# Unibit Frusteration



## telsa (May 22, 2015)

power said:


> Does anyone have any experience sharpening unibits?
> 
> And secondly, have other electricians found those unibits for 3/4" and 1" knock-out holes are CRAP? I find the 7/8" hole (for 1/2" trade size fittings) unibits are fine.....but, those bitter ones are crap!! Anyone else too?


Unibits should not be used when tungsten carbide hole saws are so much quicker, cleaner, too.


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## CADPoint (Jul 5, 2007)

I like what Telsa said, I have the 660 greenlee and I think it's tops!

I don't stress them with speed or thrust!


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## backstay (Feb 3, 2011)

telsa said:


> Unibits should not be used when tungsten carbide hole saws are so much quicker, cleaner, too.


$168.40 at my SH. You use them instead of a hole punch?


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## splatz (May 23, 2015)

backstay said:


> $168.40 at my SH. You use them instead of a hole punch?


or $120 at the Greenlee Store 

http://www.greenleestore.com/produc...steel-hole-cutter-kit-7-8-1-1-8-1-3-8-1-3-4-2


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## Southeast Power (Jan 18, 2009)

power said:


> Does anyone have any experience sharpening unibits?
> 
> And secondly, have other electricians found those unibits for 3/4" and 1" knock-out holes are CRAP? I find the 7/8" hole (for 1/2" trade size fittings) unibits are fine.....but, those bitter ones are crap!! Anyone else too?


Those things make so damn much mess I flat out refuse to use them.
But yes, I have sharpen them.


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## Cow (Jan 16, 2008)

I hardly ever use unibits. Most of the time I use them for making holes in pvc boxes only.

I use Greenlee ultra cutters instead. 1/2 and 3/4 all the time. I have a hydraulic KO punch I use on 1" and larger. Works for me.

Those quick change cutters suck too. When the cutter binds up, you rock it back and forth to get it unstuck but yet, it still doesn't come out. So you put your drill in reverse to get it unstuck, but then the cutter pops loose from from the arbor. 

No thanks, I'll keep using my ultra cutters.


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## power (Feb 27, 2012)

Suncoast Power said:


> Those things make so damn much mess I flat out refuse to use them.
> But yes, I have sharpen them.


I just tried using an end mill cutter on our vertical milling machine and it wrecked the end mill! I didn't expect the steel in the unibit to be hardened THAT much. 

Anyways, how did you sharpen yours? Grinder?


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## ponyboy (Nov 18, 2012)

Unibits aren't worth sharpening. Take care of them as best you can and throw them away when they get dull. 


Sent from my iPhone using Tapatalk


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## frenchelectrican (Mar 15, 2007)

I dont use the unibit very often the only time I used them is on plastic boxes for metal boxes I use the KO punches or hole saw depending on type of metal I bore it out.

Sharping the unibits ??? IMO just junk it when ya get done because the polit bit will be furber'ed anyway.
Not really worth the extra cost to sharpen up because they are harden steel pretty much all the way to the core.


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## Glock23gp (Mar 10, 2014)

I use stepbits for 1/2". That carbide set for everything bigger.

I have had that set (1/2" - 1 1/2") since I was an apprentice and rarely have to replace the cutters and we use a lot of stainless here because of the corrosion.

Ya it flings some burning metal (unless you bust out the oil), but it's so quick it's worth it.


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## HackWork (Oct 2, 2009)

Unibits aren't for making holes, they are for making existing holes bigger.


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## wildleg (Apr 12, 2009)

I used to keep one good unibit in my bag for the odd hole. As everyone else said, there are other ways to make better/faster holes, and definitely better production. Never even tried sharpening one, but I would consider using them as fishing weights. nyuk nyuk


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## Southeast Power (Jan 18, 2009)

power said:


> I just tried using an end mill cutter on our vertical milling machine and it wrecked the end mill! I didn't expect the steel in the unibit to be hardened THAT much.
> 
> Anyways, how did you sharpen yours? Grinder?


I just dont let them get so bad and I haven't thought about using a grinder as I dont want to heat it up too much.
I have a whetstone with a nice 90 deg edge. I hold the cutting edge tight on the course side and the open part over the side.
It seems to work OK.
The only consistent use I have found for them is opening up a 3/8" hole in a surface mount enclosure so that I can use a 1/2" sleeve anchor. We have mostly CBS construction here.


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## Going_Commando (Oct 1, 2011)

I used to be a unibit zealot, but after a few crappy ones I bought a greenlee carbide holecutter kit for $77 from amazon and I am a convert. They are also nice for drilling into live gear since you basically just have to deal with the slug instead of shards of metal flying everywhere.


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## 99cents (Aug 20, 2012)

HackWork said:


> Unibits aren't for making holes, they are for making existing holes bigger.


Which leads to the question of how do you make the hole bigger with the carbide hole cutters? I have never seen them before. I just use old fashioned Slug Busters. Never owned a unibit in my life.

Aren't you the guy who uses an impact driver on a Slug Buster, Hack? I've never done it but it might be worth trying.


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## HackWork (Oct 2, 2009)

Using an impact is better than using a wrench. But using a hydraulic KO set is best.

Since I don't do that many holes like I used to in commercial work, I mainly just use a holesaw now.

If I have an existing hole and need to make it bigger, that is when the unibit comes out. 

Using a unibit to drill a new hole seems inefficient. Why turn all that material into chips of metal when a hole saw or similar will just cut the outer diameter?


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## MechanicalDVR (Dec 29, 2007)

power said:


> I just tried using an end mill cutter on our vertical milling machine and it wrecked the end mill! I didn't expect the steel in the unibit to be hardened THAT much.
> 
> Anyways, how did you sharpen yours? Grinder?


I keep them sharp by tuning up the edge with a flat diamond hone:


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## MechanicalDVR (Dec 29, 2007)

HackWork said:


> Unibits aren't for making holes, they are for making existing holes bigger.


Ding ding ding, we have a winner! :thumbsup:

When they first were introduced they had no point:











Then they added the starter tip and were for light gauge sheetmetal:


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## 99cents (Aug 20, 2012)

Unibits still have no point.


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## HackWork (Oct 2, 2009)

For people who insist on drilling holes with a unibit, I have always told them to use a 1/4" bit to start the hole. The starter tip on the unibit is what always went dull quick, the rest of it usually stayed sharp far longer.


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## HackWork (Oct 2, 2009)

99cents said:


> Unibits still have no point.


You have a half inch KO, you need a 3/4". You pop in a unibit and 3 seconds later you have your 3/4" KO.

Or, you can go out to the truck to get your KO set and crank your wrench.


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## MechanicalDVR (Dec 29, 2007)

I have the Greenlee step bit for 1/2" and 3/4" ko sizes that I used exclusively for plastic boxes and the light gauge sheetmetal of equipment cabinets, for panels and large jboxes a carbide cutter is king, heavy stuff a knockout is the way to go. Matching the right tool to the right task is key. Kills me when i see a new guy with a unibit screaming as he's trying to burn it up on something too heavy gauge that it sits and spins.


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## 99cents (Aug 20, 2012)

HackWork said:


> You have a half inch KO, you need a 3/4". You pop in a unibit and 3 seconds later you have your 3/4" KO.
> 
> Or, you can go out to the truck to get your KO set and crank your wrench.


Good for putting a 3/4" hole in a handy box  .

Just kidding  .


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## B-Nabs (Jun 4, 2014)

99cents said:


> Good for putting a 3/4" hole in a handy box  .
> 
> Just kidding  .


I once watched an HVAC controls guy turn a 1/2" KO into a 3/4" on a handy box using one of those spinning reaming tools they use for copper tubing. I had a knockout set and offered him its use, but he declined. Must have taken him 15 minutes. I don't know why he was using 3/4" either, it was for a little 5' stub up into the ceiling for his thermostat wire.


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## 99cents (Aug 20, 2012)

B-Nabs said:


> I once watched an HVAC controls guy turn a 1/2" KO into a 3/4" on a handy box using one of those spinning reaming tools they use for copper tubing. I had a knockout set and offered him its use, but he declined. Must have taken him 15 minutes. I don't know why he was using 3/4" either, it was for a little 5' stub up into the ceiling for his thermostat wire.


Funny, when I started Zero Cash Flow Electric, I bought my Slug Busters off an HVAC dude  .


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## MechanicalDVR (Dec 29, 2007)

99cents said:


> Funny, when I started Zero Cash Flow Electric, I bought my Slug Busters off an HVAC dude  .


Confucius says: too many HVAC guys huff freon and ruin brain capacity, causing poor decisions.


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## splatz (May 23, 2015)

I keep a large unibit in the top tray of my toolbox. It doesn't take up much space and it makes holes for 1/2", 3/4", and enlarges 1/2" to 3/4" in boxes. I also use it to punch holes in top plates etc. for whatever. I use it to make or enlarge holes for bolts, rod, etc., not just conduit. A hole saw set or bigger bits would be better but this is much handier to have on hand at all times. 

If you don't want to spend the big bucks for a good one, Harbor Freight makes cheap ones, but they really are not going to last as long. However if you have sticky fingers around or just lose things a lot it might make sense to buy the cheapos. 

As for sharpening - I wrap the cutting edge in tape when I put it away so it doesn't get dull rolling around in the toolbox. If you want to sharpen it, if the one you have is a flat grind, there's not much to it with a flat stone or diamond, just never touch the round outer surface. That might not put a factory quality edge on it but it's probably the best you're going to do and trying to do more might not end well.


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## MechanicalDVR (Dec 29, 2007)

splatz said:


> I keep a large unibit in the top tray of my toolbox. It doesn't take up much space and it makes holes for 1/2", 3/4", and enlarges 1/2" to 3/4" in boxes. I also use it to punch holes in top plates etc. for whatever. I use it to make or enlarge holes for bolts, rod, etc., not just conduit. A hole saw set or bigger bits would be better but this is much handier to have on hand at all times.
> 
> If you don't want to spend the big bucks for a good one, Harbor Freight makes cheap ones, but they really are not going to last as long. However if you have sticky fingers around or just lose things a lot it might make sense to buy the cheapos.
> 
> As for sharpening - I wrap the cutting edge in tape when I put it away so it doesn't get dull rolling around in the toolbox. If you want to sharpen it, if the one you have is a flat grind, there's not much to it with a flat stone or diamond, just never touch the round outer surface. That might not put a factory quality edge on it but it's probably the best you're going to do and trying to do more might not end well.



I love those 3 for $1 gold Harbor Freight bits, toss em as soon as they show wear


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## tjb (Feb 12, 2014)

That's not how you spell frustration.


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## macmikeman (Jan 23, 2007)

HackWork said:


> For people who insist on drilling holes with a unibit, I have always told them to use a 1/4" bit to start the hole. The starter tip on the unibit is what always went dull quick, the rest of it usually stayed sharp far longer.


I just send a tek screw thru first for the pilot hole with my impact and then back it out. That seems to work fine and awesome for me.


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## telsa (May 22, 2015)

macmikeman said:


> I just send a tek screw thru first for the pilot hole with my impact and then back it out. That seems to work fine and awesome for me.


They are my universal starter bit.


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## Southeast Power (Jan 18, 2009)

I can usually make a 1/2" KO into a 3/4" KO with a 3/4 size holesaw pretty quick.
You just have to not be afraid of it hopping out a couple of times at first. 

If I need to blast a few pilot holes. I use a C-punch. Its just not worth a crap if the hole is more than 8" inside of the can.


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## Gnome (Dec 25, 2013)

I've wished on many occasions I had access to one of those. Be a lot faster when I've had to punch dozens of holes in JBs/boxes.


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## flyboy (Jun 13, 2011)

I hate unibits. I have a small scar under my left eye from using one of those friggin things.

Lately, I've been thinking about getting a tear drop tat to cover it.


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## Southeast Power (Jan 18, 2009)

Gnome said:


> I've wished on many occasions I had access to one of those. Be a lot faster when I've had to punch dozens of holes in JBs/boxes.


It might be too late for you but for a $209:

http://www.ebay.com/itm/GREENLEE-17...018201?hash=item41b7974459:g:ll0AAOSw8w1X~uRK


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## Bird dog (Oct 27, 2015)

Sometimes Unibits are the best option for drilling live panels. Second best is a hole cutter b/c it does have a shoulder.


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## telsa (May 22, 2015)

Suncoast Power said:


> I can usually make a 1/2" KO into a 3/4" KO with a 3/4 size holesaw pretty quick.
> You just have to not be afraid of it hopping out a couple of times at first.
> 
> If I need to blast a few pilot holes. I use a C-punch. Its just not worth a crap if the hole is more than 8" inside of the can.


I keep that puppy at the shop. It's mated to pneumatic-hydraulic power so I don't have to do more than step on a pedal. 

It's proved too cumbersome for field work, though.

The big holes are two-stepped. First with a 1" KO then to final with a classic Greenlee punch.


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## MechanicalDVR (Dec 29, 2007)

flyboy said:


> Lately, I've been thinking about getting a tear drop tat to cover it.


Yeah boy, cause that just screams CLASS......................and MS 13!!


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## Lone Crapshooter (Nov 8, 2008)

I thought I was weird because I did not like unibits. Ihave 2 around here someplace 1 I got from Brown & Root the other someone gave me.
Haven't seen eather one in years.
LC


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## Flyingsod (Jul 11, 2013)

I've never sharpened one. You shouldn't have to really. You know you should have your drill in low speed and not pull the trigger all the way when you are cutting the larger size steps? At that size the outer edge of the bit is turning incredibly fast and can get dis tempered from the friction heat. Use cutting oil too. My step bits last for at least five years. The ONLY trouble I have with them is if someone else uses it.

There always a step bit in my drill case because there is easily enough room to always have it. There's not always a hole saw kit with me because they are too bulky to grab for every call.

Sent from my C6725 using Tapatalk


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## Jarp Habib (May 18, 2014)

One guy I worked with had cut the flats off of a 3/4" hole saw bit so that he could thread a 1/2" bit onto the arbor as well. The smaller hole saw centered the larger and enlarged the holes just fine. I've also seen a guy just stack the two bits, only threading the outer bit. It rattled around a lot but the finished hole wasn't atrocious.


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## MechanicalDVR (Dec 29, 2007)

Jarp Habib said:


> One guy I worked with had cut the flats off of a 3/4" hole saw bit so that he could thread a 1/2" bit onto the arbor as well. The smaller hole saw centered the larger and enlarged the holes just fine. I've also seen a guy just stack the two bits, only threading the outer bit. It rattled around a lot but the finished hole wasn't atrocious.


I have a couple arbors that you can thread two hole saws on, done that many times.


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