Making Gravers - Calculating the angle

[Waggy]

I am about to start on my journey with a new lathe, and need to make some gravers. I ordered the steel to make them and the sharpening stones etc. and planned on making a 45 degree, 20 degree and 30 degree tools to get me started. Luckily I snagged a graver sharpening tool in a recent tool job lot buy so I'm off to a good start.

I was pondering how I could get the correct angle for the sharpening process and pictured myself trying to balance everything and try to read a protractor and thought there must be a better way.... here is what I came up with:

So all I have to do now is put in the dimensions of my graver and graver sharpening tool (should only have to do once) and the angle I want, and the sheet will tell me the distance (L) from the tip of the top of the diamond to the front face of the graver sharpening tool, so in the example above (fake graver sharpening tool dimensions) if I want a 30 degree angle on the graver I need to have 95.162mm of graver sticking out, then file file away!

Turns out my maths teachers were correct, I will use trigonometry every day!

Can't upload the excel sheet here but can send it to you if you want it, just pm me with your email.

PS

Just realised that the model only works for square gravers ie a = b on above drawing - head is hurting from the maths to make it work for non-square tools also.

Model also assumes that the angle where the graver enters the graver sharpening tool is 90 degrees.

Edited December 13, 2023 by Waggy

[RichardHarris123]

I love a bit of maths but won't the angle change as the length is reduced by sharpening?  Wouldn't it be easier to cut some plastic/ metal sheet to the desired angle, align the sharpening to it and insert the graver.

[oldhippy]

You sure like to make life hard. Why don't you buy them already sharpened. 

[Waggy]

14 minutes ago, RichardHarris123 said:

I love a bit of maths but won't the angle change as the length is reduced by sharpening?  Wouldn't it be easier to cut some plastic/ metal sheet to the desired angle, align the sharpening to it and insert the graver.

Yes and no, because the length is referenced to the top of the diamond, the tool will first start to sharpen on the bottom tip  and the graver will be sitting at the 'wrong' angle eg 28 degrees, as the tool face wears during the sharpening the error in angle will reduce until, just as you reach the tip of the top of the diamond it will be exactly the angle you want - ie 30 degrees in the example above.

10 minutes ago, oldhippy said:

Why don't you buy them already sharpened. 

Now where is the fun in that? 

Edited December 13, 2023 by Waggy
typo

[Dell]

I make my own gravers out of HSS hardwood dowel and a bit of brass tube and have just finished making a graver sharpener to fit my lathe using the tip over tool rest with a shaft out the side.

Dell

 

[nevenbekriev]

Do You think that this is so important to have angle exactly 30 degr, or 60 or whatever?  What if one holds the graver by hand when sharpening it? I for example sharpen my gravers without any tool that will ensure exact angles, simply holding them with hand.

Edited December 27, 2023 by nevenbekriev

[Neverenoughwatches]

23 minutes ago, nevenbekriev said:

Do You think that this is so important to have angle exactly 30 degr, or 60 or whatever?  What if one holds the graver by hand when sharpening it? I for example sharpen my gravers without any tool that will ensure exact angles, simply holding them with hand.

Been hand sharpening all my tools for nearly 40 years, using bench stones, grinding stones and disks. It takes practice to achieve what you want on the graver quickly but well worth the effort for the time saved. 

[Neverenoughwatches]

On 12/27/2023 at 8:21 PM, nevenbekriev said:

Do You think that this is so important to have angle exactly 30 degr, or 60 or whatever?  What if one holds the graver by hand when sharpening it? I for example sharpen my gravers without any tool that will ensure exact angles, simply holding them with hand.

How much sharpening do you do on flat bench stones nev compared to a diamond wheel and what size grit do you finish at ? I'm finding at 2000 grit the gravers still show some surface graining that is holding back a really crisp clean finish on the steel I'm turning.

[nevenbekriev]

I use almost only tungsten carbide gravers for lathe turning. I form and sharpen them only by diamond disk, dry, mounted on usual bench grinder motor. The disk is 800 grit, the diam. is reduced to 80mm.  No aditional finish needed, good and clean surface and  edges acheeved. It is important that the disk rotates true in plane, which needs some adjustment as the disks are soft and can be bent in needed direction.

For HSS gravers - after grinding by bench grinder with small red color disk for sharpening cainsaw chains ( I don't know what the grit is) I use arcanzas stone for polishing the edges

[Neverenoughwatches]

13 hours ago, nevenbekriev said:

I use almost only tungsten carbide gravers for lathe turning. I form and sharpen them only by diamond disk, dry, mounted on usual bench grinder motor. The disk is 800 grit, the diam. is reduced to 80mm.  No aditional finish needed, good and clean surface and  edges acheeved. It is important that the disk rotates true in plane, which needs some adjustment as the disks are soft and can be bent in needed direction.

For HSS gravers - after grinding by bench grinder with small red color disk for sharpening cainsaw chains ( I don't know what the grit is) I use arcanzas stone for polishing the edges

Happy new year nev. Thanks for that information,  i just need to experiment to get what i need.

[Jon]

These are handy if you don't get a good result by hand https://www.cousinsuk.com/sku/details/gravers-scorpers-scrapers-deburring/g34925

Finish on Arkansas stone after a 2000 wet and dry to 4000 grit film on a lapping plate. I use a glass lapping plate to get the initial shape and angle. Use plenty of water to make the lapping film last

[Neverenoughwatches]

2 hours ago, Jon said:

These are handy if you don't get a good result by hand https://www.cousinsuk.com/sku/details/gravers-scorpers-scrapers-deburring/g34925

Finish on Arkansas stone after a 2000 wet and dry to 4000 grit film on a lapping plate. I use a glass lapping plate to get the initial shape and angle. Use plenty of water to make the lapping film last

6mm plate glass as a flat bench lap ?

[Jon]

12 minutes ago, Neverenoughwatches said:

6mm plate glass as a flat bench lap ?

That'll do. Here's a cheap lapping glass plate which will be a lot flatter and give better results. https://www.amazon.co.uk/Veritas-Glass-Lapping-Plate/dp/B07Q58JFV9

You can spend a lot of money on really good quality lapping plates

[Neverenoughwatches]

5 minutes ago, Jon said:

That'll do. Here's a cheap lapping glass plate which will be a lot flatter and give better results. https://www.amazon.co.uk/Veritas-Glass-Lapping-Plate/dp/B07Q58JFV9

You can spend a lot of money on really good quality lapping plates

Thanks Jon,  i have a glass supplier that will freebie me pieces  of 6 or 10mm plate glass or toughen it for just a few quid.

[Waggy]

9 hours ago, Jon said:

glass plate which will be a lot flatter and give better results

Thanks for all the comments. I agree that the exact dimensions are not critical to the performance of the tool, I was just trying to figure out the best way to get the angle right without making a special tool or manually trying to measure and started to calculate it on a bit of paper and then the engineer in me kicked in and "if you are going to do it, do it right" so I ended up making a spreadsheet, partly just to see if I could and partly for fun. I'll look into the glass plate.

I have now made my gravers, 3 of them; 45°, 30° and 20°. I used 120 grit oil stone to get the general shape, or first cut, which took about 20 mins, then worked up through the grits on diamond sharpening stones to 3000 grit. I then finished off on a hard Arkansas stone for that near-mirror finish, so I would say about 45 mins each in total.

I was thinking about making handles for the gravers much the same as @Dell has, but then decided to use some old pin vices I had kicking around. I have attached the instructions I roughly followed from Sherline, which describes the process for making the gravers and wooden handles, maybe some will find this useful.

gravers.pdf

[Dell]

Don’t forget to stone the two flats adjacent to point and take the sharp corner off the bit that rests on the graver.

Dell