Scraper Questions

[Randy Heinemann]

I started turning bowls a little over a year ago. Mostly I have turned smaller bowls (no larger than 6") but am beginning to turn larger bowls. My lathe will accommodate up to a 12" bowl.

Concerning scrapers . . .

1. There are round and half-round scrapers. It seems to me that the round scrapers would be the most useful for me, but, in fact, which makes the most sense for the bowls I will turn (and possibly some plates)?

2. Is there size that makes the most sense? I have seen 3/4", 1", and even 1 1/2".

3. There are also different thicknesses of scrapers. I have seen 1/4" and 3/8" (maybe there are others). Which is the most generally useful?

4. As for grinding angle, is there an angle which is best for smoothing the inside (and maybe outside of bowls)?

Maybe I have not supplied sufficient information. Keep in mind, I'm a beginner, especially when it comes to using scrapers.

[Reed Gray]

I hope to have a new scraper video up before the Symposium, shooting next week....

Anyway, as far as bevel angles, most are in the 60 to 70 degree range. I prefer about 1 inch wide scrapers, and I can stall my 3 hp Robust with them. If you are only getting one, then a round nose would be best, Main reason is you can sweep and shear scrape from either side, right to left or left to right. I find the 1/4 inch thick ones to be a bit bouncy/chattery. Doug Thompson (Thompson lathe tools) has a 5/16 by one inch wide one that is just right, though you have to grind the nose profile yourself, so having a 36 grit wheel helps, or at least having a friend with one... Dave Schweitzer (D Way tools) has a 1 inch wide by 5/32 thick one that is also 1 inch wide. I have a couple of 3/8 thick ones and just don't use them any more, as well as some 1 1/2 inch wide. It is a matter of how much metal can you stick into the wood at one time. My favorite is the Big Ugly tool, another scraper... I have a bunch of videos up on You Tube about scraper, shear scraping, bowl roughing, and bowl turning in general, type in robo hippy... Some think that the bigger scrapers reduce vibration. For me, I just move the tool rest closer to the work, and never hang very far off the tool rest.

I hope to have a negative rake scraper video up later this year...


robo hippy

[John K Jordan]

Concerning scrapers . . .



Randy,

For the inside of bowls and vessels where I can't get the tool rest close to the surface, I like to use the Sorby multi-tip tools, either the straight or the swan neck depending on the piece. Mine came with a 1/8" thick teardrop scraper that can be positioned as needed to smooth different shaped insides. I don't use these tools for hollowing.
http://www.rockler.com/robert-sorby-multi-tip-hollowing-tool-rs200kt
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I use the swan neck tool to reach in a closed form but not with the tip shown but with the same teardrop shaped tip.
http://www.rockler.com/robert-sorby-swan-neck-hollowing-tools
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I usually use these tips slightly angled down or raise the rest a little and hold them flat.

For the outsides and the insides of shallower pieces where I can put the rest close to the surface I far prefer some negative rake scrapers I ground from Thompson scrapers and a Thompson skew. These are 3/4" and 1" and are amazing, always held flat on the rest. I use these without handles. By varying the burr they will aggressively shape or take whisper-thin shavings for smoothing.

385997

Since you asked about scrapers, after I remove most tool marks under power with tools like these I switch to hand scrapers to perfectly smooth the insides and outsides and remove minor undulations or irregularities still in the surface, especially the hard-to-smooth center of a bowl or platter. I have a variety of shapes and grind cabinet scrapers into shapes as needed. With these I can eliminate sanding with coarser grits.

385998

I hold these by hand without touching the tool rest, mostly with the lathe off but sometimes I use the smaller ones with the lathe turning slowly.

JKJ

[William C Rogers]

I have two Thompson 1-1/4" scrapers. I ground one for inside large bowls and the other for outside. I think between 1" and 1-1/4" is just a matter of preference. I only use tear drop scrapers for inside hollow forms. I have a inexpensive Benjamin Best 3/4" hook nose scraper that i like for smaller bowls. I sharpen these to 70 degrees and have not made any negative rake. I also have one re-purposed tool ground as a negative rake round nose at 30 degree (whatever is the lowest setting on the Robo rest) that is used for very light passes to cleanup tearout. You only get one or two passes with this before resharpening.

[Bob Ballard]

John,Do you use the StewMac scrapers on bowls

[John K Jordan]

John,Do you use the StewMac scrapers on bowls

I use a either the StewMac (the two curved ones) or the cabinet type scrapers or both, depending, on bowls and platters.

386053

I sometimes try several different scrapers until I find the one that works the best for that wood and shape. The StewMacs are great for certain woods - I want some different shapes so I bought some 1/8" O1 steel and plan on cutting some shapes and hardening. When I get around to it...

JKJ

[Kyle Iwamoto]

Question here.....
JKJ, I have that Sorby teardrop, in addition to several other insert/hollowing scrapers. I sharpen my teardrop with a shallow (or steep, depending on your perspective) angle so it's no longer square. I think it cuts better. All this hype about Negative Rake Scrapers, and you mentioning that scraper led me to think, IF I held the teardrop scraper "upside down" and used it, is it a NRS? Just tried it, it barely cuts, can't even see the shavings, since the cutter is in the way. Perhaps if I made an even shallower angle it may work better? Thoughts? Perhaps if I installed it upside down and used the tool correctly, it would work better too......
Random out of the box thinking. TIA

[John K Jordan]

Question here.....
JKJ, I have that Sorby teardrop, in addition to several other insert/hollowing scrapers. I sharpen my teardrop with a shallow (or steep, depending on your perspective) angle so it's no longer square. I think it cuts better. All this hype about Negative Rake Scrapers, and you mentioning that scraper led me to think, IF I held the teardrop scraper "upside down" and used it, is it a NRS? Just tried it, it barely cuts, can't even see the shavings, since the cutter is in the way. Perhaps if I made an even shallower angle it may work better? Thoughts? Perhaps if I installed it upside down and used the tool correctly, it would work better too......
Random out of the box thinking. TIA

Kyle, if I understand how you sharpened and used the scraper upside down, it does technically sound like a negative rake scraper but perhaps a horribly inefficient one!

I've resharpened most of my scrapers into negative rake scrapers and I'm generally pleased with the result.

I think the "negative rake" label is just a way to describe the the angle the leading bevel has with the wood. With a given included angle, the tool can be sharpened in a variety of ways and it will cut the same if it is held so the leading bevel is the same. For example, the three NRS I showed ground from Thompson steel,
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are ground to about 60-deg included angle. I hold these horizontal, flat on the rest. (I use them without handles.) I could remove the same fine shavings by grinding a the scraper conventionally, with a flat top, and with a 60-deg bottom bevel, then just hold the tool so it is sloped 30-deg downward. HOWEVER, for me, at least, that would be a lot harder to maintain fine control than when ground as shown and held horizontally.

I believe Sorby recommended grinding the teardrop scrapers with an angle a little less then 90-deg. I think I usually ground mine to about 85-deg or so but nearly any angle will work. I hold it tilted down a little (relative to the wood) on the inside of a vessel or bowl, mostly by twisting the tool a bit counter clockwise. This, in effect, makes it into a negative rake scraper. If I hold it flat but move the tool rest up so the scraper s contacting the inside of the bowl higher than the mid point, it again makes it into a negative rake scraper. Some turners actually grind these with a top and bottom bevel instead of a single bottom bevel and hold the teardrop nearly horizontal, perhaps erring on the side of raising the handle a bit.

Cindy Drozda and others point out (http://www.cindydrozda.com/handouts_Pdfs/handouts/demo%20handouts/negative%20rake%20scrapers.pdf) that an included angle of greater than 90-deg won't cut at all. This sounds like what you have if you sharpen the teardrop to some angle then turn it upside down - it just won't cut. I've found that if I sharpen at very close to 90-deg the scraper works, but perhaps not as well as at a sharper angle. This, however, lets me flip it over and cut with either side. The StewMac scrapers, very similar to the Sorby teardrop in construction, are sharpened as close to 90-deg as possible. Doing this on a grinding wheel actually make the angle very slightly less then 90-deg because of the radius of the grinding wheel.

I have a number of small negative rake scrapers I use on detail and on smaller turnings that are sharpened at nearly 90-deg that work very well, especially on end grain, giving glass-smooth surfaces in hard, fine-grained wood:
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(I use these without handles also.) They would probably cut better at a sharper angle but there is another tradeoff - the sharper the angle the less smooth the surface can be.

There is another usually ignored factor that changes the geometry and "cutting" angle for both conventional and negative rake scrapers - the burr on the scraper. The burr can be from the grinding wheel, added by honing, or raised with a burnishing tool (a process that used to be called "ticketing".) The burr has the effect of creating a tiny but sharp cutting edge, almost like a microscopic gouge. All three ways of raising a burr have their advantages and disadvantages.

1) Using the bur from the grinding wheel is the easiest, just sharpen the lower bevel last and there will automatically be a burr you can easily feel with the fingers. This will cut well but differently depending on the grit of the wheel, the type of steel, and maybe some other factors. The disadvantage is it doesn't last long. Look at the burn with a microscope and you'll see a ragged, fragile row of peaks and deformed metal. Every time this burr touches wood more of the cutting peaks are torn away until they are all gone and it quits cutting. Some people say they resharpen after 30 seconds or so of scraping to restore this burr.

2) Creating a burr with a hone is about the same but results in a much finer burr capable of smoother cuts but much finer cuts - great for that perfect surface but not as good for removing wood. I think it lasts longer than a grinder burr but maybe because I use much lighter pressure with the finer cuts. This burr can make incredibly thin shavings that float through the air.

3) The burnished burr is made by pressing a hard, usually round rod into the edge and pulling it down the edge on the bottom side at some angle greater than the bottom bevel. The sharp edge is smoothly deformed by the burnishing rod. Look at it under magnification and you will see a much smoother and sturdier-looking burr than one made by grinding. I find the burnished burr can last longer than the others, perhaps because it is smoother and stronger and chunks don't tear away as easily with use. With a light pressure and an angle closer to the bottom bevel, the burr can be very fine and good for light smoothing, or apply more pressure and a steeper angle and the burr will be bigger and more curved and cut more aggressively. Some burrs work better with some wood than other - I'm constantly experimenting to find what works best for a particular piece of wood.

The way I usually work is to first grind the bevels with the lower bevel last and create a grinder burr. I use this until it quits cutting then I use an extra fine diamond hone to hone both the top and bottom bevels until the burr is completely gone. I keep a piece of resawn MDF with polishing/honing compound smeared on it for honing my skew chisels - I often use this on the NRS to give a nicely polished edge. Then I raise a burr with either the diamond hone or the burnishing rod to suit what I'm working on.

I use the burnishing rod on all cabinet-type hand scrapers to raise a cutting burr very similar to that used by fine cabinet makers.

BTW, the instructions for sharpening the StewMac scrapers (which are much like the Sorby teardrop scraper) are to hone the sides flat before grinding with the rest on the grinder perpendicular to the stone. The video on this page describes this: http://www.stewmac.com/Luthier_Tools/Types_of_Tools/Scrapers/StewMac_Ultimate_Scraper.html The last time I sharpened the teardrop scraper I used this method and it seemed to work fine.

JKJ
http://www.stewmac.com/Luthier_Tools/Types_of_Tools/Scrapers/StewMac_Ultimate_Scraper.html

[John K Jordan]

Rudy Lopez has this on sharpening his NRS, similar to what I use but with a different curve on the tip: http://www.rudolphlopez.com/pdfs/Negative%20Rake%20Scraper%20Jig%20and%20Info.pdf

JKJ

[Bob Ballard]

John,Do you sharpen the StewMac on a CBN wheel

[Reed Gray]

Jimmy Clewes was a fan of the upside down sharpening for his scrapers, don't know if he still is. At the time I saw him chat about them, he didn't have CBN wheels, and I don't know if that still holds true or not. The idea behind that is when sharpened upside down, you get a much finer burr than you do if you sharpen right side up because the wheel is dragging the burr off rather than pushing into the top of the scraper. I did try it, and didn't think it performed nearly as well as the conventional grind on a CBN wheel. It was a very delicate burr, with little durability. Other than that, I have not been able to get any conventional grind scraper, no matter how high or low I hold the handle, to cut as well as any NRS. That included top angle does some thing, and I am not really sure what. I do get better and/or cleaner cuts than I can with a standard scraper. I am able to get much finer cuts with a burnished burr. I am able to get much cleaner cuts in dry wood than in green wood. For burnished burrs, the more conventional 30/30 grinds do not take a burnisher very well, the edge is just too thin and fragile to take the burnisher, no matter how light of a pass I take with the burnisher. You can actually hear the burr breaking/crinkling as you burnish. With an 80/30 NRS like the Sorby 'hardwood bowl NRS' it is difficult to get much of a burnished burr, and you have to apply a lot more pressure. The less that included angle is, the better the burnished burr is, as in sharper, longer lasting, and can be turned down and back up more times. I have them 80, 70, 60, 50, and 45, with the top angle being 30. It seems like the 45/30 is my favorite for now. More experimentation necessary.... Oh, V10, 1 by 5/16 inch from Doug Thompson, and M42, 1 by 5/32 inch, from Dave Schweitzer. The next size thickness in M42 is 3/8 inch, which is too thick for my tastes...

John, I can't remember, but do they tell you what metal the Stewmac scrapers are?

robo hippy

[Reed Gray]

I watched that Stewmac video again. I commented on it some time ago, maybe years ago and asked him if he had ever tried CBN wheels, and got no response. I would be willing to bet that a carbide burnisher would turn a burr on it...

robo hippy

[JohnC Lucas]

One other advantage of the negative rake scraper is it applies almost no force against the wood so you get less chatter than you do with a regular scraper. This is especially true on thin platters with wings such as natural edge bowls. I used to think that holding a scraper handle up high was the same thing as a negative rake scraper if they both had the same included angle to the edge. It's not. My older tear drop scrapers were ground about 75 degrees. So flipping them over does produce a negative rake but it still works like holding a handle high on a regular scraper. Sharpening a scraper to a more acute angle like 45 degrees and giving it a negative rake on top is a much more controllable tool and leaves a fantastic finish.

[John K Jordan]

John, I can't remember, but do they tell you what metal the Stewmac scrapers are?
robo hippy

The gentleman who returned my call about this question said it was "tool steel", no more details.

It looked like the gentleman on the video was putting a lot more force on the test board than I would ever use on a turning. The steel seems hardened but I didn't try the file test. The sharpening method and burr that works the best for us might be different, worth experimenting. I could try using the carbide burnisher on one and see if it raises the burr. No wager needed!

Another thing, his sharpening leaves a definite concave edge, making the angle less than 90-deg. Based on the size of his hands, to me the grinding wheel looks like a small radius, perhaps a 6' wheel worn down to an even smaller radius. With scraping hard, dry wood I'm happy so far with the edge ground with an 8" CBN wheel and both sides seems to cut about the same. But for other woodturning use, these scrapers might work better sharpened at 70-80 deg and used on one side only.

JKJ

[John K Jordan]

Question here.....
JKJ, I have that Sorby teardrop, in addition to several other insert/hollowing scrapers. I sharpen my teardrop with a shallow (or steep, depending on your perspective) angle so it's no longer square. I think it cuts better. All this hype about Negative Rake Scrapers, and you mentioning that scraper led me to think, IF I held the teardrop scraper "upside down" and used it, is it a NRS? Just tried it, it barely cuts, can't even see the shavings, since the cutter is in the way. Perhaps if I made an even shallower angle it may work better? Thoughts? Perhaps if I installed it upside down and used the tool correctly, it would work better too......
Random out of the box thinking. TIA


Kyle, I read your post again, and I think I misunderstood the first time - I thought you might be trying to cut what would otherwise be the bottom surface and the obtuse angle on the ground bevel. I think I see now you are referring to the acute angle between the bevel and what was the top face. Yes, I think that would make a negative rake scraper. Perhaps the reason it doesn't cut when held flat is the burr is not established, or rather, the grinder burr is upside-down. You might try it again after raising a burr with a burnisher, perhaps after honing away any existing burr. A HSS or hardened steel tool shaft should work fine. I use carbide rods mounted in handles:

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One of these is a much larger diameter rod than the other but they both will work - the smaller diameter feels like it burnishes about the same but with less force because of the smaller radius. An interesting question is whether the larger rod could be gentler on the steel and make a more durable burr.

JKJ

[John K Jordan]

One other advantage of the negative rake scraper is it applies almost no force against the wood so you get less chatter than you do with a regular scraper. This is especially true on thin platters with wings such as natural edge bowls. I used to think that holding a scraper handle up high was the same thing as a negative rake scraper if they both had the same included angle to the edge. It's not. My older tear drop scrapers were ground about 75 degrees. So flipping them over does produce a negative rake but it still works like holding a handle high on a regular scraper. Sharpening a scraper to a more acute angle like 45 degrees and giving it a negative rake on top is a much more controllable tool and leaves a fantastic finish.

I think holding the handle high is equivalent to the NRS in the geometry of the edge relative to the wood (if the included angle of the tool is identical) but not in the presentation and the amount of control you get by holding the tool horizontal and flat against the rest. With the handle high and the edge down it seems the wood would more easily deflect the tool downwards and not make as even a surface.

Funny thing about these scrapers today - yesterday I read from a woodturning book written by F.Pain in 1957. The guy showed how he ground curved edge scrapers with profiles that look very much "Rudy Lopez's" grind - Pain ground them from old files with a sloped top similar to negative rake scrapers but he doesn't call them that. He said they worked better with this grind but didn't attribute it to the grind angle but to the idea that he was grinding down into softer steel in the middle of the file. He raised a burr with a hardened rod.

Another thing he recommended 61 years ago - "Small flexible hand card scrapers shaped with a curved end are extremely useful for troublesome places." Hey, I like that idea. :)

JKJ

[Reed Gray]

Best explanation for why a standard scraper doesn't work like a NRS, and it seems to make sense, is when you hold the handle high like that you get a 'trailing cut', which would be like taking a card scraper and tipping it to 45 degrees or so instead of say maybe 80 degrees. The burr is turned too far over and works more like a rake than a cutting edge. I have applied that thought to my shear scraping too. So you start by rubbing the bevel without it cutting, and then roll it slightly past the bevel rubbing cut. It does seem to cut more cleanly.

Tool steel..... that could mean a lot of things... I did find out with the bimetal blades from Lennox that the teeth are M42 HSS.... Maybe we should find out if the M42 is available in 1/8 inch thickness.... Think the guy in the video was using that scraper on some rosewood....

robo hippy

[Kyle Iwamoto]

Kyle, I read your post again, and I think I misunderstood the first time - I thought you might be trying to cut what would otherwise be the bottom surface and the obtuse angle on the ground bevel.

JKJ

Thanks for the info! I was cutting with the top sharp surface, although handle level and "upside down". Did try sheer also, not working well..... Just trying to find a "cheap" alternative to regrinding and repurposing a high dollar scraper...... I use my skews as NRS.

Oh, I remember your cabinet scraper post from a while ago, and I've been using them. Not on the lathe though. I do know they cut skin much faster than wood...... DAMHIKT.

[Ralph Lindberg]

Sharpening scrapers "up-side down", Dave (D-Way tools) and Jimmy Allen (Boxmaster Tools) are both big fans of sharpening scrappers upside down.
Besides conventional scrapers Dave has negative rake ones, largely due to Jimmy and another local (Scott) encouraging him :cool:
Jimmy's tools are (I think) exclusively NRS.
(for those not in the Seattle are, Jimmy is well known for his box work. Dave encouraged Jimmy to develop his own tools to do boxes with, so he did. The "plan" is for Dave and Jimmy to have adjoining booths at the Oregon Symposium)

[Reed Gray]

Oh no!!! Not more tools..... If Jimmy wants to demo box turning, he is welcome to play on the lathe in my booth.... I do have a bunch of dried box blanks...

robo hippy

[JohnC Lucas]

I wish i could be a that symposium. I just checked and didn't win the lottery so guess I'll stay on this side of the Mississippi for a while.

[John Keeton]

I should have been more explicit - my post was in reference to that of John Lucas.

[John K Jordan]

I should have been more explicit - my post was in reference to that of John Lucas.

Ok, nevermind, then! The handy "qoute" feature can minimize ambiguity.

BTW, I didn't make it to the Knoxville club meeting last week so Ii don't know what tilted/offset platters were shown. The May newsletter should be out soon, I think.

JKJ

[John K Jordan]

... I would be willing to bet that a carbide burnisher would turn a burr on it...


Reed, I tried using a carbide burnishing rod on one of the 1/8" thick StewMac scrapers a few minutes ago. It certainly did raise a burr, even with light pressure. That's not surprising since it does with 10v steel.

I'm running on 10% today and wasn't able to test it on wood but I'll try to in a few days. Perhaps using them with a burnished burr would work better for woodturners than luthiers. Or at least get extended use from them with each sharpening.

JKJ

[Randy Heinemann]

Thanks for the replies. For a beginner like me, there is more information here than I can assimilate and use. I did buy a 1" Sorby round scraper and was able to sharpen it fairly well on my Tormek. I will work on refining the sharpening once I use it and find out how well it works. I've briefly tested it and it seems to work as intended. I'm sure that technique figures in to the final result as it does with all turning.

I was interested in the honing responses, though. The instructor who taught me some basics does hone his scraper with a flexible diamond hone and it does appear to yield a smoother surface than mine did when I tested it last night. Again, it's probably, to some degree, technique.

From the responses, it appears that scrapers are meant to be used with the tool rest at about middle of the piece and angled down at least slightly. Or maybe a little below center with the tool level? Is that correct?

[John K Jordan]

From the responses, it appears that scrapers are meant to be used with the tool rest at about middle of the piece and angled down at least slightly. Or maybe a little below center with the tool level? Is that correct?

Randy,

A "conventional" scraper, that ground with a bottom bevel only and flat on the top, is indeed held against the tool rest about in the middle of the work and angled down slightly (handle held up). Just where "about" in the middle depends on a few things. On the inside of the side of a bowl, for example, it is better for the tool to contact the wood a little above center. That way if the wood grabs the tool it is forced downward into air. If held below center, if the tool is grabbed a bit it will be forced down into even more wood and the resulting catch might be notable. The opposite for the outside of a bowl. For the inside or bottom of a bowl or platter I usually touch the scraper to the wood about on the center line or a little lower.

You might sometime try grinding a scraper with an upper and lower bevel to make it a negative rake scraper. These are easier to use, held horizontal and flat on the rest and simple pushed gently towards the wood and drawn along the surface. It can make very fine shavings to remove tool marks and is almost impossible to catch. I can't remember if it was mentioned in this thread but some people have ground most of their scrapers with a negative rake - I've done that too and rarely use conventional scrapers any more.

JKJ

[Thomas Wilson80]

Is there a good video how to grind a NRS from a regular scraper? Or is it just as simple as flipping it upside and grinding it the same way but at a different angle?
thanks,
Tom

[Reed Gray]

Honed scrapers.... Never considered a scraper and scraping cut as a finish cut on side grain/bowl oriented wood as a finish cut tool till I saw Nick Stagg of the Salem, OR club demo it on a lamp base. Hone off both the top and bevel of the scraper. So, I had to try it, and I found out it does work nicely on hard and dry woods like sugar maple, but no way for some thing like soft maple, or pine, or alder.

As for a NRS, the first ones were skew chisels where you didn't hone off the burr, angles of 25/25 or 30/30. There are lots of variations. Most of the ones from standard scrapers are more in the range of 20 to 30 on the top, and more blunt on the bottom. I think I said up above some where that I am liking the 30/45 to 30/60, but with a burnished burr rather than the grinder burr. I am also starting to prefer a 1/4 round nose profile. which is great for bowl work. Many other applications. Yea, I do really need to figure them out and post a video on them.

robo hippy

[John K Jordan]

Is there a good video how to grind a NRS from a regular scraper? Or is it just as simple as flipping it upside and grinding it the same way but at a different angle?
thanks,
Tom

Thomas,

I don't usually follow videos so I don't know. I posted this photo earlier of my favorite NRS ground from Thompson scrapers and a Thompson skew:

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Grinding these was in fact exactly flipping them upside down and grinding the same way.

However, I grind these with the same angle on the top and bottom just like several well known turners I've seen. Using the same angle gives some advantages. One, I can leave the grinder tool rest at one setting to grind both sides of all three. Two, making the same bevel on the top and bottom lets you flip the scraper over and use it with the curve in the other direction by putting a burr on the other side. I actually keep two of these as "left hand" and one as "right" and mark them so I know which is which without feeling for the burr.

The included angle on these is about 55-60 degrees, or about 30 or so on each side. A "sharper" (smaller) angle will cut better but the edge will not last as long. (no surprise there!) A blunter angle will not remove material as well but is capable of making a smoother surface on some materials.

I grind these in a bit different profile from what some turners use - I've seen them with a curve at the tip but I like the curve transitioning into a flat at the tip. This lets me use use the flat on mostly flat wings of pieces and more easily smooth other flat areas.

Most of my other NRS are one-sided and have a smaller angle on the top than the bottom. These little scrapers (also posted earlier) are ground from Thompson steel with a rather blunt included angle. They work extremely well in end grain on hard, fine-grained wood on things like box lids. I on many woods I get a glass-like surface that needs no sanding.

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BTW, I use all the scrapers shown here with no handles, even with not-so-small bowls and platters. As finishing tools there are no downward forces such as you might get from using a conventional scraper to remove wood. I do have sturdy handles on my box scrapers and other negative rake scrapers where the extension over the rest is larger.

JKJ

[Thomas Wilson80]

Thanks for the replies - my regular scraper seems to be kind of grabby lately and I've been toying with the idea of turning it into a NRS but didn't know the technicalities (angle, etc). Now I think I have enough info to play around. Thx

[Michael Mills]

Only some additional info..
In addition to Reed's videos I thought these by Brian Havens were pretty good also on scrapers.
www.youtube.com/results?search_query=brian+havens+scrapers
On Vimeo Stuart Batty discusses tool overhang. Look for Overhang Scrapers
www.vimeo.com/woodturning/videos/page:3/sort:alphabetical/format:thumbnail

[Randy Heinemann]

Maybe I'm a little dense but I'm still trying to understand the basics of negative scrapers.

I currently own a Sorby round scraper which, when sharpening, I matched the existing bevel on the tool (maybe 65 or 70 degrees? although that doesn't really matter for the purposes of this question).

Is the following correct? -

* To turn that scraper into a negative rake scraper, a shallow angle should be ground on the top of the tool. Based on research there is no set angle to grind but maybe something like 25 - 35 degrees?

* Then, to create the appropriate burr I can either:
- Regrind the main 70 degree angle, or
- Use a burnishing tool to create a burr on the edge.

* Concerning a burnishing tool, is a burnisher that is used on a hand held card scraper hard enough to create the burr on the Sorby scraper edge?

* Will a small diamond card-type hone maintain the top bevel and burr once created?

* What grit stones are best when creating and maintaining the bevels and burrs? I currently am sharpening my gouges and scraper with a Tormek with the standard wheel that came with it.

I'm just looking for verification of the basics at this point. From research, it appears everybody has a method and a specific top angle that seems to work for them. I also realize that a skew can be used as a negative rake scraper; maybe other tools also. I'm merely looking for verification of my understanding of the basic steps in creating and maintaining a negative rake scraper.

[John K Jordan]

You can look up Cindy Drozda Negative Rake Scraper for a PDF file where she describes a lot of this and when and how to use the scrapers.

As you said, everyone has their own way of doing these things! This is some of what I find works for me. I sometimes try different grind angles, presentation, different burrs and might find some things work better in some cases and with some wood. I'm not sure there is a "correct" way!

You can grind your round scraper in a variety of ways. One is as you said. I prefer grind so from the side it looks kind of like a skew chisel, more or less, except perhaps not as small an included angle. Lots of people put a steeper bevel on the bottom but as I mentioned earlier, for most scrapers I often keep the angle the same so I don't have to reset the grinder platform to a new angle when grinding the bottom. I like 50-60 degrees for the scrapers but smaller (sharper) angles will work too. My skews are usually 35-40 deg. Whether the sharp edge is in the center of the scraper or a little higher or lower doesn't seem to matter. If the angles are not the same, that doesn't matter much either.

With the angles on top and bottom the same, the last side ground will be the bottom if you want to use the grinder burr. For a more robust bevel, I like to hone off the grinder bevel and raise a bevel with a round carbide burnishing rod and described earlier. Sometimes I'll use the burr from the grinder until it wears away then hone away what's left of that burr and put a new one on with the burnisher.

Any burnisher good for cabinet scrapers should be good for NRS. I use carbide rods because I have them. I have also used the round shaft of a 1/4" HSS spindle gouge. A screwdriver might work in a pinch. Some people a piece of the hardened shaft of an engine valve.

A small diamond hone is good for removing a burr before restoring it with a burnisher. I hone first the top bevel then the bottom bevel. It is also good when used aggressively on the bottom bevel to raise a bevel just like with a grinding wheel but smaller. I sometimes use a hone on the bottom to make a delicate burr for the finest smoothing on fine-grained wood.

I personally like these little Eze-Lap paddle hones, either the red fine grit or more often, the blue extra fine grit. I find I have more control with these than a card-type hone since I can use my forefinger on the back of the paddle to "feel" the bevel while gripping the handle with my other fingers.

386329

(These are expensive but years ago I bought a life-time supply directly from the manufacturer for WAY less than what most retailers want for them.)

JKJ



Maybe I'm a little dense but I'm still trying to understand the basics of negative scrapers.

I currently own a Sorby round scraper which, when sharpening, I matched the existing bevel on the tool (maybe 65 or 70 degrees? although that doesn't really matter for the purposes of this question).

Is the following correct? -

* To turn that scraper into a negative rake scraper, a shallow angle should be ground on the top of the tool. Based on research there is no set angle to grind but maybe something like 25 - 35 degrees?

* Then, to create the appropriate burr I can either:
- Regrind the main 70 degree angle, or
- Use a burnishing tool to create a burr on the edge.

* Concerning a burnishing tool, is a burnisher that is used on a hand held card scraper hard enough to create the burr on the Sorby scraper edge?

* Will a small diamond card-type hone maintain the top bevel and burr once created?

* What grit stones are best when creating and maintaining the bevels and burrs? I currently am sharpening my gouges and scraper with a Tormek with the standard wheel that came with it.

I'm just looking for verification of the basics at this point. From research, it appears everybody has a method and a specific top angle that seems to work for them. I also realize that a skew can be used as a negative rake scraper; maybe other tools also. I'm merely looking for verification of my understanding of the basic steps in creating and maintaining a negative rake scraper.

[Rob Price]

I’ve been following along and decided to give this a try. I bought some cheap big beefy bowl scrapers a few years ago and they rarely see use. I refer to the biggest as “Mr Grabby” and he’s great at massive catches inside bowls. Every time it happens I ask myself why I even tried in the first place. I have used them outside bowls to remove tooling marks and ridges.

So Mr Grabby was turned into a NRS at just under 90 degrees included angle. Probably 80 or so. I’m thinking for finishing cuts, tear out, etc.

I also started my first end grain bowl today with some Cook Pine and regretted repurposing Mr Grabby. Hollowing out the bowl was all scraper, and I would have liked the xtra heft hanging over the tool rest for those early cuts. BUT, that being said I got the bowl roughed out with the scraper and feel a little more comfortable with it, a better feel for presentation angles, got a better idea of why I get catches. I know it’s end grain but it’s good practice.

I think I’ll replace Mr Grabby with a Thompson scraper...

[Randy Heinemann]

John,

I was interested in the Kelton Multi-Axis tool which seems somewhat similar to the Sorby Multi-Tip tool; at least with regard to the tear drop type tip. Do you use the small diamond hones to sharpen this tear drop tip? (Maybe you already said and I just missed it.) Or is there some way to sharpen on a regular grinder (in my case a Tormek) maybe while mounted in the shaft?

I have had quite a bit of success with the Sorby 1" round scraper over the past few days. I have merely replicated the angle on the tool when I bought via my Tormek and I don't really find that, so far at least, I have any problems with the wood grabbing the tool. For now, I think I will just continue with sharpening as a standard scraper as the finish I'm getting is actually excellent (for me at least) and should reduce my sanding by at least half if not more.

[John K Jordan]

I'm not familiar with the Kelton tool. These days I sharpen the Sorby teardrop and similar scrapers on either a bench grinder with 600 grit CBN or on the Tormek with 1200 grit CBN. I used to use the Tormek water wheel and it worked very well. Small scrapers are easier on the Tormek if used with the wheel turning towards rather than away - turning away requires a focused effort to keep the wheel from lifting off the platform but I always use it like that anyway. I always remove the tip from the tool and hold flat on the rest. I sharpen these all the way around since I rotate them to present a different edge to the surface as needed. I only use the extra fine hones on the flat top before sharpening or just before burnishing a burr, not on the bevel.

I'm glad you are getting better results with your scrapers. After some experience you'll probably find, like most people, that catches are banished to the past and the surface finish just gets better and better! Like my piano teacher always said, everything's easer once you know how. :) For me, using the hand scrapers eliminated the need for coarser grits, eliminated most power sanding, and reduced sanding by way more than half. And the resulting surface is better.

JKJ


John,

I was interested in the Kelton Multi-Axis tool which seems somewhat similar to the Sorby Multi-Tip tool; at least with regard to the tear drop type tip. Do you use the small diamond hones to sharpen this tear drop tip? (Maybe you already said and I just missed it.) Or is there some way to sharpen on a regular grinder (in my case a Tormek) maybe while mounted in the shaft?

I have had quite a bit of success with the Sorby 1" round scraper over the past few days. I have merely replicated the angle on the tool when I bought via my Tormek and I don't really find that, so far at least, I have any problems with the wood grabbing the tool. For now, I think I will just continue with sharpening as a standard scraper as the finish I'm getting is actually excellent (for me at least) and should reduce my sanding by at least half if not more.

[Peter Blair]

Randy I personally believe Robo is on top of the scraper situation!!! Watch his videos.

[Randy Heinemann]

John,

Thanks for the information about sharpening the teardrop tip. The Kelton tool looks about the same as the Sorby but maybe a little more expensive. Since I have had great success with the Sorby scraper, I may try their multi-tip tool also. I have had even the scraper lift up a bit on the Tormek, but the results weren't disastrous and the end result was great and easy to achieve. Finally found a regular use for the Tormek I bought more than 10 years ago and never really fully used. I'm sure I'll have setbacks but the scraper seems to be a great tool for finishing up those areas where there is still some tear out (which I eliminated, for the most part, by starting to improve with the Crowne (Ellsworth) gouges I bought. I also learned a cut with those gouges with smoothes the surface almost as well as with the scraper; just requires a little more finesse and control than I currently have.

[Reed Gray]

I looked at the Kelton multi tipped tool when it first came out at one of the Symposiums some years back. Been a while, but I do remember thinking that there wasn't anything that could be done with it that I couldn't do with standard scrapers. I don't remember if it was designed for hollowing or not. The hollowing tools are a whole different set of tools. Tormek is coming out with a diamond wheel, release date June 1. I know they will be available in the UK, not sure when they are coming to the US. Diamond works on the Tormek because of the very slow speeds. Even on a standard slow speed grinder, the speeds are too high, and the diamonds can't take the heat. The coarse wheel is 600 grit.

robo hippy

[Randy Heinemann]

Hope this doesn’t get posted twice. Lost the other. I believe the diamond wheels will be sold in the US in June sometime. 3 wheels with different grits. The question I have is what wheel to buy since buying more than one would be expensive at between $200 and $300 apiece. Plus switching them frequently would be cumbersome. Would a medium grit be OK for sharpening gouges and scrapers?

[John K Jordan]

Hope this doesn’t get posted twice. Lost the other. I believe the diamond wheels will be sold in the US in June sometime. 3 wheels with different grits. The question I have is what wheel to buy since buying more than one would be expensive at between $200 and $300 apiece. Plus switching them frequently would be cumbersome. Would a medium grit be OK for sharpening gouges and scrapers?

I don't have diamond wheels. As mentioned, I use CBN on Tormek and (1/2 speed) bench grinders. All mine are aluminum, bought from Ken Rizza from Woodturners Wonders.

I currently have:

On grinders
80 grit
220 grit
600 grit

On Tormek
1200 grit
600 grit on the shelf.

The 80 grit is fantastic for reshaping tools, especially heavy tools from today's tough steels. I rarely use the 200 grit. I use the 600 grit on the grinder a lot for sharpening bowl gouges and most scrapers. (I hone well after grinding.

I used the 600 grit on the Tormek for some time and it was too coarse for me, especially for my spindle gouges. The 1200 grit is a big improvement for sharpening. However, it's way too slow to shape tools. I do use it on my skew chisels too but I find that sharpening on the 600 grit grinder is faster and as sharp after I hone them on the leather Tormek wheel and strop on a board. (I resawed a piece of MDF to expose a rougher surface then smear some Tormek or stick polishing compound on the rougher surface. This is always the last step of preparing the skews I like the 600 grit for shapers.

If I had just two wheels I might get an 80 and 600. If I had just one I don't know.

JKJ

[Reed Gray]

For the diamond wheels and the Tormek, I would get the 600 as being most suitable for turning tools. I don't like anything finer than that fir a finished edge, and think the 600 grit makes an excellent finish cut edge, but not as good of a roughing cut edge.

I also watched Stuart's scraper video. A couple of things I don't agree with... He comments about the 8 to 1 ratio for scrapers, 8 inches of handle to 1 inch of overhang. I would consider this to be a very loose generalization. How much handle you need depends on how much, as in size wise, scraper edge you are putting into the wood, The larger the cutting edge, the more handle you need... If it is starting to grab, then move your tool rest closer... Also his handle grip. The way he says not to do it, as in choked up on the handle with the end of the handle under your forearm is the way I have done it for years. To me, that is a much shorter lever on the handle so you have more control. He prefers a hand on the end of the handle. While this seems to make some sense, the full arm lever on the handle is a very long lever that is bent and has a hinge (elbow) in the middle, and is not nearly as controllable. I guess this comes from his gouge holding style which is also long armed, and puzzled me until I figured out he learned to turn on a long bed lathe where it is next to impossible to hold the tool in close to your body without bending over. On a short bed lathe you can keep the tool in close to your body.. In fairness to Stuart, he doesn't use scrapers like I do... Well, probably no one uses scrapers like I do...

I am shooting the 'Scary Scraper' video on Monday.... Will post when done...

robo hippy

[Randy Heinemann]

Still confused about CBN vs diamond wheels for steel gouges and scrapers. Based on reading and this site i understand that CBN would work for me with my Tormek. Would diamond still be a better choice? I can wait till Tormek diamond wheels are available but wonder if it’s worth it. They are projected to be higher cost than the CBN wheels on the Woodturnerswonders site.

[John K Jordan]

Still confused about CBN vs diamond wheels for steel gouges and scrapers. Based on reading and this site i understand that CBN would work for me with my Tormek. Would diamond still be a better choice? I can wait till Tormek diamond wheels are available but wonder if it’s worth it. They are projected to be higher cost than the CBN wheels on the Woodturnerswonders site.

I think diamond would be fine for the Tormek and might last longer. Diamond is harder than CBN. The problem with CBN and grinding wheels is the carbon in steel will cause the diamond to degrade but only in the presence of the high heat of grinding. From what I read and wheel as slow as the Tormek would not generate enough heat to hurt the diamond. I'm pretty happy with the 2"x10" CBN wheels. I ordered them with square corners and grit down the flat sides. As mentioned earlier, I use a 1200 grit but have a 600 as a spare. I like the edge the 1200 grit gives on the tools. What to get might depend on the price.

Understand that a fine CBN or diamond wheel is great for sharpening but I wouldn't want to reshape a skew or scraper with it - I think it would take too long. I use an 80 grit CBN wheel for that.

Don't know if anyone remembers, but there was a diamond wheel available for the Tormek around 2005. I read some reviews from the UK but never heard anything else about it. Perhaps it was never sold in the US.

Funny thing - some dealers offer CBN honing plates in various grits. Although I bought some, they really don't make any sense compared to diamond plates since the diamond will cut better and last longer. There is certainly no heat generated in honing plates. Rizza has the CBN plates in a great size, 2"x8" I think, double sided with a different grit on each side and less expensive than you might imagine. When I asked about getting diamond in the same configuration he was able to special order some for me. I think I got six grits on three plates, up to 1200 grit. What I used them for first was sharpening ceramic shearing cutters for my livestock shears. I bought ceramic cutters which last many times longer than steel cutters but reportedly cannot be sharpened. They can, however, be sharpened with diamond plates. A bit of water and some elbow grease and the cutters are as sharp as new. TIme to shear the llamas and alpacas for summer.

JKJ

[Reed Gray]

From Glenn Lucas of Ireland, "I find good homes for my CBN wheels after a year." "I have had the diamond wheel on my Tormek for a year and it still cuts like brand new. The diamond is almost twice as hard as CBN." I am trying to get one for the Symposium in Portland..... Glenn favors the 600 grit.

robo hippy

[Randy Heinemann]

Good feedback. I think that, for me, given the frequency I turn, it might not matter whether I get CBN or diamond. I have experience with diamond plates up to 1200 grit sharpening my chisels and think they are the best. No maintenance and they seem toast forever. I then home with a 4000 and 8000 ceramic glass stone. Great results.
The only drawback to the diamond wheels that allegedly will be available in June from Tormek is their price. CBN would be less expensive if the prices quoted so far for the Tormek wheels are accurate.