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Table 'frame' question

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Forum topic by Mark posted 961 days ago 1099 views 0 times favorited 8 replies Add to Favorites Watch
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Mark

14 posts in 1072 days


961 days ago

Disclaimer: I’m pretty new to woodworking, learning as I go.

I picked up some rough cut beetle-killed ponderosa pine lumber, and have been working on turning it into a coffee & dining room table. The wood itself is gorgeous, but it needs something to ‘finish’ it. I came up with the idea of doing a frame of sorts around the perimeter of the tables. My plan is to build the frame out of ‘clear pine’ from one of the big box stores.

As I understand it, the wood of the main table will tend to expand most across the narrow end (my boards are running lengthwise). I’m afraid that my corner joint may be torn apart by this movement. Can anyone lend advice as to whether I ‘should’ be okay, or if I should do this some other way?

The orange & tan pieces will be 1-1/2” x 3/4” thick, with a glued half lap joint. I’d like to dowel these, but they may just end up being cosmetic plugs rather than structural dowels. The blue & purple boards will be 3” x 3/4” thick, joined to the 1-1/2” stock with glue & biscuit joints. My dovetails & box joints aren’t quite up to snuff yet, so I was thinking of doing a doweled butt-joint on these pieces.

Thanks for the help!

-Mark

-- Measure it with a micrometer, mark it with chalk, cut it with an axe, and hammer to fit.


8 replies so far

View PurpLev's profile

PurpLev

8476 posts in 2274 days


#1 posted 961 days ago

maybe I’m missing something here Mark, but why do you have so many boards to make up the frame of the table?

usually the frame only consists of 4 parts making the rectangle (general shape). in your case it seems like there are 8? did you intend the uprights to be the apron? if so, they should not be glued to the top’s frame all around but only jointed where they will allow movement.

the real movement you want to control here is the movement in the main top’s panel which resides within the frame. thats the purpose of the frame – to allow for the panels movement. although again, in this case (table) I’m not sure it’s necessary to have a frame.

all a personal persrpective though, and yours/others may vary.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Mark's profile

Mark

14 posts in 1072 days


#2 posted 961 days ago

This frame is purely cosmetic, but yes, to completely frame the main table top, there will be 8 boards. The blue & purple boards are there as an apron of sorts, to give the perception of greater thickness or heft in the table top. The orange & brown boards will just be to provide contrast to the greyish-blue streaking in the main table top boards. As far as why there are so many boards, I suppose that’s a factor of being new to woodworking and not really knowing what I’m doing. :D lol

The purple and blue boards aren’t the true apron in the structural sense. There will be a secondary apron (which won’t be visible) set back from this edge (under the table, if you will) that will be the true apron supporting the table top.

Here’s a view from underneath the table, showing this same joint, if it helps any:

-- Measure it with a micrometer, mark it with chalk, cut it with an axe, and hammer to fit.

View PurpLev's profile

PurpLev

8476 posts in 2274 days


#3 posted 961 days ago

hmmm. there are 2 thouhts that I’m having. 1 is to alter the design to accommodate the wood movement based on initial visual from you design, but that means to change your design and I would not want to do that -since it is YOUR desgin.

the other thought is to keep this design but use lumber to accommodate it (the reverse technique). in which case I would recommend you use quarter sawn lumber for the ‘uppoer’/top frame so that the wood movement on both frames would match up if the lower frame is plain sawn in which case the wood movement on both frames would tend to be up-down (oriented when looking at the top pic above). otherwise you’ll have 1 frame wanting to go up-down and the other wanting to move in-out which would create unwanted stresses in the frame components and could cup/twist the entire frame (theoretically speaking of course).

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View Mark's profile

Mark

14 posts in 1072 days


#4 posted 961 days ago

Well, I’m completely open to ideas or suggestion on how to better go about this; that’s part of learning, isn’t it?

Really the only two design ideas I’d like to incorporate are the 1-1/2” frame around the top, as well as a 3” tall edge. If either of them are impossible or may cause damage, I’ll have to rethink the design. From what I’ve seen here on LumberJocks though, nothing is impossible.

-- Measure it with a micrometer, mark it with chalk, cut it with an axe, and hammer to fit.

View PurpLev's profile

PurpLev

8476 posts in 2274 days


#5 posted 961 days ago

like you said – nothing is impossible, and every idea is a good one – as long as you know how to match the lumber and joinery to it which is why I am hesitant about offering any changes to the design you posted, but rather point out the issues at hand that should be addressed. in this case you have 2 frames with different grain orientation that will lead to wood movements in perpendicular directions which is something to avoid. using QS (quarter sawn) lumber for the top frame would address this to a certain degree. another option is to keep both frames not glued to one another allowing them to move in relation to each other.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View tom427cid's profile

tom427cid

294 posts in 1096 days


#6 posted 961 days ago

You might want to consider using a tenon for the end piece.Secure it in the middle but allow the pins on the end to accomodate movement of the top. The advantage of the tenon IMHO is that it reduces the tendency of the top to bow or cup.
Just an idea.
tom

-- "certified sawdust maker"

View HerbC's profile

HerbC

1161 posts in 1485 days


#7 posted 960 days ago

Mark,

The design you’re proposing will almost certainly fail due to the expansion and contraction of the main panel in the top of the table. If the table is 36” wide the top will “move” between 1/4 and 1/2 inch due to seasonal moisture changes. The Shrinkulator gives estimates that can be used in designing. The problem you will have with the “fixed” edging you’ve designed is that either the panel will expand after it is built, in which case the joints will tear apart at the corners, or it will shrink after it is built and the panel may split. Better to use some variant of breadboad ends, properly designed to allow for the movement and add trim to the long sides to make it look thicker there…

Good Luck!

Be Careful!

Herb

-- Herb, Florida - Here's why I close most messages with "Be Careful!" http://lumberjocks.com/HerbC/blog/17090

View Mark's profile

Mark

14 posts in 1072 days


#8 posted 960 days ago

Herb,

That’s quite the handy site there, and thanks for the warning on the corner joints just not holding.

Thanks for the tip on the breadboard ends – those are new to me, but look quite doable. In the quick research I did, the designs I’ve seen of the breadboard ends suggest not doweling all the way through the top and/or the breadboard end. Is there any reason that I can’t dowel clear through the end, if only for cosmetic reasons? I understand ‘slotting’ the holes in the tenon portion, but I think the contrast of a dowel showing through the breadboard end might be an interesting feature.

Also, I plan on finishing this table with General Finishes High Performance Water Based Topcoat. Since the table top will be completely coated & sealed, is expansion from humidity changes still a concern? I live in relatively dry Colorado, where we don’t see large humidity swings. I’m not sure if this changes anything, but thought I’d ask.

Thanks for the help!

-- Measure it with a micrometer, mark it with chalk, cut it with an axe, and hammer to fit.

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