Snapped Bolt Thread in Cast Iron Housing

[zappastix]

Hi,

RE: Snapped Bolt Thread in Cast Iron Housing

We have a multi fuel cast iron stove.

It has a door with a window (as normal), and either side thin oblong windows.

After three years of use, all the glass is in a bad way, and one has cracked in half.

After removing the door so it could lay flat, I then spent many hours trying to free the
pathetic four bolts with each head as a mix of Philips/Flat, that hold the main door glass
against metal clips.

Drenched over and over with WD 40, wacking the screw/bolts really hard, they were not shifting.
Mole grips could make a purchase - but still no go. Very rusty with grude.

I then tried Mapp Gas Blow Torch and that finally released them, so I could remove the glass,
and after cleaning the door up will be able to fit new glass with new fittings.

But things have not gone so well with the two side windows.

First, so difficult to reach the top & bottom screw/bolts on either side through the
removed door opening.

So couldn't get hammer in for flat head screwdriver, so tried WD 40 again, and finally
went to heat.

On the top on either side they finally came out BUT "both bottom ones" were solid.

So with Mole grips, managed to get a hard purchase on both bottom screw/bolts,
and then moving really, really slow they both moved a fraction and then immediately
just snapped.

>>> Of course this has left both threads in the cast iron. <<<

With the two top bolts removed, I can see that;

The threaded part of the bolts, are only 5mm wide and 10mm in length + the head.

If somehow I can remove (unscrew?) the two snapped threaded bits, without damaging
the threads - I can then use the new screw/bolts I've got.

Appreciate any advice/help - last time I did metal work was 1967 so a tad RUSTY.

Thank you in advance for any help.

Stephen

 

[RandomGrinch]

My goodness, you've had an adventure!

If you could post some pics, it might give us a better idea of what you are up against!

 

[zappastix]

Thanks RandomGrinch

I'll have to do that later on this afternoon (Monday).

Ta!

 

[Harry Bloomfield]

So couldn't get hammer in for flat head screwdriver, so tried WD 40 again, and finally
went to heat.

WD40 is not a penetrating lubricant, there are much better solutions. Try proper penetrating oil. Wrap something like cotton wool around the thread, then soak it with the oil and give it time to work.

 

[JohnD]

Plus-Gas is very good.

A can will last several lifetimes

Paraffin also penetrates tiny gaps but needs to be cleaned off afterwards and parts re-oiled as it promotes rust

 

[Keithmac]

I'd drill them out personally.

 

[RandomGrinch]

I'd drill them out personally.

Yep, but access seems to be tight according to OP:

First, so difficult to reach the top & bottom screw/bolts on either side through the
removed door opening

That's why I thought a photo might help

 

[lostinthelight]

It could be tough if its like a Broseley Winchester. If you cant get at it with a stubby angle drill sometimes the only solution is to dismantle the stove , repair and rebuild .

 

[JohnD]

if you have to drill it, use a left-handed drill. often the combination of torque, vibration and heat will wind the stud out.

I'd try to avoid stud extractors. If you snap one it will be very much harder to remove.

A drill stand and vice will hold it steadier and give better results than hand.

 

[zappastix]

Thanks for all response on this.

I'm sorry I forgot to add this about the snapped off bolt.

They both snapped off directly in line with the stove housing.

Just a thought, if I use a very thin needle type drill or say a 3mm
to remove the pressure on the centre, do you think this might release
the thread so I could pick it out?

Remember these are so short at 10mm in length.

Thanks.

 

[Keithmac]

Can you post a picture?.

 

[lostinthelight]

The other reason for a bolt not wanting to come out other than the threads actually seizing or bottoming out is pressure under the head caused by whatever its holding down expanding due to rust.
When the latter is the cause then once the head has twisted off the thread may come out a bit easier .
Getting a drill straight on is crucial and you need to drill accurately in the centre with a view to retap if it doesnt come out. Once you get a hole right through the stud you can get penetrating fluid down it so it can work from tother end of the thread . As already suggested with a left hand bit is sometimes useful.
And as said we would like pictures please

 

[Harry Bloomfield]

A method I sometimes use, is to weld a nut onto a thread. That both heats the thread up to help free it and allows a spanner to go on it to unscrew it.

 

[lostinthelight]

A method I sometimes use, is to weld a nut onto a thread. That both heats the thread up to help free it and allows a spanner to go on it to unscrew it.

Likewise, but in this instance with a 5mm thread which is level with the surface and, in a confined space , it may prove challenging.

 

[zappastix]

I'm back yet again, so late.

I will not bore you again for being so late in getting back to you all, especially after the Consumer Unit nightmare.
As you'll note, it's gone past 2.30am - my first chance to post a few images that have been requested.

If any images seem to show the inside of stove as really Red Rusty, it's not, I used one of these new yellow
work lamps that is a powerful LED. The LED changed the image colour.

Before this happened the Chimney Sweep had spent sometime cleaning it a few days before.

Uploading the images now.

Many thanks.