• Congratulations to Alex Bradley winner of the December 2024 Turning Challenge (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to Gabriel Hoff for "Spalted Beech Round Bottom Box" being selected as Turning of the Week for January 6, 2024 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Parting tool Woes

D

DaveL

Joined
May 1, 2004
Messages
43
Likes
1
Location
Corpus Christi, Texas
Website
www.davidlauffenburger.com
I have a 3/16" Diamond Parting tool and whenever i am parting off an item made of hard or grainy wood I get what i guess would equate to a catch. After the catch you can see where the wood fibers have a large area that looks like grain tearout. I normally grind it to a 25 degree angle, but i have tried between 20 and 35 with limited change. I have a 1/16" parting tool that does not seem to suffer the same problem.

I mostly turn segmented bowls out of hard exotics or hard maple, which i suspect to cause some of the problems.

Is there a better way to sharpen the tool to reduce this or is this just a normal problem with hard woods.

Thanks for any information,

Dave
 
Dave,

This link is to the WoodCentral Grinds Library.

http://www.woodcentral.com/newforum/grinds.shtml

Once there, scroll down to David's diamond parting tool. I have been using this grind for about 3 years and find it better and more durable than the double straight grind. You do want to be careful to have the cutting edge right at the widest part of the blade for most effectiveness. Can't give you angles since both are curved, and you'll have to play with the "bottom" curve a bit for best cutting.

Mark
 
Last edited:
Scraping with the tool is different than cutting with the tool. You may have to adjust your rest down a bit to get a peeling cut, but it's worth it. Also, diamond or not, they all benefit from some relief at the edges of the cut, in my experience.

Is that 1/16" the kind with fangs on either edge? I've a Sorby like that which works great at scraping angles.
 
Dave are you rubbing the bevel or just pushing it straight in. I usually start a cut with the parting tool by rubbing the bevel and then lifting the handle until it cuts. I keep lifting the handle and pushing the tool in until I get as deep as i want. The only time I don't do this is if I want a really clean edge where the cut starts. Then I push the tool straight in at 90 degrees to the work. Once the cut is started I willpush the handle down until the bevel is rubbing and then do the same cut I described before.
If you start the cut with the bevel rubbing it lifts the fibers right at the very beginning of the cut. Most of the time this is fine because I will be removing that wood later. The other cut I described takes care of this problem.
My diamond parting tool is sharpened at about 65 to 75 degrees measured from one bevel to the other. From the center line to one bevel it's would be half that. If the point is not right on the center line you get a ragged cut and it burns the wood easier. it's also a good idea to make two cuts when going deep rather than one. You won't get a catch that way and it's less likely to burn the wood. I cut down about 1/2" or so and then make the second cut and go down another 1/2" the move over to the first cut and go down. I keep stair stepping until I've gone as deep as needed.
 
You must log in or register to reply here.
Back
Top