finish scraping

[Holmes Anderson]

I turned for over 35 years before anyone "invented" the current negative rake scraper. I bought a negative rake scraper, and now it's in my misfit, unused tool drawer. Most of us used the Irish grind bowl gouge, skew, or freshly ground scraper to do fine scraping in the past. I still think a fine burr on a big scraper is a better tool. A negative rake scraper is NOT a necessity. It is a great way to spend money if that is your goal.

+1. Shear scraping yields a better surface both on the inside and outside of a bowl.

 

[Kent Reisdorph]

+1. Shear scraping yields a better surface both on the inside and outside of a bowl.

I stopped trying to shear scrape inside bowls with an Ellsworth grind. It doesn't work. Do you mean with a scraper?

 

[Holmes Anderson]

I stopped trying to shear scrape inside bowls with an Ellsworth grind. It doesn't work. Do you mean with a scraper?

Yes, shear scraping with a round nose scraper on the inside of the bowl and with a square end scraper reground into a refiner on the outside of the bowl.

 

[robo hippy]

I have seen a number of turners who use a swept back grind on the inside of a bowl with the handle held level. That is NOT a shear scrape, which to me means held at an angle. At best, that use of a swept back gouge would be more of a NRS than any kind of shear scrape. I do have one video dedicated to that topic.

robo hippy

 

[Neil S]

I have some HSS, some M42 and a lot of 10V steel and I have never did a test as to how long they last as I have left that for others. And there have been many of those and it stands that in terms of lasting in sharpness the ongoing conclusion is that (not including 15V) its 10V, then M42 and then HSS. Remember that when a pro tells you that what he is using is the best its because he's getting something for using them or he is selling them.

I'm one of those that has done a lot of my own testing of the different woodturning tool steels and can say with some confidence that tool performance can depend partly on what it is being used for. With heavy push cuts in very hard wood I found little difference between V10 and 15V....

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But M42 did just a little less well on the same test runs...

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However, with fine shearing cuts the M42 outperformed V10...

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Because of its fine carbide structure the M42 also benefited more than 10V from being ground on a finer #1k grit wheel for turning medium to harder woods, as does Tungsten Carbide...

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In my testing V15 always outperformed V10, but only marginally at times. Whether it is worth the extra cost is a judgement for each turner. I've been using V15 for decades now and I have never found it to be chippy and I do spend more time looking at edges under magnification than many other turners.

So, it is not a s simple as this steel is better than that steel. In most non-production workshops there will be very little difference noticed by most turners between these steels. If you want a quantum improvement you have to go to very fine-grained TC and the diamond grinding required with that.

I'm a little less cynical than Bill about pro-turner's recommendations, they have to make a living, but I always reserve my opinions until I've done my own testing. I've lived through all of the hype over the decades with each successive new development in tool steel and I ignore almost everything that retailers 'spruke'.

I think it is Cindy Drosda who says, 'we are just one tool away from turning greatness'. In my time basic HSS was the most significant development in turning tool steels and turning greatness has been achieved with just that by many of the great turners. IMO, the newer super steels are nice to have, but in no way essential to great turning. I believe that @Odie on this forum only uses vanilla HSS tools and it certainly hasn't prevented him from doing some excellent work.

 

[Odie]

I believe that @Odie on this forum only uses vanilla HSS tools and it certainly hasn't prevented him from doing some excellent work.

Yes, this is true Neil......

Quite a few turners swear by the exotic steels, and I believe they absolutely do hold an edge longer........But.......I also believe that many turners spend way too much time, money, and effort to attain an edge that will last longer by the use of these exotic steels.

The whole point in bowl turning is to have the sharpest edge possible from the first cut to the last cut, and that is just as possible with the "vanilla" M2 steels that I use. I will concur that the M2 steels will dull a little faster than the exotic steels.......but, re-sharping to a keen edge is so quick and easy (only seconds of time, as a matter of fact), that the exotic steels just don't make a lot of sense to me.

Besides that, it is my belief that when I use the exotic steels, I tend to use an edge that could benefit from re-sharpening a little longer than I should. A tool that is only slightly dulled will still cut, and the difference between it and a freshly sharpened edge is not that noticeable.....until it's time to start sanding......then the difference is a little more obvious.

A turning tool that dulls faster is a benefit to establishing a finely tooled surface......because the difference between it and the dulling rate of an exotic steel tool is much more clearly defined

In my opinion, there are benefits to the exotic steels, but there are big and unfortunate trade-offs to use them......specifically because they tend to keep a turner turning longer than they should, when re-sharpening is what's called for.

=o=

 

[Jon Rista]

I've never had luck trying to sheer scrape the INSIDE of a bowl with a swept back gouge. Even when I try to tilt the gouge up VERY high, so the sheer angle is fairly extreme, it just doesn't work. I don't know the specific science behind it, but sheer scraping the outside of a bowl or platter, or even the rim of a platter (which IS possible in my experience), is usually working on a flat or convex surface. Something about the concave surface of the inside of a bowl, affects the cut. I always get waves...that bouncing, ridging cut that just ruins the wood.

A proper scraper works fine. An NRS at least in my experience works much better. There are some significant differences between a gouge used even in an extreme sheer angle cut position and a scraper. In no circumstance, does it seem possible to me, to actually have the edge of a gouge at any angle to the wood, where the wood wouldn't want to dig into the gouge. I think that results in a rebound in the wood, which then snaps back, digs onto the gouge edge again, snaps back, etc. etc. Even with a scraper, from a physics standpoint as I understand it, the wood still wants to climb onto the scraper, and you can get that snap back in thewood, which then results in that oscillation. With an NRS, the desire of the wood to climb onto the scraper is lessened, and even if the wood does, it rolls off that negative rake angle much more easily than a flat scraper.

Another thing about a scraper, vs. a swept back gouge...you can present it to the wood in a much more effective manner, regardless of what the inside curvature of the bowl is. With a gouge in a sheer scraping position...well, for one, you are not always able to maintain a sheer orientation because of the bowl rim, and otherwise may not be able to achieve an effective sheer angle. A lot of the time, you end up just aggressively scraping, not sheer scraping... An NRS can be presented strait into the wood, slightly above or below angle, and take very clean fine cuts.