Sanding/Shaping Grooves

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What a simple topic, I feel embarrassed to ask. (I know, no stupid questions, but gee - sanding a groove!) I have a lot of grooves to shape and sand on the frames of the Granado, but have had this problem elsewhere. The grooves are like this on the model
1714879714434.png
in the area circled. The parts are laser cut, and in many cases, like the one above, the grooves are tapered. So the char has to be removed, and the grooves sanded to size and/or tapered. Dimensions are about 3mm wide for the upper/narrow part of the slot, and 6mm for the lower.

My go-to for this area is one or more needle files. A small square one fits the small groove, and a flat file the step. But needle files are really designed more for metal than they are for wood. I have diamond coated files, and crosscut files a bit coarser, but these fill up with wood shavings, and basically "polish" the wood, rather than sand it. Somehow, files used on external surfaces work better for me, but it's tough getting these internal areas done in a good a reasonable manner. I've ordered some needle file rasps, which I hope will remove more wood without clogging, but was wondering what you all use.

Sanding sticks and blocks are great for larger surfaces, but none of the sanding sticks I've seen have grit on the edges. And the blocks are all too large. And what they sell as "sanding twigs" are so flexible that they are unusable on wood, even if backed up with a wood strip. I could remove the material easily with an end mill on a Dremel, but wouldn't be able to keep it straight and true.

This type of thing has always haunted me, whether it's the grooves on the Granado or gunports though thicker wood. I need to find a better answer, so am hoping someone here has one (or more) for me.
 
I use high end needle files of the brand Corradi. Just perfect for the job. And they work well on wood. There is one with a sharp edge with on one side a smooth surface. Perfect for the edges.
Thanks for that. I've looked on the Corradi site, which has an incredible number of file types. What ones did you get that work on hardwood? When I filter with files for hardwood, only 4 curved riffler files come up.
 
You don't need files special for wood, the one for metal work as well on wood.
I have 3 sets of 12 pc with cut 0, 1 and 2 and the rasp 6pc set.
 
I just found Bryian's post on The Best Files in the World. Very interesting. These files use an abrasive rather than a cut, but his use is the same as mine, and others like these too. As always with quality files, not cheap, but no doubt less frustrating. I've bought half a dozen sets of needle files, all cheap I guess. Should have known better.

As to my original question of doing these grooves, I've also considered using a razor saw to cut the sides at the angle required, then file up to that. I'll be trying that as well.
 
You can also try to glue a piece of sandpaper to a small knife or something similar. To sand between these notches. Maybe a brass strip with sandpaper. Just look around what could be useful. You just have to sand away the chalk of the laser cut.
 
You can also try to glue a piece of sandpaper to a small knife or something similar. To sand between these notches. Maybe a brass strip with sandpaper. Just look around what could be useful.
Good ideas.
You just have to sand away the chalk of the laser cut.
Not in the case of tapered cuts. Quite a bit of material has to be removed for them.
 
I have been looking into the char removal issue and came across sandblasting as an non aggressive method for char removal.

Any further opinions on taking this route?



 
I have been looking into the char removal issue and came across sandblasting as an non aggressive method for char removal.

Any further opinions on taking this route?
I'm not sure about other kits, but CAF actually builds in about 0.3mm for char removal into the size of their parts. This is in an email from Tom at CAF concerning this:
Usually, the wooden parts cut by laser will be larger than those in PLAN, which leaves room for polishing, cutting, etc. I will add 0.3mm to the contour
So I prefer sanding. In fact in places where parts are glued, I intentionally use the quite coarse Perma-Grit files, as it leaves a rough surface which glue can adhere to very well.
 
You can also try to glue a piece of sandpaper to a small knife or something similar. To sand between these notches. Maybe a brass strip with sandpaper. Just look around what could be useful. You just have to sand away the chalk of the laser cut.
Steef66 Ideas are good ones. I also use foam core boards with sandpaper attached. The foam core board is easily cut to any shape and size you need. To adhere the sandpaper to I use rubber cement. I smear it on both the board and the back of the sandpaper. I allow them to dry then place the sandpaper on the board and it will stick very tightly. You can peel the old sandpaper off the board and reuse it with a new piece of sandpaper with the back coated with rubber cement.
 
I rarely bother to remove laser char from parts that will not be visible. I might give such edges a light touch with some sandpaper to make sure the char doesn’t have a powder residue but otherwise I do not try to clean off char. I have not had any trouble with fitment or glue adhesion. There are situations where I leave char in place on visible edges. When coated with my standard matte poly the charred edges take on a nice weathered look.
 
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