Blades twisting inspection

[Kaitsu]

Some time ago tstop4me opened good thread related to Low-Cost Basic Even Edge Checker. In his thread and several other discussions we have talked also about blade twisting, which usually comes in the stage when blade is mounted on to the boot. I thought to open thread to dive deeper to twisting topic. Mainly how to measure it and different measuring methods pros and cons.
PBHE is marketing machinist parallel bars, which has drilled holes. http://precisionblade.com/?p=1131

Idea is a bit similar with Low-Cost Basic Even Edge Checker what tstop4me introduced. According to my understanding drilled holes helps a bit when you are eyeballing if bars are parallel to each other's. Problem, if it can called problem, is that you needs to have also precision square or some BAT gauge to ensure that you are measuring twisting and not edges evenness. If someone has forgot how Low-Cost Basic Even Edge Checker works, here is link to video which introduces tstop4me idea https://youtu.be/4AXE9mg90Ro

I would like to introduce another way to check blade twisting. Method is very close to tstop4me idea, but rulers or some other similar are clamped in to blade stanchions. One in to the frontal area of the blade and another to the tail. Then you eyeball if they are parallel or not. This video introduces the idea. https://youtu.be/4AXE9mg90Ro

Problem in this method is that I am not sure if even stanchions are reliable datum's. Following video hopefully explains why I have some doubts about the stanchions reliability. https://youtu.be/R209bWZRS60

[tstop4me]

If we assume that the blade is initially undeformed, and if the purpose of the test is to detect deformation caused by improper mounting, then I'm not sure all this is needed.  But perhaps I'm missing something here.

Let's first take the simplest scenario: a blade with flat, parallel sides (such as Wilson Coronation Ace). We first test the unmounted blade for deformation by laying a straight edge against each side of the runner (first one side, then the other).  Assume all is good:  the straight edge will lie flat against the runner; there will be no visible gaps between the straight edge and the runner; and the straight edge will not rock against the runner. 

We mount the good blade. 

We then test the mounted blade again by laying a straight edge against each side of the runner (first one side, then the other).  If the mount is good, then the straight edge will lie flat against the runner; there will be no visible gaps between the straight edge and the runner; and the straight edge will not rock against the runner.  If the mount is not good, then the blade can be deformed:  bowed along one axis, twisted along another axis, or both.  If so, then the straight edge will not lie flat against the runner; and depending on the scenario, there will be visible gaps between the straight edge and the runner, or the straight edge will rock against the runner, or both.

With a more complicated blade geometry, for example a blade with concave side honing (such as Wilson Gold Seal), as you have noted, we are then dependent on the stanchions for reference surfaces (which, as you have noted, may or may not in fact be good reference surfaces).  Assuming they are, then we should be able to place a straight edge across the three stanchion surfaces to check for deformation similar to the above procedure.  We would repeat these tests, checking at multiple locations across the stanchion surfaces.

Is the point of your test setup (and the PBHE test setup) to make it easier to detect twist because you effectively magnify the difference between measurement surfaces?  What about bowing along a different axis?  That is, the blade is (exaggerated)

pick
(
heel

The PBHE tester doesn't pick up bowing either. 

Hope this is clear.  If not, I'll make some drawings.

[Kaitsu]

tstop4me, I can fully understand what you mean. You are basically checking flatness with the straight edge. In theory it would be also possible to use feeler gauge to get numerical value for the bowing and twisting.

But the question is, do us this method by your selves or is it just a theory?

I can say that I do not use any of these methods. My video was just a theoretical experience. So far I have used hair straight edge (what you can see also on my videos) to see that blades are straight and precision square to ensure that edges are in square compared to the side surfaces. If I haven't face any issues with these two, I haven't done any other actions. My "another personality" is whispering to me that maybe I should add twisting check to be one of my standard routines.

Reason why opened this thread is to find out how many of us are really checking the twisting and what are the methods people use. I haven't seen blade twisting to be big issue. That is probably because I haven't check that with any other methods than hair straight edge and precision square. What I have seen a lot is that skate techs won't even ensure that blades are straight after the mounting. I would say that 50% of the blades what I have checked are bowed, less or more. Some of them so heavily, that it cannot be explained with boot deformation after the blade mounting.

A bit out of the topic, but has someone else noted that straightness is not necessary same in the area where chrome has been removed and chromed are? Is it consequence of blade twisting, poor chrome removal grinding or something else, that is not so clear to me.

[Query]

I agree that laying a straight edge against the sides of the blade can easily test for lateral warping (which is called bow in https://forestandwildlifeecology.wisc.edu/wp-content/uploads/sites/111/2017/07/68.pdf), if the sides of the blade are flat. And this is the most common type of blade warp, that can easily be created by incorrect mounting at the pro shop - or by, if I understand correctly, incorrect welding (it has to do with thermal expansion when the parts of the blade is heated for welding) or other incorrect mounting of the runner to the chassis at the factory.

But if you have what that document calls cup, you have to place the straight edge along the blade in various orientations to see it. I'm not sure what would cause cup - I guess, again, by incorrect welding or mounting at the factory.

I think of a "twist warp" as a warp in which the orientation of the sides of the blade changes as you progress along the length of the blade. I'm not sure what could cause that. But again, you need to place the straight edge in various orientations against the sides of the blade.

BTW, with respect to using the stanchions for warp detection, I don't have the link handy, but I saw something that said the stanchions of Phoenix blades are deliberately designed not to be in the same plane - they are tilted differently, left or right. I'm not sure if that is decorative (they are quite expensive), or if the tilt is there for good reason. Do any of you have Phoenix blades available you could check that on?

[tstop4me]

Query, let me take a wild stab at your next topics of discussion:  blade damage due to woodpeckers, termites, worms, invasive Asian beetles ... and, of course, the dreaded toepick fungus.

[Query]

Ancient blades were made of bone. Maybe they were somewhat biodegradable.

But I don't know any modern figure skaters who still use bone. So I will ignore your suggested topics. But you are welcome to explore them further.

Skate techs and others have been using straight edges to check for blade warp for a very long time. A faster technique, used by some skate techs I have spoken to, is to visually sight along the edge. If it all lines up, as far as they can tell, there can't be much warp.

From what many hockey skate techs have told me, many, many of them check for warp every time they sharpen, because when hockey blades run into each other, they frequently introduce warp. (And I suppose one could argue that collision induced warps needn't be purely lateral - they could include side bending, and twist.) I suppose collisions could also occur in ice dance, pairs, and Synchro teams, but I haven't personally hear of any figure skaters introducing warp through blade collisions.

It was mentioned to me by a couple of skate techs, a fair number of years ago, that when CCM made some of their (hockey) blade holders (on replaceable runner systems), in some of the sizes, they accidentally warped them - so even if the blade came from the factory unwarped, they would be warp after insertion into the mounting system. I don't know if that is still true. One would hope that they responded to the complaints and fixed the issue.

The warp applied to short and long track speed skates is deliberate, because they always skate counter clockwise  around a curved track. In fact, some of them worry a lot about the exact shape of the bend, because some races are won by tiny fractions of a second. But I've never personally heard of someone deliberately introducing warp in a hockey or figure blade. Maybe YOU could have fun studying that.

[tstop4me]

Ancient blades were made of bone. Maybe they were somewhat biodegradable.

But I don't know any modern figure skaters who still use bone. So I will ignore your suggested topics. But you are welcome to explore them further.

But apparently you do know many modern figure skaters who use blades fashioned from wood.  Hence, your previous citation to a university department of forestry ecology and management document:

I agree that laying a straight edge against the sides of the blade can easily test for lateral warping (which is called bow in https://forestandwildlifeecology.wisc.edu/wp-content/uploads/sites/111/2017/07/68.pdf), if the sides of the blade are flat.

[Query]

No - the wood examples were just to get names for the types of warp that could exist.

I think wood would make a terrible skate - it abrades much too easily, and wouldn't last long. It's also probably too flexible. That's great in some ways, but probably not for ice skate blades.

Which is a shame - it would be much easier to cut a blade out of wood. If that were possible, lots of people would try to make their own blades.

Unless you know a way to avoid that abrasion and flexibility - e.g., if wood can be infused with something that retards abrasion to about the same point as metal.

[tstop4me]

No - the wood examples were just to get names for the types of warp that could exist.

The types of defects that can exist vary with the specific material and with the specific processing conditions.  And the terminology used to designate these types of defects is not universal; it varies with specific industries and specific applications.