I've received my custom order Bi-Fold doors which I was planning on
hanging like french doors with 2 hinges on the outside edge of each
doors. I've mortised the doors and the jambs to mount the hinges and I
am now trying to figure how much space to allow around the doors for
them to open and close properly. I was thinking:
1/8" for the Top
1/4" for the Bottom
1/16" X 2 for both hinge side
1/8" for the middle where the 2 doors meet.
I know I will probably have to bevel the back inside edge of each door
so that they open without rubbing each other. How much of a bevel will
I need? How can I figure this out?
Your estimates of spacing sound pretty good. I usually see between 1/8
and 1/4 between panels. If you were planning on installing an astragle
(spelling?) strip to cover the space between the doors, I'd go 1/4. If
after you have installed the doors, they touch. Pull a panel up snug to
the other and trace the line. Take the hinge pins out and set the door
up for your largest hand planer. Use the traced line as your guide to
bevel to. Or measure the distance from the edge to the mark and split
the bevel between the two panels. I'm that picky.You should find that
it is a very slight bevel, maybe 2 or 3 degrees. It will be a tighter
angle for more narrow doors.
Tom in KY, with a french door that needs planing in my own house.
I wasn't planning on using a strip between the two panels but I would
like to get the doors as tight as I can. I don't have any hand planers
and so was thinking of beveling the doors on the table saw. Do you
think that a bevel of 0"-1/8" from front to back of the 1-3/8" doors
would be sufficient or should allow more? BTW the doors are 13-3/4"
Trigonometry. Let width of the face of the door from the hinge point
to the opposite edge have dimension 'A' and the thickness of the door
have dimension 'B'. The length of the radius that the back edge of
the door swings through will be 'C'.
C = sqrt (A^2 + B^2)
You don't give the width of the doors but for example, say they are
12" wide from the hinge pin to the opposite edge and 1 1/2" thick.
Then C = sqrt ( 12 * 12 + 1.5 * 1.5) = 12.093", so with zero gap
between doors there would be 2 * .093" or approximately 3/16" of
interference between them if you tried to open them simultaneously.
With only 1/8" gap then you need to back bevel each door enough to
remove 1/32" on the back side. The required angle can be determined
by taking the arctangent of (1/32) / (1.5) or a bit over 1 degree.
Of course this kind of precision is foolish when working with wood,
and it's not quite exact if the hinge pin is proud of the face of the
door, but you get the idea.
You have a carpenter's best production answer and a good scientific
formula to determine the tolerance required.
But if you are worried about the hinge pin location or the swing of the
doors in relation to the pin location, Maybe you should find a scrap of
ply-wood or a piece of 1x6. Draw the doors as you would want them to
look and when you have the spacing that is acceptable, Use tramel
points or a home-made compass to mark the swing of the panels. One
point in the middle of the hinge pin location and the other at the
furthest corner from the hinge where the doors meet. Then mark the
other swing for the other door. If the radius marks cross then that is
the amount you need to remove.
* being your hinge pin location and I/ pointing to the other point
most likely to rub the other the other panel.
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