Resharpening disk-type oil sink cutters?

[Betzel]

Greetings,

I recently got an old set (6 pieces, double-ended, brass handled with steel disks) for a reasonable price (so I thought!) on eBay thinking they would be good enough to use, but they're not cutting very easily.

Not getting much from a fingernail scrape, so I thought I would try re-sharpening them. But, before I do, I thought I would see if anyone else had tried this / how it worked out. The thing that is difficult for me is keeping/holding them straight so the disk edge stays flat at 90 degrees, like an ice skate. And, they are just pinned, so the spindles that hold them in the brass are not great.

Anyone have a success story to share?

So far, I'm thinking maybe of wedging them (with some pegwood) into a T slot on the cross slide, oiling the pivots, then bringing them up to a cast iron lap from the screwhead polisher, held in a 3-jaw turning slow with some diamond paste on the wheel. Maybe placement like a car's front wheel on the road with too much toe-in lets it turn a little, but skid across the surface so it cuts at a slight side angle. All theory, and no practice though. Must be a better way...

TIA if you can help!

 

[DeweyC]

Greetings,

I recently got an old set (6 pieces, double-ended, brass handled with steel disks) for a reasonable price (so I thought!) on eBay thinking they would be good enough to use, but they're not cutting very easily.

Not getting much from a fingernail scrape, so I thought I would try re-sharpening them. But, before I do, I thought I would see if anyone else had tried this / how it worked out. The thing that is difficult for me is keeping/holding them straight so the disk edge stays flat at 90 degrees, like an ice skate. And, they are just pinned, so the spindles that hold them in the brass are not great.

Anyone have a success story to share?

So far, I'm thinking maybe of wedging them (with some pegwood) into a T slot on the cross slide, oiling the pivots, then bringing them up to a cast iron lap from the screwhead polisher, held in a 3-jaw turning slow with some diamond paste on the wheel. Maybe placement like a car's front wheel on the road with too much toe-in lets it turn a little, but skid across the surface so it cuts at a slight side angle. All theory, and no practice though. Must be a better way...

TIA if you can help!

Why not just remove the discs and flat polish them on an Arkansas stone?

This cannot be done using any kind of paper/film abrasive since the flex will round the edges.

 

[Betzel]

Thanks for the idea of sharpening the other two surfaces. Had not thought of that!

Because these are (75+ years?) old, made from slotted brass with a thin steel (taper?) pin as a pivot which is peened in, the process of removing and replacing the 12 would work, but it would be time consuming. Plus, there is not a lot of brass on the fine tips if I get into a pickle.

If I don't hear (or think of) a better idea, I'll try the above hare-brained scheme and report back. I'm thinking if the lap is faced smoother and the charge-film is very thin, the diamond paste will cut fast to avoid excessive wear of the pivots, and I hope not enter the pivots either, but we'll see.

I'll still wish I had bought a new set, but will eventually get over it...

 

[Bohemian Bill]

Hi All...I have a newer set of oil sink cutters for watches and the only way to sharpen them that I see it is to grind pin, punch pin out & remove the disc and mount them in a lathe and use a fine arkansas stone or fine diamond lap...The hard thing is to find or make a tiny wheel mount for true turning on lathe..maybe possible using shellac to secure or attach....Bill

 

[wefalck]

Apart from the wax chuck, I could also think of these tiny tapered wheel arbors for turning between the centres. Or you make your own arbor by turning a shoulder of the pin diameter on a piece of stock held in a collet. Fix the disc to the shoulder with a bit of shellac or CA cement.

You don't need to grind/hone the entire disc, but perhaps only a millimetre from the outside. In this way you retain the original thickness where they are mounted and don't need to tamper with the slots.

 

[Betzel]

Well, the more time-consuming ways will produce better results, but I just wanted them to cut. Now, for 25 bucks they all "catch" on my thumbnail

A light press against a very slow-turning cast-iron lap with a thin charge of diamond (5 micron) paste worked. No disassembly, and it took less than a minute on each end. These are old and for clocks and pocket watches, I think. New would have been better, but my used tool disappointment is fading.

Turns out the cutting disks have a great deal of wobble in all directions (surprise!), so not very centered. The eye focuses on the edge of the disk only, while everything else flops around. And, the lap was not running true either. So, I was better off eyeballing and doing it freehand visually against the corrosion, like watching oil streaks on a burnish. You only need a few degrees off-center to see what's happening as it cuts a snail-like pattern. This is improvement, not perfection. Some of them may be more than 90 degrees, due to slop, so one side cuts better than the other, but they work now.

Thanks to all for the constructive ideas!