surface box multiple knockouts align with trunking advise

[Telecoms_man]

Hi Guys,

I have to fit an MK 3 way grid surface mount box below 3" metal trunking and require the use of all three knockouts on the top of the MK surface box. This needs to be repeated for a number of surface boxes.

Cutting one hole in the trunking for a 20mm coupler and bushes is easy, but any tips how I can cut all three so they align?

MK have no details (that I can find) on their web site as to the hole spacing or have any templates.

My initial thoughts are either to measure carefully the surface box knockouts to find the centre & spacing of each knockout & make my own template on a piece of cardboard,

or,

offer the surface box up to eyeball & mark the centre of each hole and drill a pilot hole. Offer the surface box up again and use the knockout to align a Qmax cutter, to punch out the first hole. Fix the box to the first hole with bush& back-nut, then punch out the remaining holes.

or,

similar to the above, but cut the bottom of a surface box to use as a template & use a hole saw without the pilot drill.

Thoughts, help tips appreciated.

 

[Risteard]

Knock them out and then draw a circle in the inside of them with a marker butted up to the trunking. Then drill these out.

That's the easiest way in my view.

I'd also put an extra lockring between the backbox and the trunking if you're not putting couplers in so that you can get the accessory on!

 

[Dustydazzler]

As above its just a case of using a sharpie marker to draw where the holes will go...
cut them out and use a bush and lock ring

 

[ipf]

THINKING CAPS NEEDED, lads.

I'd definitely be getting my tape measure and 90 degree angle out.

 

[Telecoms_man]

THINKING CAPS NEEDED, lads.

I'd definitely be getting my tape measure and 90 degree angle out.

I will be using conduit couplers to space the surface box from the trunking.
Using a bush for the first hole was just to make it easier to cut second and third holes.

The issue is, all three holes have to be drilled dead on centre, else they won't line up.

Drawing round the knockouts with a sharpie will give a circle, not a point to drill. A hole saw has a pilot drill, needing a centre mark. I don't trust myself to guess correctly the centre of each circle

 

[ChrisElectrical88]

??? Come on, drilling centre of a hole int hard, you will get a couple of mm play aswell

 

[ipf]

I will be using conduit couplers to space the surface box from the trunking.
Using a bush for the first hole was just to make it easier to cut second and third holes.

The issue is, all three holes have to be drilled dead on centre, else they won't line up.

Drawing round the knockouts with a sharpie will give a circle, not a point to drill. A hole saw has a pilot drill, needing a centre mark. I don't trust myself to guess correctly the centre of each circle

Good luck then. I'm baffled.

 

[Dustydazzler]

I can’t see an issue with drawing around the holes And using a 20mm hole cutter...

unless you are miles of centre with the hole cutter it will line up well enough to fit the Couplers

 

[R-fur]

Remember the bushes have a reduced area between the thread and the hex that gives a bit of wiggle room and as you are using a coupling you will have the wiggle room at both ends so you should have no problem. Just assemble it all loose before you tighten anything.

 

[hasel5]

Heard it all now

 

[Telecoms_man]

Heard it all now

Why?

I'm trying to do a neat job. The 'professionals' have made a right cak job of everything, shoddy install, no pride in their work. Did not even fit blanking ends on the 3" metal trunking or grommet strip on the sharp edges of the trunking where they have cut a lump out to butt a horizontal piece to a vertical piece, where they should have used a Tee piece to do the job properly. They have put a bit of old metal trunking round the DNO cable running up the wall and it just stops, no neat finishing, just sharp cut edge. I'm really tempted to call NICEIC to see if they would like to inspect it.

 

[hasel5]

Think you are over thinking a very every day run of the mill task TBH

 

[ipf]

Why?

I'm trying to do a neat job. The 'professionals' have made a right cak job of everything, shoddy install, no pride in their work. Did not even fit blanking ends on the 3" metal trunking or grommet strip on the sharp edges of the trunking where they have cut a lump out to butt a horizontal piece to a vertical piece, where they should have used a Tee piece to do the job properly. They have put a bit of old metal trunking round the DNO cable running up the wall and it just stops, no neat finishing, just sharp cut edge. I'm really tempted to call NICEIC to see if they would like to inspect it.

Let's have a look at it, then. If it's a load of carp why didn't you say....instead of getting in a panic over something as basic as marking and drilling 3 x 20mm holes.

 

[Telecoms_man]

Let's have a look at it, then. If it's a load of carp why didn't you say....instead of getting in a panic over something as basic as marking and drilling 3 x 20mm holes.

Hi,

It is three 20mm holes that have to align exactly with the three 20mm knockout holes in one surface box.

Just drilling three 20mm holes is easy, but each one has to line up exactly with the pre-made holes in the surface box. Then I have to repeat it multiple times.

Just wondered how other people do it, what tips they have or what experience they have with doing this. Are there any 'tricks of the trade'?.

Think I will measure very carefully, then make a jig, to give the centre point of each hole.
Can then test it first on a bit of scrap, if it works, then will be easy to mark each set of three holes, pilot drill & pop out with a Qmax.

I'm certainly not panicking, instead, I'm sitting back, not rushing and taking time to think of the best way to achieve a neat professional looking job. I have posted in the sh** work section some of the stuff left by the 'professional' NICEIC registered electricians who just f***ed everything in as quickly and shoddily as humanly possible. I have been asked to de-cak some of their work and want to ensure it is super-neat.

 

[richy3333]

Dont make a jig. Buy an extra box and then take a saw to it to get a template from the top of it to mark and drill the holes? Thats what I'd do.

 

[James]

Hi,

It is three 20mm holes that have to align exactly with the three 20mm knockout holes in one surface box.

Just drilling three 20mm holes is easy, but each one has to line up exactly with the pre-made holes in the surface box. Then I have to repeat it multiple times.

Just wondered how other people do it, what tips they have or what experience they have with doing this. Are there any 'tricks of the trade'?.

Think I will measure very carefully, then make a jig, to give the centre point of each hole.
Can then test it first on a bit of scrap, if it works, then will be easy to mark each set of three holes, pilot drill & pop out with a Qmax.

I'm certainly not panicking, instead, I'm sitting back, not rushing and taking time to think of the best way to achieve a neat professional looking job. I have posted in the sh** work section some of the stuff left by the 'professional' NICEIC registered electricians who just f***ed everything in as quickly and shoddily as humanly possible. I have been asked to de-cak some of their work and want to ensure it is super-neat.

nice to see people who take pride in the appearance of there installs.
anyone can make it work
most can make it safe
some can make it look good
many can do it in the time required

A true professional,
MANAGES ALL THE ABOVE AND THROWS IN SOME GOOD CUSTOMER SERVICE.