Inlay- To undercut or upset.

Southern Custom

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I'm working on a SAA that has a ton of inlay in it. This is the first piece i've done with this much gold and it got me thinking. I'd like to hear what others prefer when it comes to inlay. Particularly in line work and small lettering.
To upset or undercut. That is the question. I'm experimenting now with both in various situations but I'd like to hear from those with more experience if there is a preference of one or the other in a particular application. Excluding large panel inlay. I'm concerned mainly with the tiny stuff.
 

SamW

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#4
The problem is always keeping a smooth edge of the gold inlay. Undercutting with a chisel must be carefully done so that the upraised metal does not form a jagged line. This is most easily done when the cavity has vertical walls as opposed to the angled wall of a V cut.

When possible (most of the time) I prefer to use a scribe and scribe or scratch in the undercut so as to not disturb the surface edge. When doing a larger inlay that will have clean flat metal right up to the edge of the inlay I use the scribe to very good effect.
 

John B.

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#5
There is no question that my friend Sam Welsh (TOS, the other Sam) gets fantastic results using the scribe method.
But for those who prefer the traditional upset undercut method there is no problem with the upraised metal if done correctly.
With flush lettering or line work the raised metal is removed at the time the the inlay is flush sanded down.
And it in fact acts as a good guide that everything is flush and level when the outside shadow line disappears.
Upset undercut does not work as well for engravers that prefer to shave off the raised surplus gold with a steel or bronze flat.
I prefer to sand and save the gold sanding dust. Even if you shave the surplus first, you still have to do a final sanding or stoning.
With a figure or animal type inlay using the upset undercut method it is best to undercut the perimeter outline first and flush down the raised metal and blow out the debris before raising the internal bur field.
For raised lines or letters using the upset undercut. Sand down the raised metal and clean the channel before inlaying the precious metal.
Just my way, to each his own and there is certainly more than one way to skin a cat.
 

jerrywh

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#6
Ok I get it. I usually use undercutting chisels, Like Sam says I am very careful not to scar the edges of the letters or design. I have some very small undercutting Chisels that I sharpen under the scope.
If you have a upset that is too big punch it back down some.
 
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Southern Custom

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The first inlay I did on this current project was undercut. The issue is of course scarring the opposite wall if not careful. And the graver has to be relieved so much that there's very little left to resharpen or touch up if a tip is broken. I switched to a .25mm flat chisel made from old .30mm carbide round bur shanks. It doesn't take much to get a nice groove and I've had minimal surface bulging. So far this has been my favorite method.
John, If you are reading this, you did a seminar a few years back in Vegas on inlay. I've lost those notes. I'm about to do some raised Airplanes on the sides of the SAA barrel. Any idea what a preferred gauge would be for the sheet. Gold is steep these days so saving money is always in the back of my mind but not at the risk of cutting corners. This will be inlay, not overlay.
Thanks for sharing the info guys.
 

sam

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#9
Winston Churchill uses the upset method. I undercut with a small chisel. Sam's scriber method sounds interesting!
 

SamW

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#10
To clarify somewhat...when talking about larger inlays such as animals I have only done raised inlays, not flush. So keeping a smooth flat steel surface right up to the gold is so much easier with the scribe. The scribe also lets me scratch in undercuts where other tools just don't want to fit. And I use it in tight corners for removing metal when no other tool I have will work. When engraving a set of guitar tuners with upright posts that got in the way of every cut I found my self actually scribing in lines to complete scroll work as I just could not make a tool that would work.
 

pmace

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#11
When doing small (inside) curves with the upset method do you grind a radius on the face of the punch or will a small flat raise the edge without distorting the curve?
 

FANCYGUN

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#12
For the outside part of your curves, grind various radius or radi-eye that match the curve otherwise you could get upset with your upset. I just had to say that
 

Southern Custom

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Yeah I've noticed that Marty. I now have a handy and growing collection of microscopic ounces and chisels to choose from, all stemming from this one project. And answered my own question in the process. Basically whatever works for the spot you happen to be working on at any given time.
 

John B.

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#14
When doing small (inside) curves with the upset method do you grind a radius on the face of the punch or will a small flat raise the edge without distorting the curve?
The smaller the curve the smaller the face. And I always slightly radius the face for inside curves.
For extremely small radius such as the figure 8 or the & on small Smith & Wesson I just use a tiny point punch at N-S-E and W.
This avoids any chance of the little steel center being totally undercut and falling out.
 

pmace

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#15
I can see where you would wind up with a bunch of tools ground to specific curves. How many times do you pros typically practice a cut before tackling the customer's piece? Or do you just let fly the first time? I'd be practicing until I was dreaming about it and still screw it up.
 

John B.

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I can see where you would wind up with a bunch of tools ground to specific curves. How many times do you pros typically practice a cut before tackling the customer's piece? Or do you just let fly the first time? I'd be practicing until I was dreaming about it and still screw it up.
Just speaking for myself I only have 3 regular undercutting chisels and one sharp point inlay chisel.
I undercut using H&C and square steel handles. That way my hand can feel the degree of rotation the tool needs to follow the line.
The undercutters are shaped like a small, regular flat screwdriver but with a knife sharp edge.
The wide one is 1/16 inch at the sharp end and is used for line inlay, larger scrolls and form inlays. It's made from a 3/32" cobalt square.
The narrower ones are made from 1/16" round cobalt and normally have about a 1.mm cutting edge, one is straight and one is radius.
Each of these chisels can be, and are modified on the fly to suite the work at hand.
Using a sandpaper covered wood block or an oil stone the edge can be sharpened or reshaped in a moment.
The sharp point punch is also made from 1/16" cobalt and sharpened the same way.
pmace, with experience undercutting just like riding a bike.
You don't need much or any practice to easily get back into the swing of it.
 
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John B.

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#18
When did the term upset become more common than displacement?
I know what you mean Scott.
I was just following the term that they used.
Upset has a vaguely negative feeling of doing something wrong in my mind.
Yes, impact undercutting does displace some metal upward and done right, that's no problem.
In fact it's the desired result when raising a bur field.
 

jerrywh

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#19
To clarify somewhat...when talking about larger inlays such as animals I have only done raised inlays, not flush. So keeping a smooth flat steel surface right up to the gold is so much easier with the scribe. The scribe also lets me scratch in undercuts where other tools just don't want to fit. And I use it in tight corners for removing metal when no other tool I have will work. When engraving a set of guitar tuners with upright posts that got in the way of every cut I found my self actually scribing in lines to complete scroll work as I just could not make a tool that would work.
Sam. I am interested in the scribe method you use. Is this scribe an ordinary shaped scribe. Is it ground differently. Do you normally use more than one pass with it. Can you elaborate some please.
 

SamW

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#20
Hey Jerry, yes the scribe is of ordinary "pencil" point shape, made from a square carbide blank and fitted into the end of a small wood dowel in the shape of a pencil. I hold it like a pencil and use the thumb of my left hand to help control and power it where I want it to go. I usually take at least a few passes and if really deep quite a few passes...though for the undercutting task usually maybe three passes. I find it great to clean up very tight areas of background and sculpting that are just too small for any other tool. Gives that final touch of finished work, though not conducive to making a great salary.
 

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