Question: treading on sensitive ground...graver formulas

[James]

Ok, I know this seems to be a closely guarded knowledge, but I seem to have forgotten what I once learned...But I know that somewhere out the are tables for dual angle fixture to give angles for parallel heel square gravers, adjusting for different face angle, lift (relief grind), heel angle...i.e say 55 degree face, 3.5 degree lift, it would show heel angle and "tilt".....and I'm sure that somewhere is a lucid treatise on basic mathematic relationships of the different angles. and I'm still fuzzy on the heel angle tilt, is it grind to say 120 , minus 5 degrees a side for tilt ( i.e half 120 =60 so 55 degrees for heel tilt ? I went to easygraver fixture a while back, realized i like a little more lift so revisting this subject... I know this knowledge is out there, guess I'm looking for a simple formula for dummies...

 

[Matthew Evans]

Ok, I know this seems to be a closely guarded knowledge, but I seem to have forgotten what I once learned...But I know that somewhere out the are tables for dual angle fixture to give angles for parallel heel square gravers, adjusting for different face angle, lift (relief grind), heel angle...i.e say 55 degree face, 3.5 degree lift, it would show heel angle and "tilt".....and I'm sure that somewhere is a lucid treatise on basic mathematic relationships of the different angles. and I'm still fuzzy on the heel angle tilt, is it grind to say 120 , minus 5 degrees a side for tilt ( i.e half 120 =60 so 55 degrees for heel tilt ? I went to easygraver fixture a while back, realized i like a little more lift so revisting this subject... I know this knowledge is out there, guess I'm looking for a simple formula for dummies...

The heel is based off of feel, not necessarily a formula. 15 degrees works great for most, or if you have a radiused heel, 10-15 rocking it back and forth. Not necessarily a guarded secret, but check out sams sharpening dvd, good purchase for sure.


If you need a heel on a 120 degrees graver, you will need to tilt the rotation to 30 degrees on each side and a lift of 15 degrees for the heel. Since a straight line is equal to 180 degrees with a midpoint, then if you want the angles for the graver to be 120, you divide the difference by two. (180-x)/2= y
(180-120)/2= 30.

Hope that helps, but if not, check out the finely crafted tutorials by your benevolent dictator.

 

[jerrywh]

I don't think that is what he is talking about. I have that info but it is burried. I have found that a parallel gives very little advantage. so I never use it anymore. Just me but it isn't worth fooling with.

 

[Archie Woodworth]

You might just do a search of the site...

 

[Matthew Evans]

http://engraverscafe.com/graver_angles/graver_angles.html

 

[sam]

Sharpen the face to whatever angle you wish.
Set toolpost angle to desired amount.
Dial-in the rotation angle by testing until you get the desired result.
Write down the numbers for future use.

 

[rmgreen]

Very difficult formula

 

[AllenClapp]

There is an easy way to think about this, but the calculations are messy.
First, think about taking a square graver BEFORE the face angle has been cut. If you turn it 45 degrees to one side of zero and put it down at your heel angle on the hone platen, the entire side would touch and you would get a clean rectangle across the side if the hone is turned on.
Now, think about that square graver AFTER the face angle has been cut. If you turn it 45 degrees to one side of 0 and put it on the hone platen at your desired heel angle, only the point would touch, because you have cut away the other side when you cut the face angle.
If you sharpen the heel in that position, you get a triangle heel at the tip, i.e., the traditional heel.
If you want to make a parallel heel, you will have to turn the graver beyond 45 degrees until the entire edge contacts the hone. The greater the heel angle, the more extra you have to turn. Conversely, the less the face angle, the more extra you have to turn.
I don't know how to upload the calcs here, but I will send them to Sam. He may want to upload my spreadsheet. So stay tuned. My apologies to Sam and all of you ahead of time if these calcs are not appropriate to have here.
My calcs vary slightly from the Ritter & Henley ones previously shown and I haven't found anyone who can figure out why. Unlike the Ritter and Henley ones, I calculated tables of values for frequently used combinations of face and heel angles, as well as showed the rationale behind the calcs. If anyone figures out why we don't match, please tell me. I am an engineer and it has really bugged me that I haven't figured out the issue yet.
One last comment re: the EasyGravers from GRS. They appear to be based upon the Ritter-Henley info and don't exactly give a parallel heel, but it is so close as to not be a practical difference--and they sure are easy to use and make repeatable shapes quickly.

 

[James]

Sharpen the face to whatever angle you wish.
Set toolpost angle to desired amount.
Dial-in the rotation angle by testing until you get the desired result.
Write down the numbers for future use.

Thanks, Sam. good to know thats what people do...I did that, just testing and fine tuning heel tilt, but felt like i was doing something intellectually lazy..good to know its ok

 

[James]

There is an easy way to think about this, but the calculations are messy.
First, think about taking a square graver BEFORE the face angle has been cut. If you turn it 45 degrees to one side of zero and put it down at your heel angle on the hone platen, the entire side would touch and you would get a clean rectangle across the side if the hone is turned on.
Now, think about that square graver AFTER the face angle has been cut. If you turn it 45 degrees to one side of 0 and put it on the hone platen at your desired heel angle, only the point would touch, because you have cut away the other side when you cut the face angle.
If you sharpen the heel in that position, you get a triangle heel at the tip, i.e., the traditional heel.
If you want to make a parallel heel, you will have to turn the graver beyond 45 degrees until the entire edge contacts the hone. The greater the heel angle, the more extra you have to turn. Conversely, the less the face angle, the more extra you have to turn.
I don't know how to upload the calcs here, but I will send them to Sam. He may want to upload my spreadsheet. So stay tuned. My apologies to Sam and all of you ahead of time if these calcs are not appropriate to have here.
My calcs vary slightly from the Ritter & Henley ones previously shown and I haven't found anyone who can figure out why. Unlike the Ritter and Henley ones, I calculated tables of values for frequently used combinations of face and heel angles, as well as showed the rationale behind the calcs. If anyone figures out why we don't match, please tell me. I am an engineer and it has really bugged me that I haven't figured out the issue yet.
One last comment re: the EasyGravers from GRS. They appear to be based upon the Ritter-Henley info and don't exactly give a parallel heel, but it is so close as to not be a practical difference--and they sure are easy to use and make repeatable shapes quickly.

Thanks, sir, thats a great explanation of whats really going on, it will help me visualize whats really going as the tilt angles change with different face angles. Really appreciate you taking the time to elucidate this!

 

[DocH]

There is an easy way to think about this, but the calculations are messy.
First, think about taking a square graver BEFORE the face angle has been cut. If you turn it 45 degrees to one side of zero and put it down at your heel angle on the hone platen, the entire side would touch and you would get a clean rectangle across the side if the hone is turned on.
Now, think about that square graver AFTER the face angle has been cut. If you turn it 45 degrees to one side of 0 and put it on the hone platen at your desired heel angle, only the point would touch, because you have cut away the other side when you cut the face angle.
If you sharpen the heel in that position, you get a triangle heel at the tip, i.e., the traditional heel.
If you want to make a parallel heel, you will have to turn the graver beyond 45 degrees until the entire edge contacts the hone. The greater the heel angle, the more extra you have to turn. Conversely, the less the face angle, the more extra you have to turn.
I don't know how to upload the calcs here, but I will send them to Sam. He may want to upload my spreadsheet. So stay tuned. My apologies to Sam and all of you ahead of time if these calcs are not appropriate to have here.
My calcs vary slightly from the Ritter & Henley ones previously shown and I haven't found anyone who can figure out why. Unlike the Ritter and Henley ones, I calculated tables of values for frequently used combinations of face and heel angles, as well as showed the rationale behind the calcs. If anyone figures out why we don't match, please tell me. I am an engineer and it has really bugged me that I haven't figured out the issue yet.
One last comment re: the EasyGravers from GRS. They appear to be based upon the Ritter-Henley info and don't exactly give a parallel heel, but it is so close as to not be a practical difference--and they sure are easy to use and make repeatable shapes quickly.

Dear Allen

It seems to me (I am not an engineer…) that the Ritter and Henley calculation uses the Tan(heel angle), while you use the sin(heel angle) in your formula.
Example: 50degree face, 20degree heel, 90degree graver
R&H: rotate 57.5 degrees (45 + Arcsin ((1/tan 50)*tan 20* cos 45))
You: rotate 56.7085 degrees (45 + Arcsin ((1/tan 50)*sin 20* cos 45))

Is this it? If so, which one is better
Regards

DocH

 

[tdelewis]

Does it really need to be so accurate just so the heel and face are symmetrical. and it works. The angle of the face can change according to the hardness. The heel can be long or short depending on the type pf engraving.

 

[DocH]

Does it really need to be so accurate just so the heel and face are symmetrical. and it works. The angle of the face can change according to the hardness. The heel can be long or short depending on the type pf engraving.

"Does it really need to be so accurate":

Well, I guess I will have to rely on the expert advice of this forum. The difference might be bigger for other angles, though.
I am a but a hobbyist, tinkering and trying to build my own stuff on a (almost) 0 euro budget (yes, euro). This was actually my first post here. I have not taken any courses, and have absolutely no practical experience on "how it should be done" and what is "good enough". That's why I am here

When building my first parallel heel templates based on Ritter and Henley calculations, I notice that the heel on one side of the graver was Ok'ish, but the the heel on the other side was not parallel at all (but triangular). Having checked the template (all angles are fine), I went back to to the math. Then I ran across this difference between R+H and Allen's formulas ...and out of academic interest, I posted this reply to "My calcs vary slightly from the Ritter & Henley ones previously shown and I haven't found anyone who can figure out why."

That said, I think the issue I ran into is due to asymmetric graver sides, the graver being too wide, and/or graver blank coming loose when grinding....

Regards,
DocH

 

[rweigel]

A nuts and bolts approach, using the dual angle fixture as a calculator:

Take a piece of square mild steel of 3 or 4 mm square. Clamp it in the Dual angle fixture, such that the corners of the square profile are up and down if the tool rotation is set to zero. Turn the tool rotation angle to 180 degrees. Grind the desired face angle. Turn it around to grind the desired V angle onto one side of the square with tool post angle set to zero. Make sure your newly ground side is reaching to the face completely. Set the tool post angle to your desired heel (lift) angle. Loosen the tool rotation angle, set the line formed between face and side onto the grinding disc (not powered on) and turn the tool rotation angle until this line is precisely parallel to the grinding disc. This is your tool rotation angle for parallel heel with the face, side and heel angles you choose. Once face and side are ground, one could use the piece to make a table with rotation angles for different heel angles.

I often look at the heels with the microscope when sharpening, and correct the tool ration angle slightly if they aren‘t really parallel.

Knowing the right angle to 4 decimal places does not help when the fixture‘s scale is only divided in 5 degree steps. I found this at first annoying, but adapted with my optical heel correction methode quickly to it.

Cheers

Ralf

 

[AllenClapp]

I put up tables and formulas in this forum a while back. Search for

Graver rotation angles needed to produce parallel heels.​

 

[monk]

I put up tables and formulas in this forum a while back. Search for

Graver rotation angles needed to produce parallel heels.​

tyvm 4 that. i remember lookin at the chart. it drove me nuts but should be quite valuable to the tekkies lurking here.

 

[AllenClapp]

The easy trick to using that chart is to print two copies and then mark out everything but what you use on one, keeping the other for anything you might want to try later. OR, just pick off what you normally might use and put them on a note pad to keep by your sharpening setup.

 

[mitch]

Stop searching for the ideal geometry that will instantly transform a graver into a hybrid of a magic wand and a tiny light saber, thereby making you a master of the art. Choose a basic configuration that’s well suited for the style you intend to cut, adjust the face angle for the metal you’ll be working on (steeper for harder), and then USE IT. Not for a few minutes or hours, for MONTHS. Learn to adapt to the graver and stop wishing for one that will automatically adapt to your every whim. You should be able to do 90+% of your work with this graver. Along the way you will begin to learn when and where you need something more specialized and how to sharpen those, too.

This is hand engraving, not lathe turning. There are no universally ideal angles because your hand is constantly changing positions, both as the curvature of the metal surface changes and the lines of the design change, too. Graver geometry will always and ever be a constant, and constantly changing, compromise. “Close enough” is as good as you’re ever gonna get.

 

[allan621]

Great reply Mitch, much wisdom. I was going through the Ken Hunt videos on YouTube and one was where he showed his tools. And they looked like they came out of some kind of rustic cave. Broom handles cut down, pieces of cork, handles of wooden stumps from the Paleozoic eras. And he showed how he used to sharpen tools. The main concern was that it was sharp. And with that he passed on an idea from other engravers - " if it cuts it cuts ".

Now I use two Lindsay templates The 90 degree and the knife and flat combo both used with the length measure. The reason is that I don't have to think about it. I truly enjoy engraving and get a lot of satisfaction doing fine work but its no game. If you do this for a living the less time you spend trying to figure abstract ideas the better off you are because you have more time to work.

Allan

 

[Leland Davis]

Listen to Mitch and Allan for me the Lindsay 116 universal template does almost everything I need only changing the face angle for different hardness of the steel.