Tool Edge Micrographs

[Bill Boehme]

..... I've been thinking about putting the chisel in my metal lathe. advance the cut a known amount into the work as it rotates and then use the power feel to go from one end of a turning to the other. maybe make 2 or 3 passes with each tool and then look at the edges....

I've been toying with using MDF or particle board simply because it might be more abrasive and at the same time more consistent. I'll have to look around and see what's available locally. I sharpened the chisels so far up to 1500 grit and then touched them on a leather strop to finalize the edge. That's as sharp as I get my hand plane blades and they cut wispers off wood. When I took slices off a piece of paper I couldn't believe how easily it cut. Probably not as easy as the floating silk in the movie Bodyguard (which myth busters proved wouldn't work anyway).

From an engineering perspective, my opinion is that while you are working hard to eliminate variables that would otherwise cloud the data, I am more concerned that the test methods that you envision appear to have diverged too far from real world conditions. Before proceeding into the test methods, I would suggest first clearly defining the fundamental objective. After that, variables can be more easily identified and, to the extent possible, determine if there are methods that can be used to mitigate their effects. Otherwise, I see a risk of making the test results not very meaningful.

I understand the rationale behind the idea of normalizing the way that the cutter is used in the test, but don't believe that the power feed on the metal lathe is the right approach. There is a fundamental difference between metal machining and wood turning in the way that the cutter is used. In metal machining, the power feed is a position control system whereas woodturning is primarily a man-in-the-loop force feedback system (or to state it more simply, it is anything other than a position control system).

Particle board and MDF are the next best thing to an aluminum oxide grinding wheel to my way of thinking. They both consist of a high percentage of very hard and abrasive bonding material (urea formaldehyde resin, in the case of MDF). The fact that they contain cellulose seems not especially relevant because, other than that, it doesn't have much else in common with cutting solid wood. It looks like the test would be mainly scraping an abrasive material rather than making a true cut that slices through real wood. If you're looking at gauging edge longevity, I think that scraping an edge against MDF isn't the right approach.

For all of its ambiguities, it is hard to beat cutting real wood in the traditional manner as a measure of how well an edge holds up. There is no question of when the tool quits slicing wood and there is no need to look at a photomicrograph to verify that.

I'm sure that you have turned MDF and particle board, so you are very familiar how nasty it is. Besides making a thorough mess of your shop with all of the dust that it creates, it is really bad for your lungs. If I must turn it, I will only do so outdoors with a breeze from my back and wearing my Airstream respirator. I would rather turn a banksia pod ... and I hate turning banksia pods. 😀

 

[john lucas]

Bill I find it very difficult to accurately tell when a tool is getting dull. That's why it's so hard to tell if the V11 steel holds an edge longer than HSS. The other problem is I'm really looking for sharp edge holding not just when it gets dull. I have already proven that the V11 will outperform HSS when cutting aluminum. But in that case I'm pretty sure the really sharp edge was gone fairly quickly and the less than sharp edge holds up much longer on the V11. What I would like to see is how long each of these tools holds a really sharp clean cutting edge and that's a lot more difficult to quantify.
Using the metal lathe feed may not be accurate but it has to be more consistent than feeding by hand. There are just too many variable when feeding by hand. especially on a test that might take a while since your likely to get tired and not "feel" the cut the same way on each piece. I don't know, I just figured if I'm going to the trouble to prove that each steel gets so sharp we can't tell the difference and I have these 3 exact tools why not try to see if I can tell how long they hold a really sharp edge.
Ideally I would probably put a current meter on the metal lathe and keep cutting wood until it starts to make the motor struggle and change the current draw. That would be more accurate than me trying to feel it, but hey that's probably beyond me and the tools I have. I'm just having fun with this. I think I've already proven my point with the sharpening that I've done. Each of these tools so far is far beyond where any turner would normally sharpen to, and each of the steels feels the same in my simple tests.

 

[hockenbery]

John,

You might try a strobe light. There was an article in the journal a while back and Ron Gerton did a nice demo at one of the AAW symposiums.
The big advantage of the strobe light is that it stops the rotation of the work piece in your eye. So if you are working a piece with projections you can see them.

The strobe Ron used picked up a timing mark so it adjusted to the drop in RPMS as the tools were cutting.
A cut with less resistance should have a lower drop in RPMS.
The strobe had an rpm readout.

If you had an assistant they could record the RPMS and cut with a camera.

Al

 

[Mark Hepburn]

Add in a DJ and a big flat screen and you may not get any results, but it'll be a fun experiment!

And if you wait until August 9, the Titans first game is on.

🙂

kidding

 

[Mark Hepburn]

Enough with the levity, sorry.

Bill, it seems that your point regarding the difference between cutting wood and scraping something like MDF assumes that one cannot use a gouge in its "intended" manner against MDF? Not having turned any (except to make a couple of round sacrificial pieces) I just don' know; is that correct though?

It seems that if John were to remove the variable of feed rate and angle of attack, then if the media is consistent, would would he not have isolated the data that he is looking for?

If so, perhaps something like ash would be a good candidate for turning since it is pretty consistent?

Or even as you mentioned, a quality plywood product with no voids? I know Jim Driskell over in the SWT forum turns out some amazing stuff in plywood.

 

[hockenbery]

Finding two blocks of wood that are equally consistent in density and hardness is impossible.
At a given tolerance level finding two equal pieces of MDF, ALUMINUM, OR PVC is not possible as well.
All of these materials can be cut and scraped.

Finding a couple of pieces of wood within our ability to measure is easy.
I have a KD poplar board 3" thick. It is pretty consistent throughout.
Certainly more consistent than our ability to measure in the shop.

Accuracy is fine but accuracy beyond what we can measure is of little value.

When we have elections and the margin of error of the tabulation method is +/- .5%
An the difference between winner and loser is les than .5% you have a tie and some more accurate method of counting must be employed to count the results or you still have a tie.

Al

 

[Mark Hepburn]

Finding two blocks of wood that are equally consistent in density and hardness is impossible.
At a given tolerance level finding two equal pieces of MDF, ALUMINUM, OR PVC is not possible as well.
All of these materials can be cut and scraped.

Finding a couple of pieces of wood within our ability to measure is easy.
I have a KD poplar board 3" thick. It is pretty consistent throughout.
Certainly more consistent than our ability to measure in the shop.

Accuracy is fine but accuracy beyond what we can measure is of little value.

When we have elections and the margin of error of the tabulation method is +/- .5%
An the difference between winner and loser is les than .5% you have a tie and some more accurate method of counting must be employed to count the results or you still have a tie.

Al

Al,

That's indeed true. Having precision to the nth degree is great but may not be necessary. Dry Poplar is really consistent stuff. Should work great I would think.


Mark

 

[Mark Mandell]

Consistency

I may be wrong, however it seems to me that if the same sample is used for each test the results should be valid "enough" for woodturners. In that situation gluing up a layered cylinder blank of MDF, say 24" by 12" in diameter, could work. Then, rather than trying to determine "dullness" by some subjective criteria, mount the sample tools and run them each across the 24" length a set amount of times. Then take your new pix and do the comparison of the wear on each tool's edge. This should remove the issue of variability in the material because the exact same material would be used for each run on each tool. If the MDF went from hard to soft to hard it would make no difference since each tool would be subjected to the same changes in the same order. If the goal is to show woodturners how long their tool will stay sharp, you'd have to confront the staggering variables of the whole spectrum of woods being turned multiplied by the even wider spectrum of turning styles and methods. That would seem to me to be an insurmountable amount of uncontrolled conditions. Conversely, after 2, 3, or 4 runs across the 24" of MDF, microscopic examination of the remaining edges should give you the ability to predict, with a reasonably high degree of probability, how long a given cutting edge would last in use. I suppose you could hone down the predictability further by photographing the edges after each run so as to get a progression of wear. In the final analysis, it doesn't take micrographs to tell a turner that his edges, regardless of their alloy, will stay sharper longer when cutting Pine than when cutting Lignum Vitae or Mesquite.

Of course, as stated, I could be wrong

 

[hockenbery]

I would want to see the results of the cut on the wood.
1st pass, 5th pass, 10th pass.

The views of the tool edge and the views of the wood surface are both important.

MDF does not have endgrain.
The back side of the end grain on a face grain turning is the spot to compare this where tear out will be the most.

Al

 

[john lucas]

Mark That was my thought except that I think I need 3 pieces because I would like the surface feet to be the same. If I make 10 passes each on one cylinder the cylinder of course will get smaller so the last tool won't cut as much wood. I'm thinking 3 -12" pieces cut from the same piece of wood or MDF so the grain or structure would be as close to the same as possible. I would remove the same amount of wood from each piece so each tool should get as close as I can the same wear. Then I will look at them through the microscope to try and judge wear if possible realizing that this experiment doesn't follow real scientific guidelines. Hey I'm just a redneck having fun and what redneck doesn't like to sharpen steel.
Here is a photo of the 3 tools I've made. The top one is Thompson V11 steel. The middle is Henry Taylor High speed steel and the bottom one is High Carbon steel heat treated to 60Rockwell which is approximately what the other 2 tools are. All 3 are ground to 28 degrees ( missed 25 degrees by That Much but wasn't going to grind anymore). Sharpened to 1500 grit and then stropped. They are about as sharp an any tool in my arsenal including my handplanes and carving tools. All 3 seem to be the same sharpeness and definitely sharpen than turning tools, even my skews aren't usually this sharp. So for all practical purposes I've accomplished my goal which was to prove that Particle metal and HSS could be sharpened to the same degree as High Carbon steel. Hopefully the microscopic views will tell me something.

 

[Bill Boehme]

John, the way that you have your test constructed, you might as well poke it against a grinding wheel and measure how fast the tool and wheel mutually abraded away. The problem with the power feeder is that it is an absolute positioning device without regard to force. This means that there will be uncertainty about validity regarding the meaning of wear measurements because the data can't be correlated to the way that tools are used by woodturners. Now, OTOH if you constructed a constant force feeder (as opposed to a position feeder) using a long spring, then I think that you would have a better chance of measuring wear resistance by measuring the amount of wear over a fixed length of time.

I would recommend that you talk to Jerry (steelguy) who retired from Crucible Industries as well as Doug Thompson. I think that Doug can tell you how to contact Jerry or perhaps an engineer at Crucible. Jerry hasn't posted on this forum in about three years.

 

[Mark Mandell]

I would want to see the results of the cut on the wood.
1st pass, 5th pass, 10th pass.

The views of the tool edge and the views of the wood surface are both important.

MDF does not have endgrain.
The back side of the end grain on a face grain turning is the spot to compare this where tear out will be the most.

Al

Agreed Al, but I thought John's test is for durability of the equalized edges rather that how well and how long a 1500 grit edge will cut without torn grain. Once you put the tool in a turner's hands the control factors go in all directions. An advanced turner like you can turn without torn grain far better than someone on my level, not to mention a novice student, because of your superior technique. Consequently, you'll get more performance for a longer time out of the same tool than I or others will. That's close to impracticable a test.

 

[hockenbery]

Holding the tool in something like a Jamieson handle will keep the tool presentation consistent.
The metal lathe would do much the same. This will work for scraping tests.
I suspect using the tool as a scraper will have different wear than using the tool for cutting.
Without a bur the scraping will be inefficient.

These tools will do peeling cuts on spindles
The Endgrain exposed by the peeling cut will show how the corner of the tool dulls.

I think john could do the peeling cuts with a lot of consistency.

Use 3" diameter blanks. Say 10" long. Part in every 1" for tailstock to headstock to 1" diameter
Use the peeling cut to 1" on the right side of each section.

Al

 

[Bill Boehme]

Bill, it seems that your point regarding the difference between cutting wood and scraping something like MDF assumes that one cannot use a gouge in its "intended" manner against MDF? Not having turned any (except to make a couple of round sacrificial pieces) I just don' know; is that correct though?....

No, that's not it at all. The power feeder holds constant position regardless of how much or how little force is needed. That introduces an uncontrolled variable into the test that corrupts the results. The constant force device that I mentioned previously would give much more meaningful results. I probably need to figure out a way to better explain this to people who aren't engineers because it is obvious that my message isn't getting through.

 

[john lucas]

Al I was going to tilt the tool in the cross feed vice so that it matches the angle I would use if I used the skew. Not going to do a scraping test. I want it to cut just like I would.

 

[john lucas]

Bill I'd like to rig up a device that pulls the tool with a weight instead of power feed but that's just getting way to complicated. Still I have plenty of time to think about it and may come up with something. If you did it with a weight on a slop you could measure the time it takes for each pass and plot it. When the tool gets dull I assume it would take longer to traverse the same length.

 

[hockenbery]

Al I was going to tilt the tool in the cross feed vice so that it matches the angle I would use if I used the skew. Not going to do a scraping test. I want it to cut just like I would.

I am intrigued. A fundamentals article in the making?

Matching the skew angle should work if you can match the bevel. I'm not sure how hard this is to do.
I know you will figure out a safe way to do it.

If you can have bevel on the wood not cutting and adjust the angle it may not be that hard Be sure to err on the cutting edge coming out of the wood.
If the tool can bury itself you will stall the lathe or get one awful catch that break something.

One thought is doing cutting run with straight grain might take a couple of spindles to get all the tools dull.

If you have some time left maybe do another set with the wood cut on the bias maybe 20 degrees off straight.
This should yield tearout on the side where you are lifting the grain as the tools get dull.

 

[Bill Boehme]

Bill I'd like to rig up a device that pulls the tool with a weight instead of power feed but that's just getting way to complicated. Still I have plenty of time to think about it and may come up with something. If you did it with a weight on a slop you could measure the time it takes for each pass and plot it. When the tool gets dull I assume it would take longer to traverse the same length.

If you could find a long spring like an old screen door spring instead of using a weight, I think that would work better and you could control the amount of force by how far you stretch it. Use a very long handle for the tool that is hinged at the back to a solid surface to keep the contact angle fairly constant. If you use a large diameter piece of wood or MDF, that would also help to keep the angle close to constant. If you could find a large dry hard maple log, you could cut all of your test pieces from the same log and have better assurance of uniform characteristics.

I think that you might try running each test for a certain number of seconds ... determined by experiment and then check edge wear and/or photograph it. I also think that checking with some industry experts like Doug Thompson for their thoughts would be a good idea.

 

[Jeff Gilfor]

This is an interesting concept you guys have. But...

There is no objective measurement of dullness. That is a very subjective thing. Perhaps we could measure the actual force required to get an acceptable tool finish; but then again, that in and of itself is subjective.

Alternatively, we could see how long it takes to fatten the cutting edge by some measure, let's say 10%, for instance, under the assumption that it is the broadening of the sharp edge that results in dullness. That would allow comparisons between metal type and sharpening methods, as long as the presentation, wood, and force applied is the same for all tests. Only problem here is that I do not have a ruler that shows micrometers, therefore have no way to do the measuring.

This would be an awesome study if we could figure it out. Don't think anyone has ever done anything like this.

 

[Mark Hepburn]

This is an interesting concept you guys have. But...

There is no objective measurement of dullness. That is a very subjective thing. Perhaps we could measure the actual force required to get an acceptable tool finish; but then again, that in and of itself is subjective.

Alternatively, we could see how long it takes to fatten the cutting edge by some measure, let's say 10%, for instance, under the assumption that it is the broadening of the sharp edge that results in dullness. That would allow comparisons between metal type and sharpening methods, as long as the presentation, wood, and force applied is the same for all tests. Only problem here is that I do not have a ruler that shows micrometers, therefore have no way to do the measuring.

This would be an awesome study if we could figure it out. Don't think anyone has ever done anything like this.

Jeff,

I'm not the technical guy here at all, but this sounds like it might be a a good idea. If you know how long you have had the tool against the material and the RPM, then you could you not calculate the distance the tool edge travels until it had broadened by your predetermined rate?

 

[Bill Boehme]

Woodturners seem to focus on two things when it comes to their tools (besides brand) -- the sharpening method and the steel alloy. What they really are looking for is how long will a sharp edge last and how is that related to how sharp an edge can be achieved with any given sharpening method. Neither of those question has a quantifiable answer, so there is the perpetual search for a substitute answer that that will satisfactorily scratch that itch.

If I understand the question that John is hoping to answer, I believe that information is already readily available for any tool/HSS alloy, but unfortunately not as a neatly packaged for woodturning consumption type of answer. The data that describes the characteristics of these various alloys would only serve to give the average woodturner a case of acid reflux after trying to digest the data. Just to increase the level of heartburn, for any given alloy, the method of tempering has almost as much impact on the answer as does the minor variation between different alloys in woodturning tools.

The good news is that nobody longs for the "good old days" when carbon steel was the sum total of our choices. Being overwhelmed with options is actually a great thing when you think about it. So, toolmakers, "keep on whelming us". Somehow, we'll get over it.

 

[Hu Lowery]

the truth about testing

The multi-million and billion dollar companies can't do perfect testing. The best we can do is make the test reasonably relevant to what we are doing and acknowledge that it isn't 100% accurate. Been there with my own bosses years ago, a design worked on paper. I told them it wouldn't work in the real world, too many variables we couldn't model on paper(in the computer) that robbed efficiency in the real world. Been tried plenty of times before, didn't work. The company president wanted to move ahead. We did, just like everyone before us, we found the design didn't work!

The tests and photographs will give us more information to interpret. How well we interpret the information will determine it's value.

Hu

 

[Jeff Gilfor]

My head hurts.

 

[Mark Mandell]

My head hurts.

Yo, YOU started this! 😀

Seems your neat pix have gotten upstaged by John's test parameters (Oh Oh He said "meters"). Didn't realize you'd stepped in something, eh? It may squeeze up 'tween your toes, but it will wash off.😀😀

 

[Sergio Villa]

Thank for your photos but... That a tormek sharpened and hone edge was better than a CBN or any other dry grinding was obvious.
As far as serrated edge I agree with a previous post. It cuts faster and so does a chain saw with is usually sharpened with a file.
It all depends what you want to achieve.
Rough turning = serrated edge is ok. Final turning dry gringing is OK if you have a lot of sand paper. Wet grinding with honing if you want to start with a fine sand paper.
In any case many factors related to the tool and the wood influence the cut, which is what really matters.
The peed of the lathe, the pressure of the tool, the speed and steadiness of the tool movement, the type of wood etc, etc, etc. furthermore for checking an edge probably a scanning electron microscope would be better than an inverted microscope and this better than a regular microscope.

 

[Dale Miner]

Thank for your photos but... furthermore for checking an edge probably a scanning electron microscope would be better than an inverted microscope and this better than a regular microscope.

I usually check the edge with the callous on the side of my thumb. If it feels dull, to the grinder and return seems to fix it.

I buy bowl gouges for the flute shape first, and the hoped for abrasion resistance second. The micro graphs are interesting though, and may shed new light on the abrasion resistance of the various steels.

It seems like Alan Lacer did a pretty substantial study along these lines a few years ago.

 

[Bill Boehme]

My head hurts.

That genie won't fit back in the bottle.b Might as well forget about trying and just enjoy the twists and turns. 🙂

Woodturning is so simple and yet so complex -- steel, tempering, sharpening methods ...... Just a machine that spins a piece of wood and a person poking it with a sharpened instrument -- from there, it's an endless list of complicating factors.

And, it's so addictive that we form clubs, national organizations, internet forums, publish books and journals (not magazines, mind you) and have national and regional seminars. Some of our ilk are so talented that they achieve the equivalent of rock star status and some of us enjoy making dishes for Fido, but we all enjoy it immensely. Because of that, we discuss minutiae ad infinitum and share knowledge and then wonder if we are doing art or just making wood shavings. Regardless of the answer, we keep doing what we are doing.

 

[Gretch Flo]

"but we all enjoy it immensely"

Not to mention the "escape" from every day crap!!!! I'd rather turn than listen to the news!!😀

 

[Bill Boehme]

Grant, there are lots of ways to tell if your tools are dull. You mentioned pushing too hard, but it ought to be if you are pushing with more than a few grams of force just to get the tool to start cutting then the tool is dull. With a little more experience and a sharp tool you will find that all the force necessary can be done using nothing more than two fingers of one hand at the back end of the bowl gouge handle to guide the cut. If the tool is sharp, the cut will be clean and you will get shavings. If the tool is dull, you will get tearout and dust. Taking the extra time to sharpen when needed is faster than pressing on with a dull tool.

 

[Grant Wilkinson]

Thanks, Bill. I understand that.

I re-read my post and realized that it added absolutely nothing to the discussion, so I've deleted it. I appreciate your advice, though.

 

[Bill Boehme]

That's OK and don't worry about posts that you feel may not add anything to the discussion. I wish that I had a nickel for each of my posts that didn't add anything to the discussion. I hope that my reply wasn't condescending. Not knowing the skill level of another turner, I tend to provide too much information rather than not enough.

 

[Grant Wilkinson]

I did not take your post as in any way condescending, Bill. My deleted post was off topic and I killed it for that reason alone.

 

[john lucas]

I think I've decided to just do a real world test on edge holding. I think ill turn some miniature baseball bats. It won't be very scientific it may tell me something when we look at the micro photos. Ill turn with the car on steel tool until it feels dull Then turn the same number with the other two. Hopefully the photographs would te something. I would try to turn with the other two until dull but that would be really really subjective unless one was far superior to the other which I doubt
Talked to my sharpening guy yesterday. I send them to him in a oboist a week. They sharpen knives for a fishing tournament and will be too. Hey this week

 

[Jeff Gilfor]

Okay, my head is no longer hurting. It's been a tough week at the hospital. Boss is on vaca, and I'm the designated stand-in. This is why I don't like being in charge!

Anyway,

Next I will do micro graphs of all the tool sharpening methods again, along with something to show scale.
AND (tell me if this makes sense), I will photograph a piece of wood cut with the tool in bevel rub mode. Then, I will use the tool for a set amount of time to continue cutting (let's say 2 minutes at 750 rpm), and will rep holograph the same two items (tool and wood).

What say you all?

 

[Bill Boehme]

.... Ill turn with the car

Is this like the YouTube video?

.... I send them to him in a oboist ....

John, I played the oboe when I was in Junior High, but lost interest because playing in the orchestra wasn't cool. I wanted to be in the band because playing-some loud shiny brass horn off key at football games was cool.

So, you have some uncool oboe player as the go-between?

 

[Gretch Flo]

I didn';t make much sense of John's message, typos/ ( figured out car was carbon, but rest left me mystified) Gretch

 

[john lucas]

Typing from my phone because I'm away and sometimes auto correct will do strange things. I'm also not very good at using the little magnifier that's lets you do corrections.

 

[Bill Boehme]

Typing from my phone because I'm away and sometimes auto correct will do strange things. I'm also not very good at using the little magnifier that's lets you do corrections.

I know what you mean. Typing a message is hard enough, but correcting and editing is totally exasperating.

 

[robo hippy]

Hey, these threads wouldn't be nearly as much fun if they didn't go off topic. I asked, but don't think I got an answer about how worn/broken in the CBN wheel was. So, now to add to the formula, what would a micrograph of a brand new vs a well worn CBN wheel show???

When John mentioned turning some base ball bat, I started thinking about several cylinders of the same diameter, and hooking up a gravity feed type pull, with the tool on a rail or slide.... All cuts the same distance, same diameter, same wood, same feed rate.....

Yea, I know, I am making it more complicated.... that is the engineer side of me that I inherited from my dad.....

robo hippy

 

[Robert Elliott]

Your dream systrm

No, that's not it at all. The power feeder holds constant position regardless of how much or how little force is needed. That introduces an uncontrolled variable into the test that corrupts the results. The constant force device that I mentioned previously would give much more meaningful results. I probably need to figure out a way to better explain this to people who aren't engineers because it is obvious that my message isn't getting through.

How about a modified duplicator? Driven by two syncros controled by an Adreno. You can monitor the control: feed rate, rpm, travel speed, current draw on the liner axis (tool drag), thermister on the tool for temp., an endiscope attached to the tool holder for video.

Then you have imperical data to crunch. If you synk the video camera' audio trak with the rpm input to the Adrion to create a click track you would a visual record too. = total data.

To me the hard part is making the tool tip holder.