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Tiger
8th Jun 2010, 12:26 PM
The threads on shear scraping by /Ken and Tea Lady have been excellent in deciphering an area that is easily misunderstood and varies depending on the person you speak to. I've learnt a lot from that discussion.

I usually shear scrape with a curved scraper and find that easy enough to use, I think it was Ken though that said for beginners the bowl gouge was easier to use than a scraper for shear scraping. For the technical experts or anyone else who wants to chime in, would you get a better finish with a scraper or bowl gouge when it comes to shear scraping?

Other question is, I generally find that the worst tear-out occurs on the ends of faceplate work, is there a special technique/tool that works well with all types of timbers? Tried sanding extensively but even though it looks like I have eliminated it, once I put on the finish, it looks terrible, as though someone has deliberately scratched that area.

KenW
8th Jun 2010, 05:13 PM
The threads on shear scraping by /Ken and Tea Lady have been excellent in deciphering an area that is easily misunderstood and varies depending on the person you speak to. I've learnt a lot from that discussion.

I usually shear scrape with a curved scraper and find that easy enough to use, I think it was Ken though that said for beginners the bowl gouge was easier to use than a scraper for shear scraping. For the technical experts or anyone else who wants to chime in, would you get a better finish with a scraper or bowl gouge when it comes to shear scraping?

Other question is, I generally find that the worst tear-out occurs on the ends of faceplate work, is there a special technique/tool that works well with all types of timbers? Tried sanding extensively but even though it looks like I have eliminated it, once I put on the finish, it looks terrible, as though someone has deliberately scratched that area.
Round nose scraper and bowl gouge both shear scrape well. With the round nose scraper you just have to be a bit more careful with the angle that you present the tool.

Tearing end grail:
Are your tools sharp?
Are you cutting with the grail?
Have you tried shear scraping to eliminate tear out?
What sort of wood do you use?

Tiger
8th Jun 2010, 05:25 PM
Thanks Ken for your response


Round nose scraper and bowl gouge both shear scrape well. With the round nose scraper you just have to be a bit more careful with the angle that you present the tool.

Tearing end grail:
Are your tools sharp? Yes
Are you cutting with the grail? Usually use pull cut, I assume yes
Have you tried shear scraping to eliminate tear out? Yes, I know of no other way to remove it, the normal shear cut with bevel rubbing comes close but will still leave tear-out no matter how sharp the tool is
What sort of wood do you use? Probably not the best, but Tasmanian Oak, Blackwood and Radiata Pine, whatever I can find in the workshop

KenW
8th Jun 2010, 05:40 PM
Thanks Ken for your response
Pull cut removes wood quickly but always leaves a poor finish, sometims the tear out from this cut can be realy deep. Try only using this cut at the start and then switch to bevel rub / shear scrape to finish. The wood you are using should be easy to get a good finish off the tool.

Tiger
8th Jun 2010, 05:57 PM
Pull cut removes wood quickly but always leaves a poor finish, sometims the tear out from this cut can be realy deep. Try only using this cut at the start and then switch to bevel rub / shear scrape to finish. The wood you are using should be easy to get a good finish off the tool.

I generally use the pull cut to remove the bulk of the timber but always finish with the shear scrape (but no bevel rub) to finish. I get the fine hair-like shavings but it takes me only to a point where it looks ok but once the finish is applied, it's obvious that there's still some tear-out as the finish looks blotchy on that part of the work.

I had thought that those timbers were a little more difficult to remove tear-out on. I can remember trying everything but still not getting the result I wanted, I will re-examine my technique and see if I can get complete removal of tear-out

Skew ChiDAMN!!
9th Jun 2010, 02:50 AM
I had a piece of 8mm round bar HSS stock that I wasn't sure I'd find a use for. In a fit of "well, let's try this" I ended up fitting it into one of my Oland tools and sharpening the end to a 45-55 bevel or thereabouts.

All in all, I'm wasn't too impressed with it, but it seems to be rather more forgiving than a round-nosed scraper when shear-scraping.

(Just thought I'd mention it.)

John Lucas
9th Jun 2010, 05:21 AM
A pull cut done properly will leave a beautiful finish. I developed my own style of pull cut when I was first doing hand mirrors. I didn't know that's what it's called and hadn't seen anyone do it. I was just trying to cut with the grain and that required pulling the cutter from the center of the mirror body out. I ground the left wing of my gouge really long and use that. Later on I saw Avalino Samuel use a ground just about like mine to do his hollow vessels. Then I saw Mike Mahoney really put one to use but with a more tradional swept back grind.
You can remove a huge amount of wood with a pull cut and then it will leave a rougher finish. by keeping the handle down so the cutting edge is 45 degrees or less to the wood you get a much smaller bite and really clean surface.
I use round nose scrapers on the inside of a vessel if needed. Usually I can get them clean enough with one of my gouges. I have then ground from 40 degrees to 75 degrees and use the shallowest angle that will let me rub the bevel. To use a round nose scraper I tilt it about 45 degrees and cut with the lower 1/2. If you lead with the handle and have it higher than the cutting edge it's pretty safe.
You can shear scrape with the bowl gouge but down toward the bottom of the bowl it's hard to keep the shear angle. With the round nose scraper it is very easy.
On the outside I like to use the John Jordan shear scraper. It cuts really clean and is easy to control.

robo hippy
9th Jun 2010, 04:51 PM
For finish shear cuts with a scraper, I get the best results with a burnished burr, but the burr from the grinder does a good job on most woods. I can get the same quality with a gouge (did find out that you should hone the inside of the flutes to remove the grinder burr), but the scraper just feels better to me. I use it in a pull cut mode, and at a 45 or higher degree angle. I never tried a gouge for a pull finish shear cut on the inside of a bowl. Just didn't look safe to me. Part of that is probably because I prefer to hold my tools more level, hand near the ferrule, and handle under my fore arm. A round nose scraper works fine, but I prefer an inside, or swept back to the left side scraper for this cut. Finish shear cut with a scraper on the inside of the bowl is a pull cut from the bottom to the rim. Very light.

For bad tear out, get the wood wet (I use a wet rag), let it soak in for a minute, then gently turn off the wet wood. It make take a couple of times to remove bad tear out.

For pull cuts with a gouge, it can be done as a very aggressive roughing cut, or a dainty finish cut. Depends on how hard you are pulling at the tool, and how much pressure you are using.

You may have noticed that I didn't say 'shear scrape'. That term never made sense to me. To me a scraping cut has the tool 90 degrees to the rotation of the wood, like the scraper flat on the tool rest. A shear scrape appears to be defined as a cut where you are not rubbing the bevel. I have never been able to see where rubbing or not rubbing the bevel factors into how clean or rough a cut you are making, where the angle that you present the tool to the wood makes all the difference to my way of thinking. Just one of my pet peeves. Personal rant over.

robo hippy

tea lady
9th Jun 2010, 05:46 PM
:think: Uuum! Dumb question here Tiger, but you are sanding as well after sheer scraping aren't you? What grit are you sanding too?

(I hope you can come to the "Turn-on" down at 's in July. All can be explained their. :cool:)

Tiger
9th Jun 2010, 05:54 PM
:think: Uuum! Dumb question here Tiger, but you are sanding as well after sheer scraping aren't you? What grit are you sanding too?

(I hope you can come to the "Turn-on" down at 's in July. All can be explained their. :cool:)

On some pieces, I tried sanding before and after shear scraping and it would look ok UNTIL I applied a finish. I have been know to sand up to 2000 wet and dry grit.

I am considering coming to the Turn-on but am limited to the afternoon.

tea lady
9th Jun 2010, 06:04 PM
What do you mean by "on the ends of face plate work" in your first post? :hmm: Do you mean the sides of a bowl where the grain reverses? Or is it near the rim?

Sometimes I can have trouble on a piece near the rim cos it flexes and I just can't get it right. If the bowl is very thin I try and finish the rim area first before taking out much of the meat in the middle of the bowl. It is then supported and stops the flexing. :)

Tiger
9th Jun 2010, 06:33 PM
Sides of bowl where the end-grain tear-out is prominent.

RETIRED
9th Jun 2010, 06:39 PM
On some pieces, I tried sanding before and after shear scraping and it would look ok UNTIL I applied a finish. I have been know to sand up to 2000 wet and dry grit.

I am considering coming to the Turn-on but am limited to the afternoon.That is OK Tiger. Come anyway and I am sure that someone will be able to help.

However, you will have to bring some timber for a bowl.

powderpost
9th Jun 2010, 08:35 PM
Do people still make bowls from a solid bit of wood? I haven't had a problem with end grain for a long time. :D
Jim

RETIRED
9th Jun 2010, 08:41 PM
:p

tea lady
9th Jun 2010, 11:52 PM
Sides of bowl where the end-grain tear-out is prominent.
:think: I usually sand with the lathe turned off after the initial sanding. Just to get the reversed grain sorted out. (Cos I haven't got a reverse switch on my "home" lathe.:rolleyes:) sand with the grain by hand. I find you only need to do it on the first grit. (80# for mere mortals. Only Ken W starts with 240# :p )Then you can turn the lathe on again to complete the sanding.

Hope to clear it all up at the turn on. :2tsup: Failing that we could get together some other time. :shrug: If you are still struggling.

:think: Another thought is that sometimes with blackwood I have had patches of what seems to be hard toasted areas. Only surmising here but I think sometimes if blackwood gets hot sap or something in it goes hard, and becomes impossible to sand. Ya have to go back to the chisel to get rid of it. I've never heard others mention this though, It could be my imagination. :blond: So go easy with the sanding pressure, and if the paper is getting hot move to a new spot on both the paper and the bowl. The heat kind of means that the paper is more rubbing than sanding anyway. :shrug: You can get hard patches of sap on radiata too.

Hope my thinking out loud helps. :)

Tiger
10th Jun 2010, 12:12 AM
I have done some experimenting using shear scraping with 3 tools on some pine scrap.

The curved scraper was the easiest to use mainly because it's easy to see. It removed most of the tear-out but there was still a remnant that would not budge.

The bowl gouge gave the best result, the remnant mentioned above was almost entirely removed but did leave a number of concentric tool marks which required 120 grit sandpaper to remove.

I also tried a spindle gouge because it was handy, I kept getting catches as the nose of the fingernail shape kept hitting the timber. When it wasn't catching, it produced a reasonable result but I found too difficult to use on a regular basis.

Tiger
10th Jun 2010, 02:38 PM
:think: I usually sand with the lathe turned off after the initial sanding. Just to get the reversed grain sorted out. (Cos I haven't got a reverse switch on my "home" lathe.:rolleyes:) sand with the grain by hand. I find you only need to do it on the first grit. (80# for mere mortals. Only Ken W starts with 240# :p )Then you can turn the lathe on again to complete the sanding.

Hope to clear it all up at the turn on. :2tsup: Failing that we could get together some other time. :shrug: If you are still struggling.

:think: Another thought is that sometimes with blackwood I have had patches of what seems to be hard toasted areas. Only surmising here but I think sometimes if blackwood gets hot sap or something in it goes hard, and becomes impossible to sand. Ya have to go back to the chisel to get rid of it. I've never heard others mention this though, It could be my imagination. :blond: So go easy with the sanding pressure, and if the paper is getting hot move to a new spot on both the paper and the bowl. The heat kind of means that the paper is more rubbing than sanding anyway. :shrug: You can get hard patches of sap on radiata too.

Hope my thinking out loud helps. :)

Thanks, Tea Lady. You may be right as the timber sometimes has hard and soft patches and that could be contributing. I'll try and make the turn-on and if not, we'll see what we can do. A reversing switch would help but that would take a fair bit of effort to install on my lathe.

robo hippy
11th Jun 2010, 02:59 AM
Tiger,
Do you round off the heel of the bevel on your gouges? This really helps on the inside of the bowls. If you leave the bevel as is off the grinder, the sharp heel can actually leave burnish/bruise marks in the wood. It also, on the inside of the bowl leave the bevel much farther from the cutting edge due to the concave shape of the bowl. This is why you don't have this problem on the outside of the bowl. The sharp heel can actually push the gouge into the cut which is why you get the concentric rings. I grind about half of my bevel off, and have recently discovered that I get a better cut on the inside of the bowl if I use a smaller gouge, like 1/2 to 3/8 inch. I figure this again is having the bevel closer to the cutting edge.

robo hippy

Tiger
11th Jun 2010, 03:12 PM
Tiger,
Do you round off the heel of the bevel on your gouges? This really helps on the inside of the bowls. If you leave the bevel as is off the grinder, the sharp heel can actually leave burnish/bruise marks in the wood. It also, on the inside of the bowl leave the bevel much farther from the cutting edge due to the concave shape of the bowl. This is why you don't have this problem on the outside of the bowl. The sharp heel can actually push the gouge into the cut which is why you get the concentric rings. I grind about half of my bevel off, and have recently discovered that I get a better cut on the inside of the bowl if I use a smaller gouge, like 1/2 to 3/8 inch. I figure this again is having the bevel closer to the cutting edge.

robo hippy
Thanks, Robo, won't be hard to do so I'll give it a try.

John Lucas
12th Jun 2010, 12:55 PM
Somebody explained about grinding off the bottom of the bowl gouge many years ago to me because I was having the burnished ring problems on the inside of my bowls. It works great. Over the years I 've gotten to where I grind even more away so there is a moderately short main bevel. The main reason I do this is it makes sharpening faster because the bevel is shorter and your removing less metal. It really works well if you use a diamond hone.
I've been experimenting with convex bevels for turning the inside of a bowl. Johannes Michelson uses this grind for his cowboy hats. His grind doesn't have any concave or flat areas. It's totally convex. It's interesting using this grind. There is a video on U-tube showing how to sharpen it. I'll see if I can find it and post it if anyone is interested.