Official Luthiers Forum!

Obviously a scraper but for what?

An automatic archtop making machine???

seriously- a scraper for taking the brace ends down to the same height?

Hint--The radius at each end of the cutout is .062" (1.5MM)
Hint--The cutout would need to be longer for a flat top.

Side scraper?(....incl. binding radius)

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Dave
Milton, ON

You're the winner, Dave!
Someone asked a while back about a good way to generate the binding radius.
Thought about a router bit but that scares the devil out of me.
I've always scraped facets and then sanded round but also felt there had to be a better way.
This little guy is the cat's meow, in my not-so-humble, opinion as it seems to work well on wood and plastic binding.
The length of the cutout is oversize to allow scraping one binding at a time. (top binding then bottom binding or vice versa)
The area in between makes a nice scraper for leveling the binding prior to doing the radii.
I used the vertical mill with a .125" (3MM) diameter carbide endmill which left a nice sharp burr all the way around the cutout.
Question might be how does the luthier without a mill do the cutout and resharpen later.


Nelson

Cool Nelson... I know what you mean re facets!
Do you use a standard body depth & size the scraper to that or is it oversize & you just nudge the bindings when you're ready?
orderingggg.....one to go!

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Dave
Milton, ON

Dave, the cutout is extra width to allow doing one radius at a time. I'm surprised at how well it stays sharp as I've done nine bodies and doesn't show any sign of dulling. I found that nearly the entire radius can be shaved off of ABS binding in one pass but it makes more sense to do several lighter passes.
It can cut on the push or pull stroke but, when doing wood binding, it's better to do a couple light passes and you will soon know which direction the grain is running. Seems to leave a nice burnished finish on the wood as the radius is completed and this is somewhat controlled by the tilt angle on the scraper. It is burnishing rather than cutting when held at 90 degrees.
The "radius" is probably more of an ellipse as it is begun with the scraper tilted. This lets you control the depth of cut by gradually tilting to 90 degrees on successive cuts. Hope I'm making sense here.
I do think, with a little (or a lot of) patience, that the scraper could be be made with files including a rat-tail. Or maybe drill a hole at what will constitute each radius and then waste everything in between. I'm assuming that the typical cabinet scraper is not too hard to drill if done carefully.
Would like to hear comments, guys.
Thanks
Nelson