Help, please: muddy looking engraving

[rick1@bresnan.net]

Hi All,
I was wondering what cause raised rims and scape marks on engravings. I generally use a square graver
with a 55 degree face with a15 to 17 degree heel. I also sharpen with the GRS power hone and after the ceramic lap I polish the face and heel with leather that has diamond spray on it. This seams to happen on hard and soft metals but is more noticeable on metals like brass and nickle silver. I use the graver mach with the settings usually between 28 and 34K. Any help would be much appreciated.:big grin:

Thanks,
Rick

 

[Ron Smith]

Scrapes, raised rims, and scrape marks

Possible causes:

1. You are engraving too deep for the length of the lift facets
2. Too long of a lift facet
3. raised rims: Sometimes if you strop a tool you round the cutting edge. This makes the shearing capabalities of the tool turn into a wedging action. Be careful not to roll the edge when stropping.
4. Length of the lift facet should be no more than about 1/2 mm. even shorter in some cases.
5. widening your point will help to 110 degrees or 120 width.
6. leaning your graver toward the outside of the curve will also help a little.
7. Don't cut any deeper than the length of the bottom facet otherwise you defeat the purpose of the lift.

There you go Rick. Hope this solves your problems.

Ron S

 

[John Cole]

Rick,
I was just wondering the same thing, so thanks for posting first.

I'm using a gravemeister. It's an older model and goes between 800 and 1200 on the frequency. I've been setting it aroung 1000. I've been using a square graver with a 45 face and a 15 lift. I've been noticing raised rims on my cuts, and chatter marks inside of my curves, I'm not sure if that's the same as scrape marks that Rick is talking about.

John C.

 

[Tom Curran]

Ron, by 'lift' do you mean what some others might call 'heel'?

 

[fegarex]

I'm going to give a "gerneric" answer here as I'm not really sure what is meant by scrape marks...
Most beginners have an issue with "tearing" in tighter turns. It is usually because they have let the back of the tool drop. The best solution for a beginner is to tell themselves "keep your elbow up" when going into a tighter turn.
As Ron said, the heel can be too long as well but mostly because a beginner tends to drop the back of the tool and try to make the cut.

 

[Ron Smith]

Well, lift can be accomplished two ways. 1. by creating facets at a higher lift than the keel of the graver with facets.
2., by putting a gradual bend in the graver and stropping, but that requires some metalergy knowledge and instructors are teaching the facets technique. It is easier.

And yes, it is commonly called the "heel".

Usually what happens is when one slips around on the metal from not having developed muscle memory, is that one begins to cut deeper to avoid slipping. You must lower the hand until the tool moves on it's own accord without pushing and then maintaining the height of the hand spot on. If the tool slows down (usually going deeper progressively), you normally try to push harder instead of lowering the hand to the cutting depth you want.

It also could be the co-ordination of hand and foot if you are using a foot peddle.

This is just a lack of experience and not enough cutting. Also it is good to go in stages. If you try circles right off, you will have trouble. Start with straight lines side by side. Then go to curved lines side by side and try to be consistant in depth. Once you have mastered these simpler cuts, go on to harder ones. If you do circles, you have another element to co-ordinate. That would be the left hand turning the vise into the curved cut.

Another good practice is to do very long straight fine lines and try to maintain consistant depth throughout the cut.

I hope this helps you rather than confuse you. You are in the process of teaching yourself to be sensative to microscopic movements.

Ron S

 

[John B.]

Keep the graver pointed in the same direction as much as possible.
If you're using power remember to stop or slow down while re-gripping the vise.
Remember, the vise mostly goes around the curves, not the graver.
There is only so far you can turn the graver from cutting in it's starting direction before you lever on the outside wall of the cut.
The tighter the turn the worse it gets.

 

[monk]

if you cant afford a video showing how cuts are made, an excellent demo showing the vise turning the material into the cutter is shown by steve lindsay. it's free, and shows him lettering a flute under a microscope. it very graphically illustrates this idea. it's strange that people talk of "push graving", and then say hold the graver still and turn the material into the graver. but that's the way to do it.

 

[Marcus Hunt]

If I can add my two penny worth; in addition to all this excellent info make sure you are cutting with the point of the graver. I noticed whilst teaching English Fine scroll that as the scrolls got tighter, in order to get the graver to go around the curve more, some students would inadvertently push the heel of their hand slightly away from themselves. This results in the edge of the face suddenly becoming the cutting edge and the movement required for this to happen is miniscule. To remedy it just relax and let the point do the cutting (no forcing the graver around the curve) and, as John B says, let the vise go around the curves.

 

[John Cole]

I was turning both the vise and the handpiece at the same time. Keeping the handpiece still and just turning the vise helped quite a bit, but I'm finding that I'm stopping and starting the footpedal quite a bit more. Is this fine, and do I need to keep the graver in the cut as I reposition the vise? Thanks. John C.

 

[John B.]

John C,
Just like most machines, power assist hand pieces have an of and on.
And it's OK to pause (off) or coast them while you re-grip the vise.
Just don't move your graver hand position if you can avoid it.
Keep the graver in the cut when you can.
In gun engraving this is not always possible due to obstructions sticking up.
If you do, re-position it with care before continuing the cut.
Do much the same thing with a "push" graver.
As Monk said, in most cases it's a "hold graver."
Like in lathe work (except in special situations) the cutting tool remains pretty stationary in it's long axis.
Best wishes.

 

[rick1@bresnan.net]

WOW! You guys and gals are great. I can't believe all off the great advice. Thank you, I definitely think this will help a lot. I couldn't quite figure out how you masters were getting such clean cuts. Now I think I am on my way to do some good work.
Thanks again.
Rick

 

[Kevin P.]

Tom, not to answer for Ron, but I found the two terms confusing and thought they meant the same thing.
From reading engraving books it seems 'lift' is the space between what is being engraved and the bottom of the graver. Heel is the angle on the bottom of the graver as in face 50°, and the heel at 15°. The heel is what makes for the 'lift'.
Kevin P.