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Purpose of Ceramic/Gummy Stones

Atomicman

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Sure looks like it to me, but @oldschoolskier will have to answer
View attachment 187679
I was talking about the video just being normal old side edge filing. I can't see how you can do what's on this drawing on a ski edge. The tools aren't made to do this and for good reason. Ever single instructional explanation and video I have ever come across, show side edge work the same way.
 

mdf

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Cuts into the edge.
So the teeth cut in based on the angle of individual teeth, even though the overall direction is parallel to the edge? Maybe.... if you angle the file enough. But in your picture, the teeth are darn near perpendicular to the edge.

If I remember correctly, @oldschoolskier was a toolmaker at some point. Based on that I'd acknowledge he knows more about this than me. But I'm having trouble seeing how the geometry can work.
 
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James

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I was talking about the video just being normal old side edge filing. I can't see how you can do what's on this drawing on a ski edge. The tools aren't made to do this and for good reason. Ever single instructional explanation and video I have ever come across, show side edge work the same way.
You can have the file with teeth pushing metal towards the topsheet, or towards the base.
I don’t know if it really makes a difference to the burr. It does to where some of the filings go.
 

Zirbl

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View attachment 187673 When you cut into the edge any material is pulled onto the edge so the burr is prevented, if you draw off of, you tend to drag material off the edge in doing so you are creating the burr. Pulling parallel to tends to behave similar to a draw off.

This is why some of the rotary sharpeners depending how set leave no burr and achieve a sharper edge. The rotation is into the edge, if it is reversed a burr is formed.

This is something taught when learning to sharpen tools. Those that don't learn it, learn how to remove burrs. Believe it or not it, it is a difficult concept to understand because a small portion of the edge acts like plastic and moves, by the direction we control the movement.
Thought there wasn't supposed to be any extra pressure when using diamonds stones beyond letting their weight do the job.
 

oldschoolskier

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1) There is a similar concept in sharpening knives, except the goal is opposite. I find a controlled burr too fussy to create (and too fragile in use) so I settle for a non-burred edge by cutting in (moving knife on stone as if I was whittling it). I can get a very sharp knife that way, even though a true expert could get it even sharper by doing it "right".

To be honest, if I'm sharpening knives I'm often just trying to get an AirBnB knife to minimally useful.

2) I do not see how you can cut in on a ski edge with an edge guide. Seems contrary to the whole operating principle of a guide.

3) Based on theoretical considerations, I believe a diamond stone can create a burr. But I've never had one big enough to notice. On the other hand, files often make burrs big enough to cause problems.
Exactly, you understand, diamond stones are an exception, unless you draw off, which can happen.
 

oldschoolskier

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So the teeth cut in based on the angle of individual teeth, even though the overall direction is parallel to the edge? Maybe.... if you angle the file enough. But in your picture, the teeth are darn near perpendicular to the edge.

If I remember correctly, @oldschoolskier was a toolmaker at some point. Based on that I'd acknowledge he knows more about this than me. But I'm having trouble seeing how the geometry can work.
Thank you for the compliment, wish I truly was, I do a fair bit of metal work but toolmaker in my dreams. I do know sharpening and now play a lot with carbide tooling. I recently purchased a specialized grinder to sharpen end mills and diamond wheel sets to grind the carbide. No deburring, EVER!

BTW you though ski tuning was expensive.....
 

Atomicman

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You can have the file with teeth pushing metal towards the topsheet, or towards the base.
I don’t know if it really makes a difference to the burr. It does to where some of the filings go.
Nope, if you listened in that video you posted and this has been the preferred method in every video or instruction I haver seen, the tang goes up at the top of the edge guide pointed away from ski edge which means the teeth are always angled down toward the edge. It's at about 1:09 in the video.
 

James

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You can set the file any way you want. Free will!
Not sure why @oldschoolskier punted and doesn’t explain his drawing. To me, the video is the drawing. File cuts in to the edge.
 

oldschoolskier

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You can set the file any way you want. Free will!
Not sure why @oldschoolskier punted and doesn’t explain his drawing. To me, the video is the drawing. File cuts in to the edge.
Sorry I thought the drawing was self explanatory. If you are using file ensure they push onto the edge and don't draw off. The difference is push on means you must apply force to counter act the files teeth, if the teeth are reversed and pull off the tooling actually tries and pull itself onto the edge.

This is one of those things if its easy its wrong.

Again thinking in a machining mind set makes some things obvious for me, but not for those with little or no experience.
 

Scruffy

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I have always set the file so the teeth cut in, or onto the edge, either just instinctively or watched others do it that way. I didn't think I could set the file in the guide to draw off, that the tang would clip the bindings, brakes or sidewall. So I went to my tuning bench and sure enough I could set the file in the guide to draw off without the tang hitting any part of ski or binding. Any advantage/disadvantage to filing that way other than the burr issue?
 

oldschoolskier

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I have always set the file so the teeth cut in, or onto the edge, either just instinctively or watched others do it that way. I didn't think I could set the file in the guide to draw off, that the tang would clip the bindings, brakes or sidewall. So I went to my tuning bench and sure enough I could set the file in the guide to draw off without the tang hitting any part of ski or binding. Any advantage/disadvantage to filing that way other than the burr issue?
Depending on the file they are slanted so they will pull material in one direction. What that means to a tuner is that on one side of the ski you file tip to tail and the other tail to tip. Use the file in the same direction on both sides one side get a burr the other little or no burr.

No advantage or disadvantage other than the extra work to create a proper edge and the increased risk of making a mistake which leaves a potential fantastic tune feel and ski like garbage.
 
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Cork7 Belly Flop

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So does anyone here actually use gummy stones for polishing? Is there a point to soft/medium gummies?
 

Dwight

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Gummies are not designed full polishing, the answer is no.

I touch up areas that may need some rust color taken off with gummies, where files and stones don't reach.
 

oldschoolskier

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Sometimes seeing how metal is cut gives a very good idea what is trying to be explained and greatly miss-understood even by those in the metal working industry.

 

Swiss Toni

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So does anyone here actually use gummy stones for polishing? Is there a point to soft/medium gummies?

Some people do; TYROLIT, the Austrian grinding wheel manufacturer that makes grinding wheels for ski tuning machines, makes a range of elastic files that they market as an alternative to diamond stones https://www.tyrolitlife.com/en/produkt/elastic-files/

Gummy stones are elastic bonded abrasive blocks; they are made from elastomeric resins to which abrasive has been added. They vary in hardness from Shore 30A to Shore 95D. Elastic-bonded abrasives are widely used for grinding and polishing operations in many industries. The "ceramic disks" that Wintersteiger uses for edge grinding are actually elastic grinding wheels https://www.tyrolit.co.uk/divisions/metal-industries/industries/sports-industry.html
 

Atomicman

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I don't use gummi's for polishing or removing rust. Diamonds will take the rust off and leave you with a sharp edge. Soft gummi will dull the edge no matter how ginger you try to be with the gummi.

The problem with using soft gummies from contact point to contact point is that the soft gummi wraps around the edge and dulls the edge. Just simply the nature of the soft material.

That's why I only use an xtra-hard blue gummi on the edge point at a 45 degree angle with no pressure to smooth the final edge after side edge tuning. And as James said to slightly dull the tip and tail past the contact points.
 

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