Edge Bender
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Edge Bender
I am working on designing an edge bender to bend around any shape/style of tip or tail. The one thing I am curious about is if the edge tends to spring back (when bending cold) to its original shape? By this I mean do you have to bend the edge further than the desired bend to get it to take that shape?
MLReed05: yes, you do have a bend them a bit more, by how much to get an exact shape? i don't have the exact number. when you bend the edges you are essentially plastically deforming the metal, and upon unloading a certain percentage of the deformation is recovered, but not all.
the edge bending process is more or less a trial-by-error approach. you bend, then check, then bend again and again until it looks right. or at least this is the process we use. in particular, i usually bend with a tighter radius than needed and then increase the radius of curvature to fit the shape that i want. others may have a more systematic approach.
we would be interested in seeing your edge bender design...
the edge bending process is more or less a trial-by-error approach. you bend, then check, then bend again and again until it looks right. or at least this is the process we use. in particular, i usually bend with a tighter radius than needed and then increase the radius of curvature to fit the shape that i want. others may have a more systematic approach.
we would be interested in seeing your edge bender design...
Mike,
Yes, way farther, depending on how much you anneal the edge before bending. I'm currently leaning towards not annealing at all, which means that I need to bend about 4 or 5 times as far as where I want to end up... still experimenting with this. I've noticed that in a finished ski, I can end up with a weird little kink in the base edge right where I stopped annealing. It's much more pronounced if this point falls along the tip or tail curves, and less pronounced as the annealing stop point moves toward the center of the ski (more on the flatter portion of the ski). Also, I'd just rather not have a softer edge located medial to the tip and tail curves. For one thing, the annealed edge doesn't stay tuned as long, and for another, the annealed edge doesn't tolerate bending back and forth very much before it breaks... anneal a short piece of edge, stick it in a vise, and bend it a couple of times with a pair of pliers and you will see what I mean. So, I'm going to give the non-annealed route a try and see how it works.
Cheers,
G-man
Yes, way farther, depending on how much you anneal the edge before bending. I'm currently leaning towards not annealing at all, which means that I need to bend about 4 or 5 times as far as where I want to end up... still experimenting with this. I've noticed that in a finished ski, I can end up with a weird little kink in the base edge right where I stopped annealing. It's much more pronounced if this point falls along the tip or tail curves, and less pronounced as the annealing stop point moves toward the center of the ski (more on the flatter portion of the ski). Also, I'd just rather not have a softer edge located medial to the tip and tail curves. For one thing, the annealed edge doesn't stay tuned as long, and for another, the annealed edge doesn't tolerate bending back and forth very much before it breaks... anneal a short piece of edge, stick it in a vise, and bend it a couple of times with a pair of pliers and you will see what I mean. So, I'm going to give the non-annealed route a try and see how it works.
Cheers,
G-man
I haven't drawn it up or done any testing however.....I am making a template out of UHMW ...I am thinking that I will install a ball bearing in the center of the radius at the tip and tail. I would then have a handle with a spring loaded plastic "round slug" that would roll the edge around the tip or tail.bigKam wrote:MLReed05: yes, you do have a bend them a bit more, by how much to get an exact shape? i don't have the exact number. when you bend the edges you are essentially plastically deforming the metal, and upon unloading a certain percentage of the deformation is recovered, but not all.
the edge bending process is more or less a trial-by-error approach. you bend, then check, then bend again and again until it looks right. or at least this is the process we use. in particular, i usually bend with a tighter radius than needed and then increase the radius of curvature to fit the shape that i want. others may have a more systematic approach.
we would be interested in seeing your edge bender design...
It would be basically similar to yours however the "inside wheel" would be the ski and the "outside wheel" would be spring loaded.
I only see this working if the steel is stressed beyond the point of elasticity. If doing it cold does not work do you think it may be possible after annealing?
G-man has a point about the "softening" of the edge after annealing. i've bent edges both ways, and usually shape the edges cold (i.e., no annealing) with our edge bender.
you can try bending edges around different shaped templates to see which one will give the best results, but in general i think you'll want a template that is smaller than the final shape you desire...
keep us posted with your work.
you can try bending edges around different shaped templates to see which one will give the best results, but in general i think you'll want a template that is smaller than the final shape you desire...
keep us posted with your work.
In my experience, even after a well done annealling, the bent edge springs back significantly. I'll try to quantify... my primary edge bender (I've made many, all with varying radii) has a radius of 3 1/2 inches. After bending the edge, it springs back and I end up with a bent edge with a radius of about 7 inches, which is just about perfect for my primary tip curve. Then I run the distal tip of the edge through another bender that has a radius of 7/8 inch (I have to grind away some of the edge teeth for this step). This gives me a tight bend that I can work with to get half way around the very tip of the ski where one side edge meets the other side edge. I have a whole different set of benders for the tail curve... and, I'll have to build more benders for 'cold' bending.
My main point here is that, unfortunately, I don't think that you are going to end up very close to where you want to be if you just bend an annealed edge around your finished ski tip dimension (I may have mis-understood your intent, though). But, who knows... we all seem to get quite varied results with quite similar techniques. Keep us posted.
G-man
My main point here is that, unfortunately, I don't think that you are going to end up very close to where you want to be if you just bend an annealed edge around your finished ski tip dimension (I may have mis-understood your intent, though). But, who knows... we all seem to get quite varied results with quite similar techniques. Keep us posted.
G-man
Hi Bambi,
If you just re-heat and quench the edge, you will end up with an edge that will be so brittle that it will break with the slightest flex (try it with a sample, and you will see what I mean). The step that is missing here is the heat treatment, which is done after the heating and quenching. To accomplish this, you need to slowly re-heat the edge to approximately 750 F. This re-heating will return the 'springiness" to the steel (various temps will result in varying degrees of spring). The trick is that you need to do the heat treatment re-heating very uniformly. With such a small cross-section as the steel edge has, this is pretty difficult unless it is done in an oven that is capable of such temperatures (and big enough to accept the entire length of edge).
I have considered doing just what you have questioned, but, the uniform re-heating has been a roadblock for me. Also, I have wondered if the heating/quenching/re-heating might not distort the original bend so much that I'd still have to tweek the edge a bunch to get it back to where I wanted it.
G-man
If you just re-heat and quench the edge, you will end up with an edge that will be so brittle that it will break with the slightest flex (try it with a sample, and you will see what I mean). The step that is missing here is the heat treatment, which is done after the heating and quenching. To accomplish this, you need to slowly re-heat the edge to approximately 750 F. This re-heating will return the 'springiness" to the steel (various temps will result in varying degrees of spring). The trick is that you need to do the heat treatment re-heating very uniformly. With such a small cross-section as the steel edge has, this is pretty difficult unless it is done in an oven that is capable of such temperatures (and big enough to accept the entire length of edge).
I have considered doing just what you have questioned, but, the uniform re-heating has been a roadblock for me. Also, I have wondered if the heating/quenching/re-heating might not distort the original bend so much that I'd still have to tweek the edge a bunch to get it back to where I wanted it.
G-man