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arglebargle

Laser arching visualization

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Hi all,

I'm looking for an inexpensive laser to use to check my arching. So, something to create a long line to shoot over the arch to see the contours better. I'm thinking a laser level, but don't want to spend a lot of $$.

Any suggestions? Thanks!

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A laser pointer will just make a spot; what you want is a line.

The lasers that mount to chop saws make a spot, but with the blade rotation it makes a line.  You might not want to put your instrument under a spinning blade, but I suppose you could motor-mount the laser for a custom thing.

Ones that make true lines look more expensive, like this laser level.  

There might be other things out there, or you could take a cheap laser pointer and wave it back and forth real fast.

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1.  Don't bother for doing this by eye.  Just use a ruler to cast shadows from a strong distant point light source (or whatever you're comfortable with).

2.  When I first experimented with this idea for photos I used long exposures and rotated a laser pointer on a wall or other flat surface to ensure the line was in a single plane.  I'm guessing some laser levels still cast a line and aren't too expensive, as that's what I got into next.  Try to check out the quality of the line, as in the past they have not had the same quality of line.  Even for photos, if the instrument is not varnished a ruler and the right light source is likely easy enough to set up that you don't need the laser.

Actually the last time I did a set of arches off a varnished violin we used a cast shadow and it worked great.  I didn't have my laser with me so we improvised.

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Thanks all,

I'm looking for something quick that I can pick up and use while I am working. I don't want to stop and mess with tape and lights and rulers. I've actually done all that. I do use a number of methods while I'm doing the arching. I think that this would help me (at this point in my working career and degeneration of my physical body) get to where I need to be easier. 

But I might be wrong. I'll be making a trip to **big box store** in the morning to see what they have.

Does anyone else out there use this while they are arching?

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This is using a Stanley brand laser from Lowes that projects a line along a wall or such, $30 or so? It looks good in that picture but up close the line is a bit fat and intense on my eyes. I like the shadow method for doing arching, it shows unvarnished wood well. Varnished wood shows pretty good too if you tinker with the setup.

laser_back.JPG

Haley back 3.jpg

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What I have used in the past is a slide projector with grid pattern slide focused appropriately.  I often thought about using a mirror as well to increase depth of focus but never got around to that.

 

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3 hours ago, arglebargle said:

Thanks all,

I'm looking for something quick that I can pick up and use while I am working. I don't want to stop and mess with tape and lights and rulers. I've actually done all that. I do use a number of methods while I'm doing the arching. I think that this would help me (at this point in my working career and degeneration of my physical body) get to where I need to be easier. 

But I might be wrong. I'll be making a trip to **big box store** in the morning to see what they have.

Does anyone else out there use this while they are arching?

I use a contour gauge like this one to quickly check the cross arches.

https://www.amazon.com/General-Tools-Contour-Duplicator-6-Inch/dp/B00004T7RA

 

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1 hour ago, lpr5184 said:

I use a contour gauge like this one to quickly check the cross arches.

https://www.amazon.com/General-Tools-Contour-Duplicator-6-Inch/dp/B00004T7RA

 

thats what I been using except it is plastic, it is the only one I could find long enough to do 14" https://www.ebay.com/p/Big-Horn-19062-20-Inch-Plastic-Contour-Gauge/20024493805?iid=371673706949

s-l640.jpg

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Hey Big E,

Arglebargle,

I welded this up with a stick welder almost 30 yrs ago, 2 6' GENERALS,,, looks nasty but it has worked great, flip it around to check for symmetry or hold it against templets or drawn arches for comparison. It really works great and it is very straightforward and accurate.

I have a much nicer welder now and it would be a kick to put 3 of them end to end for 18" of fun,,, Viola long arch !

Evan,

in search for more time!

 

IMG_2030.thumb.JPG.1b6df27de315d9dd6e99eedbc1e1f1d3.JPGIMG_2028.thumb.JPG.226fee023a0de9715f2619a146b35d69.JPG

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1 hour ago, Evan Smith said:

Hey Big E,

Arglebargle,

I welded this up with a stick welder almost 30 yrs ago, 2 6' GENERALS,,, looks nasty but it has worked great, flip it around to check for symmetry or hold it against templets or drawn arches for comparison. It really works great and it is very straightforward and accurate.

I have a much nicer welder now and it would be a kick to put 3 of them end to end for 18" of fun,,, Viola long arch !

Evan,

in search for more time!

 

IMG_2030.thumb.JPG.1b6df27de315d9dd6e99eedbc1e1f1d3.JPGIMG_2028.thumb.JPG.226fee023a0de9715f2619a146b35d69.JPG

Nice Evan, 

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That's it Evan.  If I could find a pin style contour gauge 14 inches or longer that would be the cats pajamas. I recently ditched all my arching templates and now use a 6 inch contour gauge to finish the cross arches.  It has speeded up the finishing and made the arches much nicer.

With the contour gauge you can check every mm of the plate if you want to...compared to the 5 stationary points normally given on the Strad posters.

I don't see why a longer pin style contour gauge could not be made for the long arch using the pins from the General and fabricating a longer bar.

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9 minutes ago, lpr5184 said:

 

I don't see why a longer pin style contour gauge could not be made for the long arch using the pins from the General and fabricating a longer bar.

Easier yet is epoxying a metal rod to the recessed side, to attach two together. That's worked fine for me.

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I have a 12 inch plastic  pin gauge. It can be used on varnished instruments  without  scratching too.

When carving , a simple pencil  line is so useful. You can pick the thing up and look at it from every angle. The gunbarrel  view of a line will show  you a lot.

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6 minutes ago, Conor Russell said:

I have a 12 inch plastic  pin gauge. It can be used on varnished instruments  without  scratching too.

When carving , a simple pencil  line is so useful. You can pick the thing up and look at it from every angle. The gunbarrel  view of a line will show  you a lot.

On the wood or on paper from the pin gauge?

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5 minutes ago, nathan slobodkin said:

On the wood or on paper from the pin gauge?

On the wood. For example when I'm making the  long  arch, which I finish first, I run a ruler and pencil down the middle.  Then make adjustments  and fill  in  the  gaps  till its done.

I make notes of the  arching  when I'm finished, using the gauge.

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A follow-up:

This is what I ended up buying, HERE.

The tricky part was finding a level that would let you turn off the self leveling option. Most blink constantly if they are not dead level. This one has that option, so you can hold it and move it where you want it. It only blinks once every 5 sec, which I can live with. So, large enough for a cello long arch and a nice bright line. I haven't really worked with it yet, but I am pleased.

Some pictures:

IMG_20181217_093241581.thumb.jpg.b9921f8550a5917c6b4693ab79dc9802.jpgIMG_20181217_093111512.thumb.jpg.752c346bfe8ac54cd076dd19c136b866.jpg

 

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Do you realize that the arching is distorted by the angle of the camera with the surface of the top/back?

In order to achieve the same arching you should then compare with a camera in the same angle and distance from the top/back and compare the resulting lines.

Regards,

Juan Tavira

 

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1 hour ago, Juan Tavira said:

Do you realize that the arching is distorted by the angle of the camera with the surface of the top/back?

In order to achieve the same arching you should then compare with a camera in the same angle and distance from the top/back and compare the resulting lines.

Regards,

Juan Tavira

 

Indeed you can "correct" the measurements if you take the angle of the camera vs de horizontal line above the camera, lets say 15º, then multiply all the measurements by "1/cos(angle)"

Juan Tavira

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Seems like a good tool for observing the arching.

But it does go against my religion. Ramping up tools is always seductive, but aiming for ultimate precision is not necessarily desirable.

For me, it's got no place in my workshop, but perhaps a place in my research kit.

Very cool regardless. :)

 

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