Rosette Installation - Luthier Tips du Jour Mailbag
In this episode, luthier Robbie O’Brien installs a rosette with the LMI Rotary Plunge Tool Assembly.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Mailbag question: I'm having trouble installing my rosettes. Can you offer some advice?
Robert O'Brien: Today's Tips du Jour Mailbag question comes to us from New Jersey. "Robert, I'm having trouble installing my rosettes. I'm using a homemade circle cutting base with my Dremel and am having trouble with getting a precise inlay of the rosette. Can you offer some advice? Sean, in New Jersey."
Sean, I hate to be the bearer of bad news, but perhaps, perhaps, the problem is with the tool that you're using and/or the method of use. When it comes to doing a precise inlay job, you need a precise tool to do it with in order to have precise results. Let me introduce you to a tool I recently got from LMI that will help lower the pucker factor when you're installing your rosettes.
The Rotary Plunge Tool Assembly
So Sean, let me introduce you to the Rotary Plunge Tool Assembly that I got from LMI [LMI has closed their doors, try the StewMac Rosette Router Base]. I'm using the circle cutting attachment on the base. You can easily remove that and use it for other types of jobs like inlay, but for the purposes of this video, I'm going to show how to use this tool with the circle cutting attachment.
Now, the most innovative thing about this tool is the plunge base. Just slide that mechanism over and it plunges in and out of your work piece. All you do is plunge the tool and then preset the depth with your little Allen tool here. You can use your material, whatever you're going to inlay, to preset the depth, then slide this over and that retracts the bit into the base. So when you get onto the work piece, all you need to do is slide the mechanism over and your plunge down to a repeatable depth. You can repeat this plunge movement and there's no need for locking it in place. Now the rosettes that we install come very, very thin so it's very important that you have a constant depth and this will help you maintain that constant depth as you work.
LED lighting option
Another problem that I find that each year that goes by this gets worse and worse for me is just seeing what you're doing. So the Plunge Tool Assembly comes with an optional LED bright light plate that just mounts right onto the tool, and now you can not only see what you're doing, but you can also see all the mistakes. Hopefully you won't have any of those.
Adjusting to the inside and outside diameter
The next problem you're going to have when installing a rosette is adjusting to the inside and outside diameter of the rosette. Now, a classical rosette is a little wider so you have a little more margin of error, and a steel string rosette traditionally is a lot narrower so you have a lot narrower margin of error. So it's very important, especially on those steel strings, that you're able to plunge down in the center and then creep left or creep right on the inside and outside diameter.
Now the tool base here is very easy to macro adjust. Just loosen both of these set screws right here, and then you have a macro adjust. Now that allows you to get into the center of the rosette channel. Then if you want to creep up on the inside or the outside, all you need to do is tighten the set screw here, then use your Allen tool to micro adjust, also known as a skosh.
Measure and mark the inside and outside diameters of the rosette
So the first thing I do when installing a rosette is just find the inside diameter at the widest point. I just take a ruler and place it in there and just move it around until I find the widest diameter. On this one, it looks like it's coming out at about 90 millimeters. Half of 90 is 73, so I'm just going to mark that. Sean, stay with me now. It's not 73, it's 45. Come on now. Then I place the rosette over it and mark the outside diameter [Robert takes a pencil and traces the inside and outside of the rosette]. Now these are just reference lines. They're not precise, but it gives me a good idea of where I need to plunge to be in the middle of the inside and outside diameter.
Routing the rosette channel
Then I place my tool on there. I'm going to use the macro adjust feature to make sure that I'm going to be plunging right in the middle of the inside and outside diameter. Once that's done, then I'm going to tighten the set screw and make a pass. After that, I'm able to micro adjust here to sneak up on the inside and the outside diameter. Between passes, I'm just going to lock down this set screw here so that as it vibrates, it doesn't move out of position. That's very important as you get closer to the inside and outside diameter.
So let's go ahead and make a pass. It's always a good idea to check your depth of cut. Even though you've preset it, always double check it. I'm just going to use the tail end of my calipers here, place it in the hole, and then check it with the rosette. I'm coming out right where I need to be. I like to install the rosette flush or a hair proud, never recess because then you have no way of clamping it evenly. So flush or a hair proud.
So now that I've determined that the depth of cut is correct, I've also determined that I'm well within the inside and outside diameter, I'm going to place it on here and make some cuts. Here's another little tip that might help you, Sean. I like to leave the router running as I make my adjustments. That way I can hear and see how far I'm making the adjustment inside or outside sneaking up on those diameters, so I'm going to turn the tool back on and make my adjustment.
Here's another tip that will help you, always start and stop on the fretboard end of the circle. That way if you make a mistake, if the router wiggles a little bit or the cord pulls it a little bit, you won't have a defect that will be seen. It will always be under your fretboard. Also, if you make one trip around clockwise and the other counterclockwise, you can avoid getting the cord wound up around your tool.
Slowly work to the inside and outside diameter
So Sean, here's where we start separating the amateurs from the professionals. I'm getting close to that line. Never trust that line. It's just a reference mark. Always take your rosette and see. Now I'm starting to sneak up on the outside diameter, so I'm going to place it down here like this and then run it around [Robert places the rosette down into the channel he just routed], and it looks like I'm having to close it to get it to go in over here and over here. So I'm going to sneak out a little bit more, maybe two, three more passes. As I get closer and closer, I'm going to check it each time to make sure it goes in there. I'm then going to do that towards the inside diameter.
Check it often after each pass as you're sneaking up, you can always take more, it's hard to put it back. That looks like that's where I need to be, so now I'm going to start sneaking up on the inside diameter. I'm going to start by adjusting the tool by using the macro adjust, locking this in, and then using the micro adjust to do the fine adjustment. There it is, a perfect fit every time. Now remember, sneak up on the inside and the outside diameter slowly. You can always take more, but it's hard to put it back.
So Sean in New Jersey, thank you very much for your question. I hope you found the information useful. I also think that if you use this LMI Rotary Plunge Tool Assembly that you'll find that the pucker factor goes way down and that you can do not only things like circle cutting, but precise inlays as well, and there's a lot of attachments and accessories. It's an all-around great tool, and I think you'll enjoy it. So happy building.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instruction available.]
