Scrapers - How much pressure do I need to use?

[Kuffy]

I just bought a round side cutting scraper from Timbecon. It is my only decent scraper so it will do all of my scraping needs except for when I use a skew chisel.
https://www.timbecon.com.au/woodturning/turning-tools/side-cutting-scrapers

I am wondering whether a scraper tends to want to pull itself into the cut and stay in the cut, or do I need to physically force it into the timber? I find I need to use more effort than I was expecting to get it give me a shaving.

Also, I am presenting the tool "downwards"..the tool tip is below the tool rest, handle above the height of tool rest if you can imagine that. This seems correct to me, because I need the burr to engage the timber.

[Jeff Leslie]

Kuffy, no idea how you sharpen but you can do away with the burr. Too many fine turners have advised to just use a sharp scraper.

I must admit I am a little confused about your statement about scrapers pulling into the cut or do you force it. If your scraper is aggressive (ala Vic Wood style), it will almost certainly want to pull into the wood. Caress it with a light touch. If you are pushing the scraper into the cut, the tool is either blunt, sharpened at too flat an entry angle or your tool work (sorry) is astray.

Google negative rake scrapers or just search this board. They are almost fool-proof but they don't stay sharp for long. What are you turning BTW?

Some woods don't respond well to almost any scraper or sheer scraper. (Hunter tools excepted).

As to the presentation of the tool to the wood.... a down incline is safe. Upwards, depending on tool shape, can be aggressive but a solution. Good luck with that cut. Try it and see if it works safely for you.

And repeat, forget the burr. That flim bit of steel will only imbed in the wood and making future cuts harder. Tip: test it with a metal detector.

[Kuffy]

Thanks. I am turning Walnut. It is soft and easy to work with. I sharpened the bevel angle to be about the same that came out of the factory. Looks like about 75 degrees. I will hone the burr off and give it a go tomorrow morning.

[Kuffy]

I sharpened the scraper with a little more dexterity this morning and it now makes light, long, fluffy shavings. It doesn't take any pressure at all to get a shaving, so I am guessing I must have slightly rolled the bevel yesterday when I sharpened free hand. I left the burr on and gave it a go. It worked so I left it like that. The timber removed the burr pretty quickly anyway.

[Jeff Leslie]

Kuffy, good to see you got a result. The angles set by manufacturers rarely are at the right/preferred/correct angles to suit a whole host of jigs. I suggest you shape the tool according to the jigs you have on hand - or get into hand-sharpening without jigs and get a nose-bleed.

Now, didn't I tell you that burr wouldn't last long? And that was on soft wood!

Ideally, you want no burr, just a sharp tool. If you put a burred chisel to say Gidgee, Mulga or Bowyakka and you are talking seconds of sharpness.

I suggest you (over time so you don't waste steel) make your scrapers more aggressive until you find the balance between ideal scraping, lasting performance and danger.

I wish I could send you a video of Vic Wood using a scraper but the bugger doesn't want me to film. Super aggressive, super light touch.

Jeff

[smiife]

Hi kuffy,
You might want to try a negative rake grind like this one......

[Kuffy]

I dont understand how a negative rake scraper can be any different to a normal scraper which is presented to the timber at a decline. Maybe its just more comfortable to hold the tool horizontal?

[Woodturnerjosh]

Here's some relevant negative rake scraper info. They are not an alternative to regular scrapers (in some cases I find they leave and inferior finish) but they do have some advantages over regular scrapers...it depends on the timber your using them on.
Like all things in woodturning there are many different ways of doing things and this is just one style of NRS.
393949

[Kuffy]

On this walnut I am messing around with at the moment, the standard scraper isn't giving me any issues and is leaving a nice finish so I will stick with it for now. However after reading that article, it seems that a negative rake scraper may be the preferred for hard dense timbers. I'll try with a standard scraper on some coolabah burl I have here, and if I have major dramas I will burn away the tool steel and make a negative rake. And if I still have major dramas, I will blame the machine and buy a new one :D

[Woodturnerjosh]

I found they worked really well on hard burls.
But I know that Bert Marsh (a turner that specialised in thin walled bowls in hard timbers) used to use a scraper sharpened to 45 degrees with no burr, on the outside of bowls he even used to rub the bevel of the scraper. I haven't tried a scraper sharpened this steep before but it's next on my list! lol

[Kuffy]

scraper sharpened to 45 degrees with no burr, on the outside of bowls he even used to rub the bevel of the scraper

If I tried that, my gravestone would read "he tried rubbing a 45degree scraper bevel on a bowl and ended up rubbing the inside of his skull on the bevel"

[Woodturnerjosh]

If I tried that, my gravestone would read "he tried rubbing a 45degree scraper bevel on a bowl and ended up rubbing the inside of his skull on the bevel"

lol, not a technique I'd recommend to beginners! Just another variation of "shear scraping"

[Christos]

The way I use the scraper is to present the cutting edge at or just below center. If I was on the final smoothing cut I would sharpen the scraper and present the scraper well under center. Please note that this will be very light cuts where the shavings are very thin. I think the shavings would be more like when you are shear scraping using a bowl gouge for example.

Oddly I saw this being done by Theo at the recent wood show and I asked him about his thoughts. Others have used the scraper tilted but I find this hard to control. So I use it below center.

[hughie]

If you sharpen your scraper and put a burr on the cutting edge, then present it with the blade level with the floor. It will most likely then with little or no pressure it will rip the blank out of the chuck or your hands or something equally nasty. :U

So if your scraping the inside try shear scraping, shear scraping is where you tilt the blade up on the edge nearest to the direction your scraping, somewhere around 45' ie / It will scrap a fine finish with very fine curly shavings, ok with this you can get away with not having the bevel rubbing and this is often the case on the inside of bowls. The blade or body of the scraper can be level of just under level to the floor assuming your tool post is on centre. With shear scraping the burr is engaged quite readily in this position.


As for pressure with this it will depend on the timber, but with soft timber you could get away with as little as one finger.


Negative scraping a current fad/practice of grinding a negative angel on the top of the scraper. It will greatly stop dig ins and so is favoured by many, it will leave a fairly good finish depending again on the timber being turned. The down side to this grind is that it isnt really necessary in my book. As if you lift the handle above the scraper cutting edge you will have a negative scraper. But then you have already had a go at this.

With scrapers its better to start with a very light pressure till you get the feel of it and this is a experiential thing, you will get it in time.
If the scraper 'self feeds' or 'pulls in' then you will have a dig in and usually a beauty. :o:D

[Christos]

One one of those times that I have to clarify what I am saying as I missed something.



.....If I was on the final smoothing cut I would sharpen the scraper and present the scraper well under center.....


Tilted under center. Not horizontal under center.

[Robson Valley]

Interesting. For me, the burr is the cutter. Leonard Lee says you can do either: a squared corner edge or burnish the edge to create a burr.
Mind you, I'm just using them in cabinet scraping tasks (gun stocks, etc).

[Kuffy]

Yes, I use the cabinet scrapers on my flat work. It's not hard to know when the burr is gone or folded over, because it just stops cutting. I gave it a quick go of turning a burr on my woodturning scraper, it worked great for about 2 seconds

[Jeff Leslie]

Yes, I use the cabinet scrapers on my flat work. It's not hard to know when the burr is gone or folded over, because it just stops cutting. I gave it a quick go of turning a burr on my woodturning scraper, it worked great for about 2 seconds

Kuffy, you obviously weren't listening when I said NOT to cut with a burr on your scrapers. In your own words, the burr lasted 2 seconds. Or are you just a slow learner?

Jeff (and what you give me will come back, with interest, as you are learning).

[artful bodger]

In my wood turning journey so far, it has been the burr on the scraper that does the cutting. The burr wears off pretty quickly so you find yourself continually grinding on a new burr. That is the way it has been for me. Honing the burr off beforehand defeats the purpose entirely. Even with hand scrapers it is the same deal, it is the burr that does the cutting. Hone it off and you don't have a scraper just a bit of metal that does not do very much unless you have low expectations.
Interesting to see the direction this thread is going.

[Kuffy]

I didn't put any great effort into turning the burr. I literally just picked up my burnisher that I use on my cabinet scrapers and turned a burr. I dunno if this was right or wrong, but it didn't work very good. If it worked well it would have been a good experiment. Instead I lost 4-7 seconds farting about. :shrug:

Jeff, you said not to use a burr. But I know that people do use a burr. So is it not fair if I try for myself to see what I like or dislike? If I still did things that way I did them back when I was an 18 year old apprentice, I guess I would still have to struggle to lift a bloody 20'X5"x5" green pine post. But as time goes on, I find new ways of doing things, mostly through experimentation. I ask myself "what if?". And then I seek the answer. Sometimes the answer draws blood, sometimes the answer takes longer, and sometimes the answer is a safer, time saving, material saving method!.

If a tutor says I must design a product with X,Y,Z dimension, and it must be made out of A material, and glued up with B glue, and finished with C finish. Is it my design or am I simply a slave to my masters.

Jeff what have YOU designed?

[Mobyturns]

In my wood turning journey so far, it has been the burr on the scraper that does the cutting. The burr wears off pretty quickly so you find yourself continually grinding on a new burr. That is the way it has been for me. Honing the burr off beforehand defeats the purpose entirely. Even with hand scrapers it is the same deal, it is the burr that does the cutting. Hone it off and you don't have a scraper just a bit of metal that does not do very much unless you have low expectations.
Interesting to see the direction this thread is going.

If you get a chance go see Guilio Marcolongo make his offset lidded boxes by hollowing the box using a conventional skew as negative rake scraper. It will totally change your thoughts on all scrapers and hollowing end grain into timbers like lancewood, gidgee! The burr would last milli seconds if there ever was one there to start with!

Burrs on cabinet scrapers are usefull for face grain scraping in traditional cabinetry, not much use on woodturning tools due to the vastly different cutting speeds involved. A hand cabinet scraper is used at very low speeds. Woodturning scrapers are used at speeds of 60 kph or more, so experience far more abrasion, heat and metal fatigue. A burr off the grinder on a woodturning gouge or scraper is next to useless imo. However a burnished burr on a woodturning scraper is a very different animal and is capable of extreemely fine finishing cuts (scrapes) in skilled hands.

[artful bodger]

^^^^ I would not use a scraper to hollow end grain. A gouge would be the tool of choice there^^^

[Kuffy]

There is a video of Guilio doing his skew chisel hollowing. Seemed to work pretty well.

https://youtu.be/W_UXcBlkoA4?t=38m10s

[Mobyturns]

There is a video of Guilio doing his skew chisel hollowing. Seemed to work pretty well.

https://youtu.be/W_UXcBlkoA4?t=38m10s

Thanks for posting the link. Guilio like to challenge ideas, hard to refute the efficiency of the material removal using a skew.

[Jeff Leslie]

Kuffy, I've had a few half-decent turners in my shed, including Vic, Guilio, Retired and Ken W.

You ask what I have designed. A fair question perhaps. I copy in most parts, as does every other woodturner. The only recent innovation that I know of is Ken Wraight's Separation series. And clearly, I and quite a few others are not Ken.

[Woodturnerjosh]

Great attitude Kuffy!
Plenty of very capable and fantastic turners advocate the use of a burr in certain situations. See what other people are doing and try and see what works for you and in what timbers and what situation. As they say "there is more than one way to skin a cat"
Veritas actually made a specific tool with tungsten rods to turn a burr on a wood turning scraper (I've never used it but some people speak highly of it)

Josh

N.B. no cats were harmed in the writing of this post. lol

[Mobyturns]

Great attitude Kuffy!
Plenty of very capable and fantastic turners advocate the use of a burr in certain situations. See what other people are doing and try and see what works for you and in what timbers and what situation. As they say "there is more than one way to skin a cat"
Veritas actually made a specific tool with tungsten rods to turn a burr on a wood turning scraper (I've never used it but some people speak highly of it)

Josh

N.B. no cats were harmed in the writing of this post. lol

A few years back now I entered a bowl in a comp that I persisted with. I had essentially given up as I thought the "Ivory Walnut" blank was an unturnable write off because it had areas of spalting and extreemly dense wood. Everything I attempted with bowl gouges simply made the surface worse, creating a corrugated finish as the gouge bounced over the hard stuff and dug into the spalted areas.

So with nothing to loose I went for a very large Sorby scraper. The edge / burr off the grinder would only last seconds on the abrasive timber, which I figured would probably consume half of the scraper by the time I finished. I gave it a break and did some more research which led me to burnish a burr on the traditional scraper profile. Initially I found it very agressive and had to modify my turning style and tool presentation angles, but it worked and solved my problem. Light cuts / scrapes at first to remove the corrugations, then more serious stuff to create the profile. Plenty of cursing later, and quite a few regrinds, reform the burr etc & I achieved a half decent finish that sanding made a mess of very quickly. More light scraping with the burnished burr then very light sanding got me there eventually. Way too much time invested but a fantastic learning exercise in retrospect.

[Jeff Leslie]

Kuffy asked for some pics. All on my Iphone so the quality is not great.

Please note Kuffy how I finished the bottom of my bowl/platter.

395576395577395578