removing broken bolt in oven...

[D.M.Chapman]

Fancy self cleaning oven - went to set it to clean mode this morning and whilst removing the shelf supports one of the bolts has broken off :-(

It was tight (they always are) but not massively so :-(

So, as I now can't fit any shelves in the over, I need to get the broken bit out somehow. Ideas? Access isn't fantastic and I don't seem to be able to get to the back of the screw (there is masses of insulation that appears to be impossible to remove.

Another possible option would be just to "glue" it back somehow - any glue that might do. I'm not sure drilling it out will work but I'll give it a go when it's cooled down (currently it's at 450 deg C :-))

Bugger. And I'm meant to have a day off to fix the fence not the oven :-/

Darren

[JimK]

couple of thoughts.... might be easier to drill/move when still "hot"?

is it snapped flush or any chance of some molegrips being your friend on a stubby bit?

or those reverse screw extractors...mixed reviews ISTR but may do the trick here?

cheers JimK

[D.M.Chapman]

Will try warm later.

It's worse than that - snapped down in a hole. It's a 6mm bolt, snapped in a 5 mm recess. No chance of getting anything on the end of it :-(

Yeah. Might be the only option I suspect. Grrrrr.

Cheers,

Darren

[Bob Minchin]

Do you need to remove it? Can you not drill another hole nearby and fit a self tapping screw instead?

Bob

[D.M.Chapman]

Not easily - it needs to line up with a shaped part of the shelf bracket that hooks over the screw. It's the only bit that actually touches the side so it wouldn't be trivial to fit something elsewhere.

Last resort will be to try to make up some sort of bracket to hang down with a thread on the end. Dads got a set of reverse drills and some easyout thingers - I'll give that a go first.

Nothing to lose (he says tempting fate ;-))

Darren

[spamlet]

If it's down a 5mm hole, y not drill it right out with a 5mm drill and tap the whole thing back to 6mm, for a standard bolt or set screw? No DIY kit is complete without a basic set of taps and dies, and a set of srew extractors: once you have them a whole new world of repair opportunities arrises. The latter are hard and break easily so unless the broken bolt is fairly loose it is generally easier to drill out the softer bolt and retap. In extremis you can put a 6mm thread inside a drilled out 8mm bolt, tap this into the broken bolt's hole and then saw it off flush to take a new 6mm bolt.

S

[D.M.Chapman]

Right, that was the plan. All was going well until the bloody captive nut thinger started to spin. Grrrrr.

Anyway, long story short and all that, I now have a 9.5mm hole in the thin steel side of the oven. Ideally, I want a captive nut thinger (what are they called?) to put in but I've no idea how this would work. I'm imagining something that I poke through the 9.5mm hole and somehow swell it on the back so it becomes captive. Does this exist? If so, what is it called (and where the hell can I buy one or two and not 1000!)

Clinch nut comes to mind - is that the thing? A quick google suggests they need access to both sides of the panel which is rather non trivial (and potentially destroy the insulation that appears bonded on :-()

Maybe something like a giant (but short!) self tapping 10mm thinger with a

6mm thread in the middle - that would be perfect. Does it exist?

Yep, had all that, and some nifty backward drills that *almost* did the job. Then the nut started spinning and it all went pearshaped from then on :)

Still, most of the fence fixed. just the awkward panel to fit. Now to explain to SWMBO why we can't use the oven tonight...

Darren

[Steve Walker]

I'm sure I've seen some square nuts with a thin spring steel piece fixed over them. They push into a square hole from the side that you can get to and clip themselves in. Unfortunately I can't think of a name for them or where to get them, but maybe someone else can?

SteveW

[Tim Streater]

They're used in equipment racks. Not sure if you're thinking of cage nuts or spring nuts.

Cage nuts go into the square holes in the risers in a rack. That way when you're trying to mount the (heavy) equipment in the rack the nut is in position and all you've got to do is push the bolt through the flange on the kit, through the square hole and into the nut, which can't rotate. Easier then to do it up.

Spring nuts slide into slots in the rack (and so their position can be adjusted) but again, once in the slot they can't rotate and so it's easier for the poor bugger using them.

These klods:

them for their equipment racks although I don't know if they're suitable for what you need.

[spamlet]

That has rather made things difficult. There are numerous different designs of cavity wall fixing but whether you will find a heat resistant one that will fit in the gap and open up properly I don't know.

One further thought is that you might find that the sealer they use for exhaust pipes (Firegum?) can be used to fill the hole. Then when it is beginning to 'go off', set the bolt with its nut already on in roughly the right position, level off with more firegum, and hold it in place with something until it sets. Then run the oven up to temp to cure it before trying any load. It might work...

In similar vein, you might be able to glue a thicker piece of ready tapped plate (or a washer with your own new 'captive nut' glued to the back) over the top of the old hole (one of the push out blanks from a pattress box might be about the right size.).

S

[Dave Osborne]

Cage nuts.

[spamlet]

Just checked, and firegum swells when it is heated, so you could set it in place with a little blowlamp flame so as to avoid the water condensation when you turn on the oven

A further, 'non glue', method, might be to make an oblong of strip steel as wide as the hole but longer. Tap this in the middle. Put a nut on the bolt, followed by a washer bigger than the hole, followed by the tapped piece of steel. Manoeuvre the tapped oblong into the hole then tighten the washer down on to it with the nut, neatly covering hole and giving you a new bolt ready mounted.

S

[D.M.Chapman]

Hmmm.... cage nuts. That's an idea. I could square off the hole with my dremel and I've hundreds of cage nuts at work - we use stacks of them. Dunno why I didn't think of that.

Dunno how important it is that the oven is sealed though - I can imagine steam filling the insulation via the hole which seems less than ideal. Also, would they cope with 500 deg C? (I guess I could just never clean it again :-))

Still, it's an idea...

Cheers,

Darren

[D.M.Chapman]

Ok, that might work. I'd prefer it to be fairly air tight (so not keen on the cage nut idea) as I don't really know what's behind the panel.

Not entirely sure I follow this...

What keeps it in attached to the side of the oven?

One thing I was pondering was a strip of steel with a couple of selftappers one above, one below the hole. Then a bolt sticking out of the strip and I can then hold the shelf bracket to that with a nut+washer. Will need to check it'll still allow be to take out the shelf bracket though. Is that what you meant?

Darren

[Alan Braggins]

Rivet nut? (Same sort of thing, but designed for one sided access.)

[spamlet]

You are clamping the sides of the oven between the tapped oblong - which you have poked, on the end of the bolt, through the 9.5mm hole - and the conventional washer, by tightening the lock nut down while you hold the hex end of the bolt at the desired position. (Its a pretty standard method to use lock nuts like this - as anyone tensioning cam chains on bikes will tell you.)

Similar idea, but in my case the strip of metal is between the two skins of the oven rather than on top of the inner one, and, with a lock nut you don't need the self tappers... But you will have to make sure the nut still leaves you room for whatever the shelf attachments are, just as you would with the self tapper heads.

As for steam, I should think that firegum would fill any gaps for you whichever way you proceed. S

[JimK]

if you mounted the steel strip on the outer side of the steel skin (depends on what/how insulation is?) that could poss. be ideal?

bit of accurate drilling of oven wall and strip, strip drilled/tapped for bolt (poss with bolt already in to assist lining it all up for self tappers through oven wall into strip.....bit of firegum if you wish for attempt at seal - though 450 sounds hot for stove/exhaust gear...

Cheers JimK

[spamlet]

My BSA exhaust clamps used to glow in the dark, and the firegum/gungum still held.

S

[D.M.Chapman]

ah, so the bolt sticks out into the over forever more. Yep, I get you. Wouldn't want the head on it sticking out though, as I'll need a nut on the end so I can remove the bracket in the future. Sounds promising though

That may well work, as long as I can get the shelf thing out with a bolt sticking out. Certainly sounds more workable than trying to fit some sort of captive nut.

Will attempt to nip to toolstation and stock up on SS bolts and nuts to have a play with. Hopefully they will have something suitable for the strip to poke through the hole.

Yeah, may pick some up. The oven only gets up to 450 deg on the cleaning cycle (which I could just ignore, but it would be a shame and would mean I'd have to clean it properly :-)). Still, firegum should be fine at that temp, I've used it on exhaust manifolds that have been hotter than that...

Darren

[D.M.Chapman]

Ahha! Yes, they look like the thing that was in there. Do I need a special tool to fit them? And, where the hell can I buy a couple :-)

Darren