• We want to encourage those of you who ENJOY our site and find it USEFUL to DONATE and UPGRADE your membership from active member to donating or premium membership. If you want to know the differences in membership benefits, please visit THIS PAGE:

    https://www.hobby-machinist.com/premium/

    Donating memberships start at just $10 per year. These memberships are in fact donations that help pay our costs, and keep our site running!
    Thank you for your donation, God Bless You

  • As some of you know, I have wanted to stop managing H-M for some time. It's a tremendous strain on my personal life. I want to set up my own shop. In September, September 15, to be exact, it will be 8 years that Hobby-Machinist has been in existence.

    I have been training VTCNC to run things here. Dabbler is going to learn too. I feel that they are ready to start taking over the operation. I will be here to help in case they need, but I don't think they will. Tony Wells is and will be here also to consult with. I will be doing backups, upgrades, and installing addons. Other than that, I will not be around. I am leaving this place in good operating condition, and financial condition.
    --Nelson
[4]

Black Silicon Carbide For Shaping Carbide Tool Bits?

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

intjonmiller

Registered
Registered
Joined
Apr 21, 2015
Messages
891
Likes
681
#1
My lathe isn't powerful enough for me to want to do much with carbide, but I received a lot of carbide bits (as well as HSS) and there are a couple that seem like they would be great for specific uses, such as threading and boring (and internal threading), but only if I shape them correctly first. I have diamond sharpening "stones" that will work for honing, but would my black silicon carbide wheels work for shaping? How much difference is there between black & green silicon carbide wheels? These are photos I took a year ago of mine:

If that's usable, great. I'll make a simple bushing to mount one of these on my bench grinder. If not I probably won't bother, as I don't care about this enough to buy more tools just for carbide bits on my low-ish power, flat-belt lathe. Too many other things on my list of future purchases. :)
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,254
Likes
5,612
#3
Silicon carbide will indeed grind carbide tooling, but it more crumbles the edge than sharpens it. You will be messing with a diamond lap for a long time getting the tool sharp after roughing it with a silicon carbide wheel. Your angle grinder diamond wheel will work, and you can mount the grinder rigidly and make a simple rest for the tool. Either way, please be extremely careful and wear the proper protective gear. Angle grinders are not intended to be used in that way. Do not grind steel with diamonds. It will ruin the wheel. If it is a brazed carbide bit you can first grind the steel away below the carbide on a bench grinder, and then grind just the carbide on your diamond wheel.
 

intjonmiller

Registered
Registered
Joined
Apr 21, 2015
Messages
891
Likes
681
#4
I'm basically "Mr Safety" that way. Safety glasses or goggles as appropriate, respirator, ear muffs, etc. My son won't even come out in the shop with me, even without anything running, without a play mask that he's decided is like my safety gear (and honestly would probably work if he ever held still long enough to be there when it was needed).
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,254
Likes
5,612
#5
Keep the guard on the angle grinder, maybe even add additional guards, make sure everything is mounted solidly...
 

RJSakowski

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Feb 1, 2015
Messages
3,379
Likes
3,860
#7
My lathe isn't powerful enough for me to want to do much with carbide, but I received a lot of carbide bits (as well as HSS) and there are a couple that seem like they would be great for specific uses, such as threading and boring (and internal threading), but only if I shape them correctly first. I have diamond sharpening "stones" that will work for honing, but would my black silicon carbide wheels work for shaping? How much difference is there between black & green silicon carbide wheels? These are photos I took a year ago of mine:



If that's usable, great. I'll make a simple bushing to mount one of these on my bench grinder. If not I probably won't bother, as I don't care about this enough to buy more tools just for carbide bits on my low-ish power, flat-belt lathe. Too many other things on my list of future purchases. :)
I use these diamond disks for sharpening carbide tooling. The have a reasonably high diamond density and I have been using the first on for several years now. They also work well for pointing tungsten TIG electrodes.
I made an adapter for a small motor to mount the disk. It does a quick job on carbide and leaves a fairly good finish.

http://www.harborfreight.com/replac...-volt-circular-saw-blade-sharpener-98862.html
 

intjonmiller

Registered
Registered
Joined
Apr 21, 2015
Messages
891
Likes
681
#8
That's interesting. That is much cheaper than I have seen for anything but ebay green silicon carbide wheels. Hmmm...
 

JimDawson

Global Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Feb 8, 2014
Messages
6,819
Likes
5,009
#9
For the last 20 years I have just been using the standard gray aluminum oxide wheel that came on my Chinese bench grinder. Seems to work well for rough shaping, you just have to push a little harder. I use it for finishing also, I just don't push as hard.;)
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,123
Likes
1,560
#10
The shop that I apprenticed in back in the mid 1960s used both black and green grit silicon carbide wheels for sharpening carbide tools and they worked satisfactorily, especially for the softer grades of carbide. Using fine grits of wheels did not cause edge crumbling to any high degree, and we did not have any diamond wheels available to the machinists on the shop floor, who, for the most part ground all their own tools. The wheels used, so far as the black wheels were concerned were A.P. DeSanno Radiac brand, C100 H02 VD2, 8" x 1 x 5/8 even after leaving the shop after 7 years, I was still in line for the worn down wheels that were still nearly 6" in diameter and just right for my grinder in my own shop, which I used until I could afford a grinder with diamond wheels.
 

ericc

Active User
H-M Supporter - Silver Member ($10)
Joined
Dec 24, 2013
Messages
302
Likes
80
#11
I have been satisfied with using green wheels to chew away carbide and steel. They kind of work, and keep the steel away from the diamonds. Then, you can use an inexpensive diamond wheel on a rotary tool to just give the edge a touch. Or those diamond hones or sticks also work. The main thing is to keep the steel part of the brazed tools off the higher speed diamond wheels. It seems to work for me. When the edge is in the right shape from the green wheel, a few rubs on the stick really helps the edge cut a lot smoother.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,254
Likes
5,612
#12
Interesting. Maybe it is just me that has trouble using green wheels on carbide. I never got any carbide sharp using one, maybe it was the wrong type or I was using it wrong. All I got was a lot of wheel dust, a hot tool, and had to hone the hell out of it with a diamond hone to get it sharp afterwards. Regardless, now I have a carbide grinder with a diamond wheel and am too hopelessly spoiled to try the green wheels again...
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,123
Likes
1,560
#13
Both types of wheels have their place; crash a carbide tool, the diamond wheel would take way too much time to whittle away the damage and cause undue wear to it; the green grit wheels, if fine enough can both rough off damage and finish to a adequate cutting edge for most purposes' If the tool is damaged much, we would grind the tool shank under the carbide with an ordinary aluminum oxide wheel, then work on the carbide. The green grit face wheel we used was fairly fine, and coolant was used in volume.
 

Bob Korves

H-M Supporter - Sustaining Member
H-M Platinum Supporter ($50)
Joined
Jul 2, 2014
Messages
5,254
Likes
5,612
#14
Both types of wheels have their place; crash a carbide tool, the diamond wheel would take way too much time to whittle away the damage and cause undue wear to it; the green grit wheels, if fine enough can both rough off damage and finish to a adequate cutting edge for most purposes' If the tool is damaged much, we would grind the tool shank under the carbide with an ordinary aluminum oxide wheel, then work on the carbide. The green grit face wheel we used was fairly fine, and coolant was used in volume.
Thanks, John. I was using a 6" 80 grit Crystolon tool room wheel, tool steel shank undercut with aluminum oxide. but the carbide never got sharp enough to be useful. Perhaps it was the lack of any coolant.
 
Last edited:

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,123
Likes
1,560
#15
Most all the lathe guys used the black wheel on a bench grinder for sharpening brazed on tools, it had no coolant, and the sharpening job was good enough for the work done; it is true that the better the tool edge, the better the finish, but we had plenty of files and emery cloth too, and a good bit of work was ground as well. We used insert tooling as well, but it was all negative rake and used mostly for roughing, both for lathe work and milling; note that this was back in the 1960s when positive rake tools were not much used, and where I worked, there was a prejudice against them "because they had only half the cutting edges than negative rake tools". The fact that positive rake tools are more productive in terms of metal removal did not enter into the equation. The clo9sest we got to positive rake was by grinding a chip breaker into the brazed tools with the black grinding wheels.
 

mcostello

Active User
Registered
Joined
Dec 29, 2013
Messages
364
Likes
162
#16
If You want to see a wheel disapear quickly, just grind steel on a green wheel. It must be seen to be believed.
 
[6]
[5] [7]
Top