Rusty bolt removal

[Me!]

I've got an old (Victorian?) station bench seat made from cast iron ends, and wooden slats. The wood is completely rotten, so I am trying to remove the coach bolts that hold the wood to the iron. However the bolts are completely rusted solid in the holes in the iron frame. I've tried oil, heat, twisting and hammering, but they are going nowhere so I have resorted to drilling them out. The first couple went OK, but then the 1/8” pilot drill snapped in the third, flush with the surface. The depth of the iron frame that the bolt passes through is about 2”, and it has got about 1” of drill bit stuck in it.
So, what do I do now? Any ideas please on how to get the bolt out that now contains a hardened steel drill bit in it! Looking around, I’ve found these things called Tungsten Carbide Burrs. Are they a possibility? Are they harder than a drill bit?

Help please!

 

[Feltwell]

I wouldn't bother spending 35 quid on those. Better to spend the money on the services of a local engineering company to remove it for you.

The option of last resort is spark erosion, (also called electrical discharge machining) - that is pretty much certain to do the job for you, but it's a specialist process and you've got to find someone near you who can do it.

The problem with cast iron is how brittle it is, bashing away at it with bigger and bigger hammers will end in disaster eventually. Have you tried pressing it out? A machine shop can do it with a proper industrial hydraulic press, but you can have a go at home with a big g-cramp.

First off, soak the bolts with proper penetrating oil for at least a week. Make a dam round them with some plasticine or blu-tac if need be - they need a good old soak.

Next, you want a tube with an internal diameter bigger than the bolt to go on one side to press the bolt into, and a tube with an external diameter smaller than the bolt to go on the other side if the end of the bolt is inside the hole - then use the g-cramp to press the bolt through. I've got an old, well past it's best socket set that is great for the tubes for this - lots of little bits of tubular metal in slightly different sizes!

If you've something you can brace it against, with great care I've used a car bottle jack. An engineering shop with a proper press though may be the way to go - they will be able to exert vastly more pressure than you can do with a g-cramp, but it's worth a try first.

 

[Penners]

It depends on the quality of the drill bit you used. If it's a cheap one, you might be able to grind it out with a pointed burr, or even drill it out with a good quality, larger drill bit.

Alternatively, assuming the bolt goes right through the iron frame, can you get any kind of a purchase on the other end of the bolt - maybe as tightly as you can with mole grips? If so, I would give the whole thing a thorough soaking with WD40 overnight - renew the WD40 regularly - then the next day I would wipe off as much of the surplus WD40 as possible then apply heat to the surrounding iron to expand it. I might even do this two or three times -heat, cool, heat, cool... This could help to crack the hold of the rust on the bolt. Then I would try turning the bolt both ways in its hole.

If that didn't work, I'd probably grind off the remaining bolt projection flush with the iron and then try drilling it out from the other end - this time with a rather larger diameter drill. Remember to drill have the drill running quite slowly and to dribble oil continuously on to the cut.

 

[Johnboy]

You could try drilling gently from the other end with a slightly larger drill bit. When you 'feel' contact with the old bit back off and try knocking the broken bit back out with a small punch. This has worked for me in the past but remember to wear googles when you punch it out as the drill bit may shatter.
As regards the other bolts is it possible to grind them off flush both sides with an angle grinder? The bit left in the frame would be a lot easier to drill or punch out then.

 

[Keith Bowman]

What diameter are the bolts (roughly)? A 1/8" pilot was a bit thin to be going through a 2" long bolt. I think I would have opted for a 3/16" pilot if possible. Can you get at the other side and drill up towards the broken bit? If so, once you are within a gnat's whisker of the broken off tip it might be possible to knock the thing back out with a suitable punch. (I tried that on a bush I was tryng to pin to a shaft yesterday and now have a bush pinned with two broken drill bits )
Alternatively a solid carbide drill bit ought to chew through an ordinary high speed steel drill bit, but they are pretty brittle and you have an inch to drill through. I know nothing about tungsten carbide burrs - sounds more suitable for attacking ceramics or glass but might be worth a try.
Do you have access to a welder? Welding on to the end of the broken bit might give something to grip.
Lastly - how about going back to plan A and punching the whole coach bolt out - the main thing is to give really rigid support to the underneath of the part it's jammed in. (Something like an anvil.) Trying soaking it with diesel for a day or two first.

Which area of Suffolk are you in? We are in the bottom left hand corner.

About three other posts before I tried to press submit but here's my offering for what it's worth!

 

[Me!]

Thank you for the replies.
The bolts are about 1/4" diameter and the holes in the cast iron are about 3/8", but far from being any gap between them it is absolutely solid! I've worked on old cars for years so I'm no stranger to rust, but these bolts are seriously stuck. The parts of the bolts above the iron (the bit in the wood) had pretty much rusted away completely, so it was that side that I hacksawed through, centre punched and then started drilling from. The other ends have all now 'gone' as well, sheared by locking two nuts together and turning, mole grips or welding extra leverage on.
I have also tried pressing them through using a two legged puller before I got to the drilling option, but no luck. I've now also had a look at trying to use a bottle jack, but the frame has an armrest above the bolts and a tie-bar below them so I can only get about 6" clearance either directly above or below the bolts in the same plane which drastically limits how I can brace any kind of press. I do have an anvil, so I am just about to go out and make some blutack wells around the remaining bolts and fill them with diesel before trying again next weekend.
I'm in north Suffolk, near Eye, but you will probably hear the cheering even from the bottom left hand corner when they finally come out

 

[Keith Bowman]

Today's tip from the VSCC forum is to fill the 'dam' with boiling vinegar, pour it off when cool and then do it again. Apparently brown vinegar is specified in the recipe!

 

[Me!]

OK, ... and do you happen to know please if blutack is boiling-vinegar proof?

 

[Keith Bowman]

OK, ... and do you happen to know please if blutack is boiling-vinegar proof?

Not a clue. But you'll be able to add to the sum total of human knowledge when you try it. The original idea comes from John Gill who suggested dum-dum. If all else fails try chewing gum!

 

[Penners]

OK, ... and do you happen to know please if blutack is boiling-vinegar proof?

Blu-Tack and boiling vinegar is a well-known recipe for a poultice, to be applied sores, boils, quinsies, goitres, snakebites, carbunkles, corns, moles, scabies, ingrowing toenails and cauliflower ears. It also makes a warming soup and an excellent brass polish.

Don't try this at home, children.

 

[philpjuk100]

Blog's the stuff for work, Blog's the stuff for play,
Blog's the stuff, when you feel rough, to chase the blues away
or you could try SNIBBO!

 

[Me!]

Well, after a week of soaking with diesel, still no movement on the remaining bolts. I didn't try vinegar as I had already filled the wells with diesel but next time I will give it a go. Possibly, if it wasn't into cast iron, and I could be a bit more energetic with the hammer then they may have moved but I doubt it. However, I bought one of these cheaper carbide burrs and a die grinder and they are fantastic. They went through the Erbauer drill bit with ease. I broke another pilot drill (a 9/64" this time) in one of the other bolts and the grinder soon removed that as well. Definitely a long overdue addition to the tool box, and one I certainly recommend.

 

[Keith Bowman]

I think it's the 2" depth that's defeating the penetrating fluid approach. Leave them soaking for a year or more and you might get a result! Drilling seems the way to go, using care and patience. I told you solid carbide drill bits would chew through broken HSS drill bits with ease - the burr thing is presumably solid carbide as opposed to the tungsten carbide burr you mentioned in the first place? To run the die grinder you presumably have a compressor - not your average DIY piece of kit (though ALDI occasionally have them for less than £100). Would the carbide burr work in a dremel type thing? A picture of the restored seat will be required when you have finished

 

[Flyfisher]

Coincidentally, I've just done exactly the same thing. Fortunately, the rusted nuts/bolts/screws were not so badly corroded that they couldn't be gently hammered out of the cast iron framework. I used stainless nuts/bolts/screws when replacing all the rotten wood so I'm hoping never to have to do the job again.

 

[LadyArowana]

Those are beautiful FF, great job. Were they in a really bad condition before you restored them?

 

[Flyfisher]

Thankyou. The softwood slats had mostly rotted, particularly at the ends where rainwater would accumulate, and a few were missing. I didn't do anything to the metal castings other than remove the worst of the accumulated moss. Unfortunately, I didn't take a 'before' photo.

 

[Me!]

Well, I've finally got around to finishing it.
So, pictures as requested -




The wood I've used is cedar which I'm planning to leave untreated unless people think that is a bad plan?

 

[MdB]

Well done Me!

erm...

Well done You!

erm... whatever - the bench looks great..

 

[FamilyWiggs]

Splendid job by me. Or you. Whoever!

 

[LadyArowana]

Yes indeed, Me has done a splendid job...... and if that comment doesn't bring Mr P out of hiding then nothing will :lol: