Shear Scraping Troublesome Blanks

[KenV]

Was working on a couple of blanks (stabilized curly mango and stabilized dyed curly poplar) that wanted to tear out -- small divots would pop off with light skew cuts.

I have a John Jordan shear scraper and grabbed it -- sharpened it and liked the outcome

Shear Scraper


I got a pile of whispy shavings similar to the picture on Johns web site. No more divots and the ones there all went away.

Have used this tool on bowls and such, especially segmented ones --

Will keep it close to the lathe

Next thing to try is brittle acrylic that goes Bzzzzzzzz and leaves little pits behind.


If you have one -- try it.

Or you can make your own with the tutorial that the late Jim Thompson (The Old Mill Rat) left behind for turners

Double-end Shear Scraper by James D. Thompson

 

[mecompco]

Was working on a couple of blanks (stabilized curly mango and stabilized dyed curly poplar) that wanted to tear out -- small divots would pop off with light skew cuts.

I have a John Jordan shear scraper and grabbed it -- sharpened it and liked the outcome

Shear Scraper


I got a pile of whispy shavings similar to the picture on Johns web site. No more divots and the ones there all went away.

Have used this tool on bowls and such, especially segmented ones --

Will keep it close to the lathe

Next thing to try is brittle acrylic that goes Bzzzzzzzz and leaves little pits behind.


If you have one -- try it.

Or you can make your own with the tutorial that the late Jim Thompson (The Old Mill Rat) left behind for turners

Double-end Shear Scraper by James D. Thompson

Ken, that is cool, but it looks pretty much like my skew. What's the difference?

Regards,
Michael

 

[KenV]

Shear scrape engages the edge in a fine shearing cut -- can be done with the burr on the flat side of the Jordan Style tool or I have done it with a closed flute on a bowl gouge presented to the surface of the bowl.

This is a pull cut with the bevel facing away from the cut.

whispy shavings finer than a skew are the result -- getting fewer whispy shavings and more dust, time to get the hone and refresh the hooked edge.

 

[mecompco]

Ah, upon closer examination of the picture I see that it only has one bevel. Not sure how that would affect the cut, but if it works, it works! If I had a forge going to heat-treat it, I'd make one--got three feet of 1084 high carbon 1.5x.25 steel on hand.

 

[KenV]

Ah, upon closer examination of the picture I see that it only has one bevel. Not sure how that would affect the cut, but if it works, it works! If I had a forge going to heat-treat it, I'd make one--got three feet of 1084 high carbon 1.5x.25 steel on hand.

I will still go with high speed steel -- the burr just lasts lots longer and the 1 by 1/4 by 6 bars are relatively cheap.

Like my high carbon steel for hand tools, but High Speed Steel changed the world in 1900.

 

[Skie_M]

When I come up against issues like that, I use a high-carbon steel scraper (actually, a RAZOR BLADE) that I've raised a small burr on. The action is exactly the same, and I put the blade in a clamp/holder to make it easier to handle. My only issue is that if I mess up and put the blade up against my work at too shallow an angle, the blade edge generally cracks and could shatter.

My other metal of choice for a small scraper is using broken leftover bits of hacksaw blades. I've been thinking about just switching over to using a demo blade, though. I like my cutoff tool that I made myself, and the blade I made it from was a demo blade and only cost me 4 dollars.

Another issue is ... it's VERY VERY HARD to find anything to use to raise that burr on a razor blade ... the metal is very hard on the rockwell scale.

 

[TurtleTom]

Worked in a sign shop once, the boss taught me to steel my razor blades on the pickup window before I ever tried to use it. Don't know if that will help but the glass was harder than the steel.

 

[Skie_M]

Yeah, but parking a pickup truck in my living room so that I can burnish my razor blade on the window glass just isn't going to work ... I need a pickup truck. And the door is too small.



And if I had a wife, she'ld kill me for ruining the carpet?


I tried to make a burnishing tool just for scrapers using a tutorial I found online, but everything available for burnishing was softer than the razor blade steel, so it just didn't work right. I think I'll just use a demo blade after all and grind the end flat 90 degrees and raise a burr on it with my buffing wheel.

 

[TonyL]

The more I read this stuff, the more I realize I know nothing. . Keep it coming though, I am learning much!

I did order that scarper thing though.

 

[Wildman]

First one to admit everyone will have times where something you mount on the lathe will give you fits. Not sure matters type of steel you attack that problem with; what really matters is your skill & technique. I use regular gouges, scrappers, or skew to shear scrap.

My introduction to shear scraping came from watching," Del Stubbs, bowl turning VHS tape." Del use two red handle Sears skew chisels one for going right & other going left shear scrapping a bowl. Roy Underhill uses same skew on his show. Back then could buy those skews he used for $19 when on sale.

I have modest success using carbon & HSS skews for shear scrapping outside bowls & hollow forms. I use heavy scrapper for inside bowls. Today more like more likely to turn my bowl gouge on its side, drop the handle down, pull the tool using wings of the gouge to shear scrap. When turning beads will often use either skew or gouge to shear scrap middle of a bead to make it even.

Point of my post is shear scrapping a great skill to have and can cure lots of sins and reduce sanding. No, don't use that procedure on every turning. Found shear scrapping an easy skill to pick up if patient. Lathe speed, tool rest height was hardest part for me. Plenty of free videos online today demonstrating how to, and tools to use so give it a try.

 

[TimS124]

When I'm trying to finesse antler or stubborn acrylics, I use the square-isn carbide insert and twist the tool handle about 45 degrees. That presents the carbide cutter in sheer-scrape mode...works very nicely.

 

[TurtleTom]

I had an interesting experience with a carbide end mill. I ordered it online but when I received it, turned out it was 5" longer than what I could use. Thinking only the cutters were carbide, I put it in a vise and started grinding with my 4" Dewalt grinder. After a few minutes I had only cut 1/32 of an inch I realized it was all carbide, but I couldn't use it the way it was so I kept at it. A few minutes more and I had only cut 3/32" but the heat buildup from the grinder caused the carbide to snap in half at the grind mark.
I didn't need the fall off so I drilled some holes in 2 wood handles and force fit them into these handles.
I now possess possibly the best burnisher I have ever seen.
Trial and error is probably the greatest teacher I have ever had. "If it's broke, I can't hurt it any more than it already is."

 

[Skie_M]

Hmmm ... yeah, a carbide insert would make a great burnisher for any steel scraper.


I'll have to keep that in mind .... thanks, Tom!

 

[TurtleTom]

I really wanted to see this Jordan tool in action so I found a YouTube video of John60Lucas giving a detailed (and up close) explanation of sheer scraping and he gets to the Jordan scraper in the 5:30 or so time frame. He runs the gamut with the tools too, he starts with a double bevel (negative rake) chisel which I've been meaning to make with an extra skew I bought for the purpose.
What I'm not too sure of and there is no mention here is the comparison of finish compared to the sheer cut skew technique.
This is the way we all need to be doing our final cuts. Well done John, and give him a thumbs up. Here is his video.
https://www.youtube.com/watch?v=7oeiVQLeOd4