Correcting for an asymmetric tang

[2bit_collie]

Hi All,
So I recently acquired a nice French 15/16 rattler grind. The only issue is that the blade doesn’t center between the scales when you close it. You can see it’s off in the photo below.

At first glance I thought this was because of scale warpage. For sure one scale displays a noticeable (but not distorted) bow while the other is nearly flat. I initially thought that this might be due to shrinkage of one scale relative to the other. However after unpinning the scales I realized that the real issue is that the tang is asymmetric. Whether it was bent, ground poorly, etc, not sure but that is the situation. You should be able to tell in the below photo that the upper edge is sloping down much faster than the lower edge is sloping up.

Interestingly, among the rest of my relatively large collection, I have seen this only one other time, on a Torrey that is also a rattler grind (hmm, is there something in the process that encourages this?).

So looking for suggestions on how to address. I don’t really care about straightening out the blade, and I don’t have much in the way of equipment for bending metal. I just want to get scales put on it that such that the blade doesn’t hit the edge of a scale. I never did solve the issue on the Torrey by the way, I just have resigned myself to always being really careful when I close the scales.

So some thoughts:
1) Just make a new wedge that is much wider. In theory if I make the wedge wide enough, the blade will miss the scale even if it is still off-center. Might have to be really wide though - the blade contacts the scale about 2/3 down. It doesn’t seem like the overlap is much, but that likely is because the blade is exerting force on the scales once it is placed between them.

2) shim up the scale on one side at the pivot hole. Not sure that this would even work, as the asymmetry will change as a function of the angle between the blade and the scales.

3) drill the holes at slightly different distances on the scales. We know that shrinkage can cause the scales to be off-center. Maybe adjusting for the distance between the wedge hole and pivot hole can compensate?

4) bending the tang - again my thought based on past experiences is that this would be difficult to do and get right.

I do have the original horn scales. Some minor bug damage but otherwise in good shape. I can make new scales if necessary and I’ve half a thought to do that just as an experiment to try out option 3.

Looking forward to your feedback.

 

[Darth Scandalous]

You could try adding an extra thrust washer on one side to correct it. It's not elegant but it can work. May need to sand out the inside of one scale where the shank rides too.If making new scales, you can drill the pivot holes at slight angle, not perpendicular. This is a little tricky but more elegant. I don't think trying to bend it is going to go well.

Can't quite tell from the photos, does it have both a bend and a twist?

 

[Mr Bedlington]

If you have access to a grinder, you could lightly grind one side of the tang, you will be surprised how little you will need to grind to make the blade sit correctly in the scales.

 

[2bit_collie]

If you have access to a grinder, you could lightly grind one side of the tang, you will be surprised how little you will need to grind to make the blade sit correctly in the scales.

I have a belt sander. I suppose that is a possibility. Thanks!

 

[2bit_collie]

You could try adding an extra thrust washer on one side to correct it. It's not elegant but it can work. May need to sand out the inside of one scale where the shank rides too.If making new scales, you can drill the pivot holes at slight angle, not perpendicular. This is a little tricky but more elegant. I don't think trying to bend it is going to go well.

Can't quite tell from the photos, does it have both a bend and a twist?

OK, that is certainly easy enough to experiment with. So I would say that it is mainly a bend, but there may be a slight twist is well. The whole thing is a bit asymmetrical, the two sides of the spine are not exact mirror images of each other. I have to think that this razor was ground using a single grindstone, not two like Die Hexe(sp?).

 

[Gamma]

I've had a lot of wedges like this. Without holding it it's hard to suggest a path. To me it looks like the tang is bent and it also seems like the grind at the tang is canted to the blade wants to sit on an angle. Could just be the photo though
Fixing a cant is a pain... you can make a tapered washer, which is not fun. Sand the scales on the inside to correct that cant, little easier. Angled pivot holes, maybe. Depends on how it maps out as you go. Adding a second pivot washer might correct for the warp but not the cant usually. Basically, the scales have to be shaped to match the grind. Sure, if you have a belt grinder you can take the tang to task maybe. The blade will look different where it was ground though.

 

[H Brad Boonshaft]

Does the razor sit flat on the “straight side up to the pivot hole? If so try making a Wedge that is tapered on only one side. Lead is easy to work and period correct.

You would not need to pin the razor to see if it would work, clamp with a spring clamp with pin rod through the holes for alinement.

If you grind the tang, use a Dremel and drum, belt sander can be risky. Dremel with a flex shaft offers lots more control.

I recently got a razor that was rescaled and had the punched pivot hole shimmed with a brass tube. The hole was crooked so the tube was also crooked. I removed the tube shim and re pinned, I use PETE thrust washers and it closes smoothly and centered.

I would first experiment with the wedge and re-grinding the pivot hole, check to see if the pivot hole is square to the razor center and that the edge is centered with the spines center line. Adjusting the pivot hole may be your easiest and less obtrusive solution.

 

[2bit_collie]

I will note that as with many razors the pivot hole on the tang is bigger than any of my available pinning rod material. So my gut feeling is that I’m not going to be able to correct by drilling a hole at an angle through the scales. For the same reason I am skeptical about the success of an asymmetric wedge, but that might have a better chance since I have the ability to drill the hole from scratch and make it a snug fit for the pinning rod. In terms of the tapered washer, that seems like it might work, particularly if I glue the washer to the scale (or the tang?) to keep the orientation constant. My gut feeling is that an additive material approach may be easier to implement than filing away material.

In response to the other question, when I lay the razor on a flat surface, focusing on keeping the spine of the blade flat - on one side the tang is flush with the flat surface, on the other side it clearly angles away from the surface. There is a taper down the length of the tang, but of course that is quite common for a straight and gets you the scale bowing at the pivot end to match the wedge bowing at the other end. My gut feeling is that this is more about a bent tang than an asymmetrically ground tang. I think the first step is to try a wider wedge. Alternatively I can try drilling the wedge holes in the scales slightly off - right now one scale is straight and the other is warped as a way of compensating for the tang issue.

 

[2bit_collie]

Hi All,
Update on this - I unpinned the razor, which was good because there was some nasty corrosion hidden by the scales at the pivot point. I did 2 things to try to correct the problem. I put in a wider wedge (using bleached camel bone) and I cut out 2 washers from 1/8” black acrylic, glued them to the inside of the scales at the pivot point and then tried to file them down to get a good fit. The blade is not quite centered, but it’s much better than it was.

 

[mr_houston]

Very nice job. It looks good.