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Straight Lines With A Dremel

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Hey I have like a drill/dremel type tool in like a mini pilla drill mounting (not router base) and I was wondering how you route/engrave straight lines for inlays? Like for letters etc?

Do you just free hand it and hope no one notices its slightly off?

I want to do a 1 (I) roman numeral into a truss rod cover, as well as f/b and head stock inlays (as yet undecided on design) and I was just wondering how its done.

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I've done this once or twice.

Print out a paper template of the shape you'd like to inlay and stick it on your lumber. Using a metal straightedge as a fence for the straight lines, cut through the template and into the underlying wood with an exacto razor knife, going over the outline several times and getting deep enough to matter. Do the curves by hand, or if you have a set of metal french curves use those.

Remove the template and rub some different-colored chalk into the line you just scored (i.e. white chalk on ebony), this will highlight the edge of the cavity you want to rout. Now take your dremel (WITH a router base) and rout out what you need to, running up to (but not over) the edge you've so carefully cut with the exacto blade.

Clean up the rout as needed (razor knife, tiny chisel).

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2 ideas:

1. I would use a guide of some sort at least. If it's mounted in a stationary base (rather than a 'portable' base like a router base) then you can run the wood against a fence of some sort. Doesn't have to be fancy; just put a piece of straight wood to the platform part of the stand, line up the bit, clamp the wood down to hold it in place, and then go from there. If you can set a stop depth, you should do that, too.

2. Use a straight-edge and an Xacto or other thin blade to score your straight lines as deep as you can. Then tape off the surrounding area to the best of your ability. Then, 'freehand'. But as you freehand, just come as close to that scored line as you can. In many cases, the rotation of the bit will send the last millimetre (between the bit and the scored line) flying. If it doesn't, use a small chisel later, with the scored line as a guide, to clean it up.

When I was inlaying my block inlays (all straight lines) I did a combination of using a hole-saw cutting attachment (used it as a mini router-base) and technique #2. Using the scoring technique, it's pretty easy to use a fine chisel (even if it's a construction-grade one... mine was like $8 or something) to clean out the bits that get left behind by not going right to that scored line. Even then, because it was my only major attempt at inlaying, I goofed one of the blocks up... I practiced on scrap first, but probably not quite enough. If this is your first inlay, I recommend putting in more practice time than I did.

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+1 to everything already said.

To re-enforce the point: Don't even consider doing it freehand or without a locking depth guide. The inlay will (or at least should be) flat, so you want a flat surface to inlay it into. You'll NEVER get a flat hole doing it freehand.

Also, if you freehand it, you WILL run over the edge. The motor is more powerfun than your grip when freehanding a delicate, precise area. It'll jump right over before you can stop it.

And show us what you've done when you make some progress!

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  • 2 weeks later...

For the guitars I did here, I made hollow block inlays, like the outlines of squares on my fretboards.

I used the LMII router base with my dremel. Since the base is rectangular, I was able to set up a fairly simple jig. After calculating the distance from the bit to edge of the router base, (which ended up being nice round numbers) I clamped down my fretboard, with two long rails running along either side of it, parallel to the center line. I clamped a couple lengths of board, moving them for each inlay position, to make stops for the perpendicular lines of the blocks. The plunge motion on that base is fairly smooth, which helps. Taking a lot of care, I was able to route the squares almost perfectly. The whole method worked very well. I used pearl purfling to make the inlays, the purfling was the same width as the diameter of the bit I used. (Well, actually, some of it was slightly wider, and I needed to sand it down a bit to fit)

I cut the pearl to size and mitred it after I made the routes, which worked well for this instance, even though it's backwards from the usual order of things when doing inlay. (I certainly wouldn't attempt this on a complicated inlay, but it made my life easier with this pattern.) I'm sure something like this could also work well for blocks, although I don't think I'd try it. I don't know if I'd attempt something like this with a more complicated inlay either.

In any case more complicated, I'd follow the usual route (a pun!?) of getting close to the line with the dremel (using a smaller bit) and cleaning up with a chisel, but something like this method could certainly help get you closer and avoid any slipups.

I have photos somewhere, I just can't find them right now. (I'm at work, I thought I had posted them online...)

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Thanks for all the info guys!!! :D

but you say make sure you have a flat base for the inlay to sit on but does that really matter? I mean if your gluing it in, and then radiusing the fretboard, surely the inlay will be flush with the f/b and the glue would have filled the space between the bottom of the route and the inlay, so its not like it will wobble of any thing?

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Consider any other type of joinery. You want as much surface-to-surface contact as possible. When you glue up a body blank, you want two perfectly flat surfaces touching the entire length of the joint. You would never let the glue fill in the gaps.

Now, with an inlay, there's more of a margain for error. The tolerances are WAY lower. A neck inlay won't have nearly the stress a body will have on it. The glue is commonly used to gap fill around the edges. Also, since it's a cavity, you can't be 100% positive about a 100% flat cavity like you can with a normal wood joint. That being said, you still want as flat a gluing surface as can be had.

Another option for the edges is to first score the outline heavily eith an X-Acto, then CAREFULLY chisel out the edges. After that, you can rout the cafuty with impunity. Greg mentioned the chised possibility as a cleanup after routing, but it'd be just as good for the initial shaping of the cavity.

FLON KLAR: How did you solve the control issues around the edges? Even at the lowest speed, I can't manage fine control freehand, but I can completely control it with the base.

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Well, I'm not saying I never go outside the lines, and sometimes I DO have to do some fill-in with the epoxy, but it's minimal. After I trace out the piece to be inlaid with an exacto knife, I very slowly freehand the outline inside the line with a very small diameter drill bit (like .010"). I find that running the Dremel at HIGH speed gives me more control than at lower speeds. Once the outline is established, then I set up the Dremel in the router base with a larger bit to remove the rest of the wood. The larger bit DOES tend to bite into the wood more, giving less control, but the outline I've made with the tiny bit gives me a little margin for error.

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