LumberJocks

Case design to allow for wood movement

  • Advertise with us

« back to Designing Woodworking Projects forum

Forum topic by DBordello posted 07-31-2015 08:16 PM 555 views 0 times favorited 6 replies Add to Favorites Watch
View DBordello's profile

DBordello

132 posts in 686 days


07-31-2015 08:16 PM

I am planning in building a grandfather clock using 4/4 Walnut. However, it is a case like any other.

It will be approximately 9” deep, 14” wide, and 78” tall. It will have two sides, a top, bottom, and mid-shelf. The front will be open, and a nonfull height back.

Full drawings

However, I am concerned about wood movement. Since I assume I don’t want the end grain showing on the top/bottom/shelf, the grain of the top/bottom/shelf well be different than the back. A couple of questions:

1. How should I attach the back? Leave it loose in a rabbit? Dado? Something else?

2. Is it better to place the top and bottom in dados, or rabbits? Dados seem more secure, but a rabbit would be more visually appealing.

Any insights are appreciated.


6 replies so far

View Kazooman's profile

Kazooman

623 posts in 1411 days


#1 posted 07-31-2015 08:30 PM

You really need something to keep the frame from racking. Imagine it without any back on it. You could put your foot on the bottom to hold it in place and easily press the top from side to side. A plywood back could be attached and would provide the desired support. You then just need to figure out a way to install a walnut panel that matches your stock on the interior for the visual effect.

View DBordello's profile

DBordello

132 posts in 686 days


#2 posted 07-31-2015 08:33 PM



You really need something to keep the frame from racking. Imagine it without any back on it. You could put your foot on the bottom to hold it in place and easily press the top from side to side. A plywood back could be attached and would provide the desired support. You then just need to figure out a way to install a walnut panel that matches your stock on the interior for the visual effect.

- Kazooman

This is a concern of mine as well. I really would like to have the back for strength. However, I don’t want the thing to rip itself apart either. Wouldn’t the plywood also constrain movement?

View Kazooman's profile

Kazooman

623 posts in 1411 days


#3 posted 07-31-2015 08:46 PM

All of the places where the plywood is nn contact with the sides, top and bottom are long grain situations. Not much movement there. Most of the wood movement will be front to back, and along a 9” span it will not be very much. . If you were to make a 14” panel out of your 4/4 walnut stock, with the long grain oriented from the top to the bottom of the case, like the sides, then it would expand from side to side. That would be a problem with the top, bottom and shelf restricting any movement.

A plywood back in a rabbit would be the typical way to build the case. If walnut veneer plywood would match your other stock that would be the easiest way to go. If you do need to use your 4/4 stock you just need to allow for expansion by allowing the panel to float in shallow dados, or perhaps floating with some molding at the edges to hold it in place while allowing for movement.

View DBordello's profile

DBordello

132 posts in 686 days


#4 posted 07-31-2015 08:53 PM

I see. The plywood wouldn’t expand, so we are good if we go that route. Would the floating 4/4 provide any strength? I’d assume since it is floating, that it wouldn’t participate.

View Kazooman's profile

Kazooman

623 posts in 1411 days


#5 posted 07-31-2015 09:03 PM



I see. The plywood wouldn t expand, so we are good if we go that route. Would the floating 4/4 provide any strength? I d assume since it is floating, that it wouldn t participate.

- DBordello

It would just be there for good looks. I assume that the case will have a nice door on it with glass to show off the workings of the clock movement. You do want the back on the inside to look nice, but in reality it will not show very much. It could even be flat black, for that matter, depending on your personal taste. That’s why I mentioned walnut veneer plywood. You might be able to stain it to match your other stock. If you simply must have the same wood, then a floating interior panel would provide the visual effect, without causing problems from wood expansion. You do need something like the plywood back panel for structural support.

View DBordello's profile

DBordello

132 posts in 686 days


#6 posted 07-31-2015 09:05 PM


I see. The plywood wouldn t expand, so we are good if we go that route. Would the floating 4/4 provide any strength? I d assume since it is floating, that it wouldn t participate.

- DBordello

It would just be there for good looks. I assume that the case will have a nice door on it with glass to show off the workings of the clock movement. You do want the back on the inside to look nice, but in reality it will not show very much. It could even be flat black, for that matter, depending on your personal taste. That s why I mentioned walnut veneer plywood. You might be able to stain it to match your other stock. If you simply must have the same wood, then a floating interior panel would provide the visual effect, without causing problems from wood expansion. You do need something like the plywood back panel for structural support.

- Kazooman

Ah, I see. I think that actually is a pretty good plan. Plywood back (in a rabbit?), with a false walnut panel for looks.

Thanks for walking me through it!

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com