Using my cnc to plane an edge glued ash Dutch Door

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Forum topic by mazzy posted 05-28-2013 01:58 PM 1446 views 0 times favorited 6 replies Add to Favorites Watch
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56 posts in 2545 days

05-28-2013 01:58 PM

I have made 3 table tops by doing conventional edge gluing: alternate grain, use biscuits to hold alignment, use TiteBond 3, use of cauls and 25 lb weights to maintain proper pressure to minimize cupping.

What I additionally do is to plane the top once edge glued using my cnc router. I measure the inevitable slight misalignments or cupping of the boards and remove just enough from each side to get a perfectly flat table top. This usually only requires taking about .125 off each side.

Now here is my question…will this cnc planing help to maintain the perfect flatness or might the boards still warp over time?

I plan on making a Dutch Door for the house entry. I will be using very thick pieces of ash (probably12/4) and cnc plane it down to size after edge glued.

Are there any special facts, suggestions, instructions, that I need to keep in mind while doing this project? I’m concerned about warping due to it being an exterior door.

All comments are welcome.


-- Mazzy, San Francisco Bay Area,

6 replies so far

View ajosephg's profile


1880 posts in 3527 days

#1 posted 05-28-2013 04:26 PM

I’d say the table top will warp, twist, cut unless you mount it to some sort of structure to hold it flat.

The door is a different animal and I think if you use rail and stile construction with straight grained wood it would be ok.

-- Joe

View 404 - Not Found's profile

404 - Not Found

2544 posts in 2935 days

#2 posted 05-28-2013 04:51 PM

If you can get quarter sawn or rift cut material you will minimise the risk of it going out of shape. Do you intend using wide planks?

View Nicky's profile


695 posts in 4058 days

#3 posted 05-28-2013 05:01 PM

Two assumptions I’m going to make before making my comments, 1-The wood has been properly air dried or kiln dried, 2-You let it acclimate to your environment before any machining operations.

Fact, all wood will move, you can’t prevent this from happening short of an environmentally controlled area. Humidity levels will impact movement. You can minimize the effects. Quarter sawn lumber will move the least. If you’ve used properly dried lumber, your warping/cupping/twisting will be minimized. Wood selection is a key factor to minimize the movement.

I live in a dry climate. When we have rain, especially storms that last multiple days, all of my solid doors swell. When I built the doors, I took the movement into account. They were all built with m&t joinery, and a few have raised panels. Some of these doors are more then 20 years old, and look just as good as the day they were built.

Different species of woods move at different rates. Take a look at to help with how much wood moves.

-- Nicky

View tbone's profile


275 posts in 3650 days

#4 posted 05-28-2013 09:39 PM

While ash is okay for exterior use, a better choice would be white oak or mahogany. The other posts that mention quartersawn lumber is also excellent advice.

-- Kinky Friedman: "The first thing I'll do if I'm elected is demand a recount."

View joeyinsouthaustin's profile


1294 posts in 2038 days

#5 posted 05-28-2013 10:06 PM

Assuming that this is not a stile and rail door, but a glued up slab, like your table tops…

IMO you need to work the wood some before the glue up. I always find the boards with tension in them in this process, and weed them out. In my experience, when I do a slab mahogany door or other door, I always stick and rest the wood in the shop about three to four weeks. Then I joint square and plane, stick and rest again, then go to final dimensions and glue up. I would recommend going to this extent for a door, and then cnc plane to final if you are wanting. On a slab door, I usually run a tongue and grove, rather than just a butt joint for the extra strength an exterior entry door needs. And remember to follow all good glue up rules, including opposing the cup and bow if not using quarter sawn.

+10 to tbone See this chart (i included a link if you can’t read this) Ash scores in the worst catagory for exterior durability, and in San Fran that would be something to think about.

-- Who is John Galt?

View mazzy's profile


56 posts in 2545 days

#6 posted 05-29-2013 01:06 PM

Great advise! Thanks to all of you.


-- Mazzy, San Francisco Bay Area,

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