# Best way to remove concentric knockouts



## 3phase (Jan 16, 2007)

I seem to always knock out one larger that I need and no reducing bushing of the correct size on the truck. I'll try that method next time.


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## MDShunk (Jan 7, 2007)

3phase said:


> I seem to always knock out one larger that I need and no reducing bushing of the correct size on the truck. I'll try that method next time.


Me too, brother. Some brands are worse than others. The Cutler Hammer outdoor 200 amp disconnects have up to a 2-1/2" knockout, and I only need the 2" knockout most of the time. That last concentric ring is only a little sliver, and it seems to want to come out anyhow. I always have a 2-1/2 x 2" reducing bushing handy for these, just in case. I prefer to use reducing bushings with a locknut on each side rather than a pair of reducing washers. Just seems so much sturdier, even if a couple bucks more in cost.


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## robertwilber (Jan 22, 2007)

I find a lot of them really dodgy.
I have often resorted to using a KO punch to be safe.


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## MDShunk (Jan 7, 2007)

robertwilber said:


> I find a lot of them really dodgy.
> I have often resorted to using a KO punch to be safe.


I had a helper that would do that quite often. I'm just too hard headed. I always try, then proceed to sometimes mess them up. There's nobody to yell at me! I guess my old helper was used to people yelling at him if he took out too many.


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## macmikeman (Jan 23, 2007)

On the big ones like the 2" that will break open the 3" all to easily resulting in an expense for the reducers, I use a short length of 2" pvc to brace the reverse side while I hit inward on the inward facing ko. Same deal for outward punches, I brace the hole with a larger size of pvc to hold the ko's in place while I hit.


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## Joe Momma (Jan 23, 2007)

MDShunk said:


> Me too, brother. Some brands are worse than others. The Cutler Hammer outdoor 200 amp disconnects have up to a 2-1/2" knockout, and I only need the 2" knockout most of the time. That last concentric ring is only a little sliver, and it seems to want to come out anyhow. I always have a 2-1/2 x 2" reducing bushing handy for these, just in case. I prefer to use reducing bushings with a locknut on each side rather than a pair of reducing washers. Just seems so much sturdier, even if a couple bucks more in cost.


Reducing bushing; is that the same as an "RE"?

If so, good tip :thumbsup:


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## Megawatts (Jan 12, 2009)

Joe Momma said:


> Reducing bushing; is that the same as an "RE"?
> 
> If so, good tip :thumbsup:


Reducing washer is the correct term.  RE's are reducing ends threads on outter and inner for like 3/4 connector into a ridged coupling. Put a 3/4 to 1/2 RE in the end for like a 1/2 greenfield connector. Like making a homemade from to. 

Plus with the KO's, you also need to use a grounding bushing.


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## Mountain Electrician (Jan 22, 2007)

Megawatts said:


> Reducing washer is the correct term. RE's are reducing ends threads on outter and inner for like 3/4 connector into a ridged coupling. Put a 3/4 to 1/2 RE in the end for like a 1/2 greenfield connector. Like making a homemade from to.
> 
> Plus with the KO's, you also need to use a grounding bushing.



I was taught to call the reducing washers "Chinese money". Concentric KO's can be a PIA for sure. I've always removed them the way MD's pics show, but even then it's a good idea to have some Chinese money handy.


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## gilbequick (Oct 6, 2007)

Here's what I do and I NEVER knock out a knock-out to large accidentally:

Take your tin snips and snip the knock-out size that you're going to be taking out in half, like this: 










Doing so takes almost all the pressure off of the next size up when you're prying and bending the one you want out. Plus, it makes it easier to get the one you want out. Give it a shot you might just like it.


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## Roger123 (Sep 23, 2007)

gilbequick said:


> Here's what I do and I NEVER knock out a knock-out to large accidentally:
> 
> Take your tin snips and snip the knock-out size that you're going to be taking out in half, like this:
> 
> ...


Real nice, I like it!


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## waco (Dec 10, 2007)

Roger123 said:


> Real nice, I like it!


I always use my dikes to cut through the concentric I want out, working from the innermost concentric out. Problem with generalized instructions is that the knockouts are sometimes stamped so badly that a knockout punch, step drill or hole saw might be the only solution.

I have also reverted to using a Dremel to cut through the "links."


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## TheRick (Apr 13, 2008)

waco said:


> I always use my dikes to cut through the concentric I want out


 
:thumbup: ME 2!


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## SmithBuilt (Jan 9, 2009)

The dikes are so simple. I'm mad at myself for not thinking of that.

I think of all time lost by my employees trying to knock out one hole.


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## waco (Dec 10, 2007)

SmithBuilt said:


> The dikes are so simple. I'm mad at myself for not thinking of that.
> 
> I think of all time lost by my employees trying to knock out one hole.



It does require a good pair of dikes. My angled Kleins did it best, but they are gone, probably in some insulation filled attic.


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## 220/221 (Sep 25, 2007)

I don't believe I have ver used sidecutters to remove Ko's. *Angled dikes* are my number one tool. I use them *way* more than sidecutters.

I don't always start at the middle and work out. Over 1 ", I almost always hold the fitting up to check the size. Scrounging for a reducing washer is a total waste of time and my stock always seems to be hit or miss on the larger sizes.

Some are not punched out enough and you need to use the snip method. Depends on when they last put a new die in the punch. 

Also, I HATE when that last little piece doesn't want to come out and it is at a difficult angle. A little 16th of an inch causes all kinds of problems.


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## 480sparky (Sep 20, 2007)

Given a choice, I'd much rather all electrical panels & large j- & pull-boxes be blank instead of having factory KOs.

If I'm forced to used factory concentrics, I make 100% sure I don't take the next-size-larger KO out accidently by using my trusty-dusty-rusty Greenlee QuickDraw 90 to it once I have the ½" KO in the middle out.

Otherwise, I use gilbequicks' method.


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## waco (Dec 10, 2007)

"Also, I HATE when that last little piece doesn't want to come out and it is at a difficult angle. A little 16th of an inch causes all kinds of problems."

That's when I use my step drill bit to clean up the hole.


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## user4818 (Jan 15, 2009)

KO's come in two categories: Those that can be removed with just fingers, and those that won't come out without a cold chisel and 3 lb hammer. There doesn't appear to be middle ground.


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## Tiger (Jan 3, 2008)

If it doesn't come out easy I knock the center one out & use a Slugbuster.


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## rexowner (Apr 12, 2008)

waco said:


> I always use my dikes to cut through the concentric I want out, working from the innermost concentric out. Problem with generalized instructions is that the knockouts are sometimes stamped so badly that a knockout punch, step drill or hole saw might be the only solution.
> 
> I have also reverted to using a Dremel to cut through the "links."


I used to drill through the desired size link, but felt this 
as a big time waster, and it's usually easier to just do
one at a time as shown in the 1st post. I sometimes
screw up and bust a larger size, but only at the worst
possible time.


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## calimurray (Apr 29, 2007)

did you ever use a hole saw? if you cut slowly it'll cut the links and the knock out will usually fall out 9 times out of ten this works instantly and perfectly.


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## paul d. (Jul 13, 2008)

EXACTLY why do the manufacturers even put concentric k.o.'s in disc.? to sell bond bushings? as a " convenience" to us poor electricians? i'd rather knock my own darn hole. too cold to work. think i'll go fishing. paul


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## waco (Dec 10, 2007)

speaking of hole saws, about the best I had for this was carborundum. It cut the links without grabbing into the metal as others do. And, I have run regular saw backwards to grind through the links.

That carborundum saw was pretty expensive and subject to wearout, but it worked.


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## 480sparky (Sep 20, 2007)

paul d. said:


> EXACTLY why do the manufacturers even put concentric k.o.'s in disc.? to sell bond bushings? as a " convenience" to us poor electricians? i'd rather knock my own darn hole. too cold to work. think i'll go fishing. paul


 
Amen to that!




Oh, and yes, I agree. Except for things like 1900 boxes and the like, tubs, panels, gutters, etc. should not have KOs at all. I hate 'mickey mouse ears' KOs when I punch out between two factory KOs. Gimme a blank hunk of sheet metal, a Quick Draw 90 and a C-frame punch and I'll give you a work of art.


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## Southeast Power (Jan 18, 2009)

I usually have a helper to teach and always hold the connector next to the KO and mark the correct size with a sharpie so that they are very aware of the importance of not screwing it up


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## cdnelectrician (Mar 14, 2008)

I agree with not having factory KO's in panels, gutters and splitters...I don't know why they haven't caught on yet. There is NOTHING worse than having a factory KO in the way when you are laying out disconnects on a new splitter, and one of the conduits falls on half of the factory KO. With all the splitters and D and E boxes being made in China these days, the whole KO usually comes out and you have to use reducing washers. On a new job, it looks like a$$!


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## iaov (Apr 14, 2008)

Peter said it. They either come out too easy or else you need TNT.I wish they would leave them out of the big boxes too. I'll put my own holes in thank you. On the tough ones I will often use a dremel to make getting the right ring out.


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## mattsilkwood (Sep 21, 2008)

480sparky said:


> Given a choice, I'd much rather all electrical panels & large j- & pull-boxes be blank instead of having factory KOs.
> 
> If I'm forced to used factory concentrics, I make 100% sure I don't take the next-size-larger KO out accidently by using my trusty-dusty-rusty Greenlee QuickDraw 90 to it once I have the ½" KO in the middle out.
> 
> Otherwise, I use gilbequicks' method.


 
i couldnt agree more.

i call em handyman specials, if you cant figure out how to make a hole 
go home


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## MrFixit-NJ (May 28, 2010)

*The KISS Factor, Keep It Simple Smartypants*

All the various solutions, while valid and likely to work, create more work than should be necessary. With the diminishing quality of manufactured anything over the last twenty-plus years it's a crap-shoot at best whether the concentric KOs (knock-outs) will easily separate or not. Through trial and much error I have found that the best/simplest way to do this is to use one or two long nose locking pliers. See the following URL for an example of them:
(NOTE: I do not endorse these, they are here as an example only)
http://www.mytoolstore.com/american/vis010.html
I place them so that they prevent the removal of the larger KOs that I do not wish to remove and then bang away with hammer and punch or sturdy screwdriver. I prefer the punch but don't always have one with me. I guess I'm too cheap to buy the extra one for my electrical tool bag. Just make sure that the pliers you get have a deep enough throat to reach the KOs.


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## JTMEYER (May 2, 2009)

+1 on the side cutters, and if I find a particularly stuborn set I've been known to use a sawzall to cut a slot out to the size I need in two directions.


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## RIVETER (Sep 26, 2009)

MDShunk said:


> RECOMMENDED METHOD (EASIEST AND BEST WAY) TO REMOVE
> MULTIPLE KNOCKOUTS
> 
> IMPORTANT: Remove knockouts ONE AT A TIME, alternating INWARD and OUTWARD.
> ...


I usually do it that way up and to the figure 3. At that point I use my dikes or [email protected] and cut thru and then bend each half towards its respective last weld. Very easy.


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## Rudeboy (Oct 6, 2009)

Paul D. = Awesome


Rip brother.


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## ramsy (Jan 20, 2009)

You guys got it all wrong.


































That's how its done.


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## John Valdes (May 17, 2007)

Take a simple task we do everyday and someone has to do a slide show on it. Are you actually that bored? I would say 99% of the people on this forum know how to remove a concentric KO. Did you just learn how and just had to share?


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## Electric Al (Mar 13, 2010)

I Agree.. The only thing I bitch about is the fact that the knockouts seldom align between pieces of equipment by different manufacturers. Why can't they standardize?


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## MDShunk (Jan 7, 2007)

John Valdes said:


> Take a simple task we do everyday and someone has to do a slide show on it. Are you actually that bored? I would say 99% of the people on this forum know how to remove a concentric KO. Did you just learn how and just had to share?


The original post was made as semi-informational as "filler" when this site first started. I'm not 100% sure why it reemerged the last couple days. I like the cutting torch approach.


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## Voltech (Nov 30, 2009)

We just got a Maxis punch. Its not often that we even see factory KO's in our cans. Of course this makes it hard when we do because we don't see them that much. I punched out some blank covers at the shop when it came in and its a great tool. Very easy


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## Mountain Electrician (Jan 22, 2007)

MDShunk said:


> The original post was made as semi-informational as "filler" when this site first started. I'm not 100% sure why it reemerged the last couple days. I like the cutting torch approach.


A plasma torch works great as well.


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## Mountain Electrician (Jan 22, 2007)

Voltech said:


> We just got a Maxis punch. Its not often that we even see factory KO's in our cans. Of course this makes it hard when we do because we don't see them that much. I punched out some blank covers at the shop when it came in and its a great tool. Very easy


That looks awesome, and not too terribly expensive. Hmmmm...Fathers Day is right around the corner.


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## Innovative (Jan 26, 2010)

gilbequick said:


> Here's what I do and I NEVER knock out a knock-out to large accidentally:
> 
> Take your tin snips and snip the knock-out size that you're going to be taking out in half, like this:
> 
> ...


Thats the method I have always used... works like a charm. Never knock out more then you need!:thumbup:


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## Frasbee (Apr 7, 2008)

I've had situations where the perforation barely makes it through the metal, and I end up beating the $hit out of it anyway. Yes, I'm referring to the center knock out.

I did work with a guy that would use either a hole saw, or unibit in that situation.


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## John Valdes (May 17, 2007)

MDShunk said:


> The original post was made as semi-informational as "filler" when this site first started. I'm not 100% sure why it reemerged the last couple days. I like the cutting torch approach.


Sorry Marc. I did not realize it was an old post revived. 
I must assume you are kidding about the torch method? Unless you guys have something new to share with the group, I am of the opinion that any cutting tools should be mechanical in nature and the use of torches would be considered hack work.



Frasbee said:


> I've had situations where the perforation barely makes it through the metal, and I end up beating the $hit out of it anyway. Yes, I'm referring to the center knock out.
> 
> I did work with a guy that would use either a hole saw, or unibit in that situation.


Some concentric KO's can be a bitch sometimes. But I have never had one beat me yet. I have used doughnuts when required....:laughing:


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## MDShunk (Jan 7, 2007)

John Valdes said:


> I must assume you are kidding about the torch method? Unless you guys have something new to share with the group, I am of the opinion that any cutting tools should be mechanical in nature and the use of torches would be considered hack work.


Oh, sure. Now you're trying to act like you don't use a cutting torch to make knockouts from time to time. Puh-leeze. :laughing:


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## Bkessler (Feb 14, 2007)

I always have a few wood chisels on me, the dullest one gets the nod for removing my tougher ko's. Which seem to be getting tougher and tougher to remove.


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## Richard Rowe (May 25, 2009)

I seem to NEVER get the correct size out, I never thought of using tin snips to cut to the size you want..... I will try that(I'm sure I won't be able to find my snips when I do this) sound like it will work.


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## jwjrw (Jan 14, 2010)

MDShunk said:


> Me too, brother. Some brands are worse than others. The Cutler Hammer outdoor 200 amp disconnects have up to a 2-1/2" knockout, and I only need the 2" knockout most of the time. That last concentric ring is only a little sliver, and it seems to want to come out anyhow. I always have a 2-1/2 x 2" reducing bushing handy for these, just in case. I prefer to use reducing bushings with a locknut on each side rather than a pair of reducing washers. Just seems so much sturdier, even if a couple bucks more in cost.


 
I use Cutler Hammer almost all the time and about 50% of the time the next ko will try to come out. Thats my only complaint with Cutler Hammer


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## william1978 (Sep 21, 2008)

Electric Al said:


> Why can't they standardize?


 They could. No KO's in any of the panels or any equipment and let the electrician punch his own holes.


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## jwjrw (Jan 14, 2010)

william1978 said:


> They could. No KO's in any of the panels or any equipment and let the electrician punch his own holes.


 

That would like be more work for me dude! Yea I know more work more money blah blah. :jester: It would be a better install but really I usally can get them out without much problem so I say let it be.


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## RIVETER (Sep 26, 2009)

jwjrw said:


> That would like be more work for me dude! Yea I know more work more money blah blah. :jester: It would be a better install but really I usally can get them out without much problem so I say let it be.


Amen to that.


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## splatz (May 23, 2015)

This is actually a good old thread. I'll admit I learned something.


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## HackWork (Oct 2, 2009)

The best way to remove KO's is to pop the first one, then cut thru as many as you need taken out in one shot with the Klein BX shears. It cuts thru them like butter. 

From the center you make 3-4 total cuts around the KO, each one cutting all the way thru every ring that you need removed in one shot. Then just take your linemans and twist out each group evenly.

This works well even on thick enclosures, I do it on meter pans all the time.


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## splatz (May 23, 2015)

HackWork said:


> The best way to remove KO's is to pop the first one, then cut thru as many as you need taken out in one shot with the Klein BX shears. It cuts thru them like butter.
> 
> From the center you make 3-4 total cuts around the KO, each one cutting all the way thru every ring that you need removed in one shot. Then just take your linemans and twist out each group evenly.
> 
> ...


That's what I'm talking about. This method is alluded to above but Hack's description and illustration is excellent. Also good call with the BX cutter. I have used that thing to cut so many things other than BX. 

http://www.kleintools.com/catalog/cable-shears/all-purpose-shears-and-bx-cutter


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## MechanicalDVR (Dec 29, 2007)

HackWork said:


> The best way to remove KO's is to pop the first one, then cut thru as many as you need taken out in one shot with the Klein BX shears. It cuts thru them like butter.
> 
> From the center you make 3-4 total cuts around the KO, each one cutting all the way thru every ring that you need removed in one shot. Then just take your linemans and twist out each group evenly.
> 
> ...


I use that method with the 1104 shears most often, they are fantastic for this.

As macmike mentioned backing them up with pvc pipe I've done that too on larger ones to brace the weak parts of the KO.


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## splatz (May 23, 2015)

MDShunk said:


> Me too, brother. Some brands are worse than others. The Cutler Hammer outdoor 200 amp disconnects have up to a 2-1/2" knockout, and I only need the 2" knockout most of the time. That last concentric ring is only a little sliver, and it seems to want to come out anyhow. I always have a 2-1/2 x 2" reducing bushing handy for these, just in case. *I prefer to use reducing bushings with a locknut on each side rather than a pair of reducing washers. Just seems so much sturdier, even if a couple bucks more in cost.*


This is the one I liked, a nice upgrade from the doughnuts. 

Likewise a reducing bushing, two locknuts, and a plug is a good alternativ


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## MechanicalDVR (Dec 29, 2007)

splatz said:


> This is the one I liked, a nice upgrade from the doughnuts.
> 
> Likewise a reducing bushing, two locknuts, and a plug is a good alternativ


Reducing washers just kind of scream 'mishap'.


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## zac (May 11, 2009)

MechanicalDVR said:


> Reducing washers just kind of scream 'mishap'.


Not more then a K.O. seal! 

Sent from my SM-G950U using Tapatalk


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## MechanicalDVR (Dec 29, 2007)

zac said:


> Not more then a K.O. seal!
> 
> Sent from my SM-G950U using Tapatalk


Too true.


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## ralpha494 (Oct 29, 2008)

It took ten years, but I think we finally got it.


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## macmikeman (Jan 23, 2007)

What is this new sport of re-opening old threads all about? Did we reach the end of the electrical rail tracks?


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## MechanicalDVR (Dec 29, 2007)

macmikeman said:


> What is this new sport of re-opening old threads all about? Did we reach the end of the electrical rail tracks?


Maybe some fear the end is coming and want to reset?

I'm just going with the flow!


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## The_Modifier (Oct 24, 2009)

Wahtever happened to MDShunk? The last I saw of him was his youtube page a few years back.


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## MechanicalDVR (Dec 29, 2007)

The_Modifier said:


> Wahtever happened to MDShunk? The last I saw of him was his youtube page a few years back.


Good question, like to know the answer myself.


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## WPNortheast (Jun 4, 2017)

1/8 hardened steel drill bit in the cordless, drill the attachment points and than all it needs is a light tap. Perfect every time


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## lighterup (Jun 14, 2013)

A carpenters hammer , my flat head Klein screw driver and as always 
KO reducer rings ( all sizes kept in stock)..


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## HackWork (Oct 2, 2009)

lighterup said:


> A carpenters hammer , my flat head Klein screw driver *and as always
> KO reducer rings ( all sizes kept in stock)*..


Yup, I like the donut/washer style reducers and keep all the various sizes. They work well and most of the time it's hard to even see that they are there.


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## TOOL_5150 (Aug 27, 2007)

I remember reading this thread back in 2007. Theres a lot of good stuff posted here back in the day.


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## telsa (May 22, 2015)

( Cordless ) Rotozip with a Dremel cutting disk -- they pair up with 1/8" collet and shaft.

Four zips, and the desired KO drops out, flawlessly.

I hate, hate, hate reducing washers... reducing bushings are fine.


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## sbrn33 (Mar 15, 2007)

The_Modifier said:


> Wahtever happened to MDShunk? The last I saw of him was his youtube page a few years back.


I don't know either but I feel I would be perfect for his Moderator spot that is not being used right now.


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## John Valdes (May 17, 2007)

I like to mark the KO with an (X).
Then lay it on a table and walk back 200 yards.
I then aim very carefully with my rifle and blow it out. Its not a clean way to do it, but it is fun as hell.
Oh...remove main first if there is one.


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## itsunclebill (Jan 16, 2007)

WPNortheast said:


> 1/8 hardened steel drill bit in the cordless, drill the attachment points and than all it needs is a light tap. Perfect every time


A non-stepped uni-bit works great as well, and placement isn't critical.


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## macmikeman (Jan 23, 2007)

itsunclebill said:


> A non-stepped uni-bit works great as well, and placement isn't critical.


I haven't ever seen a non stepped uni bit. Got a picture?


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## NormousD (Nov 12, 2017)

telsa said:


> ( Cordless ) Rotozip with a Dremel cutting disk -- they pair up with 1/8" collet and shaft.


Actually a genius idea! I have a corded rotozip I almost never use.. but now I have a reason to pick up a cordless. 

Thanks!


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