how to cut rusty steel tube from thin SS skin.

[evanvine]

£75!!!!!!! to weld up 1 fitting!!! (im in the wrong game)

Sorry to go off topic.
Broke a key in a Euro lock, local locksmith wanted £150 to replace, got a new lock + keys from Screwfix £9.

 

[Fil]

£75!!!!!!! to weld up 1 fitting!!! (im in the wrong game)! Get a blow lamp some acid and some silver solder and do it yourself!! prob less than £20! . And yes silver solder will be strong enough (you could try lead free but im not sure how it would take to s/s (just found a link on homebrewtalk.com on doing just this!!

I checked out the homebrewtalk site and think i found the loooooong thread you mean..

i tried a bit of SS brazing with silver rods to mount/seal a washer to a hex nipple, my propane torch didnt get the heat up and i was a bit kak handed trying to spoon the dry powder flux onto the hot piece, and the big metal vice heatsink i was brazing on didnt help.. not a great success that..

i dont know if my ol torch will be suitable for using a higher temp gas like map? the control knob is already a bit heat damaged and needs a bit of a pinch to ensure it bites on the control nut :)
so would be happy with a skin fitting like aleman and kev suggested..

if i use a tct cutter how do i minimise the risk of tearing the skin? i have a length of 8'x2' i can drill a hole in to drop the pipe thru and make a stable base to drill against.
should i invest in cooling oil? if so how much? or could i try drilling under an inch of water?

 

[Kev888]

Yeah, silver solder can need to be very hot; there are different grades/melting points but you do need a very hot torch, especially if there's a lot of metal attached to the joint. It can be strong enough, but its not as good as welding unless the joint has a reasonable surface area - theres a youtube vid somewhere, where a chap dimples the edges of the hole to do that.

The best way to stop tearing the stainless is to prevent the cutter wandering, and use a slow drill speed with the drill held perpendicular to the metal and an even pressure on it, though reducing pressure as you hear/feel it start to go through.

To stop it wandering I'd personally hammer something like some hard wood/dowel into the pipe so that the pilot drill has something to bed into, its mainly this that keeps the cutter located. And if possible get a cutter thats big enough to clear the existing weld - as well as being thicker the stainless around the pipe could be work-hardened.

Cheers
Kev

 

[Fil]

cheers Kev.. Exactly the sort of hand holding i need :) Is this a suitable tct cutter?? http://www.ebay.co.uk/itm/Starrett-FCW0 ... _544wt_812

it has not got SS in the list of suitable materials, and appears to have just 2 cutting teeth??

the use of the words wood hole-saw in the description also make me doubtful??

 

[Kev888]

I don't know for certain, but I'd be doubtful unless anyone has actually tried them; they look a bit 'general purpose' and don't seem to mention metal of any kind.

Also the same manufacturers make some specifically for stainless here, which suggests they feel theres a need for that addition. These certainly do work, IMHO much better than the cobalt tipped holesaws.

Cheers
Kev

 

[Fil]

I don't know for certain, but I'd be doubtful unless anyone has actually tried them; they look a bit 'general purpose' and don't seem to mention metal of any kind.

Also the same manufacturers make some specifically for stainless here, which suggests they feel theres a need for that addition. These certainly do work, IMHO much better than the cobalt tipped holesaws.

Cheers
Kev

PHEW!!! i was this close to ordering the wrong thing!!! thanks for the heads up..

and those beasts dont need additional bits or drills too thats a fantastic pointer cheers Kev.

after measuring the weld and what looks like a couple of mm heat damaged/hardened sheet it looks like i will need to cut a 33mm hole just to avoid that.

So a 1" bsp skin fitting with a holesaw to cut a 34mm hole as according to wikipedia the major thread diameter for a 1" bsp fitting is 33.249mm should be what i need :) unless a 3/4" fitting has a wide enough lip to enclose a 33-34mm hole?? the asap site is a little lacking in the description and dimensions of its bits..

 

[Kev888]

yes a 1" skin fitting should work well - though if its bigger than you want you could step it down with a socket reducer to make any subsequent taps/fittings smaller and so cheaper.

The skin fittings I got from ASAP were 3/4", they have a flange diameter of about 49mm (and a threaded part of about 26.5mm diameter) so they aren't completely out of the question if you cut your hole reasonably cleanly. The washer and nut for the outside of the skin are only about 38mm though, so you'd maybe want to add a bigger washer and find some way to keep it centered in the hole.

I don't immediately know where you could get such a big washer in stainless, though they must exist, but being outside the tank (the skin fittings seal on the inside) you could probably consider brass fittings without any particular detriment too. Or in fact mild steel, but in that case I'd put a plastic washer between it and your stainless tank.

EDIT: looking at the skin fitting prices, I'd probably do it properly with the 1" one - by the time you've mucked about and bought washers etc bodging a 3/4" one I'm not sure it'd be worth the saving. Though if you needed to adapt it to a smaller tap that would of course cost more for the adapptors as well.

Cheers
Kev

 

[Fil]

seems like a solid plan :) i wiil get the hole cut and fit the skin fitting before considering the options to plumb further.. probably a 80 degree bend and reducer to 3/4" to 19/20mm hosetail onto silicone tube to a mounted valve..fun fun fun :)

 

[wezil]

strange but true when cutting stainless use white spirit and drill slowly (make a small resevoir out of plasticene to hold it) this keeps the bit cool and stops the stainless work hardening. (oil dosen't always transfer heat fast enough) Any way GOOD LUCK! PS re: the new euro lock do yourself a favour and buy a more expensive one (check out youtube for how to defeat a cheap one!!! it's seconds to do it in!! paid £30 for mine!

 

[Fil]

thanks for the tip wezil. how much more effective would a small pool of white spirit be than running the garden hose over the work area as i was planning?

and forgive my ignorance but what is the new euro lock? or the old one for that matter ?? the only euro lock i know of is the cylinder door lock thingy (thanks google)??

the bits for the drain have arrived, so I can have a go this weekend :)

so the plan is to chop off the magority of the pipe leaving no more than 1cm standing pround behind. this is enough clearance to allow me to cut from the outside
(cutting from the inside would be awkward and dark)

i will chock up and support it upside down with a sacrificial plank underneath the cut.
fix the garden hose to run over the work area? (or pool white spirit??)

use my fully charged 18v controlable drill and slowly cut the drain out while my feet get cold n wet no doubt:)

my only concern in drilling from the outside in is will the cut indent into the pan making sealing a problem?

 

[wezil]

Cant see a prob with the hose (other than it would flood my workshop)!! and the euro lock is a cylinder thingy mostly found in pvc doors!

 

[jamesb]

Do you fancy doing mine after?

 

[Aleman]

Do you fancy doing mine after?

Converting it to a Hot Tub then James ?

 

[jamesb]

Converting it to a Hot Tub then James ?

A hot something, yes.