How accurate is the angle measurements for this device? If I place it horizontally on a flat surface, I get 17.5 degrees. How does this compare with others?
As an example, using an old abused 3/4" flat square wood chisel, the Tormek settings didn't come close to the existing bevel angle. With the "marker method", and using the WM-200, it told me the existing angle was slightly less than 24.0 degrees. Maybe by 0.2mm. I decided to make the angle exactly 24.0 degrees and set this with the micrometer and the WM-200, and ground away I went. So, the question is, can I rely on the accuracy of the WM-200 and believe that I sharpened this chisel with exactly a 24.0 degree bevel angle? Gipper
Not to be flip, but what exactly would be the point of sharpening a chisel to exactly 24 degrees (or any other angle for that matter)?
The accuracy of the WM-200 is based on accurately measuring the diameter of the wheel, accurately setting the diameter compensating side to that measurement, and insuring that the gauge is resting on the grindstone surface at both points while setting the tool angle. If any material length is removed from the tool, the resulting grind will be at a shorter bevel angle than when it was set.
The geometry of the WM-200 is spot on. If you use it as designed, and are measuring a tool that needs minimal steel removal, it will be accurate to within a fraction of a degree.
All that said, any edge tool that is within 2 or 3 degrees of your target angle is going to deliver performance exactly equal to one that is precisely ground...that is to say, after 30 years of woodworking, I could not tell you the difference between cutting with a chisel that was anywhere between 23 and 27 degrees.
Thanks Jeff.
Perhaps my goal for accuracy is higher than need be. I understand that setting the bevel angle to what it is, removes less steel than to create a new angle. Just recently, however, with another flat, square wood chisel, using the WM200, one side of the chisel measured about 45 degrees while the other side measured about 30 degrees. I decided I would remove less steel if I made the bevel angle exactly 30 degrees instead of 45 degrees, and set up for that. That caused me to wonder about the accuracy of the WM200. I had also been thinking that setting precise bevel angles would make it easier to set up again in the future.
Its still a fascinating learning experience for me, and I thank you and all the folks on this board for sharing your wisdom with me. Gipper
When I first bought my Tormek, I had trouble using the WM200. I almost made a new pointer with a longer bearing surface. (I still may someday.) Before I had a chance to do that, I happened to set up my Tormek outside in very good light. I found the WM200 much easier to use in very good light. (The same might be said for most precision tools, especially with older eyes.)
From your description, it sounds like you are having more problems than the WM200. Is the back of your chisel properly flattened and polished? From your description "and old abused chisel" I am skeptical. I have flattened and polished the backs of numerous chisels. It is a lot of work, especially with oil stones. Even with faster cutting water stones or sandpaper, it is laborious enough to make one reluctant to abuse the tool.
I would suggest you make certain the back of your chisel is dead flat and polished like a mirror. The sides should be parallel, as well. The chisel should be in fine condition, except for sharpness. Only after that would I even think about working on the bevel.
Make sure your wheel is well dressed and square with the universal support bar. Likewise, make certain you are working in very good light.
At this point, I believe you will find your WM200 is working much better. (Make sure it is not loose.)
Please post your results, good or bad. That's the way we all benefit from this forum.
Fortune favors the brave.
Ken
Quote from: GIPPER on April 25, 2011, 11:57:12 PM
How accurate is the angle measurements for this device? If I place it horizontally on a flat surface, I get 17.5 degrees. How does this compare with others?
I've found it to be very accurate. I sharpened a set of 5 chisels last week and the WM-200 settings were right on. The angle was 30 degrees and each chisel was sharp. Are you sure you had the settings correct on the 200? It should have been spot on.
rsetina
Until somebody tells me what reading the 200 gives laying on a flat surface and set for a 250mm stone, I won't know how to tell what bevel angle I actually have if the 200 reads 30 degrees. As I said before, on a flat surface, my 200 gives me an angle of 17.5 degrees. Gipper
Ken S
I have found one thing out so far, that bothers me. Using the WM200 to measure a resultant angle while adjusting the Universal Support with the micrometer, I found that by starting high and adjusting down will give me a big error because the support "binds" in its sleeve. To reduce this error, I found that by starting low and adjusting up with the micrometer, usually gives me the correct angle by the time I lock the support in place. You can start 'high' and go low but you have to bang on the support with your fist to get it to settle down to the micro surface.
Hope this isn't too confusing. I'm still trying to confirm or prove, that if the WM200 points to the 30 degree mark, the tool bevel angle will actually be 30 degrees, or any other angle chosen. So, a good starting point is to check your WM200 flat on a surface and read the resultant angle on the dial. If its like mine, that angle would be 17.5 degrees. Gipper
Quote from: GIPPER on April 27, 2011, 05:36:27 PM
rsetina
Until somebody tells me what reading the 200 gives laying on a flat surface and set for a 250mm stone, I won't know how to tell what bevel angle I actually have if the 200 reads 30 degrees. As I said before, on a flat surface, my 200 gives me an angle of 17.5 degrees. Gipper
The WM-200 will not give an accurate measurement on a flat surface. It is not intended to work on a flat surface. The entire design of the gauge is to measure the angle relative to the circumference of the grindstone.
Hi Gipper,
The angle master is very precise, in my case when I needed to use it I didn't see any difference between the sharpened bevel and the protractor set for the same angle. As Jeff has already said it regardless what setting for the diameter of the wheel you have on the angle master when used on a flat surface you will not get the same angle you can read on the angle master. It has not been designed for flat surfaces. If that would be the case you would have a flat reference surface on the angle master, but there is none. If you want to verify its accuracy I suggest you to take a chisel that you trust of being flat, measure the diameter of the stone with a ruler, the body grid for this purpose may add an error depending on your reading position, set the angle master as the manual explains and grind the chisel. At the end verify it with a protractor, if it is out the angle master you have may be defective or not in within the parameters. I got mine set it for 250 wheel diameter and set it on a flat surface and measured the angle and I got approximately the same reading as you did.
Thanks,
Ionut
At the point where you actually measure the angle (the gage has to be flat on the back of the tool) the grinding angle happens on a totally different tangent line that the one you are trying to set the angle master for when you set in on a flate surface (the line that unified the diameter wheel gage with the angle setting one). That is the reason why using a flat surface will add an offset to your angle measurement.
Thanks,
Ionut
Thanks Jeff
I believe that the 17.5 degree angle read on the scale of the WM200 when placed on a flat surface, is correct and accurate. I have also determined that if the 200 scale could read Zero degrees, you would find that placing the instrument on the grindstone set at Zero (not possible) would contact the wheel perfectly flat. So what's the big deal? None. I just wanted to verify how reliable the WM200 was in measuring bevel angles.
With some math and some graphics, I think I can safely say that this is a remarkable "instrument" in its design. Probably something that should be treated very delicately when in use or in storage. But I'm going to use the 17.5 degree mark on a flat surface as a means of checking the calibration of the instrument. If its different, you can bet that your bevel angles will not be what you think they are. Gipper
Thanks Ionut.
Certainly the angle changes with diminishing stone diameter. If you use the "flat surface" test, that angle would change from 17.5 degrees to approximately 20.0 degrees with a 250mm diameter stone to a 200mm stone respectively. That's only a 2.5 degree change but if the proper adjustments weren't made, it would produce a bevel angle far less than what you might want. The angles I'm talking about are "built-in" angles accounting for the wheel circumference plus a desired bevel angle on a tool. The constant angle is what I call the "flat surface angle". Gipper
Gipper,
If using the WM200 seems iffy to you, here's an alternate method:
Perhaps like you, I am somewhat of a tinkerer. I use the TTS100 turning tool gage. Its two point contact (which I believe is patented) compensates for wear of the wheel.
Set the universal support bar to one of the two settings. This becomes your fixed distance.
Place your chisel in the SE76 jig and use the WM200 or black marker technique to get the angle you wish. Note the protrusion distance from the front of the SE76. Make up a "gage block" for this protrusion distance. I use a piece of cardboard with a pencil line. Note the angle on the gage block.
The next time you set up your Tormek, set the universal support bar using the TTS100 and set the protrusion distance of your next chisel using your cardboard gage block. Your bevel angle should be consistent.
If you wish, you can make up gage blocks for different angles, such as paring chisels instead of struck chisels.
The handbook shows a very similar method using wooden spacer blocks.
I like methods which are accurate, but do not rely on ongoing measurements.
Ken
Quote from: GIPPER on April 25, 2011, 11:57:12 PM
If I place it horizontally on a flat surface, I get 17.5 degrees. How does this compare with others?
I do get about 17 or 18 degrees. But this is true only when the diameter is set to 250 mm.
So, this verifies that your WM-200 and my WM-200 are the same.
Now, if I keep the WM-200 settings the same, and set it on the outside of a 250 mm diameter wheel, it will make a 17.5 degree angle with the surface of the wheel. That is what it's designed to do.
Quote from: GIPPER on April 26, 2011, 02:16:23 PM
Just recently, however, with another flat, square wood chisel, using the WM200, one side of the chisel measured about 45 degrees while the other side measured about 30 degrees.
Huhh? This makes no sense. If the front of the chisel makes a 45 degree angle with the back of the chisel, then the back of the chisel MUST make a 45 degree angle with the front of the chisel.
To make this happen on a typical wood chisel, you set the WM-200 to 45 degrees.
If instead you want the angle to be 30 degrees, you set the WM-200 to 30 degrees.
Hi Herman
You're right. It doesn't make sense but it's a fact. On the right side of the chisel, it measured 45 degrees (edge to heel) while on the left side of the chisel, it measured 30 degrees (edge to heal). Obviously, either the wheel was not square or somebody sharpened it by an unsteady hand. In any case, I decided to reshape the chisel so it would have a 30 degree bevel (and would be square to the shank). It seemed to work pretty good and I now think I have a pretty good chisel to work with. Gipper
Hi Gipper,
How wide is the chisel you are working with? 15 degrees difference is humongous that would lead to a very large degree of un-square edge compared to the sides of the chisel. Is the chisel body badly twisted? At that degree the un-squareness of the wheel would be more than obvious and your side to side movements would be wavy, I mean the chisel would not be moving in the same plane as you would move it side to side. How did you measure the bevel angle?
Is the universal support securely tight at the time when you start sharpening?
Thanks,
Ionut
Hi ionut.
Not sure how to address the questions you pose so let me first try to answer your questions directly.
A. the chisel is 1" wide
B. the chisel is not twisted as best as I can tell
C. I measured the angles using the WM200
D. The Universal Support was tight.
Please understand this was my second attempt at sharpening a chisel with my new Tormek T-7.
The Set Up
1. Used the Square Jig in the horizontal position
2. Protrusion was by hand and the max. allowed by the jig and the tool length. Actual protrusion unknown
3. Black Ink marker on bevel surface
4. Measurement with WM200 left and right side by adjusting USupport. Until scratch ink off bevel surface each side then measure angle with WM200
5. Different bevel angles obvious by sight on each side
6. Chisel was snugly secured in the Jig
Final Set Up
A. Maximum protrusion allowed by jig and chisel shaft length to lock in place squarely
B. Set Chisel bevel to 30 degrees using the WM200
C. Reshaped and sharpened chisel.
D. Did not change grit on grinder
E. Did hone with flat honing wheel by hand
F. Results Good
Gipper
I understand you but this Tormek machine is a very simple machine and very effective, you do not have to know anything about sharpening and still be able to get good results first time. When it comes to edge square difference of a 1 -2 degrees than the complication comes up too, but 15 degrees difference between the left corner of 1 inch chisel compared with the right corner is far too much or I do miss something. If I would try to replicate that difference just by adjusting the height of the universal support and using the WM I would have to make a big change. Does the chisel stay approximately in the same plane while grinding and moving it left –right over the stone? Was this chisel grinded before on a dry grinder and is possible to have lost its tamper? If that happen differentially it may be an explanation of the angle difference but you should still see a plane change of the chisel while moving it left to right over the stone.
There may be another cause but still would not explain such a difference. The back side of the chisel is not flatten, and the area you clamp it in the SE-76 is not in the same plane with the cutting edge but even then the first thing you will see would be a very un-square cutting edge in relation with the sides of the chisels.
Ionut
Quote from: GIPPER on April 28, 2011, 05:01:24 PM
On the right side of the chisel, it measured 45 degrees (edge to heel) while on the left side of the chisel, it measured 30 degrees (edge to heal).
Ok. When you put it that way, it makes sense. I helped frame a roof once that was shaped like that. The thing is, if the back or your chisel forms a flat plane, the edge that's been machined cannot be a flat plane. The surface has to be concave, like a magnifying mirror. Someone perhaps did this on purpose.
Anyway, you can confirm these angles by using the v-shaped notches on the edge of the WM-200.
Incidentally or Coincidentally, the Angle formed on the TTS-100, between the two moving disks and the center of a grindstone whose radius is 125 mm, is 17.5 degrees. No coincident for sure. That explains why a WM-200 AngleMaster shows the same degree angle on a flat surface. Now I can sleep tonight in piece. LOL.
Gipper