Sanding, before or after engraving/cutting?

woods
qa

#1

I’ve never used a laser before and I have a TON of ideas to add engravings to many of my woodworking creations.

This question is directed at woodworkers who also use lasers. When you are making something that needs “something special” to be engraved into the face, do you find that you need to sand the piece before you engrave? Or do you engrave your piece, finish assembly, and then sand the whole piece?

Because of the height restriction on the Glowforge (1.5"), some of my pieces (wooden Mugs specifically) would not fit in the bed to be engraved. Therefore, I’ll need to engrave BEFORE assembly. My current workflow would say that I’d have to sand everything AFTER the engraving and assembly, but I’m concerned that I would end up just sanding off whatever I just engraved on the piece. But if I sand it down to final grit first, and then engrave, I think that would not be good for the final shaping that you do at assembly with sanding all irregularities, glue drips, etc… away.

Would you say that the solution is just to engrave my design deeper than normal to account for material being sanded away at the end?


#2

Somewhere or another, in a YouTube video I suspect, I remember it was mentioned that you could purchase prepared wood, zap it with your laser beam, assemble, and apply a finish and have a completed product very quickly. So, certainly one way to do it is to sand the pieces first. I suppose sanding off glue and smoothing out joints could happen after that. Two steps maybe? Sand whole piece, then final sanding after laser?

Honestly, never used a laser myself either. So, I don’t know that this is helpful.

You or your spouse didn’t happen to write an article for Backwoods Home Magazine, did you?


#3

I’m speaking from absolutely no experience, but I would assume a before-and-after approach… Before so that there is minimal variation in the wood grain in order to get a better image (not as much of a concern with the Glowforge cause it should automatically compensate) and then a light cleanup pass afterwards to get rid of any unwanted smoke or burn marks. you could theoretically avoid sanding it afterwards if you mask the work piece appropriately :smiley: I’m sure the others will correct me if I am wrong lol


#4

@scatterbrains Nope, neither of us have written any pieces for Backwoods Home Magazine. Both of us are quite crafty and have our own constructive hobbies. She is a seamstress and costume designer, I do woodworking and programming. VERY useful skills that I hope will translate well into using this laser. I can’t wait to start figuring out how to use software to design things, I’ve always hand drawn my creations and just used pencil and paper. I’ve always said, “I’m on a computer 8+ hours a day for work, why combine it with woodworking?” and now I’ve got a very good reason to change that thinking.

@scatterbrains and @dhanvinddvs Sanding before (probably to 220 grit) and after (up to my 2000) might be the way to go. It will be a little weird to just sand the one surface and then skip it after assembly, but that might be how this needs to happen.

Still certainly open to other suggestions as well!


#5

I’m guessing that it would depend a great deal on how intricate your engraving is going to be.

For example, I sent for and received an informational packet from one of the other major (and really high quality) US Laser cutter / engravers, and the packet includes a very cool piece of engraved wood…really amazingly intricate & the number of dpi is astounding…sanding such intricate tiny dots & thin lines would certainly be degraded by any amount of sanding, no matter how light.

Thicker / wider, less dpi, etc would not be affected as much, of course.

Also, and interestingly, the wood definitely has a burnt smell to it. Not really unpleasant, but very noticeable for sure; same as if you took a hot soldering iron and burned designs onto it.

It’s faded somewhat in the months since I received it, but it’s still noticeable.

I know dan said walnut smells like smores, so I guess depending on the wood you use, it will be more or less pleasant.

Maybe this could open up an additional side of our art!

Magnolia Tree wood, for example, has an odd, sort of perfumey smell to it when burned…so maybe we can choose which wood to use depending on what we are making…

Oooohhh…lemon tree wood for making Tea Mugs??

This could be brilliant!

Or a total flop. We’ll see.


#6

Scratch & sniff laser trinkets… hmm. :mask:

Hemp products may prove interesting! :laughing:


#7

I’m in Colorado, I can do that!
Where the line blurs between laser art and edible…


#8

My experience so far (I do mostly vector laser work, but I do have a line of engraved coasters) has been that you usually have to either sand before or use pre-sanded, then sand after as well to get off smoke marks. My coasters have a single-depth layer of engraving, so to get smoke marks off the borders afterward, I just do the same thing I do with my vector-cut stuff, and carefully sand flat across the top with my Porter-Cable orbital sander, starting with 220 grit paper (I use pre-sanded plywood, so you don’t have to start any coarser than that). That way the depressions stay dark and defined – I finish them with Van-O-Var afterward so I don’t have to worry about the resin left in the depressions, which is generally always uniform in color. If I need to gently sand fine details, though, the two best solutions I’ve found are Dremel’s finishing abrasive buffs, which start at 180 grit and go up, and alternately (if I need to save money), I make my own abrasive buffs using a Dremel screw mandrel and various grit equivalents of Scotch-Brite pad (you cut a little circle out of the Scotch-Brite, then screw it on to the mandrel and use it the same way you’d use the pre-made abrasive buffs). Hope this helps!


#9

I have cut buffs from felt and fabric, but never thought about scotchbrite. That stuff is also color coded from mild to aggressive. Purple I think is the most abrasive.
Yep, got a screw mandrel sitting in my jeweler’s bench.
Thanks for the idea!


#10

Sure thing @printolaser, I can’t take credit for that Scotch-Brite trick though, got the idea from a clerk at my local Woodcraft when I was trying to figure out how not to be constantly running through $4 packs of Dremel abrasive buffs all the time :slight_smile: Yeah, they’re definitely color-coded – I can’t remember all of them, but I do know that green is usually somewhere around 300-320 grit, though I’ll have to go looking for purple if it’s coarser, green’s the coarsest I’ve been able to find. I’ll see if I can locate a color chart for them.


#11

Found it – here’s a pdf from Evergreen State College’s Biophysics Department of all the color grades, with grit and steel wool equivalents, material compositions, and use cases: http://academic.evergreen.edu/projects/biophysics/technotes/fabric/finish.pdf


#12

Another great link for the bookmarks hopper!


#13

Anyone know if a 40W laser can cut the Scotch-Brite pads? I too don’t like paying for the Dremel abrasive pads given how quickly they wear out. I have found large head screw mandrels online, but the though of spending a couple of hours hand cutting with scissors is not appealing.


#14

I was wondering the same thing. According to this MSDS (http://multimedia.3m.com/mws/mediawebserver?mwsId=SSSSSuUn_zu8l00x4Y_9oY_S4v70k17zHvu9lxtD7SSSSSS--) they are nylon fiber based. The sources I have read say that Nylon is safe from a chemical perspective, but my melt and drip.

Worth a try in your Glowforge. :slight_smile:


#15

I don’t plan on trying to print anything that melts and turns goopy, but this got me thinking. I wonder if it would cause a problem if I taped something like parchment paper to the bottom of the crumb tray to catch drippy bits.


#16

I would skip the parchment paper and go with Aluminum foil. Much less flammable…


#17

It mentions on the chart that, while the Scotch-Brite pads may be made of nylon, they’re impregnated with granules of other, mostly oxide and carbide, materials (which are what give them the different abrasive grit counts). These might give you some issues, as they’re randomly distributed through the pads and may block some of the laser’s intensity in places – though I suppose, even if they just ended up perforated, you might be good. Honestly not sure how it would end up – interesting idea though!


#18

I should look up and understand that color code.
Abrasives are my friend.


#19

Definitely worth trying! It will also be interesting to see how it handles various types of sandpaper as well. Having made many custom power sanding aids, it would be nice to be able re-design some of them & have the GF take most of the drudgery out of the task.


#20

Great idea @lcuellar63, I may have to do that myself! Maybe flip the paper over to the backside, then use just enough power to cut through the backing?