Anyone know anything about strong magnets?

23 replies
Found 10th May
ok need to trace a pipe located in an gable end wall covered in skim of cement and krend render (approx 2.5" total thickness)
idea was push magnet to end of pipe from inside and dust iron filings on outside of wall to locate pipe and carefull drill thru from outside so as to not crack render. mad i know but gotta be worth a shot.

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23 Comments

why not just by a pipe/stud detector from b&q? I don't think your idea would work.

Original Poster

bigtimthecrispman

why not just by a pipe/stud detector from b&q? I don't think your idea … why not just by a pipe/stud detector from b&q? I don't think your idea would work.


i do have one and it gives me a rough idea but thought the magnet idea would give more visual accuracy, i have tried this on thin board with a smallish magnetic hook and it worked there but there are a vast amount of magnets available and obviously some suppliers won't be quite as honest with specs.


Neodymium magnet can be very powerful you might be able to "find" its location with a hand compass or possibly a compass in a smart phone. ALiexpress take a while but maybe Amazon have some of the magnets.
aliexpress.com/who…rod

A hand compass is best because you can see the dip or lift of the pointer to get the height right.

Metal detector is the way to go if it's a metal pipe. As above, small ones are sold specifically as pipe and stud finders.
amazon.co.uk/s/r…77W

Old speakers have magnets in.. not sure how strong you need or if you have any old speakers..

Just been reading about possibilities using Neodymium magnets in Break You by Blake Crouch. I've been the Desert Places series over the past week or two making me a bit paranoid. DONT help this guy he might be a SERIAL killer

google " oids magnets" these are strong magnets usually found for a couple of quid

Original Poster

unfortunately its a plastic waste pipe and the reason this is the best suited method is simply because we want a "surgical" cut as the stuff the wall is rendered in is quite expensive and apparently a **** to match on colour.
There is a standard of measurement for magnets but it is more related to physical aspects i don't understand.
having tried a magnet which was advertised as having 18kg draw and finding it unable to hold more than a few kilos on direct contact and with penetration of only a few centimetres thru thin but not thick plasterboard this was £4 so don't want to keep buying ones that are not suitable
As the pipe is imperial its approx 1.5 inch in diameter this would be the optimum size but the ability to penetrate the cement is likely to be the problem here.

Replace the pipe with a new one mounted on the outside of the render.

Original Poster

michaelgold

Replace the pipe with a new one mounted on the outside of the render.



i intend to replace the pipe but that still leaves me with the problem of getting the water out of the bath room so i will still require a neat hole to be cut for the new pipe.

maddogb

i intend to replace the pipe but that still leaves me with the problem … i intend to replace the pipe but that still leaves me with the problem of getting the water out of the bath room so i will still require a neat hole to be cut for the new pipe.


I don't fully understand what your doing so I might be totally off the page.

I would leave the old pipe where it is, disconnect it from inside the bathroom. Get a long drill bit and drill a new hole right through to the outside then use a core drill inside and out to the correct diameter of hole.
Fit new pipes, Mounted outside going into your downpipe.

But if you just want to locate the exit point from your wall. Drill through the pipe inside. When you get through the brick ease off the pressure on the drill and let the drill bit do the work.



Edited by: "michaelgold" 11th May

Original Poster

michaelgold

I don't fully understand what your doing so I might be totally off the … I don't fully understand what your doing so I might be totally off the page.I would leave the old pipe where it is, disconnect it from inside the bathroom. Get a long drill bit and drill a new hole right through to the outside then use a core drill inside and out to the correct diameter of hole.Fit new pipes, Mounted outside going into your downpipe.But if you just want to locate the exit point from your wall. Drill through the pipe inside. When you get through the brick ease off the pressure on the drill and let the drill bit do the work.



you're along the right lines, thing is the old pipe will likely have just been cut off when the wall was rendered, at best they will have shoved a bit of stone or pebble in to the hole then covered with a dash of cement then the krend.
I suspect because of this and the thin fragile layer, any attempt at cutting or drilling from inside may leave one large ugly hole, drilling inwards with a core will give us the best chance of getting a neat hole with no subsequent need for patching of the render.
also with walls 18" thick accessing the inside of the pipe laying between floor joists with any precision is almost impossible.

If you've got an old hard drive you don't mind ripping apart, they've got Rare Earth magnets inside. Ridiculously strong!

Original Poster

miikeyblue

If you've got an old hard drive you don't mind ripping apart, they've got … If you've got an old hard drive you don't mind ripping apart, they've got Rare Earth magnets inside. Ridiculously strong!




cheers for that, i probably have half a dozen older ones i could pull apart may save some cost, really interested if there is any patterns or combinations that may achieve the desired result, kinda like how they do those levitating bars but opposite lol

maddogb

cheers for that, i probably have half a dozen older ones i could pull … cheers for that, i probably have half a dozen older ones i could pull apart may save some cost, really interested if there is any patterns or combinations that may achieve the desired result, kinda like how they do those levitating bars but opposite lol



I know nothing about diy so can't advise further on that. Magnets are only small too so you may need a few. They're also a pig to remove from the drives... They're fitted to a bracket, I found the best way was to bend the bracket with a couple of pairs of pliers to create a gap under the magnet.

It may not get you the results you're looking for but if you have them laying around it could be worth a go.

Why not just carefully drill a small guide hole using the smallest drill bit you have from inside then drill the main hole from the outside?

Original Poster

joedastudd

Why not just carefully drill a small guide hole using the smallest drill … Why not just carefully drill a small guide hole using the smallest drill bit you have from inside then drill the main hole from the outside?


its a 32mm pipe going thru a wall 18" deep between two joists some 18" apart, not that easy and given u need the floor up doing it whilst balanced on those joist combine to give very little chance of success.

Original Poster

miikeyblue

I know nothing about diy so can't advise further on that. Magnets are … I know nothing about diy so can't advise further on that. Magnets are only small too so you may need a few. They're also a pig to remove from the drives... They're fitted to a bracket, I found the best way was to bend the bracket with a couple of pairs of pliers to create a gap under the magnet.It may not get you the results you're looking for but if you have them laying around it could be worth a go.



i found an old maxtor 40gb and pulled it apart, only 1 screw holding the actuator magnet in place quite an easy job to get at but prob gonna need four of them to get a circular shape and will probably be then too big but you are right it is very powerful.

I hope you will tell us when the deed is done.

Original Poster

john52

I hope you will tell us when the deed is done.



i've just ordered some magnets off ebay, hopefully they will be up to the spec described as i found a calculator for field strength (https://www.kjmagnetics.com/fieldcalculator.asp)
using the hdd magnets i was able to move one magnet by another through approx 1.5" of sandstone so initial tests look promising.

Original Poster

ok the magnets arrived and having inspected the pipe run to the rendering i was able to insert one magnet at the end of the pipe and get the other magnet to stick to the outside of the wall as planned, would like to get some iron filings to see what the effect is before i go ahead and use the core drill to cut thru.
btw the magnets off ebay were n52 25mm diameter 20mm thick..

Put cornflakes in a blender and when they are dust run a magnet up the side of the blender bowl. The iron added to the cornflakes will adhere to the magnet.
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