Making Scrapers

[Nikos Matsablokos]

Hello, I've been on this forum for a while and the information that many kind makers have shared here is invaluable. I decided to post for the first time because I've seen many topics here regarding how to sharpen a scraper, turn a burr but none regarding how to define the shape of the scraper. Meaning taking a square sheet of steel and shaping it to take the form of the various shaped scrapers that are used in making a violin.

How does one define the shape before taking it to the stones? How do you cut the steel? Do you use a grinder, belt sander or a file to shape both the outline (general shape of the scraper) as well as the bevel? Thanks in advance.

[Andreas Preuss]

 For the rough cutting I use a grinder, then I use a fine file to smoothen the rough surface created by the grinder. To sharpen I use wet stones. I’m using 90 degree-edge scrapers. 
 

For the form I d say every one has his/her own ideas what works well. I think you need only 3 scrapers: one for archings(.5mm) one for ribs and other flat surfaces (1.0mm) and a small egg shaped scraper for some details.

[Davide Sora]

For cutting and rough shaping I use the grinding wheel, then files to give the final shape. For the actual sharpening I finish the edges with a single-cut file and then a pass on the water stones, but without insisting too much on the latter, just to remove the marks of the file. Than a very light pass with the burnisher to turn the edges. This is for the double-edged scrapers (90 ° bevels) that I use almost exclusively, for the single-bevel ones you will have to sharpen them on the grinding wheel like a chisel, then on the stones. The burnisher is optional, you can use them with or without the turning the edge.

Regarding the shapes, I agree with Andreas Preuss, although I believe that 3 is related to the types of shapes (flat, curved rounded, and curved pointed), not the number of scrapers

These are the ones I use, only one is single bevel, can you find it?

 

[Bill Yacey]

 When you cut the initial shape using a grinder or cutoff wheel,  you are burning the steel, and it won't hold a good edge until this steel is removed. Filing is good, but you might have to remove a 16th of an inch or so. 

To avoid this, cutting just a little at a time to avoid over heating the steel, and quenching in water to keep it cool, helps.

[Davide Sora]

22 minutes ago, Bill Yacey said:

 When you cut the initial shape using a grinder or cutoff wheel,  you are burning the steel, and it won't hold a good edge until this steel is removed. Filing is good, but you might have to remove a 16th of an inch or so. 

To avoid this, cutting just a little at a time to avoid over heating the steel, and quenching in water to keep it cool, helps.

This is a fundamental warning, thank you for pointing this out. I took it for granted, as a scraper is like any other steel tool, the rules for sharpening (not burning the steel) are the same.

Sometimes I forget that taking things for granted doesn't provide good teaching.

 

[Nikos Matsablokos]

1 hour ago, Davide Sora said:

For cutting and rough shaping I use the grinding wheel, then files to give the final shape. For the actual sharpening I finish the edges with a single-cut file and then a pass on the water stones, but without insisting too much on the latter, just to remove the marks of the file. Than a very light pass with the burnisher to turn the edges. This is for the double-edged scrapers (90 ° bevels) that I use almost exclusively, for the single-bevel ones you will have to sharpen them on the grinding wheel like a chisel, then on the stones. The burnisher is optional, you can use them with or without the turning the edge.

Regarding the shapes, I agree with Andreas Preuss, although I believe that 3 is related to the types of shapes (flat, curved rounded, and curved pointed), not the number of scrapers

These are the ones I use, only one is single bevel, can you find it?

 

Quite a variety, thank you for the information. Using a grinder isn't a little dangerous? I  am asking because its such thin material I would be afraid in case it grabbed on the wheel and started flying all over the workshop  This is a nice collection of scrapers, if by single bevel you refer to the 45 degree bevel angle scraper then I think I spotted it. Here it is:

 

[Bill Yacey]

Additionally, you can break the steel if it's hard enough. Lightly score it with a fine cutoff wheel in a dremel tool, then clamp in a vise close to the score line and give it a sharp wack with a hammer. It should snap nicely on the score line.

[Davide Sora]

1 hour ago, Bill Yacey said:

Additionally, you can break the steel if it's hard enough. Lightly score it with a fine cutoff wheel in a dremel tool, then clamp in a vise close to the score line and give it a sharp wack with a hammer. It should snap nicely on the score line.

Or use one of these, but they are not very common in luthiers' shops.

I saw one at the violin making school, it works great!

https://youtu.be/3rXGjcFrPvw?t=506

 

[Andrew tkinson]

If you have access to some good tinsnips (metal shears) and the steel plate is not too thick the shapes can be cut out quite quickly. However the steel will probably get a bit distorted during cutting so try to keep this to a minimum by maybe nibbling small sections off rather than trying to cut the outline in one audacious 'sweep' of the snips. Files then can be used to shape the scraper steel I have encountered. If you cut the scrapers a bit larger so some distortion can be filed out and some can be squeezed out in a vice. I wouldn't use new files as the hardish steel will not be very kind to the sharp teeth of new files.

However, this may be a bit more trouble than grinding and I do admit that I am a bit of a luddite so I have no dremel or powered grinding wheel.

Edit. I have just seen Davide mentioned using a bench mounted metal shear device just before I hastily wrote this post. These will cut the steel with greater ease than my handheld tinsnips.

[Davide Sora]

4 hours ago, Nikos Matsablokos said:

Quite a variety, thank you for the information. Using a grinder isn't a little dangerous? I  am asking because its such thin material I would be afraid in case it grabbed on the wheel and started flying all over the workshop  This is a nice collection of scrapers, if by single bevel you refer to the 45 degree bevel angle scraper then I think I spotted it. Here it is:

You guessed! but it was too easy

Grinding wheels are dangerous, especially those that turn fast. But if properly set up and used properly they are manageable. To tell the truth I have always been afraid of grinding scrapers perpendicular to the wheel, but it is a fear of mine and it can be done safely (with due precautions, such as leaving a very small gap between the wheel and the plate support, using almost no pressure and holding the scraper very firmly against the support plate). However, in order not to risk I use an old slow turning wet grinding wheel not suitable for serious sharpening (because it turns swinging up and down and is very worn), holding the scraper freehand and at various angles, not perpendicular. It is much slower but does not burn the steel, even if the wheel surface is badly damaged. Not to be done on an expensive Tormek...

[waldguy]

The steel is a little thin on this instructional (from a paint scraper), but the scrapers can be cut with shears, then shaped with files or by light grinding.

The author includes a few templates.  Preview not showing below.  Youtube search "Maestro Kimon The Scrapers"

 

 

[Jeffrey Holmes]

I don't do new making any longer (presently), so my scrapers are geared to restoration (but some "making" tasks are required for that too).

So, for what it's worth, I use three thicknesses of spring steel (I stashed away a bunch nearly 40 years ago) for my scrapers. The thin stuff is flexible enough to easily bend to a contour in your fingers. The thickest rather stiff.

I have a double edge (90 degree) on the stiffest stuff, and a single edge on everything else.

For the single edge scrapers, I cut the steel close to the shape I want and use a wet grinder to refine and bevel them. Rarely need a file.

[Nikos Matsablokos]

I thank all of you for the very detailed replies. I was considering getting a grinding machine to sharpen the primary bevels of my tools. Either a Robert Sorby Pro Edge which is a belt sander used for grinding the bevel of the tools or a normal bench grinder (haven't decided which one I am going to get yet).

Based on your replies I guess both of these tools could prove useful for shaping the outline of the scraper, after having cut it with metal snips.

[Dave Slight]

Although they are hard steel, because they are thin, it’s still possible to cut them with a hacksaw.

Alternatives are to grind a line, or use a cut off wheel in a dremmel, to partially score the scraper. Line this up with the jaws of your vice, and give it a good blow with a hammer, it should snap off cleanly.

A grinder, disc sander, or linisher can be used for rough shaping, but if you don’t have access to any of these, it’s easy enough to shape them using a bastard file, or similar. Just takes a bit of time.

Refine the shape with finer files, then finish on a sharpening stone. Be sure to have removed all traces of grinding/filing, before using the burnisher to turn the edge.

One of my favourite scrapers was made from the blade of a blunt Japanese saw. Since then, I’ve used the rest of the blade to make some others, which are all excellent.

[nathan slobodkin]

Also important you use the right kind of steel. For thin scrapers I use "blue tempered shim stock" such is used by machinists to shim or space parts. for the thick scrapers the commercial scrapers sold by tool suppliers can be good or repurposed saw blades. You may have to experiment to find the steel which works best for you. If you are going to turn the edges good burnishers can be hard to find. I use a jewelers bezel pusher. 

[Nikos Matsablokos]

I bought some sheets of steel from Cremona Tools that should be good for that. They are sheets of steel that are used to make the Japanese saw blades, which I hear are very sought after as a steel for scrapers. Got enough of that to make a whole set of scrapers.

And if that is not enough, well I had the pleasure of using two of my Japanese saws to cut (by accident) through a piece of lumber with nails embedded in it. Needless to say that the saw went into the wood having teeth on it and came out of it without any  

So i have two very nice useless saw blades to use for scrapers, in case the sheets from Cremona tools aren't enough.

[Jeffrey Holmes]

1 hour ago, nathan slobodkin said:

Also important you use the right kind of steel. For thin scrapers I use "blue tempered shim stock" such is used by machinists to shim or space parts. for the thick scrapers the commercial scrapers sold by tool suppliers can be good or repurposed saw blades. You may have to experiment to find the steel which works best for you. If you are going to turn the edges good burnishers can be hard to find. I use a jewelers bezel pusher. 

Yup.  That's essence;y what the spring steel (it is blued) I mentioned is primarily used for.  My experience is it makes very nice thick scrapers too.

 

[Bill Yacey]

Lie Nielsen has this scraper stock, two pieces for $15.00. One piece is .020" and the other is .032;  Good value for the money.

Scraper Stock

[Muswell]

2 hours ago, nathan slobodkin said:

Also important you use the right kind of steel. For thin scrapers I use "blue tempered shim stock" such is used by machinists to shim or space parts. for the thick scrapers the commercial scrapers sold by tool suppliers can be good or repurposed saw blades. You may have to experiment to find the steel which works best for you. If you are going to turn the edges good burnishers can be hard to find. I use a jewelers bezel pusher. 

I use a carbide burnisher,  it was a bit spendy but worth every penny.

[David Burgess]

I'd like to try some PM V scrapers. If they hold as well as my Powdered Metal knife, and burnish nicely, that would be my go-to.

[Michael_Molnar]

I use 0.020” blue spring steel stock for scrapers. 

[Bill Yacey]

A piece of drill stock heated dull red and quenched makes a very hard burnisher.

[Bill Yacey]

Just now, Michael_Molnar said:

I use 0.020” blue spring steel stock for scrapers. 

My friend gave me his old scrapers, and he had made some from thin spring steel, .008 thick. At the time, I never would have considered such a thin scraper, but in use, it works very well.

In use, I get a certain tactile sort of feedback on how well it's cutting.

[Urban Luthier]

For what it is worth, I have been able to improve how sharp I can get my scrapers by honing the edge on a ceramic stone and and lightly burnishing with an inexpensive carbide rod. Under a 10x loupe, the edge has a mirror like finish. 

[Jeffrey Holmes]

2 hours ago, Bill Yacey said:

My friend gave me his old scrapers, and he had made some from thin spring steel, .008 thick. At the time, I never would have considered such a thin scraper, but in use, it works very well.

In use, I get a certain tactile sort of feedback on how well it's cutting.

Yup.  Agreed.