I don't know the size of this vice, so this may not help…

With the vice dismantled, can you set the two parts on the bench-drill or mill to drill the screws out and re-tap the holes? They are quite likely either BSF or BSW, so finding replacement screws might be difficult, though.

It used to be possible (may still be for all I know) to buy special vice jaw screwdrivers. These were stubby things, of hexagonal section, to take a wrench and/or cross-drilled for a tommy bar. The 'other' end was pointed, intended to sit in the slot of the opposite jaw's screw. The driver was engaged with the screw ro be removed, and located in the opposite screw by gently tightening the vice. Cam-out prevented! You might be able to use one of the screwdriver bits intended for magnetic drivers, etc., but a larger diameter is better for the gorilla-like forces usually required.

The straight blade screwdriver bits out of the common, inexpensive, 1/2" drive hand held impact driver sets make an adequate substitute for the proper vice jaw screwdriver on smaller vices. But the drive hex is smaller so not as easy to get monster gorilla force on.

Given that I've used the big straight blade on mine about twice in 40 years I'd probably weld a bar directly to the blade head for maximum leverage at minimum distance.

There is always the good old weld a nut on standby. Its claimed that the heat helps release things.

Clive

Neither molasses or WD40 are ideal for this job. Molasses is an inconsistent natural product and how good or bad it is at removing rust is in the lap of the gods. Vinegar is more reliable but I would go the whole hog and buy a proper chemical rust remover. Be careful when buying because one type converts rust into a hard black covering – absolutely not wanted in this case.

Although WD40 isn't completely hopeless as a penetrating lubricant, it's not much cop either! Again, buy some proper Penetrating Oil and use that instead.

Heat is a good way of opening up rusted joints. Metal expands and contracts with heat and cooling and this tends to shatter rust and weaken thread-locker. Physical shock tends to break rust too, hence Impact Drivers.

Patience is a virtue if the screws are to be removed without damage.

I'd try:

1. Mechanically clean the screw heads and then with rust remover.
2. Heat jaws with a blowlamp – too hot to touch rather than red-heat, and allow to cool. Repeat.
3. Apply penetrating oil and leave overnight
4. Test for loosening, if still tight repeat steps 2,3,4

Dave

As Kiwi Bloke and Mike say, using the vice itself to stop cam out is a good strategy. heat and patience are also your friends, but if all else fails resort to an angle grinder to get the heads of the screws off.

Neil

.

That could get very messy [countersunk screws]

MichaelG.

If the screw slot is already gone too far by camming out.

Try tightening first, sometimes this actually does work.

you can use an old screwdriver and hammer to 'chisel' on the outer edge of the screw slot. Lots of anticlock medium taps with a 1lb hammer.

If too much screw head is being chiselled off it's time to break out the welder, mig or stick, hit the screw head with it till it glows, don't hit the jaws the weld will be mega tough to grind off. Then chisel it again, it will come out, if there's nothing to chisel use a spot punch.

Hydraulic Cylinder Oil for best penetration, Motor cycle fork oil same.

Regards Ian.

Normfest Oxim Ultra seems to work as well as most things I've tried as a penetrating oil, as does the Lidl one, though the latter only turns up occasionally.
Also worth a try is a 50/50 mix of ATF and acetone.

One I've not tried it yet, though I now have some in stock, is tincture of iodine.
I saw that one advocated on a British Motorcycle group on Facebook.

I too used an impact driver bit, which I re-ground previously to have a shorter spade part, tightened in the jaws of the vice and with a large spanner.

If anyone is planning on replacing the jaws with new hardened ones, drop me a PM as I know someone who makes them to order. Record No 1s might be a bit small to be cost effective though

Bill

Edited By peak4 on 23/03/2020 12:54:47

Hit it with a hammer OUCH! Robert Butler

Plus gas is a very penetrating oil,the cheapest is diesel fuel,it always seems to find its way out of steel fuel cans via the joints. I use an impact driver for tight screws,though the short vice driver sounds a good idea must work in a similar way to the special tool for removing the screws in automotive dynamos,I am pretty certain that the screws are Whit thread,if csk whit screws are not available try using UNC they are same pitch as whit except for 1/2 inch and 5 degree difference on the thread angle will not matter on a vice jaw screw,if the screw slot,a 1mm or 1.5 mm cutting disc in an angle grinder can be used to cut a deeper slot it will of course put a cut in the vice jaw but a narrow slot will not matter.

As others have said, be careful about replacement screws. 'Fraid I can't remember the details, but the screws in one big Record vice I reconditioned had a countersink included angle of less than 90 degrees and were of a finer pitch than I expected. I was expecting Whit. or possibly UNC, but they were possibly finer than BSF. Had to make new ones.