What woodworking tool do I need to smooth out narrow grooves?

January 23, 2022 3:28 PM

I removed paint from a few doorframes, and now I'm going to sand them down and repaint. What is the best way to smooth out the grooves in the detail? I held up a pencil in this photo to show the size of the grooves (approx 1.7 mm): link

I'm sort of a basic woodworker. I've been reading about different kinds of rasps, files, and rifflers (a word that is new to me today), but nothing is exactly what I'm looking for I think. I guess I am imagining something like a metal file in the shape of a cotton swab/cotton bud.

I already bought some contour sanding pads for the job, but I'm just wondering if there is a better way of working with this - there are seven doorframes, each with multiple grooves.

BONUS QUESTION: if anyone is able to identify what the metal circle in the photo that was hidden under the paint, that would be cool too.

posted by cincinnatus c to Home & Garden (31 answers total)

I’m also a basic woodworker and I would probably wrap a piece of sandpaper around the edge of something thin and stiff (like a credit card) and stick it in the groove and sand along the grain.
posted by mekily at 3:34 PM on January 23, 2022 [3 favorites]

Response by poster: That's what I tried, and the contour pads I bought do the same job. But the grooves are pretty rough and they are endless, and sandpaper falls apart, so I was hoping there would be a metal tool that could do the bulk of the work, with possibly some final sanding to follow.
posted by cincinnatus c at 3:51 PM on January 23, 2022

Yeah I'd get a big roll of 80-grit paper, and a card or similar stiff object, and go to town.
posted by coriolisdave at 4:09 PM on January 23, 2022

I'd use a small handsaw with a light touch for the endless parts, then finish with sandpaper around a credit card anywhere the saw got too awkward.
posted by flabdablet at 4:11 PM on January 23, 2022 [1 favorite]

Try searching for the term "cabinet scraper." I haven't seen anything with the exact profile you're looking for, but you might be able to get away with the basic rectangle. Be sure to find and watch a video or two about how to use them and keep them sharp. They are basically microplanes, with a very sharp burr for a cutting edge.
posted by bricoleur at 4:21 PM on January 23, 2022 [3 favorites]

The corner of a sharp chisel can be used to clean out grooves. Just scrape, though, don't try to chisel the groove.
posted by pipeski at 4:42 PM on January 23, 2022

What about something like a dental tool, like something from this set? These look like they’re meant to be used in a rotary tool, but dental burs appear to come in various sizes and shapes and are pretty sharp.
posted by MadamM at 4:43 PM on January 23, 2022 [1 favorite]

A rabbet plane up one side and down the other could do it, if you have future use for a rabbet plane. Or a regular plane followed by a gouge to clean up the bottom, possibly.

For abrasive removal I'd probably try clamping scrap onto a handleless file as a 'ski' that lets it slide along maintaining the groove angle. It might not work tho.
posted by away for regrooving at 4:49 PM on January 23, 2022 [1 favorite]

Search for the term “sanding stick”. They come in a lot of shapes ranging from a thing that looks like a nail file to a cotton swab to a wedge thingy with bands of sandpaper you wrap around it. Generally they are for miniatures and small hobby things or precision manicure things.
posted by Mizu at 4:50 PM on January 23, 2022 [1 favorite]

I may be misunderstanding the question but I would fill the grooves with sandable, paintable wood putty and then sand everything flat/smooth.
posted by caseyblu at 4:55 PM on January 23, 2022 [1 favorite]

(I see rasps/files with lifted handles also exist, I'd never seen one.)
posted by away for regrooving at 5:04 PM on January 23, 2022

Another vote for filling the grooves if they're uniformly and completely below the "correct" surface, and no parts are proud of the surface, especially if you're painting. Even if you aren't painting, filler comes in a range of colors, or you can make your own with fine sawdust, ideally from the wood you're filling.

Unless the grooves are very shallow or cover a significant portion of the surface, don't want to have to remove material all the way to the full depth of the groove in a way that won't form a noticable variation in the larger surface. Just fill them in.
posted by pullayup at 5:27 PM on January 23, 2022 [1 favorite]

I'd try some coarse steel wool. Or a small wire brush, maybe on the end of a rotary tool.
posted by zengargoyle at 5:39 PM on January 23, 2022

Response by poster: The idea of simply filling in the grooves, as suggested by caseyblu and pullayup, is thrilling! These door frames are original Victorian architraves, and I live in an area where people obsess about tiny details like this AND I have spent quite a bit of money and a lot of time and like 99% of my mental health reserves over the last year or so painstakingly and safely removing 125 years of mostly lead paint from these fuckers to restore them, and just contemplating filling it all in and sanding flat is pure pleasure. I'm not doing it, but it's amazing to think about it as a solution!
posted by cincinnatus c at 5:47 PM on January 23, 2022 [2 favorites]

I'd probably try clamping scrap onto a handleless file as a 'ski' that lets it slide along maintaining the groove angle

Clamping scrap onto the side of a handsaw to limit its maximum depth of cut would probably be a good idea too, if you're going the handsaw route.
posted by flabdablet at 5:54 PM on January 23, 2022

For the longest time I was apparently only looking at the top half of the pic. Yeah, I'd definitely use filler and preserve the profile as much as possible.
posted by rhizome at 6:04 PM on January 23, 2022

With a little practice cabinet scrapers are sw-eet. Lee Valley has a bunch. For semicircular channels, or a handle and little blades; I’ve used the latter on old muntins, did the job.
posted by clew at 6:07 PM on January 23, 2022 [1 favorite]

If filling isn't an option, I'll add another vote for a cabinet scraper.

If that doesn't work you could try a block plane or jack plane. It took me some practice to get the hang of using planes, but they come in handy for smoothing like this where you need to take off a fair amount of wood.

Or an orbital sander.

One thing to consider: you may need to sand or plane all the wood of the door frame evenly down to the deepest groove to smooth it out. Which may make your door reveal slightly bigger.

I should note that I'm an amateur/novice woodworker, so please take my advice with that in mind!
posted by caseyblu at 6:10 PM on January 23, 2022

you may need to sand or plane all the wood of the door frame evenly down to the deepest groove to smooth it out

I think several people here are missing the point that the grooves are supposed to be there, as parts of a profile that the OP is trying to restore, not destroy. A few more photos from a few more angles would probably have made this clearer.
posted by flabdablet at 6:15 PM on January 23, 2022 [2 favorites]

ah, I understand now - as flabdablet says above: if you're trying to smooth a profile/groove that's a decorative part of the frame, then my suggestions won't help.

I thought they were gouges you were trying to bring even with the door frame.
posted by caseyblu at 6:23 PM on January 23, 2022

You could make up some custom scraper tools from wood blocks and scrap steel, along the lines shown here by the always-inspirational New Yorkshire Workshop.
posted by flabdablet at 6:30 PM on January 23, 2022 [2 favorites]

Response by poster: Yeah, sorry, this is Victorian architrave that looks something like this but original: link

I want to PRESERVE the grooves that are kind of messy after a project that involved removing 125 years of paint + goo/varnish.
posted by cincinnatus c at 6:31 PM on January 23, 2022

i was going to vote for filling also, tho clearly im missing something about why not to fill - but here a video about home made wood filler - https://woodworkjunkie.com/make-wood-filler-with-sawdust-how-and-why

my other suggestion was also going to be either a) a cabinet scraper and / or b ) a finely tuned expensive block plane (eg lee nielson etc) .. the issue is that there is a learning curve to just learning how to use and adequately sharpen these two sharp implements , so maybe you could go to a woodcraft store of you have one nearby and have them help you with the blade sharpening.

idk .. feel like some of this is ground thats already been covered .. so .. for whatever its worth

my instinct would be to avoid sanding.

it looks like pine maybe , or a soft wood - go buy a piece somewhere and test whatever you are teaching yourself about on your scrap pieces first.
posted by elgee at 6:38 PM on January 23, 2022

If you wanted to spend more time on building tools than on doing the actual work (a tradeoff I've regularly chosen when scripting repetitive IT tasks, because repetition is boring and error-prone) then you might even consider cutting the edge of a piece of scrap steel into a complicated shape that matches the entire profile, then fixing that to the end of a little sled built to slide straight along the doorframe as guided by its edges.
posted by flabdablet at 6:40 PM on January 23, 2022 [1 favorite]

Response by poster: you might even consider cutting the edge of a piece of scrap steel into a complicated shape that matches the entire profile, then fixing that to the end of a little sled built to slide straight along the doorframe as guided by its edges.

Not sure I've got the chops for that but I could build a time machine and go back to when my building was made in the 19th century and return with some offcuts? Might be easier.
posted by cincinnatus c at 7:00 PM on January 23, 2022

Not sure I've got the chops for that

If I were going that way I'd start by transferring the profile onto a piece of paper with a contour gauge, then cut the paper along the profile with nail scissors, then glue it to my scrap steel piece, then shape the steel down to the paper edge with a Dremel. Shouldn't take more than an hour or two.
posted by flabdablet at 7:23 PM on January 23, 2022

Also sometimes you can find a pro to do it affordably, esp in a city with lots of restorers.
posted by clew at 7:32 PM on January 23, 2022 [1 favorite]

A molding or contour scraper is generally the way to build up or repair one off millwork. Lee Valley has these contour card scrapers if the grooves are round rather than square.

However a few door frames at 16ish feet each is getting into the range of being painful to do each groove individually. You are looking at hundreds of feet of groove to clean out. Well worth getting a custom scraper blade made that you can rig with a block of wood to act as a fence. Custom molding knives can be had for around $100 and knife makers can often work off a picture.
posted by Mitheral at 9:27 PM on January 23, 2022

Best answer: If it were me, I might be tempted to get some scrap wood of a similar type to audition various Dremel sanding bits. You should be able to find something that will clean out the groove without gouging the wood too easily, and some of the bits are the kind of disc shape that should fit in there nicely.
posted by amtho at 9:43 PM on January 23, 2022

Best answer: Oooh - searching for Dremel specifics, and it turns out there are multiple articles for how to sand grooves.

Here's something like Dremel bits reviewed -- but I'd definitely try them out on scrap wood first, partly to test them, and partly to learn how to do it well.
posted by amtho at 9:47 PM on January 23, 2022

Uh I was missing the scale. Forget rabbet planing that lil groovelet side.

But what's fun: a single pass with a small vee gouge could do it, if the groove profile either matches or is slightly shallower than a standard gouge profile. If the grain is cooperative, this would be a breeze.
posted by away for regrooving at 11:08 PM on January 23, 2022