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cross grain scratches in mahogany and end wedge quesions
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Author:  Jeremy Douglas [ Thu Aug 28, 2008 11:50 am ]
Post subject:  cross grain scratches in mahogany and end wedge quesions
I just installed an ebony end wedge into my dread w/mahogany b&s. While I was sawing the channel with a razor saw I had a couple slips(as I always do with that saw [headinwall] ). So now I've got a couple scratches on either side of the wedge. I may be able to sand them out without a noticable dip in the wood but I thought I'd ask - is there a way to fill them if they don't come out after final sanding?

The grain in the ebony endwedge runs perpendicular to the mahogany in the sides - how should I go about sanding this? I don't know if it's normal to have the grain running that direction in the wedge but I thought it would look better.
Author:  Hesh [ Thu Aug 28, 2008 11:55 am ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
How deep are they? You can check this with a thin piece of paper inserted into the scratches.

If they are .005ish or less use a ROS (random orbit sander).
Author:  Jeremy Douglas [ Thu Aug 28, 2008 12:05 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
I can't even get a piece of paper in there.
Author:  Dave White [ Thu Aug 28, 2008 12:20 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
Cut a bigger (wider) wedge - with a saw that doesn't slip, chisel out the old one and in with the new.
Author:  JRessler [ Thu Aug 28, 2008 12:32 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
As Hesh said, it's hard to tell how deep it is in the photo. Go ahead and try to sand it out. This isn't a particularly vulnerable area since there is an end block there. If it is too deep, in addition of using a wider wedge, you could add some purfling.

Next time, you could clamp a block as shown in the photo to cut it. Of course you would need to do it before glueing on the top and sides. This not only keeps the saw from going where you don't want it to go, but gives you a nice straight cut as well
Author:  JRE Productions [ Thu Aug 28, 2008 12:34 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
I do have a general sanding question on this though:

How do you block sand this area? I have a rosewood endgraft on the archtop. I am block sanding the sides to remove any iregularities of the sides before bining. When I get to this area the sanding direction is wrong. An ROS works great but don't you guys final sand with a block? If not, how do you get rid of the ROS sanding marks?

PS: That is how I did mine Johh. It worked great..so thanks for that tip

Thanks,

Joe
Author:  JRessler [ Thu Aug 28, 2008 12:40 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
I generally use a chevron pattern, so it doesn't really show. If I am using a straight grain, I will sometimes just sand the wedge with a very narrow sanding block, with self stick sandpaper cut flush to the edge of the block. Some guys finish sand with a RO sander - a good RO sander with 220 grit won't show sander marks
Author:  Hesh [ Thu Aug 28, 2008 1:19 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
A couple of things:

Since my crap is still all packed up from my move I can't get you a picture but a 6" engineer's scale with 120 grit self stick on the side you don't use as often, I am in the US so the metric side got covered.....(actually to my disadvantage but that is another subject...) works great for this. The 120 grit helps hold the engineer's scale in place while I cut my butt wedge.... lines first with an X-acto knife with #11 blade and then later with a 42 TPI Zona razor saw.

I use 1/8" wide fingers of computer paper to measure my depth and uniformity of cut with the target being to just cut the depth of the side so that my butt wedge is clamped and glued to the end/tail block.

Using the engineer's scale if the knife or saw slips it's no biggie, either the part of the butt wedge area that will be chiseled out anyway is scratched our I cut my finger off. The important thing is that the guitar does not get damaged...... (veiled reference to high emphasis placed on workmanship in another thread....... :D).

A good ROS will not leave scratches and my Festool ES 125 is a good ROS. So I use a block to square up my sides but my final sanding is done, for the body, with my ROS using 120 and later 240. I have received compliments from two pro finishers with one even asking me what ROS I use because he never had to prep my guitars prior to finishing.

The Festool gets the credit - not me.
Author:  Jeremy Douglas [ Thu Aug 28, 2008 2:15 pm ]
Post subject:  Re: cross grain scratches in mahogany and end wedge quesions
Well I started out with a metal ruler as a guide. I figured once I had a channel that would be enough of a guide - wrong duh Hopefully I'll be able to sand them out. If I had to guess I'd say it's less than .007"

Quote:
How do you block sand this area?


That's what I was asking about in my second paragraph. I'm thinking once the sides are sanded, I'll tape off beside the wedge then use a small sanding block.
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