Sharpening Question

[David Coburn]

I've been watching some videos on Youtube to see if I was doing the cuts right... One of them was demonstrating a scraping cut with a bowl gouge. The video would have little pieces of text pop up that gave details that were relative to what was happening in the video at any given moment. One poped up and said "tool must be razor sharp."... I know a little bit about razor sharp and have to say that none of my lathe tools are razor sharp so I'm wanting to understand if razor sharp in regard to a lathe tool is the same as say to a paring or chisel or a carving tool... I don't hone any of my gouges that I'm using on the lathe. I come straight off the grinder to the work...

Any comments on this would be appreciated.

thanks,
david

[Steve Peterson]

I don't bother honing because I don't think it would matter after about 5 seconds of cutting. I have seen some videos where they use a diamond home between sharpening, but usually never right after. The only time I might do it would be for the very last light pass where you want the gouge to be as sharp as possible.

Steve

[Reed Gray]

A am a straight off the grinder and to work type. I think most are. Honing can extend a slightly dulled tool for a bit, but eventually you have to go back to the grinder. A very light touch is required for sharpening. A scraping cut is when the cutting edge is at 90 degrees to the spinning wood, so for a scraper, you would have it flat on the tool rest. With a gouge, you are holding the tool level, with the flutes rolled all the way over on the side. Scrapers cut with a burr.

I have several turning clips up on You Tube as well. Type in robo hippy.

robo hippy

[Harry Robinette]

I hone, straight off the grinder the tool is sharp BUT it can be sharper if you hone the burr off. If you let the burr brake off you have a flat spot and are starting with a dull tool. Some say it's not enough to worry about but to me dull is dull so why start with a dull tool for 3 or 4 seconds of my time to hone the burr off.
AS always JMHO

[Thom Sturgill]

I agree with Harry and will add a bit that I learned from Cindy Drozda. IF you are using high vanadium tools, the vanadium carbides can not be cut with AO wheels, but mearly dislodged. CBN wheels make a big difference. All of the HSS we use have some vanadium - M2 is 2%, M4 is 4%, and Doug Thompson's tools are 11% IIRC.

Several people that I know (all experienced turners) have changed from course wheels to fine (100+) CBN wheels as they find the edge much better and longer lasting. A *sharp* edge is the joining of two flat planes. A serrated edge is formed if the grinder leaves grooves or the flute is grooved. A finer grit wheel makes these 'grooves' smaller, reducing the serration I hone both the flute and the bevel of most tools to prolong the life of the tool, although i will admit I do it less since I upgraded to a CBN wheel.

[robert baccus]

I think it's a mistake to use one rule for every situation. Cutting or finishing procedures should be according to the situation. I grind on an 80 blue wheel for general hogging and cutting. For crazy grain, tight situations and finishing cuts I have 4 grits 0f 6" diamond plates(buffer body) and I definitely go to these honers. Techniques are like sandpaper--use the right grit for the situation.

[Reed Gray]

To hone, or not to hone, that is the question. From the extreme like Mike Mahoney and Jimmy Clewes, they like a 60 grit wheel because 'a more serrated edge cuts better', to the Tormek users 'because an edge with less teeth doesn't dull as fast. I haven't been able to notice any difference between the CBN 80, 180 or the Tormek. They all cut fine. An edge that is appropriate for a hand plane isn't good for turning. I could spend a week with a hand plane and not make as many shavings as I could in a full day at the lathe. The higher the shear angle is, the cleaner the cut is. Mostly, as near as I can figure, with a high angle, it does a better job of gently lifting the wood up as it cuts. A fluteless gouge makes it easy to get to 70 degrees or more. Rubbing the flute gives a slightly cleaner cut. How big your burr is depends on how coarse your wheel is as in coarser = bigger burr, and how hard you are pushing into the wheel. Most of the time we push way too hard, and grind rather than sharpen. That wears out tools much faster, and again, bigger burrs.

robo hippy

[Guy Belleman]

Thom, you make some good points to consider. Here I have just been sharpening away and focusing more on buying good gouges than thinking about the whole issue. Although there are different scales, a little research shows that Aluminum oxide grinding wheel has a hardness of 9 Mohs, yet the Vanadium carbide in many gouges has a hardness of 9-9.5 Mohs. And a CBN (cubic boron nitride) wheel has a hardness of 9.5-10, second (it seems in many references) to only diamond. Guess I had never really connected the dots, which I guess I should have. Since I just bought several of Doug Thompson's tools and was thinking that the grinding wheel was wearing down faster than usual, I should begin looking at CBN wheels.

[David Coburn]

Wow... The thing I keep seeing is $$$$$$ geeze this got really expensive fast. I'm already in for.... new lathe, new tools (two bowl gouges, bowl scraper, narrow parting tool), various new finishes, sandpaper, sanding pad for my drill, wolverine, varigrind, woodturningblanks4u blanks, roughedoutbowls blanks.... wait give me a minute, I'm sure there's more... I know I don't want to add this up...

but you know, again, I haven't had this much fun in the shop a very long time..

It's been worth every penny..

cya,
david

[Joe Bradshaw]

David, let me chime in with a few things. I use the CBN wheels and they are great as has been stated. It takes longer for my grinder to get up to speed than it takes to put a new edge on a tool. New turners are told to take a picture of their wallet, because turning is a vortex that sucks you and your money in. Remember that you are just one tool away from excellence.
Joe

[David Coburn]

Joe,

Great response... Could I simply cut to the chase and ask "which tool that is so I can just not buy all the others?"... :cool:

david

[Bob Hamilton]

Hi, David:
That may have been one of my videos you saw. I do hone my tools on an MDF wheel charged with honing compound, so they are pretty much as sharp as my bench chisels and plane irons. I recently tried out some tools that claimed to be sharp and ready to use right out of the package and I was quite surprised at how long the edge seemed to last on the bowl gouge compared to my own gouges. For the last few weeks I have been skipping the honing on my gouges and they still seem to cut very well straight from the 80X wheel. There have only been a couple of times that I encountered some very fuzzy grain that I felt the need of that extra degree of sharpness that the honing wheel produces.

Take care
Bob

[robert baccus]

David, do that and you have removed half the fun. Bob, for what it's worth, I tried a hard felt wheel with green compound years ago and had the same results you did. Knife makers tell me honing on anything with compounds is an art. Anything but a brush on the wheel will actually turn an edge roundish giving the edge a radius. I went to 6" diamond discs of various grits and have great results. Scary sharp. The thickness of the metal behind the edge seems to matter a lot for edge endurance. Several sawmills have changed their sharpening profile in this direction. May be something to grinding a second bevel if you grind a pointy shape normally.

[Brian Ashton]

First off you started out talking about scraping and then concluded that you don't hone your gouges. Two very different tools I suspect you already know.

My answer for each:

Scrapers

I generally go straight to the work from the grinder. If I have a very fine finishing cut, either flat or skewed, I will give the edge a honing. It just gives that little bit extra that makes life so much easier.

Cutting tools i.e. gouges, skews

I hone all the time. Years ago I used to do a lot of production turning and without exception I found a honed edge to be more than worth the effort it took to hone. In my case though, I didn't actually hone, I went straight from the grinder to either a hard rag buffing wheel (for gouges and the likes) or spinning mdf wheel (for flat bladed tools), both charged with white or grey compound.

In the beginning of my production career I followed the crowd and didn't question the rhetoric being stated. But being the sort that is always trying to improve the process I decided to utilize the knowledge gained in sharpening carving chisels to see if it gave any advantage.

I found the advantage very worthwhile:
Fatigue from standing at a lathe 8 hours a day spitting shavings all over the place was reduced significantly because the tools cut through the wood so much more effortlessly and over a day it made a great deal of difference to the hands and forearms.

Tools lasted quite a bit longer. Depending on what I was turing, predominantly fir and pine, hitting a single knot can destroy an edge at 2000 plus rpms. On a freshly ground chisel I found them far less resilient to knots than a honed or buffed edge. I don't think the edge from honing or buffing was structurally stronger but I suspect the keen edge just cut through the knot better. I could hit much more knots before the tools lost it's effective edge.

I could turn quite a few more legs or what have you before the tool lost it's useable edge when I honed or buffed compared to an edge straight off the grinder. If I remember correctly it was something like 3 or 4 to 1 or 2, depending on the wood and number of knots... Over a day where I could turn about 6 legs an hour that adds up.

Also a keen edge often doesn't need any sanding at all which can really increase production.

The down side, though it wasn't for me, is that skews don't perform well with a flat bevel. To get around this I started turning with squared chisels and only honed or buffed one side so the other side maintained its hollow grind.

Gouges were easy because I buffed the flute heavily and only lightly touched the bevel maintaining a nice hollow grind but gaining a "razor" edge.

YMMV

[Steve Schwartz]

David,

I hav been shear cutting for years and my simple answer is that I shear cut right off the wheel. I only hone skews. The long answer is that shear cutting depends on 1) do you have a fingernail or Irish grind profile? 2) are you using an 80 grit or finer wheel on a slow speed grinder? 3) your flutes should be almost flush to the bowl and cutting with the lower flute. 4) handle should be tipped down to a 30-40 degree angle off vertical.

[David Coburn]

Wow.. A ton of information here... No way I could give a decent comment to all of it... Thank you all for taking the time to post your thoughts... Plus I know I'm posting a lot of question of late... I hope I'm not wearing everyone out... I used some Transtint and India Ink yesterday, so you can see I'm moving from one thing to the next pretty quickly..

Thanks again,
david