To finish wood first, or do CNC operations then finish?

(Evan Day) #1

I have a few basic projects under my belt now with my SO3, so I am working on completing more “finished” and presentable pieces at this point. However, this presents a problem.

On some pieces, if I am staining or using polyurethane on the wood, it gets in my V-carving, I get sanding dust and other issues into those areas (when they are tacky with poly), or I can’t really stain neatly into the finer details. So I’m curious if the professionals out there ever consider staining or putting poly on your stock first and then doing CNC work? Yes I know that is risky, as you have wasted time and materials if something goes poorly during the machining. Or do you always conduct finishing (final sanding, poly, stain, etc.) only after all machining is complete?

(Jerry Gray) #2

Sometimes it’s a good Idea to poly first, so you can easily remove stain/paint that you want in your Vcarving, from the surface, because it doesn’t soak through the poly.

(mikep) #3

I’ve done both ways, but for the finishes I use it doesn’t seem to make a lot of difference. I’ve used an acid brush in v-carved text with beeswax/tung oil, and it works well, but I don’t use much stain, so can’t comment there.

(Carl Hilinski) #4

I do both depending on what the final product needs to look like. On the Tree of Life image below, I stained the plywood with cinnamon dye stain and then put about five coats of polycrylic over it. Once it had cured a bit, I put it in the S03 to cut the image.The lines here are natural

In some cases, I want the lines to be white as in this Tree of Life version. Here, I painted the surface green, applied four to five coats of poly and routed the pattern. Then I slopped paint into the routed lines. When it dried, I sanded it with 220 grit sandpaper, which removed the paint outside of the lines but didn’t dig into the green because of the 4 to 5 coats of poly.

Finally, there are times when I want dark lines. In that case, I’ll rout the lines first and then apply the stain. The stain will clump up in the routs and be much much darker than the rest of the surface. Even light stains like honey will be very dark in the grooves.

One of the advantages of using poly before cutting is it can help hold down the expansion of the wood after routing the lines. Often, the routed lines will expand a little more in cross-grain areas once they get hit with a waterbased finish which will lead to uneven line thicknesses. Putting the poly on before cutting the lines seems to reduce this a little. Don’t use waterbased, you say. I can’t use oil-based stuff because my neighbors (rightfully) complain about the odor.

(William Adams) #5

I will further note that sometimes functional / mechanical aspects dictate an order of operations. When I made a case for my Bear Custom Kodiak T/D, I had to make the arrow holder completely first, then stain and finish it and the interior of the case, then assemble the case and cut it open and stain / finish the exterior:

(Evan Day) #6

Thanks for the replies from all. I’m rapidly finding that the “science” of CNC work (CAD/CAM, feeds and speeds, etc.) comes fairly easily for me but the “art” (finishing, staining, sanding, overall aesthetics) is like Greek to me sometimes. My dad was a master carpenter and could build beautiful furniture-type pieces from scratch. I learned from him how to build things that are structurally strong (the “science”), but never picked up the finesse for the “art.” I wish I had paid more attention. But, I’m learning all the time.

I’m like you @Boothecus, I’m working in a corner of my garage, so I’m not ready to be using oil-based stuff (and the odor, mess, and cleanup work that is part of it). Pretty much everything I do will either be acrylic or water based finishing.

(William Adams) #7

For the art aspects, it’s mostly a matter of proportion and taste — the problem is, taste is a moving target, and we’ve gone from a culture which accepts quality as a matter of course, and thus allows a brass hinge to be covered over in darkened shellac and wax, to one which is so starved for good quality things that we fetishize what should be unobtrusive and a natural part of the structure by brightly polishing it.

We do list a site for golden section calipers at:

and the sector has been popularized recently as a layout tool:

I would suggest studying beautiful and inspiring things, and learning to appreciate and understand the reasoning which applied to the choices which the craftsman made.

Remember the old saw:

  • a person who works with their hands is a labourer
  • a person who works with their hands and their mind is a craftsman
  • a person who works with their hands and their mind and their heart is an artist

One of the best books on design I ever read was about flower arranging. We have a link to one book on design on the wiki:

and I think everyone should read Creative Lettering Today by Michael Harvey (if that interests you, go ahead and get The Elements of Typographic Style by Bringhurst) as well as The Nature and Art of Workmanship by David Pye, which distinction between the craftsmanship of risk vs. the craftsmanship of certainty speaks to the dichotomy of handwork and CNC.

(Carl Hilinski) #8

There is a product I really like that borders urethane and acrylic. Minwax makes a waterbased, oil-modified polyurethane that you can get at Lowes (but not Home Depot). It will slightly yellow like a urethane but will dry in two hours and is cleaned up in water. It has no odor. It doesn’t seem as soft as polycrylic. Here’s a link to the stuff Good luck finding it in a rattle can though.

(Jonathan K) #9

On the finishes to try, I really want to get my hands on some Rubio Monocoat:

no solvents, dries/cures to 80% hard in 2 days, and no VOCs.

(Carl Hilinski) #10

Amazon has it. But it’s not Prime so you’ll have to pay for shipping.

(Jonathan K) #11

just need a proper project excuse to use it though, been in metal lately :smile: