Is there any trick to make unscrewing easier from old wood?

[tibi]

Hello,

I am now disassembling my great grandfather's workbench made from oak. I need to replace some boards on it and I have found that there are many nails in the workbench, that were probably added later for holding things together by my granddad.

There are some flathead screws that are holding vice hardware and the wood is so dense that I have no chance to unscrew them without spoiling the flat head.

Also I have one nail that I am unable to beat out from the other side. The wood would break sooner than it would eject the head out of when beating the tip with a hammer.

Is there any trick that would soften the wood around a screw/nail so that it can be unscrewed/pulled out more easily? Would steam help here?

Thank you.

 

[TRITON]

I think steam would cause the surrounding wood to swell, making it tighter.
One way is to tighten a screw before undoing it, or maybe use an impact screwdriver. Failing all put on a center mark then drill off the head. Once the head is off and the vice removed there should bee a stub of the screw you can grab with molgrips. Molgrips are fantastic for taking out old screws or bolts where you only have a small bit to grab on to

 

[Gordon Tarling]

If the screws are steel, they'll almost certainly be rusted in the oak. If you can't unscrew them by using vice grip pliers or similar, then perhaps look at using some sort of plug cutter to cut the wood around the screw, then you can fill the hole with a suitable dowel.

G.

 

[tibi]

If the screws are steel, they'll almost certainly be rusted in the oak. If you can't unscrew them by using vice grip pliers or similar, then perhaps look at using some sort of plug cutter to cut the wood around the screw, then you can fill the hole with a suitable dowel.

G.

Yes, they are rusted. However I would need to put new screws for hardware in the same place, that is why I wanted to preserve as much original wood as possible.

 

[steve66]

Ditto for the plug cutter method, you can cut a plug to refit afterwards

 

[D_W]

I don't know of anything - once they rust in place, they're a bear and the cross section of good steel in the center is reduced, increasing the chance that they'll break.

The only way to reduce pressure on the screws is to drill close to them (with obviously unwanted results).

 

[D_W]

(I probably could've added extra words - unwanted results not being failure to extract, but rather the holes left behind and something to deal with if inserting newer screws).

 

[Tris]

I'd second Triton's suggestion about tightening the screw slightly if possible, then I'd try heat from a soldering iron with a chisel tip in the screw head. It might be possible to get enough swell and shrinkage to break the rust bond and undo them.
If that doesn't work I'd go with Gordon's suggestion.

 

[D_W]

follow up question here - but with my experience in something like this being that you can often get one or two out (especially with nails) or 90% out or whatever and have a few that won't come out because they're too badly rusted.

If you're going to try to apply a lot of pressure without something like a hammer/impact, a brace is probably helpful, or a specialty bit for a ratchet if you have anything like that Then you can get a good feel for what's going on and try to go both ways to loosen the screw before bringing it out. The wood is going to flex a little bit either way, so stuff like tapping on the top of the screw probably won't do anything. As good of a blade as you can get (crisp, square and if you can, maybe roll a small burr on the ends of the drive bit as is typical for gunsmith's stuff to keep a screwdriver in place) and then something like a ratchet or brace will give you a feel for what you can get.

I'd avoid impact (just personal experience) as I've not had great luck with it on something that can bounce without breaking loose (as in, the screw can flex a little bit without any rust actually letting go).

The burr on a flat screwhead should help prevent the bit from lifting a little bit and ruining the slot. Slow with hand pressure on something like a brace, though, and you can feel a lot of what's going on- though sometimes rust letting loose feels the same as a screw starting to break (especially if the screws are coarse grained).

I spent a day for a guy once knocking nails out of oak boards (a wealthy local guy who was selling his land for development - several farms - but wanted to keep every single thing he'd ever stored on any of the farms) and the conclusion of it was that I could get about 90% of the nails out, the others weren't removable without splitting or sawing them out and then he never used the wood or got rid of it because nobody wanted it (don't blame them).

 

[Ttrees]

I'd not be hopeful of the screws holding out, though saying that I normally encounter "brassish" screws in iroko doors, another timber with seemingly a good amount of tannin,
but do find some windows with small steel ones.
Normally the rust has rotted the surrounding timber and they just pull out with the latches/catches or whatever ya call em.
I just do my best to clean out the slots and deepen if necessary, half the time they break
and I drill a hole either side of the screw, a beater flathead screwdriver, old pliers which you don't mind destroying when you grasp it with a vicegrips.

A narrow plug looks nicer and hides better than a square one!

Tom

 

[Bingy man]

You could also use a screw extractor ( various types available) a centre punch used lightly followed by a small pilot hole drilled into centre of screw ( enlarge hole if reqd) insert the screw extractor and turn anti clockwise. The extractor has a left hand thread which I turn will remove the screw . Works fine with brass and steel but not so easy with hardened or stainless steel. I find you get little or no damage to surrounding timber and by examining the screw you will know if it’s come out intact . Nails are a bit more problematic as you don’t have enough surface area to work with so the previous posts advising a suitable plug cutter is probably the best way . Drill out enough to expose the nail head or if you want to reduce any surface damage then use the same procedure but from underneath -you only need 1/2 “ exposed to as others have suggested get a pair of mole grips , pliers etc onto the exposed section and remove nail- I use a lot of reclaimed timber so I get this problem a lot . I use a pair of linesman pliers which have serrated lines which grip anything you can get hold of but they need a decent hole .

 

[Richard C-D]

As a restorer I've had to get screws out of up to 250 year old furniture and usually succeed by heating the screw as already mentioned. I use a heat gun unless I need to avoid blistering the polish when a soldering iron on the head will work. After a couple of minutes try tightening the screw very slightly before unscrewing. If it turns a little tighten back and then unscrew again, hopefully it will turn further. Repeat if the screw is hard to turn but it should start to come out after four or five turnings. Sometimes heating again will help, then repeat.
Don't force it too much as you will either break the screw where the thread starts or shear off half the screw head. Use the right size screwdriver and check the slot is clear of muck or paint, a slight tap on the driver will help. I've got extractors but never used them so can't comment but if a screw won't shift at all will the extractor work any better.
Nails will come out better with heating but you might need to remove some wood to get at the head.

 

[recipio]

The American store Rockler sell a nifty screw extractor. It simply removes a plug of wood around the screw and then you can use a molegrips to twist the screw out. It works a treat although maximum size is only 3/8 " Replace it with a glued dowel which is absolutely fine for inserting new screws.

 

[Sandyn]

I think using a pancake style induction heating coil might get the screw or nail red hot and burn the surrounding wood enough to slacken it.

 

[--Tom--]

Screwdriver bit in a brace is very hard for slotted screws to say no to. It’s the main reason I’ve kept my brace.
Otherwise make sure you have a screwdriver bit that fits the slot well and then apply as much torque as you can. If the head snaps off you can revert to the drill and plug approach.

 

[Rob_Mc]

Whenever I need to get a difficult nail out with minimal damage I usually reach for my Slide Hammer Nail Puller. If you haven't seen or used one before the video below shows it's operation;



Once you've driven the jaws in to get a hold of the nail head you can exert a lot of leverage to pull the nail out easily. It's surprisingly effective in practice. Have pulled some big nails out of both hardwood and softwood.

This was the one I bought from Amazon a few years back;

https://www.amazon.co.uk/gp/product/B001CKAR4Q/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1

 

[cerro]

Snap-on screwdriver insert in the screw and give it one or two hard blow with a hammer, then unscrew always works for me.

 

[glenfield2]

I don’t know if it’s any use to your job but I’ve got a lot of nails neatly out of boards by punching them in and then pulling them out with pincers or pliers from the reverse - less damaging to the wood surface than punching back from the ‘pointy end’

 

[tonywatkins]

I agree with the advice to use a brace. I know from bitter experience that a drill/driver is likely to wreck the head. Probably best not use a modern screwdriver, even if it appears to be the right size, as the heads usually taper in so that the pressure is put on the top edges of the slot, not the whole sides of the slots. If that's all you have, can you hollow grind it so that the sides are parallel and exactly the right width for the screw slot?

 

[tibi]

I will need to buy an extractor, as the heads are so soft. Screws do turn, but the flat heads just destroy themselves before I can apply any torque.