Bulino tip breaking

[PS_Bond]

After seeing the work at the Game Fair the other week (and studying the tools more closely) I thought I'd have a go at trying to build shades in steel. So I've ground a 2mm square (tool steel, nothing more elaborate) to a 70 degree angle long "heel" - around 10mm long - with a 55 degree face. I've taken the face much smaller than my norm, which improves the visibility - but. Cutting mild, flicking out the chip on lines, or trying to pop out a dot seems to take the tip off about 1 in 3 attempts. At the moment, I'm not sure if I'm trying to take too much out in one go (I'm still inclined to be a bit unsubtle in material removal), or the face should be steeper, or I'm just being ham-fisted in technique (no slips though).

Setting a steeper face is obviously an easy solution, but how much steeper makes sense?

 

[Andrew Biggs]

It could possibly be the tool steel that you are using. Maybe try a regular graver? The tip shouldn't be that easy to break on mild steel.

My bulino graver is about the same as yours and I have no problems with it. I even do a lot of normal shading with it as well. The trouble is once you get past 55-60 degree faces it almost becomes impossible to see the cuts you are making.

Cheers
Andrew

 

[PS_Bond]

It could possibly be the tool steel that you are using. Maybe try a regular graver? The tip shouldn't be that easy to break on mild steel.

Communication error on my part, sorry - this is the remains of a commercial graver after I'd shortened (snapped, not ground) the original to length, so I'm (mis?)using tool steel as distinct from HSS or carbide/carbalt/Glensteel/etc. I had wondered if I'd made the face too small, but that's daft - the shear force across the tip is the same regardless of face size.

My bulino graver is about the same as yours and I have no problems with it. I even do a lot of normal shading with it as well. The trouble is once you get past 55-60 degree faces it almost becomes impossible to see the cuts you are making.

Hmm. Must be me being ham-fisted then. It's one of those things that's quite difficult for a newbie - "how deep should the lines/dots be" isn't something that is easy to measure other than by comparison; that's part of what I was trying to analyse at the fair. Well, maybe it'll be easier once I get the castings from FEGA delivered... Then at least I'll have something to compare against directly.

Thanks!

(added - the long "heel" is done at about 12.5ish degrees, seemed a comfortable lift - forgot to put that bit in)

 

[Andrew Biggs]

It's not one of those old 6" carbon gravers is it? They can be delicate sometimes. I started with a couple of those and they broke/blunted reasonabley easy.

Perhaps you are going to hard with your graver.................try shallower cuts and a lighter touch maybe???


Cheers
Andrew

 

[PS_Bond]

It's not one of those old 6" carbon gravers is it? They can be delicate sometimes. I started with a couple of those and they broke/blunted reasonabley easy.

It's no more than 1-2 years old, either a Vallorbe or a Glardon IIRC.

Perhaps you are going to hard with your graver.................try shallower cuts and a lighter touch maybe???

Sounds like that might be the case, ta. Having mostly used copper, I'm inclined to make heavy cuts which don't seem to translate well to steel.

I might polish up the bit of steel more too - it just occurred to me that the pits, whilst mostly polished out, could be either causing jumps or - worse still - may have some scale remaining in them which I can't imagine helping (70HRC?).

 

[Brian Hochstrat]

Try putting a mirror polish on the heel. The used portion of the graver is very small but can get quite a bit of pressure at times, so any scratches that are in the heel right next to the tip create a weak point and the tip will fracture at that spot. Just like a spring on a lock back folding knife, if there are any scratches the spring will fracture at that scratch. After polishing the heel on the ceramic lap with diamond spray, I hit it on some 3M micro grit paper, 50000 grit I think. this will leave a nice high polish, also I started using the GRS X7 gravers lately, it was an experiment that has worked out, I don't like them for scroll cutting but they seem to really hold up for dot work. Also, technique will help save points, you want to cut out of the dot, not stick the tool in and pop out, it like scooping ice cream on a micro level, as you enter the metal drop your hand a fraction and lift on your graver lightly, with practice you will get a uniform diamond and your tip will last good. One thing to keep in mind the bigger the dots the more abuse the point takes. Hopefully, that helps-Brian

 

[PS_Bond]

Thanks Brian - that wasn't something I'd been thinking of. Scratches are stress risers... I should know better.

The polish I'd thought was "good enough" does still have some scratches in it; I'll go back & work through the Spyderco ceramics (I think the ultra fine is supposed to be 2000 grit, but not sure on whose scale) again then hit it with some .5 micron diamond or similar.

Yes, I'd been trying to flick out the dots - I'm finding the angle of attack a little wierd at the moment when compared with cutting lines. I'll worry about making larger dots when I can do the smaller ones consistently - although I'm probably trying to make them too large at the moment. I saw the close-ups Coop did of your dino knife; was that blacked as well as dotted?

Mind you, before I can make decent use of the techniques I need to spend more time my drawing...!

 

[Brian Hochstrat]

Yes, all my work gets blackened, in the right light cast it would not need it, but the ink (I use printers ink) will help the work show up when the lighting is poor. Shows usually have terrible lighting and they are where the work is seen most often in real life, so you need all the help you can get.

 

[Marcus Hunt]

Peter, I now use the 'DeCamillis Patent Bulino Grind' for all my bulino gravers. It's dead easy to make using a dual angle fixture. It's basically an 80º with no heel. I use a 50º-55º face. Just put a graver blank into the fixture, put the face on and then with a post angle of 10º grind the tool at 50º. Grind evenly on both sides until you have a face approx 1mm across. No need to heel the tool. It's great for dots and fine line work but don't try to go around corners with it! It's rare for the tip to break, it just kind of dulls after long usage.

 

[tolesh]

Marcus, Could you please post a picture of the tool. Thank You

 

[Christopher Malouf]

Marcus ... thank you for that post!!! Chris has made his bulino gravers for a couple of folks I've visited and I never did get the geometry on those.

Thanks again....now I can finally get mine right (just like Chris' that is).

Chris

 

[joseph engraver]

Bond,
Tool breakage always comes down to the sensitivity between the hand and the bulino tool. Learn to cut lightly and when you can, cut even lighter. Once you have achieved it, then you will cut deeper without tool point failure. Good luck.

 

[PS_Bond]

Thank you gentlemen; that seems to have corrected what I'm doing wrong. With a better (read "any") polish on the steel, the cuts show up well even if they are shallow; when I'm cutting below the level of the dents & dings is when I'm more inclined to snap the tip. Now, even my shallower dots are showing up - with elongated tails because I keep going in too shallow.

Marcus, that sounds like the grind I'm using (albeit a 70 rather than an 80 - given how long it took me to do this one by hand, I'll wait a wee while before making up an 80 as well); I went back & rewatched Chris deCamillis' FEGA presentation and it all makes a bit more sense now.

Thanks again.