Scraper Questions

[Michael Mills]

Only some additional info..
In addition to Reed's videos I thought these by Brian Havens were pretty good also on scrapers.
http://www.youtube.com/results?searc...avens+scrapers
On Vimeo Stuart Batty discusses tool overhang. Look for Overhang Scrapers
http://www.vimeo.com/woodturning/vid...rmat: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.

hones.gif

(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