Citric Acid and Pitted Cutters

[Vann]

Maybe this should be two threads, but anyway, here goes.

I bought a Stanley No.78, not because I need one (I’ve got a Woden W78) but because it came with some Record 050 cutters, and my Record 050 came with just one cutter (a ½“ plough).

The cutters turned out to have a fair amount of rust, so into the citric acid they went.

Now here I digress. Have you noticed that irons that emerge from the acid bath are darker on the business end than the top end of the cutter? I used to think this was an effect caused by hardening/quenching.

But when I look at these two Record 03 irons, I notice that while they’re darkened on the face (up to, or just short of the slot), on the back they don’t show the same darkening. I conclude that these are laminated irons, and only the harder steel on the faces has darkened – as both face and back will have been quenched simultaneously. So maybe the blacking is the result of the higher carbon content of the harder steel.

And if so, does that mean that the citric acid is leaching the carbon…?

Anyhow, back to the main story.

When they came out of the acid, the extent of pitting at the sharp end is more obvious.

I have started flattening the face of several irons – first on the coarse, and then on the fine side of my old combination India oilstone.

It looks like these will be able to be saved if I grind off the first 1 to 3 16ths of an inch.

However the beading cutters are another story. If I grind them back that much, they’ll become plough cutters.

Has anyone here tried to repair a cutter in this state (let alone 6 of them)? Should I invest in a slip and try manually grinding the hollow bead back that much? I’m loathe to abandon them, as the chances of finding more beading cutters are not that great.

Ideas…? Suggestions...?

Cheers, Vann.

 

[GazPal]

The acid is etching the hard and softer steels at different rates and this is much of the reason behind colour and differences in reaction. It's handy if someone wishes to find whether or not a blade/iron is laminated, or how far it's been hardened from it's edge. I doubt the acid leaches carbon, although - if strong enough - it can thin a blade/iron by quite a degree within a matter of days if left in the solution.

The blades you have may be worthwhile restoring via grinding and re-shaping with slips, but it'll be a fairly long process unless you've a bench grinder with stones contoured to match the sizes you're aiming for. Well worth the effort by hand, but much easier with a powered grinder.

 

[Sheffield Tony]

Given the amount that you'd need to grind off, I honestly think I would just buy some O1 ground flat stock and start again. Assuming it is to be a user.

 

[Jelly]

I would think it was worth trying a die-grinder with a very small burr or stone on those bead-cutters, it's going to be arduous with a slipstone, but you could (with a steady hand and a spray bottle to let you lubricate/cool the grinding) probably follow the original bevel with a die-grinder, and then use the slipstone to refine the ground edge.

 

[AndyT]

Ouch!

They do look too far gone unless you are going to use them as blanks for a new shape.

I'd keep a lookout for some more cutters if you really want to use some - they aren't that rare, and most cutters will fit most plough/combis with a little modification to the adjuster notch. If you really really want to use a particular size, people like G&M Tool sales regularly split old sets.

 

[Cheshirechappie]

Before you try regrinding, it may be worth checking how much can be ground away before the cutter becomes too short to engage the adjuster and still present an edge to the work. It would be irritating to spend a couple of hours grinding back to and honing a really good edge, only to find the cutter is now 1/16" too short to work.

 

[Vann]

I've been meaning to update this thread for a while. Now that I've linked it to another thread, I guess I better get on with it...

I repaired the box, and ground most of the cutters back beyond the worst pitting.

The plough and T&G cutters were not too hard to do.

The beading cutters however, are more of a problem. Only the 5/16" cutter (centre) was reasonable. The other beading cutters are in the "too hard" basket. I guess I'll tackle them one by one when and if I ever need them.

Cheers, Vann.

p.s. It's a good thing I brought them out to photograph when I did - there's rust forming on the T&G cutter