Tutorial on Shear scraping.

[RETIRED]

On a hot Saturday afternoon Vic Wood, Ken Wraight, Jim Carroll, Tea Lady and myself gathered to do a photographic tutorial on Shear Scraping.

These are the results and hopefully will give everyone a better understanding of the methods.

I confess that until now I did not know how to shear scrape successfully.

I turn spindles and have never had to do it. Normal scraping yes but shear scraping- no.

The first rule of shear scraping is the tools must be razor sharp.

The next one is that the tool must be presented to the timber at an angle less than 90 degrees in the direction of travel.

[KenW]

SHEAR SCRAPING with a BOWL GOUGE.

Photo 1: Vic Wood doing a shear scraping cut with a bowl gouge.
130882

The gouge has two cutting edges, the top edge (which you can see) and the bottom edge (that you cannot see).
The cutting edges must be razor sharp and slightly convex.
All of the cutting is carried out by the lower cutting edge, the angle of presentation of this edge to the work is critical in shear scraping.
The bottom cutting edge should be presented to the work, between 10 and 45 degrees from vertical. This is controlled by holding the handle of the gouge low on your body.
The gouge should be rolled over so that the top cutting edge is almost touching the work.

Photo 2: shows the position of the cutting edges and the handle of the gouge.
A 5 cent piece was placed under the top cutting edge to show how close this edge is to the work. If the gouge is rolled over too far and both the top and bottom cutting edges touch, the gouge will stop cutting (but never catch).
130883

Photo 3: close up of tip of gouge (with coin spacer).
130884

Photo 4: Vic uses a slightly flatter presentation angle than me and makes a wider cut, which is shown by the wider black marks. This wider cut will leave a smoother surface finish than my more vertical cut.
130885

Photo 5: I normally work on hard woods that tear very easily, and I tend to make smaller pieces with limited access, therefore I shear scrape at an angle closer to vertical. The smaller area of cut is shown by closer black marks.
This steeper angle of cut will give you the best chance of eliminating tear out, however it will leave some surface lines, these lines are very shallow and remove easily with sand paper.
130886

Photo 6: Vic shear scraping using a spindle gouge.
130887

Photo 7: Shear scraping produces fine hair like shavings.
130888

[KenW]

SHEAR SCRAPING with a ROUND NOSE SCRAPER.

Photo 8: Vic shear scraping with a round nose scraper. I sharpen my scrapers to 50 degrees, you will notice in the photo Vic uses a much more agressive angle. Both Vic and I polish the top of our scrapers and remove the burr.

The scraper, like the bowl gouge, is presented to the work at an angle, between 10 and 45 degrees from vertical. The scraper must be moved so that the lower edge that is sitting on the tool rest cuts the wood first. In the photo the cut is being made from the center of the bowl towards the outside (with the grain).

130889

It is almost impossibe to have a catch with a bowl gouge when shear scraping, the same can't be said for a scraper.
The scraper MUST be presented to the work at less than 90 degrees or it will catch (the angle formed between the top surface of the tool with respect to the face of the work).

Photo 9: Shows the scraper being presented at the correct angle, less than 90 degrees, and is therefore SAFE.

130890

Photo 10: Shows the scraper being presented at the incorrect angle, greater than 90 degrees, and is therefore UNSAFE.

130891

[RETIRED]

Thanks to Tealady for the photos.

Thanks to Ken for the captions and Vic Wood for checking it.

Thanks for teaching me too.:D

To be continued..........

[Mulgabill]

Thanks , Vic, Ken, Jim, Tea Lady. This tutorial explains why I, at times, have some trouble with the round-nose scraper. Presenting it at the wrong angle. I await the next instalment.

[jefferson]

Good God, anyone would think these guys know what they are talking about..... :D:D:D:D

Lesson no. 245 and all for free. :2tsup:

[dai sensei]

Thanks for the tute :2tsup:

I have used the bowl gauges before for shear scraping, but don't use the scraper, probably because the first time I did I obviously used it the wrong way you indicated and it caught :-.

I would also like to argue that the bowl gauge cant catch when you roll too far, I can make anything catch :-:U:U

[artme]

:2tsup::2tsup::2tsup:

[steck]

I would like to add my thanks to the chorus!!!!:2tsup::2tsup::2tsup::2tsup:

[Ed Reiss]

good one, guys :2tsup:

[Texian]

This is excellent. Thank you. Thought I was the only one doing scraping and shear scraping with the bowl gouge. Am scared of regular scrapers; have one and never use it. Very encouraging to learn that I have been doing it somewhere near right all this time.

[rsser]

Thanks gentlemen (& TL)

What's the plus in a long bevel on a scraper?

[pommyphil]

Great stuff, many thanks


:2tsup: Phil.

[Calm]

Thanks guys - like i said in the other thread before - clear as mud :D:D

Also as i proved myself - easier to explain then actually do

Cheers

[Ozkaban]

Thanks , Vic, Ken, Jim and Anne-Maria. Great tutorial :2tsup:

I think I get it now. Gotta go practice some :D

Cheers,
Dave

[KenW]

Thanks gentlemen.

What's the plus in a long bevel on a scraper?
Ern, I find that a scraper with a long bevel takes a finer cut and stays sharper longer.
The down side, the scraper must be used with a delicate touch or it will take a very agressive cut.

Photo 12: Vic showing how light a grip he has on the scraper, when used to do a normal scraping cut.

130936

[KenW]

Thanks for the tute :2tsup:


I would also like to argue that the bowl gauge cant catch when you roll too far, I can make anything catch :-:U:U
Neil, that's why I said "almost" impossible to have a catch.
There is always somebody with the extra skills needed to make a gouge catch.:roll:

[Manuka Jock]

Photo 12: Vic showing how light a grip he has on the scraper, when used to do a normal scraping cut.

130936

When I was shown this scrape with the bowl gouge , the position of the bottom hand as displayed by Vic on the photo was emphasized .
In fact I was told that there was no other way to hold it other than with the butt of the handle nestled in the palm of the hand .
It works well for me too .

Jock

[Daddy3x]

Learned how to shear scrape with a bowl gouge at a workshop I visited, still can't get consistent results, so a lot more learning and practicing left. I have been reading that some of you flatten the top side of the scraper prior to using it, much like when one buys a new bench chisel or plane. After that is done you grind it forming a burr on the top of the scraper, hence a fresh cutting edge. I have also seen some running a hardened nail along the edge at a right angle to the top to roll the burr even more. Honing the top would fold the burr back to the front, correct? Need some clarification here. I really appreciate the pics and insight on the gouges, new way to think about when at the lathe tomorrow.

Scott

[rsser]

Yes, lap the top of the scraper. The finer the polishing job you do here the smoother the cutting edge, just as with bench tools.

Some use a lapped top as is, some like to turn a hook with a hard burnishing rod or even just a diamond hone after the top is lapped.

A burr created with a dry grinder is jagged and leaves a poorer finish.

Edit: ideally you wld hone the bevel too. A Tormek wheel will take it down to 1000 g (advertised), while the honing wheel charged with Tormek compound is said to get down to 1 micron.

[NeilS]

Thanks to everyone for their expertise, time and efforts on this much needed tutorial.

I yepped my way through the instructions until I got to the following point from Ken...





.....the angle formed between the top surface of the tool with respect to the face of the work).



...and Photo 10....

There is always one slow learner in every tutorial group...:B

I get the words with Photo 9 and 10, but the lines are confusing.

If I understand the concept correctly, the shear scraping angle is the same for Photo 9 and 10, but the tool has been swung out (like it's on a hinge fixed to the shear scrape angle) beyond 90deg to 'the face of the wood' in Photo 10. The superimposed lines don't help explain this.

The only way this can be clearly shown is if each photo is taken side on to the top surface of the scraper AND tangentially to the point at which the tool touches the wood. A precise point in three dimensional space that will clearly show the angle of the face of the scraper to 'the face of the wood'.

My rudimentary examples (using a blackened piece of wood to represent the scraper) are attached. First photo, angle less than 90deg. Second photo, more than 90deg. Both photos taken with the same shear scrape angle of about 30 deg (the line with dots) from the line of rotation, photo 3.

Hope the collected gurus don't mind me butting in on their tutorial...:rolleyes:

.....

[Daddy3x]

Thanks Ern,

I have been using the dry grinder set at the scraper bevel, then going straight back to work. So to clear up, after initial lapping/flatting, in the future just run a quick few passes with a diamond hone/card on the top, then raise the burr if desired? Sounds a whole lot easier than what I had been doing! It may take me a bit to understand everyone's wisdom here, but believe me, I am learning plenty! Thanks Scott

[rsser]

This is a bit OT but did mention using a sharp tool.

There are various ways.

Min: Grind the bevel at the angle you want. Flatten and polish the top.

Earlier posts suggest using the scraper as is. There is a case to be made however for another step and that is raising a burr with a hone or burnisher coming up from the bevel side. Maybe at 80* or so but I'd have to check. Look at the Lee Valley site for the Veritas turning tool burnisher eg.

[rsser]

Thanks for the bevel angle insight Ken.

[KenW]

Thanks to everyone for their expertise, time and efforts on this much needed tutorial.

I yepped my way through the instructions until I got to the following point from Ken...




...and Photo 10....

There is always one slow learner in every tutorial group...:B

I get the words with Photo 9 and 10, but the lines are confusing.

If I understand the concept correctly, the shear scraping angle is the same for Photo 9 and 10, but the tool has been swung out (like it's on a hinge fixed to the shear scrape angle) beyond 90deg to 'the face of the wood' in Photo 10. The superimposed lines don't help explain this.

The only way this can be clearly shown is if each photo is taken side on to the top surface of the scraper AND tangentially to the point at which the tool touches the wood. A precise point in three dimensional space that will clearly show the angle of the face of the scraper to 'the face of the wood'.

My rudimentary examples (using a blackened piece of wood to represent the scraper) are attached. First photo, angle less than 90deg. Second photo, more than 90deg. Both photos taken with the same shear scrape angle of about 30 deg (the line with dots) from the line of rotation, photo 3.

Hope the collected gurus don't mind me butting in on their tutorial...:rolleyes:

.....
Neil, butt in all you like.
Your photos and description are spot on.
Thanks for the help.

[Calm]

I dont agree with the notion of a burr - a burr is not part of the cutting edge but a jagged overhang (yes a spark grinder is coarser than a tormek and a honing/lapping but a burr is a burr)

When i was a Beef slaughterman my knives were sharp enough to shave with and i can tell you a burr does not help a sharp edge but hinder it, A true sharp edge is perfectly flat & straight and will last for a long time - a burr is going to break/chip off and become a jagged edge very quickly. A butchers knife is sharpened/lapped on a stone and a "steel" is then used to stand the edge up straight - but it is not a burr it is the edge . If you get a burr when sharpening a knife you need to remove it and sharpen again.

I dont see that a turning tool is any different an edge is the intersection of 2 lines - a burr is a jagged edge with the interesecting lines at different angles to the edge you were grinding for, so if that is the angle/intersection you wanted then grind the tool to that angle in the first place.

Just my 1.5 cents worth. maybe 4.5 cents allowing for the experience here.

cheers

[tea lady]

The discussions I recall on "using a burr on a turning scraper" all boil down to not too. the burr is too thin and just break of and embeds itself in the work. Rusting at some stage in the future. And also helping to blunt your scraper faster cos you are trying to cut more and more metal as the process continues. Sharp is necessary, but not with a burr. :cool:

[rsser]

There are jagged burrs (from a dry grinder) and a smooth burnished hook. See the parent thread.

Veritas make a burnishing tool claimed to produce a hook that cuts.

I've done this and put it under the 'scope and found a longer smoother edge than I got from a dry grinder, but it was still not a consistent hook. Maybe my poor technique.

The Lacer test referred to in the parent thread, on the cross grain of end grain, was not complimentary about the finish off a scraper without a hook. But his bevel was ground at 60 g on a dry grinder.

[tea lady]

There are jagged burrs (from a dry grinder) and a smooth burnished hook. See the parent thread.

Veritas make a burnishing tool claimed to produce a hook that cuts.

I've done this and put it under the 'scope and found a longer smoother edge than I got from a dry grinder, but it was still not a consistent hook. Maybe my poor technique.

The Lacer test referred to in the parent thread, on the cross grain of end grain, was not complimentary about the finish off a scraper without a hook. But his bevel was ground at 60 g on a dry grinder.:think: So like a hook on a cabinet scraper? I dunno. A lot of farting around for not much gain it seems to me. :shrug: May as well have the scraper with no beval at all and burnish a burr.:shrug: Prolly would end up with the same "effective angle" as the angle on a Ken W or Vic Wood scraper.

[Sawdust Maker]

Thanks for this thread and discussion everybody
I think I'll ponder and ruminate on all this for a few months and then see if I can ask a sensible question

[powderpost]

Both methods.. with a burr and without a burr, work well. I put the argument about a burr on the tool into the same category as the argument about grinding angles and honing methods.
You also need to take into account the type of timber, (with varying amounts of silica and/or hardness), turning speed and type of steel.
I learnt about shear scraping from Del Stubbs In Brisbane in 1987. He advocated using a burr. I have always used a greater angle, probably about 60 degrees straight from a dry grinder and then as the surface was refined, polished the top surface of the tool and restored the burr with a fine stone.
I agree totally that the tool must be sharp. I also agree with the tool presentation illustrated, this is most important.
Shear scraping is much better than sanding, especially for laminated projects. It prevents "bleeding" of dust from one colour into an adjacent another.
Just some opinions from an old turner at the other end of the country.. :)
Jim

[robo hippy]

I could and probably should write a book on this subject. bowl turning DVD out in a year or two.

I have never understood why when you drop the handle on the gouge, and roll it far onto its side so you are cutting with the edge, and not rubbing the bevel it is called a shear scrape. You are cutting at a shear angle, but not scraping. A scraping cut is, to me, having the scraper flat on the tool rest, pointed slightly down hill, and plunging straight into the wood. This is a roughing cut. You can do the same cut with a gouge, tool level/parallel to the ground, flutes at 90 degrees to the wood rotation, and cutting without the bevel in contact with the wood. These are roughing cuts, and will remove a lot of wood in a hurry, and leave a fairly rough surface, as it pulls more at the wood fiber rather than slicing. Scrapers are my main tool for roughing out bowls.

Having the scraper at a 45 or so degree angle on the tool rest is a shear cut, and you generally don't rub the bevel, though you can. This is more of a pulling cut, and is an excellent finish cut. This is the same cut you are making with the gouge in the 'shear scrape' mode.

For sharpening scrapers, I have a 75 or so degree bevel, rather blunt. The bevel shown on those in the pictures seems to be more like 45 or so degrees. They do tend to be more grabby.

For most of my scraper cuts, I like the burr straight from the grinder. I have an 80 grit CBN (see thread on diamond grinding wheels) wheel which leaves a very smooth face on the tool. This raises a nice smooth even burr, which is very durable, and is fine enough to make good finish cuts, and strong enough for heavy roughing cuts. I do hone off the old burr before grinding a new one. You can hone the grinder burr off and use the scraper with no burr, and it works okay. You can raise a burr by first honing off the one from the grinder (both on the top of the tool and on the bevel) and then a light pass or two with a triangle burnisher (never could get a good burr with a round burnisher), or use the Veritas burnisher. This light burr is only good for very fine finish cuts and will dull/wear out quickly. It is totally unsuited for roughing work. A burr that is raised by honing is less durable than this.

You can burnish a heavy burr by applying more pressure. This burr is great for heavy roughing cuts, and finish cuts. It can be burnished down and raised again a few times, just like the burrs on a card scraper. The burnished burrs do give a slightly better cut than the grinder burrs for shear/finish cuts, but it depends more on the wood as to which gives the better finish cut. Some times the softer woods seem to finish better with one than the other, and some times it seems to be the other way around. Same with the harder woods. I never seem to get the same results every time. this could be me rather than the tool. I haven't found any noticeable difference in the durability of the grinder or burnished burr for roughing or shear cuts. I would expect that a finer grinder wheel would raise a more consistent and durable edge than a coarse wheel.

Generally, for my finish cuts, and touch up work on bowls, I prefer the scrapers for this job. Maybe it is because I can see where I am cutting rather than having the gouge covering the cut.

robo hippy

[RETIRED]

I think by definition it is called scraping because the cutting edge is not supported by the bevel as in a slicing cut.

[tea lady]

Generally, for my finish cuts, and touch up work on bowls, I prefer the scrapers for this job. Maybe it is because I can see where I am cutting rather than having the gouge covering the cut.

robo hippyThat's a good point. You can see what you are doing better.:2tsup: I was trying shear scraping with a gouge yesterday and it was working well. :cool: It seems to be self righting. :shrug: If you do something slightly wrong sheer scraping with a scraper it whacks itself down on the tool rest. There is no where for a bowl gouge to go cos its already there.:cool:

[NeilS]

Leaving aside definitions of what is a shear/scrape/cut (for now), my experience and understanding is much the same as Hippy's.

Some differences.
Some of my fine finishing 'scrapers' have angles as fine as 10<link rel="File-List" href="file:///C:/DOCUME%7E1/BRON%26N%7E1/LOCALS%7E1/Temp/msoclip1/01/clip_filelist.xml">° to 20<link rel="File-List" href="file:///C:/DOCUME%7E1/BRON%26N%7E1/LOCALS%7E1/Temp/msoclip1/01/clip_filelist.xml">° (like a knife), the others range through all of the angles mentioned so far.

I have never found raising a hook by burnishing worth the trouble (for woodturning, anyway), although I do raise a very fine burr on my knife edge scrapers with the power strop which is much closer to the burr produced by a burnisher than a grinding wheel, i.e. they are smoother and less fragile.
<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:DoNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style><!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <w:DoNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]--><style> <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:612.0pt 792.0pt; margin:72.0pt 90.0pt 72.0pt 90.0pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> </style>
Must admit that I do a lot of burr maintenance at the lathe with the fine diamond honing plate between visits to the grinder.

On the definitions, I'll leave the gurus to hammer that out between them. However, I do think it's important to do so. Agreed definitions avoid confusion, which is particularly important on an online forum like this. Having just said I will leave it to the gurus, I'll throw in the following thoughts.

Burrs are in effect micro bevels, which may in fact be rubbing even though the primary bevel is clear of the wood. See attached diagram. So, not wishing to put too fine a point on this (pun acknowledged), is a 'scraper' with a burr, that is rubbing, scraping?

Perhaps the angle at which the cutting face of the tool is presented to the face of the wood could be a better basis for a definition. Scrapers as used in general woodworking are inclined at 90° or less to the surface being planed. The wood removal action changes once you are at or below 90°, the fibres are grabbed and pulled, not severed first then parted from the board or blank. In which case, the first photo back in Post 21 would be shear scraping and the second photo a shear slicing cut (as long as it lasts).

.....

[RETIRED]

the first photo back in Post 21 would be shear scraping and the second photo a shear slicing cut (as long as it lasts).That is my definition too.
In photo1 the bevel is well clear of the timber hence a scraping action.
In photo 2 the bevel is almost rubbing resulting in a cutting action.

[robo hippy]

It came up on another forum once about what types of cuts there are. One turner said there were two, one rubbing the bevel, and two not rubbing the bevel. My peculiar/particular definition is that that is part of it, but not all. Not rubbing the bevel doesn't make it a shear or scraping cut. I can make very clean cuts, and rough cuts without rubbing the bevel. 90 degrees to the rotation of the wood, like when the scraper is flat on the tool rest is a scraping cut, and when the tool is at a skewed angle like when the scraper is at 45 degrees, you have a shear cut. I can rub the bevel and get a shear cut, with both scraper and gouge, and I can do the same cuts with a scraper. I think I am confusing myself a bit here.

As to the scrapers maybe catching when doing shear cuts, I have never had a problem. Most of the time I use an inside (swept back to the left side) or round nose scraper, and don't work above the center line of the blade. Actually, most of the time I drop the handle, and work on the wing rather than on the nose as the nose gets dulled by heavy scraping cuts first. Basically the same as a shear cut with a gouge.

robo hippy

[jefferson]

I won't buy into all the technical stuff, but "sheer cutting" can also be quite aggressive in removing wood - not just good for finishing cuts and removing tear-out.

IMHO, it is a mandatory technique to be shown to beginners and intermediates alike. Safe as houses - if you follow the rules of course - and the ripples (which cause some concern at first), just disappear with 240 grit paper.

And even then, if you do it right, there are very, very few ripples.

There endeth the lesson from the LG. :D

Stacks of 80-180 grit paper here going to waste. :):):)

Eagerly awaiting how the experts decipher this all in Plain English for we learners. :rolleyes::rolleyes::rolleyes:

Happy typing.

[KenW]

I have never understood why when you drop the handle on the gouge, and roll it far onto its side so you are cutting with the edge, and not rubbing the bevel it is called a shear scrape. You are cutting at a shear angle, but not scraping. A scraping cut is, to
me, having the scraper flat on the tool rest, pointed slightly down hill, and plunging straight into the wood.

Any time you are making a cut without bevel rub, you are scraping.


This is a roughing cut. You can do the same cut with a gouge, tool level/parallel to the ground, flutes at 90 degrees to the wood rotation, and cutting without the bevel in contact with the wood.

Again this is a scraping cut and very dangerous.

These are roughing cuts, and will remove a lot of wood in a hurry, and leave a fairly rough surface, as it pulls more at the wood fiber rather than slicing. Scrapers are my main tool for roughing out bowls.

A scraper shoud never be used as roughing tool. A scraper can be very dangerous when used for roughing and leaves a very poor finish.

Having the scraper at a 45 or so degree angle on the tool rest is a shear cut, Shear Scrape.
and you generally don't rub the bevel, though you can. This is more of a pulling cut, and is an excellent finish cut. This is the same cut you are making with the gouge in the 'shear scrape' mode.

For sharpening scrapers, I have a 75 or so degree bevel, rather blunt. The bevel shown on those in the pictures seems to be more like 45 or so degrees. They do tend to be more grabby.

I did mention that you needed to use a scraper with a bevel angle of 45 degrees with care. It will however leave a better finish than a scraper with a blunter angle and stay sharper longer.

For most of my scraper cuts, I like the burr straight from the grinder.

IMHO puting a burr on a tool with a grinder is not a good idea. The resulting burr is a mixture of molten steel and some of the grinding wheel (called sintered metal). The burr is not very strong and wears away fairly quickly. Some of the burr is left imbeded in your turning which helps blunt your scraper on the next pass, leaving even more metal in your work.
To prove this, I have scraped a light coloured bowl with a scraper that had a burr from a dry grinder, then put it outside in the rain. The bowl went rusty in small spots.

robo hippy
I thought this thread was surposed to be about shear scraping.

[NeilS]

I won't buy into all the technical stuff, but "sheer cutting" can also be quite aggressive in removing wood - not just good for finishing cuts and removing tear-out.

.

Agree with you LG about the value of the shear cut. However, I'm surprised that you find it can be quite aggressive. By laying the tool over (with scrapers) or dropping the handle and rotating (with gouges) you are in effect decreasing the cutting angle allowing for a more controlled shallow cut or scrape. That's why we finish with these.

If we are both talking about the same thing, a shear cut should produce a thin narrow shaving that isn't removing much wood at all. If the bevel is rubbing it should be very difficult to get aggressive with this cut, I would have thought. Or, am I misunderstanding something, LG?

.....

[NeilS]

I thought this thread was surposed to be about shear scraping.

It is, but I would have thought that making the distinction between shear scraping and shear cutting helps us better understand what is scraping.

.....

[tea lady]

(Boldly striding out into hot water. ) I don't think Sheer cutting exists. :C At least not for long cos it will catch very easily and put a huge hole in the side of your bowl. DAMHIK!:rolleyes:

[KenW]

It is, but I would have thought that making the distinction between shear scraping and shear cutting helps us better understand what is scraping.

.....
Neil, I haven't noticed anybody correctly describing shear cutting so far in this thread.
I have kept away from describing shear cutting, as I find the description hard to put into words. If not done correctly shear cutting can be very dangerous.

Shear scraping with a bowl gouge can remove large amounts of wood, you just need to press the tool into the wood a lot harder.

[TTIT]

I reckon we'd all be better off calling it something else other than 'shear scraping' cos all that does is lead everyone into arguments over definitions. The "action" Ken and Vic demonstrated in the photo's works beautifully once practiced and that's all that matters. Maybe leave 'cut', 'slice', 'dice' etc out of it - how about 'microdefragulation'. Nah??! Open to suggestions then :shrug:

[jefferson]

If we are both talking about the same thing, a shear cut should produce a thin narrow shaving that isn't removing much wood at all. If the bevel is rubbing it should be very difficult to get aggressive with this cut, I would have thought. Or, am I misunderstanding something, LG?

.....

No, Neil, the bevel isn't rubbing, I am still sheer scraping. But I am now taking a largish narrow shaving with my HT Ellsworth grind on the outside of the bowl in the manner described. When I was first shown the method by Ken W, I was barely taking anything. A little too cautious.

All I am saying is that the more confident I am with the cut, the more of the curlies that I can see without 2x glasses. And I am probably presently the tool closer to 45 degrees than before, so the shaving have got to be fatter (I think).

Still trying to work out how to sheer scape the INSIDE of a bowl yet..... :B:B:B

[Ed Reiss]

Still trying to work out how to sheer scape the INSIDE of a bowl yet..... http://cdn.woodworkforums.com/images/smilies/blush-anim-cl.gifhttp://cdn.woodworkforums.com/images/smilies/blush-anim-cl.gifhttp://cdn.woodworkforums.com/images/smilies/blush-anim-cl.gif

OK Jeff, do we have to start referring to you as "LG" from now on??? :D

Sheer scraping the inside of a bowl is not much different than doing the outside, and in some cases even easier.
The main points to keep in mind are to keep the tool rest as close as possible to the work, keep the scraper heeled over to about 40 - 45 degrees, and definitely use a light touch.
You might just want to practice on some small, shallow bowls, say in the 100mm range.

[RETIRED]

Still trying to work out how to sheer scape the INSIDE of a bowl yet..

When we get the pics that is the next stage.

[tea lady]

When we get the pics that is the next stage.Those pics are in Jim's camera, and people keep wanting to buy stuff. So stop it just for a sec guys.:rolleyes::D

[Frank&Earnest]

Thanks guys, much appreciated. :) It has taken a while but finally the gurus have confirmed the definition I gave a few months ago: however one wants to pussyfoot around with "descriptions", the defining element is the angle between the upper surface of the tool and the surface of the wood, which has to be less than 90 degrees, like you do pulling a flat scraper against a flat surface. With the scraper it is obvious (BTW the SAFE and UNSAFE pictures are not geometrically correct, but the description should help) (edited to add: should have continued reading, Neil S beat me to that :).) with the gouge the "... will not cut.. " etc. observations amount to the same thing, only the curves of the tool make it more difficult to show.

[rsser]

My 2 bits worth ...

With a bowl gouge correctly presented & shaping a bowl outside, I can come up from bottom to top pushing the tool. With a decent lathe tango and fine cuts, I don't need to scrape the outside to improve the finish with most wood species but some are just ornery.

Correctly presented: cutting on the gouge wing at an acute angle to the travel of the wood.

Can only do this with a swivel head lathe. Long sweeping arcs. Piece of p*ss when it all comes together.

Maybe this is sheer slicing.

With fixed head lathe, I wld rough out the form but then have to refine it with pull slicing cuts; bevel rubbing, handle dropped low so shaft up high. Hard to get a flowing line so scraping was often nec to refine it.

[Calm]

...........................
Still trying to work out how to sheer scape the INSIDE of a bowl yet..... :B:B:B

Yeah Jeff - very easy


BUT FIRST


















you need to turn the bowl around - cos it's easier when the back is against the headstock, not the front/inside :D:p:p:D

Cheers

[robo hippy]

Ken W,

I wish I didn't live so far away. I would love to spend a turning session with you guys. I started playing around with scrapers because I knew they were around before gouges. I found out a lot of things about them, and would bet I know some tricks you don't, mostly because I use them all the time. You can probably show me some tricks about the gouge as well. In my experience of 14 years of turning, and some 8000 to 10,000 bowls, I don't consider a gouge to be more safe or dangerous than a scraper, or the other way around. My experience hasn't shown either tool to be more or less prone to catching. There is good technique and bad, and many methods will work.

As to the burr, I do have different wheels, and may end up getting the diamond wheel from Woodcraft. I just have to experiment. My CBN (check the thread about diamond grinding wheels) wheels do give me a better burr than the aluminum oxide wheels do. It is as durable as a burnished burr. I do turn green wood to final thickness, soak them in LDD (liquid dishwashing detergent and water), then dry. No problems with iron spots. A burnished burr should give the same results, or at least better than the rough wheel burrs.

Shear cuts for the inside of a bowl, like Ed said, scraper at 45 degrees, again, a good burr, and very light cuts. I pull cut from the bottom to the rim, and an especially light cut on the rim. If the bowl is rather thin, or larger in size, it is best to do this in 1 to 2 inch stages as you are turning out the inside of the bowl, even if it has been cored. I use my left hand as a steady rest, applying the same amount of pressure with both the scraper and my steady hand. Thinner walls, and bigger bowls will want to vibrate a lot more when working the rim. Do round over the rim before you use your hand as a steady rest.

robo hippy

[KenW]

Ken W,

I wish I didn't live so far away. I would love to spend a turning session with you guys.

robo hippy
I agree it's a pitty we live so far away, it would be a fun time to share our collective knowledge and experience.
Just as Vic, Jim and I had a good time taking the photos and comparing our different styles.

One major difference in our turning, I never turn wet wood only dry.
I also use the hardest woods that grow downunder, as far as I know you have nothing on your side of the world comes close to our desert hardwoods.

I spend a lot of time teaching beginners, so I try to show safe methods of tool use that are easy to learn with the least chance of mishaps.
The cuts that I make in my workshop are often completely different, and I never teach them.

I only sharpen my tools on a Tormek, using the new black wheel (even finer than the original wheel), and always polish the tool until there is no burr left. On realy hard woods, a sharp tool cuts much better than a burr.

[KenW]

My 2 bits worth ...

With a bowl gouge correctly presented & shaping a bowl outside, I can come up from bottom to top pushing the tool. With a decent lathe tango and fine cuts, I don't need to scrape the outside to improve the finish with most wood species but some are just ornery.

Correctly presented: cutting on the gouge wing at an acute angle to the travel of the wood.

Can only do this with a swivel head lathe. Long sweeping arcs. Piece of p*ss when it all comes together.

Maybe this is sheer slicing.

With fixed head lathe, I wld rough out the form but then have to refine it with pull slicing cuts; bevel rubbing, handle dropped low so shaft up high. Hard to get a flowing line so scraping was often nec to refine it.
Ern, I agree with your comments.
One use for the shear scrape is working a nasty piece of wood, the other use is slowly working up on a shape. Shear scraping takes so little off (with light pressure)that it is easy to creep up on a shape or line.
When I turn a bowl I hold it by the bottom of the blank and turn the outside and inside without turning the blank around. Mounting the bowl this way leaves very little room for the tool when turning the outside, the shear scrape overcomes this problem.

[KenW]

Thanks guys, much appreciated. :) It has taken a while but finally the gurus have confirmed the definition I gave a few months ago: however one wants to pussyfoot around with "descriptions", the defining element is the angle between the upper surface of the tool and the surface of the wood, which has to be less than 90 degrees, like you do pulling a flat scraper against a flat surface. With the scraper it is obvious (BTW the SAFE and UNSAFE pictures are not geometrically correct, but the description should help) (edited to add: should have continued reading, Neil S beat me to that :).) with the gouge the "... will not cut.. " etc. observations amount to the same thing, only the curves of the tool make it more difficult to show.
Thanks for the help with the description.
When it came to taking the photos I had lots of helpers, they all seemed to disapear when it came to writing the captions.

[woodwork wally]

Thanks to you all involved in this presentation . It helped reinforce that lesson Ken gave at Groggy's day cheers www

[jefferson]

Ken W., good help is always hard to find.... :D And we all so much want to improve your typing skills to say 20 wpm.

Calm, I am still waiting on Jim C. to tell me when I can order a VL600 ie a decent lathe. Not a toy Stubby. :D:D Swing well over 1200mm INBOARD.

, you better give the WWW a hand. Poor bugger. Teach him how to be erudite.:wink:

Ed, the Little Grasshopper I am. For some time yet. :rolleyes:

Just remember though that my forum and other friends are helping me learn to turn. I am also "only" 50, have retired, have an understanding wife and no neighbors within coo-ee. Plus a decent shed. Plenty of time on my hands and hardly in need of any new tools (excepting the VL600 of course). And lots of time on the lathe.

So, when some of my detractors (mostly Stubby owners or from Ballarat or both) are in need of company at the lathe, I'll be there. :D:D:D With a Vicmarc. :2tsup:

Now who else was cheeky???? Not Ern, not F & E...... Field covered I think.

Good to back in the land of the living.

[tea lady]

Thanks for the help with the description.
When it came to taking the photos I had lots of helpers, they all seemed to disapear when it came to writing the captions.:C You are much better at putting into words what you were saying on the day.




Now who else was cheeky???? Not Ern, not F & E...... Field covered I think.

Good to back in the land of the living.Good to see you up And about again.:2tsup: You may have missed..... I bought a "useless" 6 mm parting tool the other week. :whistling: :D

I think the angle pics of the scraper could be a bit better. Will have to have another go! You can't really see what is happening.:doh: (Where are Jim's pics? He was on the other side of the lathe so may have a better view.:cool: )

[jefferson]

Tea Lady,

I was going to bite hard on this one. I'll only say this: go and buy some 10mm square African ebony blanks and part to your heart's content with your "usefull" 6mm PARTING TOOL.

[tea lady]

Tea Lady,

I was going to bite hard on this one. I'll only say this: go and buy some 10mm square African ebony blanks and part to your heart's content with your "usefull" 6mm PARTING TOOL.:p:D

[NeilS]

Neil, I haven't noticed anybody correctly describing shear cutting so far in this thread.
I have kept away from describing shear cutting, as I find the description hard to put into words.

Fair enough, Ken.

If this thread is not the place, perhaps a separate thread on shear cutting is needed, with helpful photos of you making the cut, like the ones you used to start this thread.

Anyway, I think this thread on shear scraping is proving to be very helpful for both the developing and more experienced turners on the forum.

.....

[Tiger]

Good thread but a difficult one to describe adequately. I think a short video would be very beneficial, perhaps something on Youtube, would that be possible?

[bobsreturn2003]

sheer scraping is a great finishing tecnique have modified a scraper at 45degrees across and 30 deg sharpen to shear scrape as told by john jordan . he discussed this and hollow turning in sydney and cairns , many years ago . arnt we lucky some turners like the reef . have found it a safe way to clean up . check his website for details .cheers Bob

[issatree]

Hi All,
Often wondered what this was, & how one could do it, then Whammo.
Saw it on a U tube some where, & I think is that really all it is ?.

I've been doing that for Years.

Regards,
issatree.
<input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden"><input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden"><input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">

[Cliff Rogers]

When we get the pics that is the next stage.


Those pics are in Jim's camera, and people keep wanting to buy stuff. So stop it just for a sec guys.:rolleyes::D
Did these ever happen or did they end up in another thread somewhere? :?

[RETIRED]

Good thread but a difficult one to describe adequately. I think a short video would be very beneficial, perhaps something on Youtube, would that be possible?That may happen over Christmas.


Did these ever happen or did they end up in another thread somewhere? :?Nope. Jim and I got busy and forgot. See above answer.