conduit


1/2 conduit and connectors is 7/8 hole

3/4 is 1 1/8 hole

1" is 1 3/8 hole.

Holes saws are your cheapest route. But they tend to wander and make to large of hole.

You can get a unibit for 7/8 or 1 1/8, but they are not cheap.

Anything to make a decent hole is pricey

You can buy j-boxes with KO's in them

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[7635tools]

Generally with emt conduit you go a 1/16” less on hole saw diameter for a tighter hole on the connector. Although I haven’t had an issue with a 7/8” hole saw for 1/2”, I do have better luck with 1 1/16” for 3/4 and 1 5/16” for 1”.


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[Pingel85]

Terry D hit it on the head. If you buy an electricians hole saw kit it would be 7/8, 1 1/8, and 1 3/8 for 1/2, 3/4, and 1” respectively. If you have a specific size conduit you’d be looking for just let us know and we can get you the correct size hole.

 

[theoldwizard1]

You can get a unibit for 7/8 or 1 1/8, but they are not cheap.

This seems pretty reasonable. Step Drill 1/4"-1-3/8" Molybdenum M7

I have a smaller one from the same company and it works well.

 

[sky jumper]

if all he needs is 1 use then a $2 wood spade will work. drill a 1/8" pilot hole and go to town on that s.o.b. yeah it will destroy the bit... the $2 bit... but it will make the hole just fine.

 

[3rdgen]

Carbide cutters work way better then a hole saw if you can find the cheap ones on Amazon

 

[nadogail]

I have been known to borrow or rent a tool when I needed one for a "One Time" use. If possible I return the tool equal or better than it was when I received it. If the tool was loaned to me without a charge, I often include a "Care Package" with the tool or shortly there after.

Pastry is currency.

 

[Terry D]

if all he needs is 1 use then a $2 wood spade will work. drill a 1/8" pilot hole and go to town on that s.o.b. yeah it will destroy the bit... the $2 bit... but it will make the hole just fine.

In metal?

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[AP514]

I JUST DID A 1-1/8 HOLESAW FOR MY 3/4.

I used wood block on back to help keep holesaw from wandering(as suggested here on forum)

 

[reader2580]

You can get a unibit for 7/8 or 1 1/8, but they are not cheap.

Harbor Freight has a step bit set for $20. Menards also sells a Performax step bit set for $20.

I am doing a pretty big electrical project right now and I have used both hole saws and step bits to drill holes in electrical enclosures. The step bit is definitely easier, but not big enough for large conduit,

 

[acer66]

In metal?

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Yeah, I just did that because that was all I had on hand.

 

[Norcal]

Yeah, I just did that because that was all I had on hand.

Sounds a bit Neanderthal to me.

 

[Crazyjake8493]

A step drill bit (even a cheap one) would work just fine for adding a knockout or two. Most go up to 1-3/8". If you plan on doing more in the future, I'd look on ebay for Greenlee punches. I needed two sizes to punch some holes in a stainless steel brewing kettle, and I found a listing for 8 different sizes including the two I needed, for about $30.

 

[acer66]

Sounds a bit Neanderthal to me.

Hehe it was indeed not one my proudest moments.

 

[Terry D]

Knockout punches are by far the best way to make a hole, especially when you get to the larger sizes. I know they make the cheaper unibits or step drills, and they are probably fine for a small amount of holes, but at least the amount of times I use them, it would not be cost effective to have to keep replacing them. Keep them lubricated when drilling and they will last much longer

 

[rburke65]

Stop and ask an electrician, when you see a truck, if he will punch it out for you. Most times they are happy to help.

 

[Norcal]

Knockout punches are by far the best way to make a hole, especially when you get to the larger sizes. I know they make the cheaper unibits or step drills, and they are probably fine for a small amount of holes, but at least the amount of times I use them, it would not be cost effective to have to keep replacing them. Keep them lubricated when drilling and they will last much longer

I prefer a KO punch, but in the case of the OP, a hole saw is going to be the most cost effective solution, and most people would find other uses for it.

 

[Terry D]

I prefer a KO punch, but in the case of the OP, a hole saw is going to be the most cost effective solution, and most people would find other uses for it.

I agree, in post #2 I said a hole saw would be the cheapest. But as you know, contractors/electrician like us spend a lot of money on stuff to make holes

 

[sparky 1971]

I have used many hole saws over the years. They work just fine. I now use the carbide cutters up to 1-1/4", and the ko set for larger. Varibits only get used to make a hole bigger.

 

[AP514]

I used a Bi-Metal from HD....did ok job

 

[DeeKay]

Before I had a KO set I preferred step bits to hole saws( for smaller stuff). Just make sure you pilot drill because that's always the first thing to go on them.