How To Grind A Hss Turning Tool

[Hukshawn]

Here's that doAll bit that was kicking my ass... I was bound and bent to finish it... and from what you said about it's longevity, I wanted to use it.
critique it, and go!
The cut is pretty damn good. like butter. and I cranked the lathe up to 1400 rpm. seems I need to do some belt tightening in high gear tho

 

[higgite]

Dan,

Those are great looking tools. I have a CBN wheel that I got when I was grinding my own tools when I first got a mini lathe, then I got lazy and asked Santa for some HSS insert tools. But, you have given me some inspiration to crank up the grinder again and grind a thread relief tool or two. Of course, then I'll have to make a new QC tool holder... or two. Which means I need to ask Santa for a dovetail end mill... or two. Which means....
Jeez, a lazy hobby machinist's work is never done.

Tom

 

[BriancCc]

Here is the tool I ground and a block I faced with it. I'm open to advice. I'm using a 6" bench grinder with 48 grit wheel. I did this off the tool rest. I'm using this on a Clausing 100 with a lantern tool post. I'm using a armstrong holder, which holds it at like a 8deg angle. So that is like, the work angle is 8deg added to tool back rake, and work angle is 8deg less front clearance than tool angle, right?

 

[Dan_S]

Whoa, Dan, that is awesome! Super-clean grind done with skill! Did it work as good as it looks?

O yea, it work great

. Can I ask which wheel you're using? Is the corner of the wheel sharp or radiused? What grit works best for shaping and/or finishing?

Right now I'm using the 8" d-way 180 grit wheel.
http://d-waytools.com/cbn-wheel-8-x-1-1-2-x-1-arbor-hole/


It leaves an excellent surface finish right of the wheel that can quickly be honed. I plan to get the 80 grit wheel for the other side at some point, as it will remove material even faster.

Have you ground any turning tools with this wheel? I'd sure like to see some pics if you have them.

I took photos of the two below this morning as I know for sure I ground them with it. I use mostly carbide now, so I only go to HSS for specialty stuff. The honing was done with a cheap diamond credit card hone.

large threading tool 3/8" shank.



vertical sheer tool 3/8" shank

 

[Dan_S]

Dan,

Those are great looking tools. I have a CBN wheel that I got when I was grinding my own tools when I first got a mini lathe, then I got lazy and asked Santa for some HSS insert tools. But, you have given me some inspiration to crank up the grinder again and grind a thread relief tool or two. Of course, then I'll have to make a new QC tool holder... or two. Which means I need to ask Santa for a dovetail end mill... or two. Which means....
Jeez, a lazy hobby machinist's work is never done.

Ask Santa for a shaper, then you can make the QC tool holder with a ground HSS bit.

 

[mikey]

Here's that doAll bit that was kicking my ass... I was bound and bent to finish it... and from what you said about it's longevity, I wanted to use it.
critique it, and go!
The cut is pretty damn good. like butter. and I cranked the lathe up to 1400 rpm. seems I need to do some belt tightening in high gear tho

Okay, you definitely know how to grind the rake angles and that is usually the hardest thing for guys to get a handle on. If the cut is good then that is what counts. With that said, I would suggest you grind your next tool with a bit more mass backing the tip. Use a protractor and draw a line at 80 degrees, using the side cutting edge as a base or reference. Once you grind to that line there will be more mass backing the tip for strength.

Doing good, Hukshawn!

 

[mikey]

Here is the tool I ground and a block I faced with it. I'm open to advice. I'm using a 6" bench grinder with 48 grit wheel. I did this off the tool rest. I'm using this on a Clausing 100 with a lantern tool post. I'm using a armstrong holder, which holds it at like a 8deg angle. So that is like, the work angle is 8deg added to tool back rake, and work angle is 8deg less front clearance than tool angle, right?

Brian, thanks for the pics. It really helps to see the tool better.

The overall tool shape is fine for a facing tool. It is difficult to estimate side rake but it looks to be about 12 - 14 degrees to my eye and that's fine for steel. I make the front clearance angle somewhere around 22 degrees or so; minus the 8 degree tool angle, this gives you 14 degrees of clearance, which is great. There is very little nose radius; I can't see any but it could be my eyes. You have no back rake other than that provided by the tool holder angle so call that 8 degrees.

This tool should face well. The only thing I would suggest is to try honing a little nose radius on the tool - it will give a better finish. A facing tool cuts mainly with the side cutting edge, up near the nose, but the nose does participate. Try honing a tiny nose radius and see what happens.

You will find that a tool rest helps to control your angles, and it's safer, too. It will improve the finish on the tool because the tool isn't bouncing around as you grind. Honing the edges will also greatly improve the finish cut so if you prefer not to use a rest then hone to a clean edge. A sharp tool will cut curliques in paper with it's edge.

You're doing great! Share with us as you progress, Brian!

 

[mikey]

O yea, it work great


Right now I'm using the 8" d-way 180 grit wheel.
http://d-waytools.com/cbn-wheel-8-x-1-1-2-x-1-arbor-hole/


It leaves an excellent surface finish right of the wheel that can quickly be honed. I plan to get the 80 grit wheel for the other side at some point, as it will remove material even faster.



I took photos of the two below this morning as I know for sure I ground them with it. I use mostly carbide now, so I only go to HSS for specialty stuff. The honing was done with a cheap diamond credit card hone.

large threading tool 3/8" shank.
View attachment 140755
View attachment 140756

vertical sheer tool 3/8" shank
View attachment 140757
View attachment 140758

Thanks, Dan. So, 80 grit to shape ... got it. I'll make sure my friend sees this post.

 

[Hukshawn]

Okay, you definitely know how to grind the rake angles and that is usually the hardest thing for guys to get a handle on. If the cut is good then that is what counts. With that said, I would suggest you grind your next tool with a bit more mass backing the tip. Use a protractor and draw a line at 80 degrees, using the side cutting edge as a base or reference. Once you grind to that line there will be more mass backing the tip for strength.

Doing good, Hukshawn!

Just to make sure I understand you, don't cut such a sharp angle on the right side of the cutting tip? let's call that right side face a 45° to the adjacent side. you'd like me to go as shallow at 80°. am I understanding correctly?

 

[Hukshawn]

All of these rake terms I read in the south bend - how to run a lathe book, are making much more sense now...