Bevel Angle accuracy

[Hugh Proudman]

Hi,

I am writing to ask for some help. I am sharpening a batch of woodworking chisels for a school - using whichever Tormek is free that day. Sometimes a T4 and sometimes a T7.

I am able to produce nice sharp bevels that are square. The chisels are suitable for the students to use.

However, the bevel angle that I have produced does not match the angle that I set on the AngleMaster. I am aiming to create a 25 degree bevel, but am consistently creating one at 30 degrees. In order to grind a 25 degree bevel, I find that I need to set the AngleMaster to 20 degrees.

This is a repeatable process, so in a sense this doesn't matter that much; just do what works.

However, as this is in a school I would like to understand what I am doing wrong so we can ensure the students don't learn my mistakes.

I have been careful to set the stone diameter on the AngleMaster, and have had other people watch my approach - to see if they can spot something that I'm doing wrong. Nothing stands out.

I have also watched the excellent Tormek Chisel sharpening class - part 3. I can't spot anything obvious that I'm doing wrong. One difference in my approach is that I tend not to use the Micro Adjust on the Universal Support. Instead I just edge the chisel backwards or forwards in the Square Edge Jig - till it matches the Angle Setter on the AngleMaster.

I will try using the Micro Adjust next time but would be grateful for any tips and suggestions on what I'm doing wrong - particularly if anyone else has experienced this problem.

Many thanks, Hugh

[Dutchman]

From the first use I also had problems with the anglemaster. Clumsy and inaccurate.
Therefore, I designed a simple and accurate method to set the angle, based on measurement of distances.
See https://forum.tormek.com/index.php/topic,1849.0.html
Various spreadsheets were then developed, based on that method.
However, Tormek has finally responded with the development of a new angle adjuster, the KS-123.
See my testreport on https://forum.tormek.com/index.php?msg=40399

[tgbto]

Although I concur with @Dutchman wrt the tool's clumsiness, the AngleMaster should be well suited to setting/measuring an angle on chisels. A systematic 5° difference is especially intriguing.

Can you maybe post a picture of :
- How you set your angle using the WM 200, taken from the side so we can see the markings on the WM-200, where the plastic contact the wheel and if there is any gap between tool and the back of the chisel ?
- How you measure your angle ?

Cheers,

Nick.

[Ken S]

Welcome to the forum, Hugh.

Let me take two guesses, hopefully favoring the scientific portion of SWAG (Scientific Wild Ass Guesses).

First: When you use the Anglemaster, is the angle pointer positioned so that the bottom touches the grinding wheel?

Second: Since the 5° error seems consistent, especially since these are school machines, is it possible that your pointers may be worn. We have had a few posts where these are the problem. I suspect that this wear occurs from measuring while the machine is still running, but that's just a guess.

Third, I would suggest that you email support (support@tormek.com) The two pointers are both available as replacement parts. I do not speak for Tormek; however, I would not be at all surprised if Tormek gifted you the spare parts. Support is very experienced and dedicated.

Please keep us posted.

Ken

[Dan]

.....How you measure your angle ?

Cheers,

Nick.

To me, this question is very important. it may be a good part of getting to solve your angle problem. It took me a while (mentally!) to get what was happening with the finished angle. What confused me was the curve on the bevel.

In order to measure correctly, we need to measure just the angle at the bevel tip (even though it is not easy) as that is where the cutting edge is.
If we measure over the whole bevel, the angle will be greater as the concave curve sweeps up away from the tip. Not sure if it is 5° difference or not but that will also change if you are using a T8 or T4 due to the wheel diameter difference.

The second picture in this post shows what I mean.
https://forum.tormek.com/index.php?msg=31650

I know you are using the anglemaster now but I must say that I ended up using the Calcapp to get the desired angle and I have to say I use it for all knives, chisels and planes now. It is extremely accurate. I haven't used the AngleMaster for a very long time.

https://connect.calcapp.net/?app=qq0pg0#/

Big thanks to member cbwx34n for this.

Danny

[Hugh Proudman]

Hi Danny,

Many thanks for your reply.

Although I concur with @Dutchman wrt the tool's clumsiness, the AngleMaster should be well suited to setting/measuring an angle on chisels. A systematic 5° difference is especially intriguing.


Can you maybe post a picture of :
- How you set your angle using the WM 200, taken from the side so we can see the markings on the WM-200, where the plastic contact the wheel and if there is any gap between tool and the back of the chisel ?

I will take a photo of my WM-200 in use this afternoon.

- How you measure your angle ?

I measure the resulting bevel angle using either my Veritas bevel gauge or my Axminster Tools gauge.

Cheers,

Nick.

Many thanks, Hugh

[Hugh Proudman]

Many thanks for your reply, Ken

Welcome to the forum, Hugh.

Let me take two guesses, hopefully favoring the scientific portion of SWAG (Scientific Wild Ass Guesses).

First: When you use the Anglemaster, is the angle pointer positioned so that the bottom touches the grinding wheel?

When I first started sharpening chisels for the school, I was not positioning the pointer correctly. I was placing it on the back of the chisel, not touching the stone. However, for the last few weeks, I have been positioning it on the back of the chisel, but also just touching the stone. I believe this is correct.

Second: Since the 5° error seems consistent, especially since these are school machines, is it possible that your pointers may be worn. We have had a few posts where these are the problem. I suspect that this wear occurs from measuring while the machine is still running, but that's just a guess.

The school AngleMaster is warn just as you describe, but I have been using my own AngleMasters - I have two. Both have tiny patches of wear from the stone, but I would estimate the wear as about 0.25mm. I don't think this accounts for my 5 degree error.

Third, I would suggest that you email support (support@tormek.com) The two pointers are both available as replacement parts. I do not speak for Tormek; however, I would not be at all surprised if Tormek gifted you the spare parts. Support is very experienced and dedicated.

Please keep us posted.

Ken

I will keep you posted as I tussle with this. I really appreciate everyone's encouragement.

With best wishes, Hugh

[Dan]

Hi Danny,

Many thanks for your reply.

- How you measure your angle ?

I measure the resulting bevel angle using either my Veritas bevel gauge or my Axminster Tools gauge.

Many thanks, Hugh

Hi Hugh, thanks for getting back to us here. I think we are a bit intrigued as to what may be the problem.
When you say that you "measure the resulting bevel angle using either my Veritas bevel gauge or my Axminster Tools gauge" it was not exactly what I meant when I was trying to get info about how you measure it. What I meant was - what part of the bevel are you measuring? i.e. if you are measuring the bevel from apex to the other end then the measured angle will be greater than the real cutting angle.
See this crude drawing I just made to try to illustrate what I mean:


The green line is the real measure of the angle and the red one is not an accurate measure due to the shape of the curved concave bevel. This could account for the higher angle you are "seeing".

Sorry if this is just me repeating myself but you didn't mention if you were going over the whole bevel or not when measuring... As I said this would be more slightly pronounced using a T4 with the smaller diameter wheel.
I won't say it again, I promise

Danny

[Hugh Proudman]

Hi Danny,

Many thanks for your reply.

- How you measure your angle ?

I measure the resulting bevel angle using either my Veritas bevel gauge or my Axminster Tools gauge.

Many thanks, Hugh

Hi Hugh, thanks for getting back to us here. I think we are a bit intrigued as to what may be the problem.
When you say that you "measure the resulting bevel angle using either my Veritas bevel gauge or my Axminster Tools gauge" it was not exactly what I meant when I was trying to get info about how you measure it. What I meant was - what part of the bevel are you measuring? i.e. if you are measuring the bevel from apex to the other end then the measured angle will be greater than the real cutting angle.
See this crude drawing I just made to try to illustrate what I mean:


The green line is the real measure of the angle and the red one is not an accurate measure due to the shape of the curved concave bevel. This could account for the higher angle you are "seeing".

Sorry if this is just me repeating myself but you didn't mention if you were going over the whole bevel or not when measuring... As I said this would be more slightly pronounced using a T4 with the smaller diameter wheel.
I won't say it again, I promise

Danny

Danny,

Many thanks for your very polite clarification! I now see what you were getting at.

I suspect this is at least part of the issue that I have been experiencing, although the problem that I now have is that I don't know how to measure the real cutting edge angle - as it is so much smaller than the Veritas gauge that I have!

I will try taking some macro photos of a chisel blade in profile, to see if that helps illustrate what I am doing.

Thanks again, Hugh

[Dan]

Yes, much more difficult to measure such a small part but you should be able to guestimate it, maybe by just putting the bevel gauge on the tip at a slight angle so it doesn't contact the top end of the bevel???

[Hugh Proudman]

Yes, much more difficult to measure such a small part but you should be able to guestimate it, maybe by just putting the bevel gauge on the tip at a slight angle so it doesn't contact the top end of the bevel???

So, after today's experiments... this time on my own T8 - just to make the comparisons more complicated!

I have concentrated on getting the Pointer positioned well and used the MicroAdjuster to bring the chisel up to the Pointer. See the attached picture.

I have ended up with a square bevel that is flat-ish - because I'm using a 250mm diameter diamond wheel. I can't see a lot of curve on the bevel pictured against graph paper.

Using my Axminster bevel gauge, I estimate my bevel angle is somewhere between 25 and 30 degrees. Counting squares on graph paper (in the resulting bevel image) and Pythagoras gives an angle of about 27 degrees.

Unless anyone has any further suggestions, I think this is about as far as I want to take this.

As most of the students will be using chisels with secondary bevels at 30 degrees, my priority is to end up with a primary bevel of 25 degrees - that they can hone to 30 degrees for their cutting edge.

At least I now have a clearer understanding why using the 25 degree setting on the AngleMaster doesn't match my bevel gauges.

I can continue setting the AngleMaster closer to 20 degrees without feeling too much of a fraud!

[Hugh Proudman]

Although I concur with @Dutchman wrt the tool's clumsiness, the AngleMaster should be well suited to setting/measuring an angle on chisels. A systematic 5° difference is especially intriguing.

Can you maybe post a picture of :
- How you set your angle using the WM 200, taken from the side so we can see the markings on the WM-200, where the plastic contact the wheel and if there is any gap between tool and the back of the chisel ?
- How you measure your angle ?

Cheers,

Nick.

Nick,

Many thanks for your help. Here is an image of my chisel and Pointer positioned on the wheel. Is this how you position yours?

Thanks, Hugh

[Hugh Proudman]

From the first use I also had problems with the anglemaster. Clumsy and inaccurate.
Therefore, I designed a simple and accurate method to set the angle, based on measurement of distances.
See https://forum.tormek.com/index.php/topic,1849.0.html
Various spreadsheets were then developed, based on that method.
However, Tormek has finally responded with the development of a new angle adjuster, the KS-123.
See my testreport on https://forum.tormek.com/index.php?msg=40399

Many thanks for this. It is very interesting to understand the theory of the angles and tangents  involved with wheels and blades as they apply to sharpening systems such as Tormek. The KS-123 looks very impressive; quite like the blade angle guide on a T1.

I'm not sure, however, whether the KS-123 can be used to sharpen chisels. It seems unlikely. Have I misunderstood?

Many thanks, Hugh 

[Dan]

I know I have said it already      but the Calcapp is just so useful and very easy to use for knives, planes and chisels (and others!)
Very accurate, easy to use, reliable and repeatable. Sorry, I am not on commission! Just enjoy using it.
Danny