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ScottB

ScottB

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Noodler,

Ok, as the OP and a mechanical engineer I will chime in. First off, it is a reasonable way to make the measurement. It might be accurate and it might be off some.

The bottom edge of the true bar should be flat, that is what you are paying for. The sides may or maynot be flat. Since you are using them as reference and zeroing your angle gauge, it might not be that critical, I would have to think about it some.

Your digital gauge is meant to measure 0--90 deg angles. It has one decimal place in the display. We want to measure .25 deg, .50 deg, .75 deg, ect...... The max measurement should be 5.0 deg, like you see on the SVT gauge. Typically a measurement device has +/- 1% accuracy if it is very good. 1% of 90 is 0.9 deg, 1% of 5 is 0.05 deg. Not sure if the digital device will distinguish between .25 deg and 2.0 deg??

Lastly, true bars are typically made with a knife edge so you can see light coming under them well. Since you laid your bar on its side, the light has to go between a lot of length of bar compared to a knife edge. This will effect it, and make it hard to see if you are matching the edge angle. If your clamp technique matches the edge angle, you are good and not an issue.

Having said all this, your setup might work just fine. Only way to tell is measure some skis and compare them to what another trusted device or technique gives for results. I suggest use my feeler gauge method after you use your digital gauge. It would be best to measure skis with low base bevels and high ones (like 0.5 and 1.5 deg)

There is a digital bevel measurement device for skis on the market. I think it is more expensive than the $300 SVVT device Phil posted. I have used the SVVT device and it is a quality unit.

I guess Swiss Toni read my mind.

Lastly, I always measure my angles on a new ski to see if I need to have it ground flat and re-beveled. Over time all skis will need it done, so I occasionally check my often skied skis to see if its time.
 
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Noodler

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Noodler,

Ok, as the OP and a mechanical engineer I will chime in. First off, it is a reasonable way to make the measurement. It might be accurate and it might be off some.

The bottom edge of the true bar should be flat, that is what you are paying for. The sides may or maynot be flat. Since you are using them as reference and zeroing your angle gauge, it might not be that critical, I would have to think about it some.

Your digital gauge is meant to measure 0--90 deg angles. It has one decimal place in the display. We want to measure .25 deg, .50 deg, .75 deg, ect...... The max measurement should be 5.0 deg, like you see on the SVT gauge. Typically a measurement device has +/- 1% accuracy if it is very good. 1% of 90 is 0.9 deg, 1% of 5 is 0.05 deg. Not sure if the digital device will distinguish between .25 deg and 2.0 deg??

Lastly, true bars are typically made with a knife edge so you can see light coming under them well. Since you laid your bar on its side, the light has to go between a lot of length of bar compared to a knife edge. This will effect it, and make it hard to see if you are matching the edge angle. If your clamp technique matches the edge angle, you are good and not an issue.

Having said all this, your setup might work just fine. Only way to tell is measure some skis and compare them to what another trusted device or technique gives for results. I suggest use my feeler gauge method after you use your digital gauge. It would be best to measure skis with low base bevels and high ones (like 0.5 and 1.5 deg)

There is a digital bevel measurement device for skis on the market. I think it is more expensive than the $300 SVVT device Phil posted. I have used the SVVT device and it is a quality unit.

I guess Swiss Toni read my mind.

Lastly, I always measure my angles on a new ski to see if I need to have it ground flat and re-beveled. Over time all skis will need it done, so I occasionally check my often skied skis to see if its time.

I didn't mention it, but I did verify the that my true bar was also "true" across the body of the tool. You have a point about the additional contact area using the side of the bar, but I believe that will still provide accurate results if you check the edge in multiple spots (just in case the bar was placed in a "transition zone" where the bevel angle is different/changing).

I have multiple digital angle gauges. Two others that do provide measurements to the hundredth place. I will repeat the test using one of those. The whole point of my post was how to do this on-the-cheap, but still have confidence in the results. Holding the true bar on the knife edge in contact with the ski edge and then using feeler gauges is a bit "fiddly". So I was looking for something easier, but still trusted.
 

MingDao

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Why not use precision mechanical bevel protractor?
Like in the picture:
https://imgur.com/9jKOQ1H

mechanical bevel protractor.png


Edit: fix image
 
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Doug Briggs

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This revived thread got me thinking again about a better "poor man's" method to accurately measure base bevels. I've been starting back into my golf club building and remembered that I have a few digital angle gauges that I use with a golf club spec gauge to measure loft and lie angles. I thought about how I could use a digital angle gauge to measure the base bevel. What I've come up with seems to be working quite well.

I grabbed my true bar and placed it flat across the base of the ski. Then I placed the digital angle gauge on the true bar and zero'd it out (to calibrate it to the flat of the base). Then I used an Irwin Quick Grip clamp to clamp the true bar flat against the surface of the base edge. The Irwin clamps have a pivot integrated into the clamp so that the true bar is able to rise off the ski base surface and match the flat of the base edge. You can wiggle the Irwin clamp and feel that the true bar is sitting flat against the base edge. You can also shine a light from behind the true bar and see that the bar is fully seated against the base edge. What you get is a fairly accurate reading of the ski base edge bevel angle.

Here's a pic of the setup:

View attachment 72621

Anyone have any concerns with this method?

The hardest part of this method is that the ski can't move after you zero your Digital Angle Gauge (DAG). That is mighty hard to achieve. I've tried.

As to not flat bases mentioned early on, it is pointless to try for an accurate measure of base bevel without flat bases.

Why would you want to check out a non-flat ski? To get a reference to how bad the base edges really are. When I work in the shop, I can use a true bar to determine how much base material is creating a convex base and get a rough idea about how far off the base edges are. Of course, I can get a quick idea of how bad the base edge is rounded from wear with my (vision adjusted) eye.
 

Tricia

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Big J, your welcome. If you ski in soft snow mostly, edges don't matter. When I got involved in a local race program, and skied on very hard snow, edges became a lot more important and I had to get up to speed on what mattered. Buying a ski that was un-skiable due to base bevels was an eye opener for me too. Once corrected, it became my favorite ski.

This revived thread got me thinking again about a better "poor man's" method to accurately measure base bevels. I've been starting back into my golf club building and remembered that I have a few digital angle gauges that I use with a golf club spec gauge to measure loft and lie angles. I thought about how I could use a digital angle gauge to measure the base bevel. What I've come up with seems to be working quite well.

I grabbed my true bar and placed it flat across the base of the ski. Then I placed the digital angle gauge on the true bar and zero'd it out (to calibrate it to the flat of the base). Then I used an Irwin Quick Grip clamp to clamp the true bar flat against the surface of the base edge. The Irwin clamps have a pivot integrated into the clamp so that the true bar is able to rise off the ski base surface and match the flat of the base edge. You can wiggle the Irwin clamp and feel that the true bar is sitting flat against the base edge. You can also shine a light from behind the true bar and see that the bar is fully seated against the base edge. What you get is a fairly accurate reading of the ski base edge bevel angle.

Here's a pic of the setup:

View attachment 72621

Anyone have any concerns with this method?

The best way to measure base edge bevel is to use a MBAS BaseMan


It uses the method outlined in the OP, unfortunately it costs 250 euros which is probably more than most people would like to pay. Noodler’s method should work fine, I have all the bits except the clamp, when I find something suitable I will defiantly try it. If you could drill and tap some flat stock and use a thumb screw to raise it you could maybe do away with the clamp.

I didn't mention it, but I did verify the that my true bar was also "true" across the body of the tool. You have a point about the additional contact area using the side of the bar, but I believe that will still provide accurate results if you check the edge in multiple spots (just in case the bar was placed in a "transition zone" where the bevel angle is different/changing).

I have multiple digital angle gauges. Two others that do provide measurements to the hundredth place. I will repeat the test using one of those. The whole point of my post was how to do this on-the-cheap, but still have confidence in the results. Holding the true bar on the knife edge in contact with the ski edge and then using feeler gauges is a bit "fiddly". So I was looking for something easier, but still trusted.

Every tool has the potential to wear over time. I know the tool that @Philpug posted above needs to be calibrated from time to time. How often do the digital devices need to be calibrated?
 

KingGrump

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Chinese ones go for 25 bucks on Ebay. On paper it seems ok for measuring even small angles. I do not have one, however.

Not sure the word precision and $25 belongs in the same sentence unless the connector between them is "not."
 

James

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I have a Starrett version of that angle guage. I'll take a look, but getting an accurate reading between .75, 1, 1.25 etc is dubious. That unit is probably more like $200, but it's been a long time since I looked at them and it could be double that now.
 

Uncle-A

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@ScottB Well Done, and it is good to see someone is thinking economically, the fancy machines are pricey but very precise measurements were made long before the fancy machines were made available. Your method works well and at a reasonable price what more could the average home tech ask for. Thanks for sharing it with the community.
 

Wilhelmson

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A file guide with magic marker will give an indication of the angle for the whole running length of all four edges. Other methods give you single point snapshot of the angle.

What happens when your file guide tells you your $200 instrument is off, your $200 instrument shows your $650 instrument is off and your true bar method tells you your file guide is off?
 

James

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File guides with magic marker are fairly innaccurate if that's a concern. It's quite easy to get the marker off.
 

Dave Marshak

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I haven't followed this whole thread, but...

The base edge is about a tenth of an inch wide, so a 1 degree bevel is one-thousands on the side. You can't measure that with a protractor, even one of those fancy Starrett ones won't work on that small width of edge. Maybe you could measure it with a true bar and a feeler gauge, but you need to assume that the ptex base is perfectly flat, and the entire base edge is uniformly beveled. What if the bevel extends into the ptex? Or the bevel begins in the middle of the base edge and the inside part of the edge is flat? Good luck finding that with ordinary shop instruments.

You best bet is to mark the edge and use a good quality base file guide, but even that is sketchy.

dm, P.E.
 

Wilhelmson

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If method 1 confirms method 2 to a reasonable extent that might be the best you can do.
 

Uncle-A

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What we are talking about is so fractional that we have difficulty measuring it. The variables are many, is the base perfectly flat, is the angle from the manufacturer square or come pre ground to their own specs etc.. So just do the best you can with the method of your choice. The use of a feeler gauge seems to work with a true bar and it is reasonable so the challenge is can you do better at the same price?
 

oldschoolskier

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It is assumed that everyone works to absolute precision. Right!

Consider a simple gauge that you can set an angle and then look for light on the ski. While anything under 1 degree is a guesstimate, you are likely close enough to measure 0.25 without a problem.

Remember it is not the tool but the user that makes the difference.

https://www.kbctools.ca/CatSearch/1410/protractors
 

Dave Marshak

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It is assumed that everyone works to absolute precision. Right!

Consider a simple gauge that you can set an angle and then look for light on the ski. While anything under 1 degree is a guesstimate, you are likely close enough to measure 0.25 without a problem.

Remember it is not the tool but the user that makes the difference.

https://www.kbctools.ca/CatSearch/1410/protractors

These threads all go the same way. Someone asks a question about a difficult measurement problem, people propose simple solutions that don't work in the real world, and someone doubles down on how accurate their unworkable method is.

Protractors are designed to scribe long lines. You can't use them on small scale stuff. Measuring a base edge with a protractor is equivalent to gapping spark plugs with an architect's rule.

The only way to know your base angle is flatten your base and set the edge angle carefully with good quality tools. Otherwise, your base angle is whatever the last shop did, and they do them all the same. They definitely weren't listening when you told them to set it at 0.75 degrees.

dm
 

oldschoolskier

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These threads all go the same way. Someone asks a question about a difficult measurement problem, people propose simple solutions that don't work in the real world, and someone doubles down on how accurate their unworkable method is.

Protractors are designed to scribe long lines. You can't use them on small scale stuff. Measuring a base edge with a protractor is equivalent to gapping spark plugs with an architect's rule.

The only way to know your base angle is flatten your base and set the edge angle carefully with good quality tools. Otherwise, your base angle is whatever the last shop did, and they do them all the same. They definitely weren't listening when you told them to set it at 0.75 degrees.

dm
Strange.....machinist used the to build the precision devices we have today not to long ago.

Its the user, not the tool that makes the difference.

If you believe things can’t be done you can’t do it, if you believe they can and work at it, it will be done.

Have watched (in person) old craftsmen work to a 1/10,000 tolerances by listening to how a tool cuts. Again its the knowledge and the practice that allows this. The machine it was done on was not designed for that type of work, but that was all that was available.

As to the protractor...set it, lock it and sight it with a bright light. Using a vernier protractor you can measure to accuracies beyond what any skier will ever need.
 

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