The111

Recently I purchased my first edge tool. It is a popular multi-edge tool, and I had no problem with it on my side edges, however I did have a problem on my base edges. To start, I set the angle to 1 degree which I knew was my current base edge angle, and using a file I ran the tool VERY lightly over the edge. Immediately I noticed that ptex (base) material was being removed along with metal filings. This concerned me, and eventually I realized what was happening. It's much easier to show with diagrams. Looking at the image below (angles exaggerated for clarity), you can see that 0.25 in of file is exposed from the "guide" (the part of the tool that rests on the side edge), while the actual base edge is only 0.1 in.



As you try to lower the tool into place, your goal is to have 3 surfaces of contact between board and tool: they are higlighted in red below. The problem becomes apparent... when the file is aligned with the base edge, and the guide is aligned with the side edge, there is a huge gap between the base and the "base guide" (the long part of the tool which should rest flush on the base).



What REALLY happens though is shown below. Since the tool cannot find 3 surfaces of contact, it rotates slightly and finds 3 POINTS of contact. They are shown in red below.



Notice the file is ONLY contacting the vertex between the base and the base edge. This perfectly backs up my original observation of ptex being removed when I was attempting to file only my edge. If you file for long enough like this, you will remove both ptex and metal, the image below shows what material will be removed.



The image below shows the tool finally able to sit flush, and the side effect I've called "vertex shift."



At this stage you will have made your base edge 3 times as long, and it is now 2/3 ptex and 1/3 metal. Is this a big deal? I don't know the answer to that question... which is one reason I'm making this post. Opinions please! :-)

Below there is one solution I came up with while working on my base edge, but it is not perfect:



If you don't insert the file all the way, it cannot reach the ptex. However, the original problem still remains, which is that you start off at a 3-point contact situation (though your ptex is now saved by the "gap"). However the tool is not sitting flush... the red lines below show that angle.



If you file for long enough though, just with the earlier case which ended in vertex shift, the tool will eventually be able to sit flush. However, there is a new side effect:



The red above shows the material removed with this solution. I've called this side effect "edge step."



So, which one above is worse? I believe my board now has edge step since I used my "solution 1" method. I cannot see the edge step, since it happens at a SUPER small scale with only a 1 degree angle. And while it may seem silly to be analyzing such tiny pieces of geometry... isn't that the whole concept behind edge tuning? That very small geometry changes, to a very small piece of metal, will totally change the way your board rides? And don't we use tools to do this because it IS too small to see what's happening with your naked eye? I am really curious to hear people's input on this, and I'm totally expecting more than one response suggesting that I am making a big deal out of nothing. I've run this by some knowledgeable people already who keep telling me something is wrong with my images, but they won't specify what. If there is a real problem with my analysis, I am more than happy to hear it. Or if the images are correct, but everyone agrees that neither side effect I've described is a big deal, then I'm more than happy to hear that too. But... it was disturbing to take a brand new tool, to a brand new board, with very light pressure, and the correct angle set, and notice that more ptex was being removed than metal. That is what motivated this whole thing... and it is somewhat telling that the analysis perfectly backs it up, with the "3 point contact" putting the file right on the ptex/metal vertex.

Incidentally, there is a second solution which I cannot implement without designing a new tool:



If the guide could move, so that less file were exposed, all of the problems above would disappear. I have purposely left the name of my tool out so as not to throw any manufacturers under the rug, but if there are any tools out that have a feature like the one I show above, or in general don't have the shortcomings that mine has, I would love to hear about it!

Thanks!

Qball

Solution: buy a file and a cheap base file guide. You shouldn't have to take away base material to sharpen the edge unles too much edge has been filed away.

CheeseForSteeze

I would suggest buying a base edge file guide. I have an adjustable one that cost only $35. It has guide bead non-concentrically mounted on the base guide with notches. You rotate it to lift the guide at the appropriate angle.

Another problem you are going to encounter if you simply partially engage the file into the guide, in addition to creating the edge step, is you are going to form a non 90 degree angle. If angle formed by my base and side edge beevels must not be 90 degrees, I would always prefer it to be obtuse rather than acute and no more than 0.5 - 1 degree. The reasons are the edge will tend to chamfer off less quickly (requiring less sharpening) and since I personally detune to ride park features, the chamfer I intetionally induce is strong to blunt strikes against objects.

I'd also strongly recommend you set your base bevel, first. This is angle is critical because it's the one that really affects the ride. The side edge is only beveled to keep it as close to 90 (or slightly more) as possible to the base edge.

The other option you have is to shim the third contact point (on the base edge) with something. Perhaps you could use tape or something of that nature. If you are really into getting a good detailed tune out of your entire board, I'd really recommend picking up a good base and side edge file guide.

Thes ones I use are these:

Side edge: SwixSport.com : SwixProduct / File Holders Edger Pro, edge sharpener A bit pricy, but the best side edge tool I think you'll find. The bearings in the guide are smooth as butter.

Base Edge: Amazon.com: Base Bevel File Guide SKS Vario Adjustable All Angle: Sports & Outdoors You can clearly see that bronze "guide" bead as I describe above. This one I chose on a whim over the Swix ones and it works quite well.

I set a 1.5/1.5 base/side on my boards though I have ridden 2.0/2.0 and 1.5/2.0. I'd recommend starting with a 1.0/1.0 if the factory hasn't already set one.

davidj

Dude, you some kind of engineer or something ? This is a great writeup of the problem . It is for precisely this reason that I don't have a base edge tool (just use a side edge tool) to do my own tuning. Instead I use a very fine hand-held diamond stone to smooth out the base edge occasionally... nothing more.

I have an oooolld Gnu which I am going to convert into my rock/experimentation board within the next year or so. Once I do this, I'm going to see how the vertex shift affects the board's handling. Sorry, no answers here, but if there's a tool that answers the bell, I'd be most interested. If I find one I'll post it.

BurtonAvenger

Tape your base if you're that paranoid.

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Angry Snowboarder Because someone has to call it how they see it!

The111

Interesting. It's hard for me to visualize... but are you saying the bead lifts up the "base guide"... filling in the "gap" in my second image? In a perfect world this would solve the problem (as would shimming with tape or something else), but the real issue is how much do you shim? Or in this case, how much do you push the bead out? It's all happening at such a small scale you can't trust your eye. Too much shim (or adjustable bead) or not enough, and you don't solve the problem... you could even make it worse with way too much shim.

Or maybe I'm misunderstanding what the bead does.

Very good point. Until the base guide sits flush (and the edge step is completely cut out), you are cutting a smaller angle than you want, which leads to an acute "base-side angle" (assuming 90 degrees was your goal). I agree with your reasoning for obtuse being preferable... adding to those reasons that an acute angle is probably grabbier, in a bad way.

Still trying to figure out exactly how that tool works to solve my problems, but I am definitely open to buying a "base only" tool... even though I did invest $60 in my multi tool. And yes, 1.0/1.0 is my goal and I believe what my edges are already set at. I just want to do a very light filing at that setting to confirm it, and after that move to stones for the long run.

The111

Guilty as charged.

Nice to hear somebody else was at least aware of this. The experts I've consulted so far have said the problem is non-existent. I don't think I'd trust myself to do it by hand like you are though. I guess once the edge is SET you can use diamond by hand for SHARPENING only, which it sounds like what you're doing. But I do want the extra assurance that I properly set my angles with a file, once, before starting all that... and that is what a base tool supposedly lets you do.

The111

How much tape? Where?

Ballistic

color or blacken the metal edges before filing them. Then when u have filed off material its easier to immediately see and monitor your prrogress. It helps limit overfiling.

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Vancouver, BC

davidj

You're right, no "setting", only "sharpening" for me. I'm going with what the manufacturer claims for base and side edge bevel. Boy, will I be pissed if I find out they lied to me !