Help, please: What am I doing wrong?

[Doc Mark]

For the last week, I've been practicing English Small Scrolls. I've been cutting them with a Lindsay "carbalt" graver shaped to a 115 degree Lindsay "Universal" tip. I was so pleased that the tip remained intact for several days, without even the need for sharpening! I must have cut 60-70 scrolls with this tip. So, last night the tip finally failed. I resharpened it with the same Standard Lindsay templates on the same GRS diamond wheels that I used before and polished the tip on a ceramic wheel with diamond spray. Bam! the tip snapped after 15 secs.! Resharpened again, same result! This went on 3 more times, with one only lasting ONE STRAIGHT CUT before snapping the tip! I'm using the same practice plate, the same settings on my Monarch handpiece etc. I just can't get my mind around what is suddenly changing. Any bright ideas?

Frustrated,

Mark

 

[Barry Lee Hands]

The tip of any carbide is easily damaged by heat, and it does not turn colors when its too hot, did you per chance grind it too fast? it does not take much to overheat the very edge.

 

[Doc Mark]

That is a possibility Barry. I keep dunking the graver in water when sharpening, but it may have overheated. Should I just keep cutting back until I reach a neutral point? How far back would you think could be damaged by grinding heat?

 

[Barry Lee Hands]

Use the coarsest stone you have to grind it back .020 inch or so (the coarse stones run cooler), and go slow, a little bit at a time, then sharpen normally, but only a little bit at a time, remember, you dont have to get the whole thing hot to ruin it, just the cutting edge.
I use mineral oil on my power hone to avoid this problem, its messy, but it works.
If you use mineral oil on the stones, you will find out why I wear black most of the time

 

[JohnR]

Hello Doc, my fix was to Dub the graver point. All you're doing is dulling the very tip of the graver where it is very brittle and can snap. After sharpening hold the graver vertical on a 2000 stone and very lightly drag it about 1/2 ". I was breaking tips like crazy on the 303 ss handle until I read this fix from Steve. I know this is contrary to what we are taught as beginners, to always keep the graver super sharp. But this worked great for popping out chips on hard surfaces.....Hope this helps JohnR

 

[tim halloran]

Mark: To Avoid Overheating The Graver While Sharpening, Simply Sharpen Without Turning On The Power Hone. To Sharpen Carbide You Don't Need Power. You Don't Need It For Sharpening Most Any Graver, Except When You Really Blow Out The Tip, Especially Carbide. I Only Use Power To Hog Material When Creating New Gravers, Or The Badly Chipped Carbide. And Then I Use Windex On The Wheel As It Keeps The Tool Cool And Helps Slury Off The Metal Your Grinding, Which Helps Keep The Wheel From Loading Up With Particles. Build Your Self A Backstop Or An Enclosure To Catch What Comes Off The Wheel. Don't Skimp On The Windex As Its Cheaper Than Diamond Wheels. Also Always Put A Small Flat On The Bottom Of A Carbide Tool, As It Strengthens the Tip. Also Keep Your Heel As Short As Possible,As You You Can Really Put A Lot Of Torque On The Tip When Cutting Small Tight Scrolls.

 

[Christopher Malouf]

Doc,


I'm using a Carbalt graver for just about everything now. Shaping the top and sides of the graver with the smaller template is where you would generate the most amount of heat. Might wanna try regrinding another graver at a slow speed using a rough wheel as Barry suggests just to eliminate that possibility. It may get hot to the touch but it shouldn't ever get hot enough where you need to cool it rapidly.

Carbalt gravers seem to perform best when the face is polished on a porcelain lap and the heels are created on the same lap. Carbide is much more brittle than steel gravers and like any brittle material, it is most likely to break along a facet created during the grinding process using a lower grit. Similar to a piece of glass that is scored and then broken. Using the porcelain wheel will also give you greater control/precision in creating a shorter heel.

The question for me has always been "to dub or not to dub" the tip. Usually, the only time I do not dub the tip is when I am shading. When I do dub the tip, the extent to how much I remove from the end of the point is determined by the hardness of the steel I am working in. Sometimes trial and error.

I have cut 303 stainless many times for motorcycle parts and because of John's experience with the Palm Control handle ... it is precisely why the Palm Control handle on my desk will continue to sit next to this keyboard and stare at me for a very long time to come. I am confident that if you dub the tip slightly, you will find that the Carbalt graver will cut true for hours in just about any material you put in the vise.

Take care,

Chris

 

[Kevin Scott]

carbide breaking

I could be wrong, but I think I read where you should not dunk the Carbide in water etc when sharpening. Something about the rapid temperture change makes it more brittle? Or maybe it was about HSS? Anyway, the other answers sound like they will solve your problem.
Kevin

 

[Doc Mark]

I usually dub the tip when I'm cutting stainless but not cold rolled plates. So, I will give these a tiny dub after sharpening, can't hurt right? It's really hard on graver tips when "popping-out" the teardrop or plunge cuts needed when cutting English Fine Scroll.

Chris, you are probably correct in that doing the sides, top and the relief facets are where the heat can build-up.

Kevin, now that you said that, I believe I read that somewhere on the Forum too! Obviously I didn't remember it while I was sharpening! But, someone did say that with Carbide, you can keep the tip cool with fluids, but don't quench it, if it becomes hot. At least, I think that's what was said.

 

[nomentalgiant]

I'm just taking a different approach so... are you using home made practice plates or store bought? It's possible you've found a bad spot in the metal.

 

[Doc Mark]

James, they are just the regular cold-rolled plates from GRS. I'd already done the scroll outlines and was doing the "inside work" when the tip failures started.

 

[Christian DeCamillis]

Doc, Everyone here has given good advice. The number one thing that will help with carbide is to polish the face and heel. By polish I mean under a scope It should be a mirror no lines at all.
Dubbing the point will help tremendously. If your doing bu lino you cant. For shading normally not.
Something that may be happening as well is that carbide is made by pressing powdered metal. It only stands to reason that sometimes there will be some flaws or voids. I have had this experience many times. If you grind it back a way often the problem goes away because you have ground past the flaw.

A good way to get a mirror polish on carbide is of course a cast iron lap. The other I have used is a piece of corian. Cut it round and drill a hole in the center. Place it on the power hone charge with a diamond paste and you will get a polish like nothing else. This will give for a softer point so for general engraving it works well, for bulino and shading I prefer the cast iron. One other thing I have used and it works much like the corian is to glue a piece of formica to an old lap and charge with diamond paste.

Chris

 

[JAT]

Hello, here's some info that may help. Carbide used in machining is almost never sharp, it's more of a blunt edge, like a 90 degree angle, give or take. When you sharpen carbide, or use it to cut, you either have it dowsed with coolant or you don't touch it with coolant if it's hot. Carbide can withstand a lot of heat before it looses it's temper but a sudden change in temperature will destroy the cutting edge if it doesn't destroy the whole thing. I also use store brand windex while I sharpen on my powerhone, WITH THE DIAMOND WHEELS ONLY, don't spray it on your ceramic or all the diamond will wash off, use the ceramic dry. I will also drag my graver across the ceramic wheel giving a twisting motion, with the machine off, to put a tiny radius on my carbide bits. However my latest discovery is stropping the heel on regular notebook paper. A notebook will give a little bit and conform to the shape of the bottom of the graver, and I mean a whole notebook or several sheets stacked. If you just use one piece on a flat surface you will lose that conforming action several sheets of paper will give. I have a super sharp graver for shading that still has a small radius on it and I have another with a larger radius that I use for cutting outlines. Try the paper thing, you wouldn't believe how abrasive paper can be, I think it might be the kaolin clay used to make paper that really does it, but hey whatever works. Happy cutting

 

[ddushane]

I've been using carbide on almost everything I cut lately, most is 416ss but some different kinds of damascus. I've been using a leather strop with real fine compound on it between sharpenings. I put my heals on with the ceramic lap, about the thickness of a hair, I usually pull one out and check it, now I'm going bald because of it I use the uniform heals. I've probably been getting my tips too hot and chipping because of it, I'll get in a hurry and the tip will get hot to the touch. I'll quit that now that yall have mentioned it and try to be more patient. I find myself sharpening more and know when my tip is dull more than I did when I first started learning to engrave. I know the more I do the more I'll learn the feel of it. I haven't tried dubbing the tip, I'll give it a try.
I appreciate all yalls comments on the subject.

Dwayne

 

[Doc Mark]

Thanks for all the help guys! I've pretty much given up on that particular Carbalt graver. I tried several more times to resharpen, with dubbing, but it continues to snap on the 1st or 2nd cut. I just started fresh with a new blank. I still can't understand how I could have damaged it so badly, considering that the first sharpening lasted several DAYS! Oh well, I'll get over it.

Is there any advantage to going to something non-carbide, like Glensteel? Even though they dull quicker, they don't snap large chunks of tip off as easily. I love my carbides and particularly the C-max gravers but maybe the tougher high-speed steels would help when "popping" the larger chips used in English Fine Scroll.

Hey, Marcus, what graver metals do you prefer?

JAT, that's a great idea about using a pad of paper to radius the heel. I'm going to try that one! Simple and Cheap, my kind of solution!

 

[Marcus Hunt]

I can't work this carbide thing out either Mark. I don't overheat the point as I'm using a Power Hone but I find on certain cuts with English small scroll the C-Max will just give way. I can be cutting for 5 or 6 hours straight and then for no apparent reason it will just give way. The sides of the graver are mirror polished on a cast iron lap so there shouldn't be a problem but I've started to notice a pattern to the tip fractures.

The amount of spring in the graver seems to be important (just as it always has been with fine scroll) and if the face starts to get too large it can't release the bur easily. This seems to exert undue pressure on the tip of the graver as one tends to employ a lifting action to release the cut. Grinding the back of the graver so the face reduces in size definitely helps.

Fractured points also seems to happen with very small, tight radiused cuts where there might be a fractional sideways pressure exerted on the side of the tip. This tends to happen as I'm getting tired towards the end of the day.

 

[handengraver]

Hello Doc,

I write to You with an envy for your frustration. I have a thousand better excuses to be frustrated, but that's not the reason of my note.

Might You have a strong (or not so strong) magnet on or around your workbench? Magnets can be a kiss of death to the graver's sharpness. Perhaps You could demagnetize the blade.

Please, try that. Good Luck, and cheer up, its only a blade!

Greetings - Ivan

 

[monk]

i'm with barry on the mineral oil. creates boogers & such, but is cheap, safe & effective.
if using the lindsay, why the power hone ? i use one for the old style gravers. but his angled templates with the carbalt cutter. btw the mineral oil cleans up well with a tooth brush, water, & dish soap.

 

[mitch]

Chris touched on something I haven't seen addressed yet:
"Something that may be happening as well is that carbide is made by pressing powdered metal. It only stands to reason that sometimes there will be some flaws or voids. I have had this experience many times."

All square gravers ground to finish size from larger stock- carbide, momax, c-max, carbalt, etc.- are very prone to having some corners/edges that are more cleanly ground than others. Before grinding and sharpening ANY of these for the first time, examine all four edges very closely at the highest magnification you have available. You will almost always find that some have microscopic cracks, pits, & flaws, but there should be at least one that is clean & free of defects. If need be, inspect both ends of the blank and pick the best end & edge. That is the one you want for your point- regardless of whether that happens to be the one the mfr has already ground a starting angle on (they don't check- so you have to!).

You will go crazy trying to keep a decent point on a defective edge.

 

[Christian DeCamillis]

One more thing that could be happening is called edge build up. Some call it cold welding. Depending on the steel you cut. When it comes to stainless and carbide this is a problem. What happens is the metal that you cut becomes welded or part of the graver point it happens on a molecular level. finally what happens is the metal that has built up goes taking with it the carbide it has become welded to. So the tool chips. Actually though what is happening is that it doesn't chip for normal reasons it just gets dragged along with the built up metal. Sounds strange but that's what happens.

Doc, seems that this is unlikely in your case since it breaks right away. Try turning the blank around and see if it happens on the other end if you have enough left to do that.

I grind all of my carbide with a wet grinder and diamond I made from an old faceting machine. I can grind it fast never gets hot and I don't breath that dust which is not good for you.