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Power honing?

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G'day all.

I'm looking at mounting three discs on a lathe arbor I've had made.

The purpose is to charge two with honing compounds, in an attempt to polish gouge bevel and skew bevels, to bring them up to say 1000g or better finish. The third I will profile for gouge flutes, for a one-time polishing out of milling marks, and subsequently clean and recharge simply to take off the burr.

What I'm trying to do here is the replicate to a modest degree the fine edges that flatworkers get on their plane irons and bench chisels, by shaping and then honing/polishing both the planes that form an edge.

This is a proof of concept exercise.

Now we turners often just take a tool off a dry grinder and have at a lump of wood. Downunder the finest 8" wheel is 80 grit, and 120 in 6".

There's clearly some advantage in getting a less ragged edge than those will do. And there's examples in the history of woodturning of honing - with a hand held stone, hard felt wheel, or even a leather wheel with honing compound on a Tormek.

My question is for the abrasive tech-savvy.

Could you go from say an 80g finish to 1000g in two steps using honing crayons or diamond paste, applied to the edge of MDF, hardwood, maybe hard felt discs mounted on the lathe arbor? Or maybe a very true disc edge with 3M micro-abrasive glued to the rim?

Downunder we have a range of honing compound sticks of diff colors but I can't discover the particle sizes. Veritas make a green stick but ditto. The Tormek paste is a mix of 3, 2 and 1 micron Alox particles - a bit too fine.

Now I have a reason for an array of discs used edge-on mounted on the lathe. Because if this could work, it would be a simple job of getting a 12mm diam rod in front of them, mounted from the tool rest holder, so you could use your Tormek or Jet jigs to replicate and hone a gouge fingernail grind that you'd formed using the BGM in front of your dry grinder.

(And HSS tool users don't need wet grinders so we could save ourselves a bundle by unbundling wet grinder technology: the jigging from the wet grinding).

Now please, no debate about the merits of honing/polishing. That's not what this post is about.
 
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From when I worked at Lee Valley I can tell you the green compound Veritas offer is said to be 10000 grit. I used the belt sander/grinder to hone and could achieve that kind of sharp edge quickly. Mounting a jig to work in tandem with the sander/grinder appeared to be a simple effort. A student of mine also successfully uses the Kelton vari-grind arm on his mk2 power sharpener to get his turning tools to 8000 grit.
 
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While I admire your interest is getting rid of the tooling marks in the flute of your gouges but your interest in getting an edge similar to flat workers plane blades and bench chisels following normal sharpening procedures is, if you think about it, not worth the effort.

Thinking in terms of distance of edge travel how much total distance does a bench chisel travel before needing to be resharpened? Two feet, ten feet, a hundred feet? And how many mortises does a flat worker have to make to reach the distance before the edge is gone?

Now you've got an 8" bowl spinning at 900 RPM...how long will you be turning on that bowl before you need to resharpen and how much wood will go past the edge before you need to resharpen? Answer: LOTS more than the bench chisel. And why? Because we're not trying to get the same surface from the tool.
 

john lucas

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I've been playing with a Sheppac wet grinder which is similar to the Tormek. I go from the fine stone to the Green compound that Lee valley sells. It does give a very sharp edge but not as good as I want for my carving chisels. When I look at them under a magnifier the still have lines from the fine stone. I don't remember what the grade of the fine stone is but I think it's more like 200 to 400 grit. I can tell by watching people who have truly sharp carving tools that mine don't cut as easily. They'll shave hair but but that's not the best way to tell a really sharp tool.
When I sharpened on the sandpaper scary sharp system where I go through the grits up to 1200 and then polish with the green bar the tools cut easier and cleaner.
Now as Cyril (sp- brain fart) Except for the skew or for finishing cuts I don't see an advantage to going that fine. I can do 99 percent of all I need to do straight off the 100 grit wheel that I have on there now. Every once in a while I have tearout problem that fights me so I will use my diamond hones to and then go to the green compound. That usually works in those situations. I think changing to a tool with a finer sharpening angle works better, especially if it is honed. Most of the time when I have the tearout problems I switch to a 40 degree bowl gouge or my detail gouge which is ground to 35 degrees. These work and I don't have to stop and hone a tool.
 
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Disks that are broad enough to use their edge, or spaced wide enough to use their flat surface going away? You want the broadest possible resting place for a straight edge, though a gouge is a one-point-tangent item.

One thing I would NOT use is an MDF surface, as in another thread. The floor sweepings and crud that are incorporated into MDF can be pretty coarse, and if you get it warm, the glue is going to burn an edge. Leather is great for strops, even though it is a traditional material. With the grease in the stick to hold the abrasive in place, you should do fine.

I like the Chromium followed by Cerium oxide for mine, though I have a ceramic stone and slip that'll do nearly as well. Last buff with the white is on hard felt for me, but it takes a light touch to avoid rounding the edge.

Not that any edge so produced is required, and perhaps not even desired for HSS turning tools. Some of the alloys actually appear incapable of taking a proper edge like a forged carbon tool, where the crystals are lined up on the surface. Those that can may have fragile edges which will not take kindly to being whacked by a knot with some decent momentum.
 

john lucas

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I hate to disagree with MM on the MDF but I used it for several years until I gave them to a friend. I found some paper wheels at a bargain and bought those. Now I want some more shapes so I will probably go back to the MDF with the Green bar as an abrasive. What I like about the MDF is that is is so easy to shape into whatever you need for that tool. There are probably different grades of MDF and some may be as rough as MM says so I would pay attention to that when you by it. I get mine from a local cabinet wood supplier and it's higher quality than Lowes.

Will it get sharp? I cut a tendon in my palm with a chip carving knife when the wood broke. It didn't hurt at all and cut really deep. Hope none of you ever have to go through that.
 
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Thanks for the experience folks.

I wasn't going to buy into the 'whether' side of it, but it may help explain the scope: Farrance's orig test of wet grinding and honing showed that a gouge used on a spindle would last longer. IIRC Lacer's tests in AWT showed something similar ( + cut cleaner? need to double check).

So let's say there's some logic in the Tormek system: wet grind on the coarse graded stone ( c 280 g), regrade the stone for a finish around 1000g, then polish on the leather wheel using the paste with 1-3 micron particles.

From what I can understand of the writings of Brent Beach and others, what honing does is produce a straight edge. Off the dry wheel, the edge looks like a mangled saw edge and the teeth are fragile and likely to be torn off in the face of any kind of pounding. An edge without those teeth is stronger.

John, thanks for those tips. Yes, I had a Scheppach before going to a Tormek and the rough graded wheel is about 200g. Had you regraded the wheel to fine? Will stay aware of MDF diffs. Hard felt can also be shaped I'm told.

MM: was thinking of 3/4 MDF with some distance between them, used on the edge running away from the tool edge. Perhaps hardwood would work better. Though something like diamond paste might just get pressed into the end grain of both which is the whole circumference with MDF.

Light touch, slow running with abrasive in a wax carrier? A skew could be wider than the edge but traverse it, as with a plane blade on a Tormek. Yes, I see the risk of dubbing; another would be a 2ndary bevel at the tip. Where do you source Cerium Oxide? [Edit: yes, leather sounds good. Never seen a strop. Is a tanned side used or the furry side?]

Ceramic rods eh? What grit? Good for flutes and flats; do they work hand-held around the edge of a fingernail grind. Ah, no, you don't do that grind do you. Have just seen on the market here various shapes of Alox rods up to something like 600g.

David: thanks for that info. Yes, another route altogether. I have a 1" belt sander waiting to go, with a selection of grits in Zirconium and Trizact. Recovering from a broken wrist however means the brain work is leaping ahead of the brawn work atm.

Thanks again everyone.
 
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It's the edge where you can catch the dirt. They debark and chip right in the woods nowadays, and it's not exactly clean or thorough. Big vans full of chips are less efficient than hauling logs, but a lot more cost effective than leaving the limbs in the woods to rot. Squeal of the pig.

Anyway, as I understand it from the folks at the mill, the center of the MDF is more open and uses cruddier material, while the surface layers are pulped finer and pressed tighter to take paint. If they did the interior to the same standard as the exterior, the weight and cost would be astronomical.

You could always use the bore and slot method to run leather around the outside and avoid the problems. My carving mentor used an ancient PTO belt about a quarter inch thick with compound on his tools. Even cut mirror images into the leather for various sweeps. He said white pine or bass would do as well. Not sure if they've imported Linden down there, but it's great wood for a lot of things.
 
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Thanks MM.

Haven't seen any Linden down here; we have a white pine but prob not the same species as yours.

What do you mean by 'bore and slot' method for mounting leather?
 
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Thanks Mike.

What are the Cratex wheels made of, do you know?

Have heard of dense foam rubber wheels charged with abrasive.
 
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What do you mean by 'bore and slot' method for mounting leather?

Looks like an old-fashion keyhole. A hole is bored perhaps 3/8" from the rim, and a narrower slot kerfed in to allow two thicknesses of leather to pass, where they are grabbed in a slotted dowel, twisted tight and secured with glue. Makes for as near to a bumpless setup as you can get.

Alternative wouldn't work well with MDF, because it involves wetting and stretching leather over the wheel. Gluing on the face of a disk would pose little problem.

Looks like the Cratex wheel might be similar to one which arrived with my ancient B&D garage-sale 5" grinder. Crepe wheel with a fine - undefined as in the Cratex - abrasive embedded. Since it rotated toward the edge, I was always a bit reluctant to use it where it counted, instead inverting and working without a toolrest to hone. I was not impressed, and used it little, having an old washing-machine motor and felt wheel to work with.
 

john lucas

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I have used the smaller cratex wheels to sharpen ring tools and hook tools. I get them from RioGRande jewelry supply. I don't know what grit they are.
 

john lucas

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I just re-read MM's post. I think he is talking about the same way the sandpaper is attached to the sanding drums that I use. There is a hole in the center with a slot cut. The sandpaper goes into the slot and a slightly oval shaped aluminum rod is inserted and twisted to pull the sandpaper in and lock it in place. It's a good idea for the leather.
My leather wheel has a mitered cut and is simply glued down. It has less of a bump but after about 3 years it's starting to come loose so I need to glue the loose end.
When I was doing leather work we used to use what they call a scarf joint in wood. We beveled both pieces of leather and glued them together. this way there wasn't any added thickness. That's exactly how bandsaw blades are silver soldered together.
 
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FWIW. I got the leather belt for my strip sander from Lee Valley. The directions specify the rough side out.

Tried it last night for the first time. Really loved the cut I got! Silky smooth end grain on alder as a test. Alder end grain can tear out looking at it, so I was impressed. Some tear out on a freshly sharpened gouge without being honed on the leather belt. Absolutely none with the honing. Used the green stick. YMMV.
 
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