Grinding Wheel Grit

[Tim Boger]

Your opinions please,
I use the Wolverine system with a Delta 8" Grinder, the wheel I have is a blue
120 grit. I do dress the wheel occasionally, perhaps not as often as I should but I feel the issue is not related to that .... what I have is a relatively rough surface on my gouges after sharpening. I think for the most part I'm sharpening correctly by method but wonder if anyone here uses a fines grit to maintain an edge as compared to the 120" which seems to remove material quickly and as I said it leaves a rough edge.

Thanks,
Tim

[Gordon Seto]

120 is on the fine side already. Too fine a grit would run hot. The Norton SG are supposed to be the best grinding wheels for turning tools; they come in only 46 & 80 grits.
http://www.woodturnerscatalog.com/store/Sharpening___Grinders___Wheels___Norton_SG_Wheel__ _norton_sg?Args=
Does your set up run smooth?

[Scott Conners]

I use a 150g white norton for touchup sharpening, it works quite well in that it leaves a pretty good surface and doesn't take material off too fast, but still plenty fast enough. I do find it needs dressing much more often than my 60g white wheel. I find having the wheel dressed concentrically and balanced so the grinder isn't vibrating makes a big difference in grind quality too.

I sharpen (not shape) carbon steel tools on this wheel too, and don't have heat problems. Leave shaping edges to a heavier grit, but if you're just renewing an edge, fine grit saves metal.

[Tim Boger]

120 is on the fine side already. Too fine a grit would run hot. The Norton SG are supposed to be the best grinding wheels for turning tools; they come in only 46 & 80 grits.
http://www.woodturnerscatalog.com/store/Sharpening___Grinders___Wheels___Norton_SG_Wheel__ _norton_sg?Args=
Does your set up run smooth?

Hey Gordon,

I guess part of my issue is not having had the opportunity to check out any other turners tools and their sharpening techniques.

I do think my current wheel runs true / smooth.

I did attend a WW Show several years ago when I was just getting interested in turning and remember a fellow that was doing a demonstration and his ground surface appeared almost polished smooth ... probably was I suppose for the show.

Thanks for the link, I need to do more research.

Thanks,
Tim

[Tim Boger]

I use a 150g white norton for touchup sharpening, it works quite well in that it leaves a pretty good surface and doesn't take material off too fast, but still plenty fast enough. I do find it needs dressing much more often than my 60g white wheel. I find having the wheel dressed concentrically and balanced so the grinder isn't vibrating makes a big difference in grind quality too.

I sharpen (not shape) carbon steel tools on this wheel too, and don't have heat problems. Leave shaping edges to a heavier grit, but if you're just renewing an edge, fine grit saves metal.

Hey Scott ... that's what I was hoping to get feedback on, may I ask what speed your grinder runs at?

Thanks,
Tim

[Steve Schlumpf]

Tim - I use a 120 grit and 150 grit wheels on my grinder. I have the Woodcraft slow speed grinder and use the 150 for freshening up the edges of all my tools. I find that by using a very light touch I can sharpen everything and get right back to the lathe! Lot of folks don't like the finer wheels because with just a little pressure you can generate a lot of heat and blue the edge. True. Just use a very light touch and you will be fine!

[Tim Boger]

Tim - I use a 120 grit and 150 grit wheels on my grinder. I have the Woodcraft slow speed grinder and use the 150 for freshening up the edges of all my tools. I find that by using a very light touch I can sharpen everything and get right back to the lathe! Lot of folks don't like the finer wheels because with just a little pressure you can generate a lot of heat and blue the edge. True. Just use a very light touch and you will be fine!

Hey Steve ... that's what I have in mind, how do you think a 3600 RPM grinder would effect the sharpening procedure with the 150 grit wheel?
Tim

[robert hainstock]

The only answer to your deliema is to hone the tool after sharpening. I hone mine with a six in hi speed buff sressed with white diamond. Tormek just released a DVD on thier sharpening system which IHMO is the last word on sharpening. the finished Tormex tool surface looks polished, and this sharper tool not only cuts longer, it cuts better. I achive pretty much the same results with my 8 in slow speed setup and buff/hone. :)
Bob

[Steve Schlumpf]

Tim - the faster the grinder - the lighter the touch!

[Tim Boger]

The only answer to your deliema is to hone the tool after sharpening. I hone mine with a six in hi speed buff sressed with white diamond. Tormek just released a DVD on thier sharpening system which IHMO is the last word on sharpening. the finished Tormex tool surface looks polished, and this sharper tool not only cuts longer, it cuts better. I achive pretty much the same results with my 8 in slow speed setup and buff/hone. :)
Bob

Hi Bob ... I was wondering if "Honing" was going to come up in this post, I appreciate your feedback. Does the buff w/white diamond smooth the already ground surface or just shine it up?

Thanks,
Tim

[Andrew Derhammer]

How are your wheels dressed? If I remember a post from Doug Thompson he said he uses a start dresser that leaves a very rough surface to the wheel compared to a diamond dresser.

[Tim Boger]

How are your wheels dressed? If I remember a post from Doug Thompson he said he uses a start dresser that leaves a very rough surface to the wheel compared to a diamond dresser.

Hey Andrew,

I have the Wolverine Dressing Attachment but have recently been using the little T bar dresser .... seems to quickly remove the surface layer and square it up.

Maybe I need to give the Wolverine dresser another try and see if my edges improve.

Tim

[Scott Conners]

Tim, I have a variable speed grinder, but almost always sharpen at low speed (~1800). If you are dressing with a hand held t-bar dresser, you are making the wheel square and fresh, but not necessarily concentric (round). That can make your gouge bounce on the surface, leaving a rougher finish. Try the wolverine dresser again, you need to use a VERY light touch with it, as the bar has lots of flex. The less vibration when your grinder is running, the better.

[Tim Boger]

Tim, I have a variable speed grinder, but almost always sharpen at low speed (~1800). If you are dressing with a hand held t-bar dresser, you are making the wheel square and fresh, but not necessarily concentric (round). That can make your gouge bounce on the surface, leaving a rougher finish. Try the wolverine dresser again, you need to use a VERY light touch with it, as the bar has lots of flex. The less vibration when your grinder is running, the better.

Scott ... I think you may have pinned it down, as you've mentioned it, I have been having problems with the tool bouncing a bit while sharpening. I'll give the diamond dresser a chance to round the wheel and we'll see if it improves.

Thanks Scott,
Tim:)

[Doug Thompson]

I think Scott's got it too, a wheel that bounces doesn't cut clean. The fine wheels need to be dressed as soon as you see the gray/black ring appear.

I do use a star dresser on a 46 grit wheel to get a very agressive wheel for roughing, for a finish wheel I use a single point diamond dresser I bought from Bill Grumbine... I don't recall what it is but it works like a charm.

[Jeff Nicol]

Tim - I use a 120 grit and 150 grit wheels on my grinder. I have the Woodcraft slow speed grinder and use the 150 for freshening up the edges of all my tools. I find that by using a very light touch I can sharpen everything and get right back to the lathe! Lot of folks don't like the finer wheels because with just a little pressure you can generate a lot of heat and blue the edge. True. Just use a very light touch and you will be fine!
I am on the same page as Steve, right off the grinder to the work and I have no troubles. If the tool cuts the way you want it, good, but if you are not satisfied with the cut then you need to do something else. When I am roughing bowls the grind off of a 60-120 grit wheel does every thing you will need. Just before I do my finishing cuts I will go back to the grinder and take a very light pass on the wheel. This lets me cut hair fine little curls and it is ready for sanding.

Hope we had the right answers!

Jeff