carbide vs steels (discussion with ooc moved from a newcomer thread)

[Hu Lowery]

A late breaking decision after typing this, think I shouldn't post it in the original thread. I had excerpted Odie's post, going to copy it in it's entirety and my reply into a new thread to not lead the original one further astray.

Apologies for my earlier post, one of my flaws!

Good post Hu.......

Looks to me like you are missing some pretty important points, though.

First.....There is nobody saying you can't use carbide to whatever degree you wish......I do. There is nothing that says a new turner can't use carbide exclusively, if that's what they wish to do. I've given an opinion of why carbide, when used the way EW tools are intended to be used, is giving a misconception that it's as good as traditional tools. I've explained why I disagree with that notion, and you and anyone else are free to believe whatever you wish........all is an opinion, and we are all free to have our own beliefs and conclusions about what information is relevant to our own turning efforts.

There is one very major difference between carbide and HSS.......available shapes. Unless, there is a carbide tool that is shaped like a traditional gouge, then no carbide tool can do what a gouge can do. About the best that can be done is a well executed sheer scrape. If there were a carbide gouge that could be sharpened without much problem, I'd be one who might be interested in a little more information on that......

Hu, I wonder if you wouldn't mind expanding on your comment that initially a carbide edge isn't as sharp as it could be. We use carbide cutting tools and inserts where I work, and I don't believe I've ever heard this before.

Since you mentioned "sharp to dull cycle (s2d)", consider that this cycle may not be the same from individual to individual. Some turners, such as myself, don't wait to resharpen HSS tools before there are signs that it needs sharpening. This means the S2D cycle is even further abbreviated, and as long as resharpening is a refined skill that it may only take seconds to true up an edge......then the results are that the extremely sharp edge of a freshly sharpened tool (because of s2d cycle) is in existence for much longer than one single sharp edge that a carbide tool has. A new turner doesn't care to sharpen, because he doesn't know how.....yet......and, is basically the reason why carbide is so appealing. To someone who sharpens without thinking about it, the no-sharpen carbide appeal doesn't mean a thing to him.

In response to your last comment: I'm in disagreement with your assertion.......I'd bet the farm you certainly could tell the difference, if we are talking about turning designs and shapes that result in not having as much visual appeal, because less sanding is key to their success.......🙂

ooc

Odie,

First let me be plain, I wasn't talking about anyone in this thread(the earlier one now), just my experiences as a beginning turner when I asked about and even tried to buy carbide tools one old turner sells. He has given me the cold shoulder ever since! Met the same response other places too. Like having to draw on a board before you could draw on a computer, many feel you have to be able to turn with old school tools before you can be an accomplished turner with carbide.

Carbide is available in as big of pieces as you need, no reason a carbide gouge or other tool couldn't be made. Talking somewhere in the neighborhood of five hundred to a thousand dollars, maybe more, for a decent sized tool blank. The tool may snap the first time there is a catch or you try roughing a turning blank with big air gaps with it too. Aside from that, some nasty hazards involved with grinding carbide. It isn't a suitable material for making traditional style tools out of, however not impossible at all. Look for boring bar blanks and I think you will find carbide big enough to make tools out of. Very stiff, excellent for low shock long reach applications. However even chatter can be enough to shatter a carbide boring bar.

As far as not being able to have the same shape with a carbide insert or tool as with a conventional tool, there is no reason to have the same shape anywhere but the cutting area of the tool that is being used which is usually a tiny area after roughing. That is very possible to have the same. In practice the different cuts might require changing inserts or tools using the inserts but turners often change tools with traditional tools too. With present inserts commonly used you can't make huge cuts with the carbide. No reason except cost not to use bigger inserts though. I can't get behind roughing with carbide myself, I have seen how brittle it is too many times metal turning.

The downsides of carbide are cost, initial set-up, and a learning curve when someone is already comfortable using other tools. The cost also often impacts someone using dull carbide. No tool is perfectly sharp from the moment it touches the material we are turning. The level of sharpness each turner finds acceptable is the issue. If we demand the same levels of sharpness from carbide we can get it. Like people using dull sandpaper to save a few cents, people use dull carbide to save a few dollars and then complain because it is dull. It can be sharpened if a person wants to, and it can be replaced.

As to the greatest initial sharpness, the sharpness of carbide is an ongoing debate last I knew with people arguing the sharpness down to sublevels that are ridiculous in my opinion. I suspect any coated material isn't quite as sharp as naked material and most carbide is coated too, further fueling the flame. I have seen a master knifemaker sharpen steel to where it would cut you deeply without dimpling the skin of your arm. Literally start cutting before you could feel it touching your arm. I have never seen carbide sharpened to that level. No reason some steel lathe tools couldn't be, but would it serve any purpose? We can spend an extra five or ten minutes putting an edge on a gouge that can be destroyed in a moment.

I do recommend a traditional gouge with at least lightly swept back wings for a beginning turner. Mine looks a lot like a Jamieson or Ellsworth grind with an extra relief cut to make hollowing easier at the moment. Plan to take the wings further back, will have to try a full Irish grind or similar sooner or later but I can't recommend what I haven't tried. The swept back wings are more forgiving from what I have found. I don't know about flute shape for a beginner, I strongly suspect that some shapes force grinds that are less forgiving than others.

If you make a finish cut with new carbide, particularly new carbide with any coating polished off flat across the top, I think you will find that there is little or no discernible difference in the amount of sanding required.

A teaser to throw out on the HSS side, I ground a special tool to crown custom rifle barrels from HSS. It was a very high rake, very fragile tool. I never took a thousandth of an inch at a time off with this tool, too heavy of a cut. The finish this tool left was final finish, not even lapping compound behind it. I don't think carbide is tough enough to make the same tool out of, I don't know if it could be shaped to get an equal finish or not. My tool grinder's ego says not.

Hu

 

[Bill Boehme]

There are solid carbide end mills that are larger than bowl gouges, so yes something with bowl gouge shape could be made -- if things were so simple. Since everything has a downside carbide isn't exempt. One problem with carbide is that it can't withstand shock loads without breaking. So where is the shock load, you might ask? It isn't at the cutting edge. It's where the tool contacts the rest. The contact area is essentially zero and so any impact loads caused by interrupted cuts or hard knots can translate into concentrated pressure points where the loads would be many thousand pounds per square inch. Anybody who has ever handled a carbide end mill knows that if you drop it on a concrete floor, don't even look down. It will just make you sick.

I have one carbide cutter that is incredibly sharp. I think that it was originally a manufacturers display item because the carbide actually has a mirror finish that makes it look like a piece of silvered glass. Carbide is tough, but also brittle. Those two properties create a dilemma for the toolmaker. An extremely sharp edge will not last long before it fractures to something that is OK sharp. OK sharp is ... well, OK, but not great. If the cutter is being used to cut wood, it will stay OK sharp for a very long time. Meanwhile, a woodturner using HSS tool goes back to the grinder to touch up his tool every time it gets down to just OK sharp because he knows that it won't be OK much longer. Carbide formulations are always being improved so someday all of the various problems of carbide may be overcome. But, I don't expect price to be one of those problems that will be solved anytime soon.

 

[Odie]

Hello Hu and Bill........

As Bill points out, carbide might be a bit hard to adapt to turning tools as a solid piece because of it's brittleness. It might be safe to say that a solid piece carbide gouge would already been marketed by now, if that configuration were feasible.....but, I don't know, just guessing. We are probably limited to "insert" style of carbide cutters, and that might be a problem for a U shaped flute.....?

Are you saying you know someone who sells carbide wood lathe tools, but won't sell one to you? Well, probably time to find someone else who will. There are a number of current manufacturers who do make wood lathe carbide tools of various configurations.

Don't know if carbide is in the future for turning, but unless there is some kind of major improvements to their design and application.......I would have no interest in them.......other than the couple Hunter tools I do have.

One off-hand comment about the longevity of sharpened edges on HSS gouges: Yes, they do dull very quickly, but not as quick as you would think......considering the cutting can be directed to nearly the entire length of the edge. You only may get ten or fifteen seconds of super sharp, but once it dulls, you can adjust the cut to where the edge is still freshly sharp.

ooc

 

[Bill Boehme]

With some wood and especially green wood, there is no problem doing an entire turning without sharpening HSS. Other times with wood that is very hard or has lots of silica, several sharpenings may be required.

 

[Steve Worcester]

Could you make a carbide gouge, yes. Because the woodturning market is small (by comparison to the industrial metal lathe use market)it would be entirely cost prohibitive. That said, as Bill and others have pointed out, it doesn't make sense from a material durability standpoint.

But you need to separate the current tools into a few categories. Easy Wood and others that use a flat top are carbide scrapers. I can't say using them is wrong, saw a women the other day make a beautiful bowl out of EW tools and it surprised me. I am not an EW fan (but their machining and finish are really nice), but the learning curve and ease of use gets people into turning with quick results (and at that stage) acceptable results.

With a Hunter tool or any that use a cutter with a gullet, you can use it like a finishing gouge. (Under full disclosure, I am a Hunter dealer and consider Mike a friend). The problem is the gullet is the not as deep as a gouge's flute but they essentially do the same thing. So if you were to try and take a cut with a Hunter Osprey as aggressive as a with a gouge, it chatters and refuses. But as a finisher, it works excellent. But because the bevel is smaller, and only about 11 degrees, it takes a bit of a learning curve to accomplish that.

My goal has become teaching EW tool users to learn to use a gouge. You obviously can't poke and stroke a gouge like an EW tool, so it takes a little bit of patience.

 

[Hu Lowery]

Hello Hu and Bill........

As Bill points out, carbide might be a bit hard to adapt to turning tools as a solid piece because of it's brittleness. It might be safe to say that a solid piece carbide gouge would already been marketed by now, if that configuration were feasible.....but, I don't know, just guessing. We are probably limited to "insert" style of carbide cutters, and that might be a problem for a U shaped flute.....?

Are you saying you know someone who sells carbide wood lathe tools, but won't sell one to you? Well, probably time to find someone else who will. There are a number of current manufacturers who do make wood lathe carbide tools of various configurations.

Don't know if carbide is in the future for turning, but unless there is some kind of major improvements to their design and application.......I would have no interest in them.......other than the couple Hunter tools I do have.

One off-hand comment about the longevity of sharpened edges on HSS gouges: Yes, they do dull very quickly, but not as quick as you would think......considering the cutting can be directed to nearly the entire length of the edge. You only may get ten or fifteen seconds of super sharp, but once it dulls, you can adjust the cut to where the edge is still freshly sharp.

ooc

No turning tools available from carbide. However if you really look at the "latest greatest" turning tool powdered metals I think they more closely resemble carbide than mild steel. When I read an article many many years ago they found no steel they tested got sharper than plain mild steel, the softest material tested. Of course nothing got dull faster either.

As both Bill and I pointed out, it simply isn't feasible to make turning tools out of carbide. Unthinkingly bump a tool rest a little hard and your tool might snap. When carrying solid carbide cutting tools around the shop I carried them with both hands even if it seemed silly. Shatter a small cutter or two at sixty or eighty a pop and you don't mind looking silly with the next one you have to buy! Odds seemed about even of one breaking dropped on a wooden floor, a miracle if it didn't dropped on concrete! Product liability alone is enough to insure we will never see a production turning tool out of present day carbide.

I can easily buy carbide insert turning tools from other sources and certainly will buy at least the insert holders for my hollowing tool. I was just illustrating how strongly some feel that you can't "be a real wood turner" if you don't learn with traditional tools. At some point there is truth to that. I have turned wood for about five years and in no way shape or form resembled a wood turner when I used my cue lathe to turn wood. However, learn to get results with hand held tools and I don't think it matters much at all what the cutting surface is.

There is no technical reason U shaped, V shaped, or parabolic inserts couldn't be made for a gouge. Many odd shapes are made now. With the same demand as common machine shop inserts I would guess they would run from thirty to over a hundred each depending on size. With the limited demand from wood turners the price would be staggering. As far as I know there are no inserts specifically made for wood turning now. Although some are advertised as wood turning inserts and talking about the trough in the top making them far better for wood turning, that trough in the top has been in tooling long before any carbide was in use. It is a chip breaker so that materials that tend to make long dangerous curls break into shorter safer pieces to have around the machine shop.

Hu