Negative Rake Scrapers

[rayf6604]

Do any of you use a specific angle for your scrapers? I did see one recommendation that it's handy to grind both the upper and lower angles the same to make things easier. An included angle of 60° was also suggested as a good starting point, does that sound about right?

I use a 60 degree angle for the lower bevel of the tool and 30 degrees for the top and I find that works well

Sent from my SM-G928F using Tapatalk

 

[21William]

So your included angle is 90°? Sounds quite obtuse. For my ordinary scrapers I tip the grinding table down the (normally suggested) 8° which gives me an included angle of 82°. As said I'm thinking of trying an included angle of 60° which is within the range suggested by some. I'm wondering how long the edge will last though.

Having another look I've just found this which suggests an included angle of of 65°-75°.

http://www.cindydrozda.com/handouts_Pdfs/handouts/demo handouts/negative rake scrapers.pdf

On that basis I think I'll shoot for the middle and give 70° a try!

 

[Penpal]

There you go
View attachment 23308View attachment 23309

Had one each of these real gung ho initially then into a plastic bucket a little tricky to sharpen both have their place thanks for the pics woody.So many names Woody.

Peter.

 

[21William]

Just found this, it's several pages long if you click through the links. Not read it myself yet.

http://www.docgreenwoodturner.com/scrapers1.html

 

[rayf6604]

So your included angle is 90°? Sounds quite obtuse. For my ordinary scrapers I tip the grinding table down the (normally suggested) 8° which gives me an included angle of 82°. As said I'm thinking of trying an included angle of 60° which is within the range suggested by some. I'm wondering how long the edge will last though.

Having another look I've just found this which suggests an included angle of of 65°-75°.

http://www.cindydrozda.com/handouts_Pdfs/handouts/demo handouts/negative rake scrapers.pdf

On that basis I think I'll shoot for the middle and give 70° a try!

There are indeed many angle options for negative rake scrapers. I watched the YouTube video of a Turner who had hit on the 60/30 option but you'll find what works best for you.
The edge doesn't last long, but then neither does the edge on a normal scraper. The beauty of the negative rake is that the tool can e used with the handle down rubbing the bevel, this reduces the chances of a dig in, that is more prevalent with a standard scraper. This was pointed out in the video and I have found it to be true

Sent from my SM-G928F using Tapatalk

 

[Bill Mooney]

Re. The wedge tool.

Mine has a flat along the top of the shaft so I can turn it over & hold it steady on the table so the bevel can be ground.

 

[Penpal]

Re. The wedge tool.

Mine has a flat along the top of the shaft so I can turn it over & hold it steady on the table so the bevel can be ground.

Thanks Bill.

Peter.