trouble with ladder pattern

[neil1967]

Hello All,

So, I've been having some trouble recently with making a simple ladder pattern. When I first learned how to do it, it came out beautifully, like a series of sine waves. Here is a photo.



But now, whenever I just layer it up, cut grooves with a grinding wheel and draw it out flat, there are the right kinds of lines in the grooves, but the spaces between the grooves (the peaks left over) are broad and just...kind of speckly--no lines. No matter how narrow or broad I leave those in between spaces it's the same, and I just can't figure out what I'm missing from that original time I learned it in a class. Any thoughts or suggestions would be greatly appreciated!

Thanks.

Neil

[Ed Caffrey]

Two things that I can think of.... the depth of the cuts, and the amount of draw. Ladder is what I called a "stock removal" pattern, which means the pattern is created by removing stock from the billet. By their nature, most stock removal patterns are critical of the cut depth, and the amount of drawing out you do. A very general rule for these types of patterns is that if you wish to end up with a blade 1/4" thick, you cut the ladders on a 3/4" thick billet, 1/3 the thickness of the billet on each side. Any of these type patterns can be deformed by too drawing or even erased, by too much grinding, so forging them as close to shape and finished size as possible is a must.

In the photo you posted its obvious that the portion of the blade near the tip (where the spine swoops down to the point) was not forged closely to shape, but ground, because the pattern does not follow the blade's profile. The reason you have the "speckles" between the ladder rungs is due to the steel being draw lengthwise too much, which caused the distance between the rungs to widen out, and in turn, raised what was the bottom of your cuts closer to the surface. Then, when you ground the blade, the grinds extended to, or beyond the bottom of the original cuts, causing the "speckles" (the little semi-circular areas).

Just about any of the stock removal patterns (ladder, birdseye, etc) that are accomplished in the traditional manner, can exhibit these problems, because the pattern does not go all the way through the billet. Some folks have overcome this issue by pressing in the pattern on a forging press, but this is a very wasteful process, where about 60-75% of your billet gets ground away. The up side of that is that the pattern goes all the way through the billet, so it cannot be ground out/away.

[neil1967]

Ed,

Thank you for the feedback/advice. In the pattern pictured, that to me was more of what I've been TRYING to achieve, where the waves go all the way through, and unfortunately I don't have a picture of the "speckled" billets I've produced (I'll try to take one and post it soon). I think the speckling is a result of the pitting that normally appears on the surface of any billet that, if you were to simply draw and fold, draw and fold to build up your layer count, would appear on the surface befpre any subsequent manipulation. What I'm having a hard time understanding is not so much how the speckling gets there, because in a way having speckled peaks and then waved lines from the troughs makes MORE sense to me than what I see in the picture I posted, where the lines of the waves run through the troughs AND the peaks. I guess I'm just wondering how that works so that as I try to do more ladder, I get the lines all the way through like those shown in the pic I included. Does that make sense? Thanks again for the advice on not drawing out too much, as that may very well be contributing to my problem.

[Sergio Segre]

I have met the same problem as Mr Neil. Up to now I have cut the groves in a billet of rectangular setion, and then flattened it and ground the bevel.
If I understand correcly Mr. Caffrey's advice the billet to be cut must heve already a bevel.
Sergio

[Woodchuck Forge]

Also remember that the billet is going to stretch out and pull the pattern with it. If you want a tight pattern like above then cut or forge tightly spaced grooves. The number of layers in the pattern make a difference also. I would recommend 250 layers to 500 max. Good definition can also be a factor of the type of steel being used. Contrasting materials make a huge difference. 10xx and 15n20 is the most common combination. If you round off the peaks this may also help.

Keep on trying and you will get there.