farmbag72 Posted March 8, 2012 Report Share Posted March 8, 2012 I am building an open cabinet of sorts to help organize knick-knacks, widgets & whatchamacallits in my shop. Several of the cubbies are going to be bit on the small side to finish once I assemble. Could I cut plywood pieces to size, polyurethane aall pieces & THEN cut dadoes? I'm wondering if the poly might gum up my dado set or router bit depending on which way I choose to cut dadoes. I asked the same thing on another woodworking forum & was given advise but my concern about dado set/router bit gum-up wasn't answered. Quote Link to comment Share on other sites More sharing options...
Jfitz Posted March 8, 2012 Report Share Posted March 8, 2012 I wouldn't hesitate to machine pre-finished parts, if the poly is cured. My 'test' is usually to lightly sand the poly - if it is cured, it results in a nice fine powder that shows the poly is cured. I do not thing that would cause any problem with gumming or clogging. Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted March 8, 2012 Report Share Posted March 8, 2012 Cut your dadoes in the unfinished wood. Go to the table saw and rip some strips of scrap to fit in the dadoes and rock on with your finish. The strips of wood will protect the dadoes of finish. Quote Link to comment Share on other sites More sharing options...
rodger. Posted March 10, 2012 Report Share Posted March 10, 2012 I would have no problem doing this. It's not different than buying prefinished plywood and then cutting dados for assembly (which I have done with no problems). Quote Link to comment Share on other sites More sharing options...
AceHoleInOne Posted March 10, 2012 Report Share Posted March 10, 2012 Just a caution if you do pre-finish. Finishes don't reach optimum hardness until fully cured. Remember, fully cured is not dry to the touch, fully cured is the chemistry doing its thing inside the finish. So if a finish is dry to the touch, the finish could still be soft inside and be susceptible to easier scratching. The longer you can wait, the better. Quote Link to comment Share on other sites More sharing options...
rodger. Posted March 12, 2012 Report Share Posted March 12, 2012 Just a caution if you do pre-finish. Finishes don't reach optimum hardness until fully cured. Remember, fully cured is not dry to the touch, fully cured is the chemistry doing its thing inside the finish. So if a finish is dry to the touch, the finish could still be soft inside and be susceptible to easier scratching. The longer you can wait, the better. Good tip Ace! I Didn't think to mention that. Quote Link to comment Share on other sites More sharing options...
Mike M Posted March 12, 2012 Report Share Posted March 12, 2012 I often prefinish panels (both plywood and solid wood) before machining. This is especially useful for the interior parts. It also has other benefits such as less tearout when cutting dados and easier cleanup of glue squeezeout. I usually do a couple of coats of Arm-R-Seal and let it cure for a couple of days. My only caution is to mask off any areas where I want glue to stick such as the ends of shelves that go into the dados. Quote Link to comment Share on other sites More sharing options...
Rapid Roger Posted March 12, 2012 Report Share Posted March 12, 2012 I've never done what you are suggesting but, I don't see a problem with it. My only concern would be marring up the finish while doing the cutting of the dado's. I usually do all machine work including sanding and then line the dado's with blue painters tape before finishing to keep a fairly clean glue surface for assembly. Obviously there is no ONE way to do anything.......just my way and your way. Rog Quote Link to comment Share on other sites More sharing options...
wdwerker Posted March 12, 2012 Report Share Posted March 12, 2012 Using a zero clearance throat plate when cutting the dado's helps prevent chip out. I have taped the cut lines with blue tape as well, then cut thru them. Finish really has to be dry and cured. I always finish some scraps using the same steps and number of coats whenever I finish something. Test for dryness and quality of cut on the scraps, it keeps fingerprints and miss-cuts out of your good parts. Quote Link to comment Share on other sites More sharing options...
TheOneHandedHandyMan Posted March 13, 2012 Report Share Posted March 13, 2012 I often wondered how long to wait for a finish to "fully" cure. I've heard a day, a couple days, a week, a month... All I know is that after only 24 hours, the finish is dry but not rock hard. It will still dent and scratch until it is fully cured. Quote Link to comment Share on other sites More sharing options...
farmbag72 Posted April 17, 2012 Author Report Share Posted April 17, 2012 Just wanted to thank everyone for their input. Unfortunately, the project this question was for has been slid to "the back of the line". My wife & I are expecting our first child (a boy!!) in July & I have to get the nursery finished before I can do anything else for me in the shop. I MIGHT be able to squeeze out a toy truck while I wait for drywall mud to cure in a few weeks. Thanks again!! Quote Link to comment Share on other sites More sharing options...
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