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Using LMI’s Gramil
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=8577		 Page 1 of 1
Author:  James Orr [ Sat Sep 23, 2006 10:55 am ]
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This question is for anyone, but in particular, Colin S.

In this thread: http://luthiersforum.com/forum/forum_posts.asp?
TID=7671&KW=binding#forumTop

Colin wrote:

The Schneider gramil that LMI sells it a very good tool, I have one and it
works just fine. Normally I use one of the older style violin purfling
cutters, the straight type with the wooden handle. I always use it prior to
routing the channel as it prevents tearout especially on the top,
sometimes I instead of using the router I just get out the chisels and use
the low tech method of removing the wood.

Could someone explain this more? From what I picked up from CarltonM
this week, the gramil cuts a line. I imagined this was fine line, like
scoring a tile before breaking it. How deep does this thing cut? Is it
difficult to get a squared channel this way? It seems fun. And more likely
to succeed than my stew mac dremil base.
Author:  A Peebels [ Sat Sep 23, 2006 11:00 am ]
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I've never done it this way, but some of the builders make multiple passes with the gramil, then cut out the excess wood with a chisel.

Al
Author:  Dave-SKG [ Sat Sep 23, 2006 11:23 am ]
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I have one, have used it...But...I guess depending on your definition of "fun" that's not how I would describe it. I think as a scribe, prior to routing...good. As "THE" method...learning curve and much frustration is my first description... as getting a good square corner isn't all that easy for me. Now for Bozo...he uses a small bladed carving knife and works magic! Definitely a learned skill. It's definitely worth your time to learn, but I think you will learn to appreciate Ribbecke's and Guitarjigs setups/jigs once you have done one or two by hand.
Author:  James Orr [ Sat Sep 23, 2006 11:24 am ]
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That's what I was thinking too, Hesh. Just cut it over and over again until
it's as deep as the binding is tall. What about the bottom ledge though?
How does we stay perfectly straight with that line? My understanding is
that the gramil cuts from the top?
Author:  Jim Watts [ Sat Sep 23, 2006 11:25 am ]
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I use a gramil to precut the lines prior to routing, but the way Colin describes it is its intended use. How deep you cut depends on how much pressure you apply and the setting of the knife blade. The in/out position is also adjustabe. The blade is of a similar desinge to a flat marking knife, the kind that cuts in both directions. They work well. I've never completely done it by hand however.
James, you could also cut the side line with this if you wanted to. It doesn't have to be just the top.Jim_W38983.8522800926
Author:  James Orr [ Sat Sep 23, 2006 11:35 am ]
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I'm thinking about that top radius, though?
Author:  letseatpaste [ Sat Sep 23, 2006 12:04 pm ]
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Good timing on this thread, I just used my gramil for the first time a few hours ago. I don't think you're going to cut it all that deep with the gramil itself. Obviously I'm still very limited in my experience, but I'm starting to sort out my method. It's best to take a pretty light cut, and then it's easier to go over it again with a little more pressure to really define the line. You also want to pay close attention to grain orientation when you cut. The gramil cuts both ways, so that's not a big issue.

I turned my blade so the angled part is towards the waste side, is that correct? It was situated the other way when I bought it.

I haven't started with the chisel just yet, but I expect a mortising type chisel would be a big help in keeping the channel square.

As far as the top radius goes, I just don't think it matters much. The channel depth is not going to change that much if the gramil's off a degree or two, when you're talking about marking something only a 1/4" high. It's not the same situation as a router, where the router base might be sitting 3-4" in from the perimeter of the guitar.

I figure it's going to be a bit frustrating, but I think it might be one of those things that gets easier and quicker the more you do it. It's fun making shavings and listening to music or a movie rather than wearing ear muffs and goggles and getting sawdust everywhere. Of course, I haven't done it yet, so I may be singing a different tune later.
Author:  jfrench [ Sat Sep 23, 2006 1:35 pm ]
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Jon,

Yep... flat side to mark the edge, angled side toward the waste.
Author:  Joe Beaver [ Sat Sep 23, 2006 1:51 pm ]
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I do it as many others here, use the gramil to score then use a dremel with the stew mac base to cut the ledges.

A couple things that help me... make sure the blade is razor sharp before you use it, and always pull it toward you. That way if you slip you won't cut anyone important. (just kidding about that last part, but do pull it toward you)

By using the gramil first I get a cleaner edge than I would otherwise. It also shows me where the router rode up and didn't quite get it all. Joe Beaver38983.9533796296
Author:  James Orr [ Sat Sep 23, 2006 1:55 pm ]
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Jon, that's awesome! If you have any way to take some pictures of the
different phases, it seems like they'd be really educational. As your cut
gets deeper, does the knife have trouble moving?

If I were doing this for a living, I'd want to move more in a production
direction with a big routing fixture. But agree about how nice sitting
down and doing it slowly could be. It seems old-worldy.
Author:  letseatpaste [ Sat Sep 23, 2006 3:15 pm ]
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I'll be putting pics up on my blog tomorrow probably, I'll post some here, too. I worked on it a bit more tonight, still working on my chisel technique.

Yeah, it gets harder to move the deeper it gets. I did notice that the knife really wants to dig and wedge into the spruce, so you have to really make a point of going lightly on the top. It doesn't take much pressure to establish a good marking line. On the rosewood back and sides, I'm realizing that making multiple passes and cutting pretty heavily with the gramil helps a whole lot when you begin to chisel out the ledge.
Author:  Colin S [ Sat Sep 23, 2006 8:23 pm ]
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I just make a light defining cut first, to cut through the fibres of the top (and sides) this is the important bit to prevent tearout with the router, I'll then increase the depth gradually until I have cut to the depth I want the purfling. I usually cut to about 1mm on the sides rather than the whole 2mm or so thickness of the binding. Usually I then rout. I have never worried about the top or back radius, over the distances were talking about it makes no difference.

If I'm going to use a chisel, I'll take some of the wood out with a 2 or 3mm chisel first then re-cut with the gramil, to near full depth, trying to cut too deep means having to force the gramil, and as you know forcing an edge tool is never a good idea. Clean up with a wider chisel to define nice flat surfaces. Stand back and call your better half to show them how clever you are (they will smile and pat you on the head, then wander away muttering).

Colin
Author:  letseatpaste [ Sun Sep 24, 2006 7:16 am ]
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Here's what I'm learning so far, bullet point style:
-If the grain starts fighting you at all while you're chiseling, change direction.

-I'm finding it helpful to keep my gramil handy and to keep cutting as I deepen the channel.

-It goes faster and cleaner if you take light cuts with the chisel.

-First time around, don't cut your binding channel to full depth, because you're bound to screw up some areas the first time around while you wrap your brain around this process. The channel I'm cutting now is only big enough for the binding itself. You can see near the neck end where the channel gets rough along the sides. I'll go back and mark and cut it a little deeper for side purfling. The reason it's rough there is because I didn't mark the line very deep and also because I didn't...

-... have ample lighting. I'm on the way to the hardware store to buy a decent shop lamp or 2 that I can move around my shop as needed.

-Keep your chisel sharp.

I'm definitely not an authority on any of this, but I wanted to share what I'm figuring out as I'm doing it. So take all my advice with a grain of salt, but post your own experiences, too.
Author:  Sam Price [ Sun Sep 24, 2006 7:30 am ]
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[QUOTE=Colin S]

If I'm going to use a chisel, I'll take some of the wood out with a 2 or 3mm chisel first then re-cut with the gramil, to near full depth, trying to cut too deep means having to force the gramil, and as you know forcing an edge tool is never a good idea. Clean up with a wider chisel to define nice flat surfaces. [/quote]
I love this technique. It's quieter, and because I get a REAL kick out of the feeling of honed chisel blade against wood, I cannot bear to use a router. I really hope I don't have to eat my words...

A word about the wood grain...I found out the direction of the grain, and drew arrows in pencil across the top and back to indicate which direction the hand cutter travels in.

The secret is with the gramil/purfling cutter is a REALLY sharp blade, and a very steady hand. Forcing, as Colin put it, makes you go off course very quickly, and also makes you say very nasty words.

[quote]Stand back and call your better half to show them how clever you are (they will smile and pat you on the head, then wander away muttering).

Colin[/QUOTE]

Hehehe..too true..




Sam Price38984.688900463
Author:  Sam Price [ Sun Sep 24, 2006 7:55 am ]
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Hmmm, good idea.. I'm gonna try the 1000 grit...I usually strop on leather and fine grinding paste...
Author:  Martin Turner [ Sun Sep 24, 2006 8:41 am ]
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A strop and honing compound will beat 1000 grit stone for finishing off a blade IMO.kiwigeo38984.7381597222
Author:  dunbarhamlin [ Mon Sep 25, 2006 4:32 am ]
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Wow! Maybe my blades were a rough batch - they certainly didn't qualify as sharpened - I'd describe them more as crudely shaped. In the end, I found some scalpel blades that are just the ticket.
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