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Using carbide - when to rotate?

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Feb 8, 2020
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1) Can we get a forum on sharpening? Seems like there'd be a lot of sharpening-related discussion.

2) I do like using carbide-tipped tools for the occasional turning that I do, but unless they get a nick, I don't really know when I should rotate the tip for a new edge.
Any "tips"?

I did put together a jig to ba able to sharpen a variety of tools with my bench top belt sander, but I have more tools than workspace, and tend to go back to the carbide tool so that I don't have to pull out the sharpening apparatus any time I want to do some turning for a few hours.
 
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1) Might be good to familiarize yourself with the search feature. Seems there is a sharpening discussion coming up at least once a week (and many non-sharpening threads quickly become threads on sharpening)

2) Generally most I have seen suggest to loosen and rotate the cutter a little bit before every use session, while others simply say to rotate the cutter whenever it seems to be getting dull.. Typically the "once per session" thing works best on round cutters. I rarely use carbide, and might want to suggest looking into a flip top cart that you can mount an actual grinder onto (with jigs) to roll it out near the lathe when you are turning , that way you can just step over to grinder and resharpen and back to turning quite quickly, and indeed with practice, faster than you can rotate a carbide cutter.. (flip top cart for ease of rolling it out and back in to storage, and use the other side for a work table or something?) and as to sharpening setups, there's designs for sharpening stations (and roll carts), and ways to sharpen out the wazoo (refer back to #1 on forum search) within the forums here.
 

Roger Wiegand

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As a "lumper" and not a "splitter" I'm not a fan of many lightly populated specialty subfora. OTOH, I have my view of most forums I frequent, including this one, set up so that all the subforms collapse into one feed based on the most recent posts, so I guess I don't actually care.

As to rotating carbide, I think you at some point need to turn enough to know when the edge is dull. With conventional tools it's very easy to develop this skill-- if you even suspect that the tool is dull you resharpen or, my preference, hone, and if the cut gets dramatically better you know you let the tool get too dull. With this kind of feedback you learn very quickly. With carbide I could imagine either keeping a "reference tool" to compare your in-use tool to to make the same kind of comparison or rotating the cutter, see whether the cut improves, and if it doesn't go back to the previous edge.

I've just noticed that the surface isn't what it once was on my jointer/planer, so I'm planning a happy afternoon of turning cutters on the spiral head sometime real soon now.
 
Joined
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1) Might be good to familiarize yourself with the search feature. Seems there is a sharpening discussion coming up at least once a week (and many non-sharpening threads quickly become threads on sharpening)

2) Generally most I have seen suggest to loosen and rotate the cutter a little bit before every use session, while others simply say to rotate the cutter whenever it seems to be getting dull.. Typically the "once per session" thing works best on round cutters. I rarely use carbide, and might want to suggest looking into a flip top cart that you can mount an actual grinder onto (with jigs) to roll it out near the lathe when you are turning , that way you can just step over to grinder and resharpen and back to turning quite quickly, and indeed with practice, faster than you can rotate a carbide cutter.. (flip top cart for ease of rolling it out and back in to storage, and use the other side for a work table or something?) and as to sharpening setups, there's designs for sharpening stations (and roll carts), and ways to sharpen out the wazoo (refer back to #1 on forum search) within the forums here.
Respectfully, your point on #1 reinforces my suggestion that a forum topic specifically related to sharpening be created. I make the suggestion not only for my own benefit, but for the others who, like me, did not find their answer through the search results.

Otherwise, thank you for tip #2. Between the table saw, router table, band saw, motorcycle, workbench, waste bin and lumber cart all in the space of a 1-car garage, I end up rolling the lathe into the driveway for any turning (likewise for the saws and router table). The practice does keep the dust down when it can all be blown away with a leaf blower, but tool availability is a hassle.
 
Joined
Feb 8, 2020
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As a "lumper" and not a "splitter" I'm not a fan of many lightly populated specialty subfora. OTOH, I have my view of most forums I frequent, including this one, set up so that all the subforms collapse into one feed based on the most recent posts, so I guess I don't actually care.

As to rotating carbide, I think you at some point need to turn enough to know when the edge is dull. With conventional tools it's very easy to develop this skill-- if you even suspect that the tool is dull you resharpen or, my preference, hone, and if the cut gets dramatically better you know you let the tool get too dull. With this kind of feedback you learn very quickly. With carbide I could imagine either keeping a "reference tool" to compare your in-use tool to to make the same kind of comparison or rotating the cutter, see whether the cut improves, and if it doesn't go back to the previous edge.

I've just noticed that the surface isn't what it once was on my jointer/planer, so I'm planning a happy afternoon of turning cutters on the spiral head sometime real soon now.
I do dig the idea of a "reference" tool and/or making that comparison after rotating, thanks! I don't envy the job of rotating all those cutting heads!
 
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A simple way to test for sharpness is by dragging a fingernail across the tool edge at a low angle. A sharp tool will easily dig in, a usable but degraded edge will take more force or a higher angle to catch the nail and the rounded facet of a dull tool will just slide off. Any sharp tool including a new carbide insert will serve as a reference.

You can do a lot with carbide tools, especially the Hunter line, but there are versatile and productive tools like a bowl gouge or skew chisel that only exist in steel (so far). I am still waiting for the ultimate alloy that stays perfectly sharp forever. Until then sharpening will be part of the turning game. I would suggest making a rolling cart with drawers about 18" square that will hold a bench grinder and platform and a rack of tools that can move w/ your lathe. If you are going to reap the advantage of using steel, sharpening has to be accessible, predictable and hassle-free.

There's already plenty of discussion related to sharpening. I doubt a separate subforum is necessary to encourage or contain it. The search function works well enough on this forum as is. When learning sharpening it helps to pick one popular method and stick with it until proficiency is achieved.
 
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Respectfully, your point on #1 reinforces my suggestion that a forum topic specifically related to sharpening be created. I make the suggestion not only for my own benefit, but for the others who, like me, did not find their answer through the search results.
Umm what could be easier than going to the top right corner of this page and hitting search?

For example.. simple search on sharpening carbide: https://www.aawforum.org/community/search/23059/?q=sharpening+carbide&o=relevance

or the aforementioned sharpening station idea https://www.aawforum.org/community/search/23060/?q=rolling+sharpening+station&o=relevance

Lots of results, and "leads" to other results or searches.. (And BTW, I rarely if ever use forum search feature on forums I visit, so if you have a bit more "search-fu" than I do you may get even better results)
 
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I think more than anything, experience will tell you when the tool is getting dull. Since the carbide lasts a long time and can be bought back to better than dull but not sharp as factory, you will figure it out. I can't remember the guy's name, but he used to write for American Woodworking magazine, but been so long, that may not be the correct magazine name either. Some one wrote in and asked how to tell if the table saw blade was dull. He commented, "if you are setting the fire alarm off, it is dull".....

robo hippy
 
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2) I do like using carbide-tipped tools for the occasional turning that I do, but unless they get a nick, I don't really know when I should rotate the tip for a new edge.
Any "tips"?
Dan, I use carbide scraping (and Hunter style) tools quite a bit, and I confess that, after several years, I don't have the answer either. I can share my experience, for what that may be worth. First when it comes to carbide scraping tools I make heavy use of all three sides, not just the front end or tip. While the tip may see more use, I will work from 8 o'clock, around the tip, all the way to 4 o'clock. So when I do finally decide to rotate, I don't turn the cutter a little bit, but a quarter turn. To that end the first thing I do with a new tool/insert is to mark the "north" position. With the insert off the tool, I mark it with a Sharpie. I start from inside the screw hole, go across the top, down the bevel and across to the bottom. That way if and when the markings on the exposed surfaces wear off I still retain the marking on the protected surfaces. When it comes time to rotate the cutter I use the sequence north, south, east, west, then pitch. If you have to remove an insert from a tool you can take a different color Sharpie and mark the cutting edge of the insert to indicate where to position it when remounting (the color on the cutting edge will quickly wear off when next used). With Hunter cutters I use the same method to mark north, but a smaller degree of rotation.

I tend to use a cutter for at least one project, and sometimes more, if they aren't important pieces. If I'm going to rotate/change an insert I tend to start out with the old edge, then change when I'm getting closer to the final cuts. I try to have a low threshold for changing edges. I figure if the insert cost 20, then a change out is a 5 dollar decision. But, I don't only use carbide scrapers, so the final surface may be achieved with another tool, e.g. a NRS. Hence I may use a given carbide edge longer than someone else might choose to do.

One final thought. I just now replaced a square cutter on a tool and I was somewhat dismayed to find that the insert had chipped along the bottom surface where it couldn't be readily seen without removing the insert. From now one I will be removing and inspecting the insert each time it is "rotated" and not just turning it on a loosened screw.
 
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I use carbide cup cutters 6,8,10mm on my various hollowers. Generally move them based on their ability to cut as I use hardwoods a lot, rarely do I find the cup cutters chipped unless I have done something silly like catch the chuck jaws, then I will remember. I have had a go at moving them based on time and usage, this wasn't so successful as I have several hollowers and use them all but not necessarily in succession. My general test is to run my finger over them, much the same as testing a knife blade
 
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