Spooky Geometry

[wowilson]

So, I have 2 brand new C-Max 105 deg. Gravers. I set up the face, then go to shape my heels. The numbers that I have in my GRS book say 50 Deg. face, 15 and 45 for the heel. When I did this the results were way off. I started over from scratch. I checked that my fixture was correct. Reground the sides at 37.5 deg. and fiddled with the setup until I got a good result. So what's the problem? The problem is that it took one number on one side and a different number on the other. Have any of you ever run into such a thing? What numbers do you all use for your heel? Thanks Wade

 

[scott99]

Sounds confusing to me, I don't really understand your problem. Are you trying to make a parallel heel?Check the TIPS section on the Forum there you will find all the answers you are seeking.

scott99

 

[Marrinan]

Wade, To figure your angle for any heel use the angle of the belly, say a 90 subtract that from 180 divide that by 2 and your heel angle would be 15 degree lift and 45 rotation or heel. For the 105 you would get 180 minus 105 equals 75 divided by 2 equals 37.5 degree rotation and a fifteen degree lift. The lift is a matter of personal choice. I use 17 degrees myself. Fred

 

[wowilson]

Thanks for the response. I am familiar with sharpening gravers. What I am trying to get across here is that I am following the rules and not getting the right outcome. I believe the numbers that I have in my chart are incorrect. And what I would like to know is, if anyone uses a 105 deg. graver what settings are you using to get a full length heel. Thanks

 

[tim halloran]

wowilson: Buy yourself an Easy Graver sharpening fixture, it takes all the guesswork out of sharpening. You'll get exactly the same angles every time, and if your a professional engraver you will save enough time sharpening that the fixture will pay for itself in no time at all. I have experienced problems with their pre ground gravers also, because you can't get them centered in the quick change tool holders. The tool sharpening fixtures with multiple changeable angles are part of the problem because you can't get dependable repeatability on every angle.

 

[wowilson]

Yes I looked at those when I made the big payout. So far I have only used 90s but now I am branching out in to different geometries. I don't even know if its worth fooling with 105s yet so the thought of buying a fixture is not on the radar. I really thought someone would just say "yes, I use this for my horizontal angle and this for my Vertical." I guess that is not going to happen so I respectfully withdraw my question. I will grind my 105s into 90s.

 

[tundratrekers@mtaonline.n]

Marinan did give you that info.
michael

 

[GTJC460]

The blank is probably not true to your fixture.

One of the most important things to do on your own is to create the reshaping grind yourself with your fixture. The way I do it is set the post angle to 2' and the rotational angle to whatever I'm grinding. This does two things. It trues up the blank to your fixture and it reshapes the graver.

I true up every graver I make. Flats and point gravers alike. Make your reshaping grind about 3/8" long.

 

[fegarex]

The numbers are correct. 45 degrees is the rotation number for a full length heel. Sounds like your fixture needs to be recalibrated. There is instructions for this with the tool. Or, just do it "by eye" as you did.

 

[Southern Custom]

I am still amazed at all the fiddling with geometry. I really can't remember the last time I did this since I bought some of Lindsay's templates on a whim.
I've been extremely happy with this type of setup and the speed to re sharpen is nothing short of blistering.
This brings me to the question, what am I losing by using a parallel point, or what would I gain by using standard geometry. Strength? Controlability?
It has me wondering if I should revisit some of my old gravers.
Layne

 

[sam]

I can engrave equally well with a conventional heel or parallel heel. The parallel can produce less heel drag in a tight radius though, and since it's taller than a conventional heel, you can't "run out of heel" by cutting too deeply (which I never did/do with a conventional heel anyway).

I seen no difference in strength between the two types.

At present I'm using the GRS EG105 and EG120 geometries and they perform beautifully for me and are extremely fast to resharpen.

 

[Southern Custom]

Thanks for that Sam. I have noticed the lack of heel drag with my new gravers and that's one thing I liked about the parallel heel. I am glad to hear I'm not losing any strength with this geometry.
I have been experimenting with a few methods to strengthen my parallel heel gravers for harder steels and had contemplated playing with some standard gravers. Nice to know that the grass isn't any greener with a standard heel.
Layne

 

[Willem Parel]

Layne, you can effect the strength of your parallel Lindsay point bij using ( making) other spacers ( the tube you have for the distance between point and fixure).
The standard tube is 31.80 millimeter ( I think this is 1 inch but I know only the metric indication) makes 45 face and 16.3 heel, 41.3 mm makes a 41 face and a 14 heel and 22.20 mm. tube makes a 50 heel and a 19.5 heel.
I've got this information from Steve and if you ask him I am sure he will give you the information in inches.

 

[Beathard]

That confuses me... Does that mean as the graver gets shorter, due to sharpening, the geometry changes?

 

[Gemsetterchris]

That confuses me... Does that mean as the graver gets shorter, due to sharpening, the geometry changes?

It would in a template, but it takes forever to get a blank that short by re-sharpening the point..or then you make a new one.

 

[Beathard]

I have used over an inch of a graver working on one really hard gun. Not sure I will have that problem again, but templates don't sound like a good idea if the geometry changes.

 

[Willem Parel]

That confuses me... Does that mean as the graver gets shorter, due to sharpening, the geometry changes?

Gerry, you can slide the graver further in and out of the fixture, so the geometry doesn't change, while your gravers getting shorter you can pull them out a little more and set the tube so the distance between the fixture and your point has constantly the same length and you get every time when re sharpening the same angles.

 

[JJ Roberts]

The graver blanks you get from GRS and Lindsay are not true, just put a blank in your dual angle sharping fixture and set tool dial on 45 degrees and the post dial on zero lay the on the graver on the diamond wheel and turn on the power hone. It only a few seconds to see how untrue the blanks are, this was shown to me by a friend who is a former Tiffany engraver, he take the extra step and trues up his gravers before sharping. J.J.

 

[tundratrekers@mtaonline.n]

If you learn to sharpen by hand,no worries about this stuff.
Don't have to remove from the handle,and can adjust all angles to suite the work and you.
No need for an hone,stones will do fine.

If you are able to engrave uniform lines, there is no reason you cant learn to sharpen.
Why deny yourself this fundamental skill?
Once mastered , you are free from the aids and the numbers .
Who wants to save some $ ?
michael

 

[Chujybear]

I'm curious about the idea of truing up the graver first..
I do notice that the blanks aren't true, but doesn't the relief serve to create your true canvas for proper edge?