Sizing Cabinet Doors to Tolerances

Layout tips for a beginner, plus advice on final sizing after assembly. October 20, 2013

Question (WOODWEB Member) :
Ive been building cabinet doors for the first time, square-sticking flat-panel, shaker stile. Im happy with the results, but I find that building cabinets with two doors is difficult when laying out the measurements correctly for the rails. (Im not having any issues with actually cutting and putting together.)

For example, I have a span of 40. Im using Blum soft-close hinges so I have quite a bit of adjustment once installed. I start with a 40 opening for the two doors, edge-to-edge. I subtract 3*(5/64) from 40, 5/64 gap on each side of the door and the gap in the middle, then divide that by two for the width of each door. The rails have a 1/2 tenon on each side.

So, now I determine the rail length by subtracting the width of the two stiles from the width of the door and adding 1 for the two tenons. Ive been going through this calculation with excel, and for this case I end up with 12.13281. Ive been rounding this to the nearest 32nd, about. Im guessing there is an easier way to do this (I can use metric too). Maybe I just need a better yardstick with 32nd's. I'm just estimating. Any help is appreciated!

Forum Responses
(Cabinetmaking Forum)
From Contributor G:
Use a 1/16" as your number instead of 5/64 and then you can sand the little bit off to size them. Or if you are trying to get perfect sized doors out of the clamps then subtract 1/64 from each stile.

From contributor X:
I would oversize the doors and trim them down to the correct size until you get a handle on things. There is more to getting accurate sized doors than just having a good math formula. It is crucial that all parts are cut to exact sizes (stile width & rail length need to be dead-on). Every little variable adds up,1/64's and 1/32's add up to 1/16's real quick if parts aren't cut accurately.

From contributor P:

Also keep in mind that if you set up your shaper fence to take a little bit off when you do your cope cuts you need to account for that.

From contributor U:
Excel. The bit of time for you to put together a mini spreadsheet to do single doors or whole jobs will pay back big in the long run.

From the original questioner:
I appreciate all of the suggestions. I think my next set of doors will be a lot easier now, hopefully without having to think as hard about it all. I bought a 24" jumbo caliper and it's really great for dialing in the shoulders on the tenon. I stacked the stiles side-by-side and put the tenon from one end of the rail into one of the stiles. I then measured the whole thing with a big caliper from one side of the stile all the way across to the other shoulder of the tenon. If I make the rails a bit oversize then I can just take a little bit off of the shoulder. This caliper reads metric too, so I find that easier. The caliper with excel is a pretty good combination.

From contributor M:
The simple response is that experience will make the door building process easier and quicker. If you are getting down to 1/32 to 1/64 of an inch in you calculations you have to realize that your table saw scale/fence needs to be that accurate and you have to push the wood through accurately. The cope and stick setups on the shapers have to be that accurate. The simplest method I found is to build to the full opening size then join off what you need to make the fit and clearance. Note you don't want to take too much off the stile because it may affect the appearance. In my opinion you are over-thinking a simple process.

I always build to the opening size while over sizing my doors by 1/16'' by increasing the width of the outside stiles by 1-32''. That way I don't need a caul when I clamp to protect the edge surface. Once the doors are together I join off from each side what I need to make the fit right, which gives me a little latitude for a custom fit if needed.

There are many ways to build doors, almost as many ways as there are cabinetmakers. I've been building doors since 1970. On some projects I finally gave in and bought doors from Conestoga - they are inexpensive in comparison to building your own. Like I said, ''on some'' projects''. I enjoy having control with grain selection and design so I do build most of my doors. In time you will find what works best for you.