Stuck on a project - need guidance

[Cpl_Eyeball]

I have been working on a desk for my daughter already for at least 2 years on and off (mostly off).  This is my first project using mortise and tenon joints and I think I am just afraid to take the next step with gluing everything and the drawer slides installation.  What words of wisdom can you offer to give me that much needed nudge?

Questions:

1. Should I tape the tenons, apply the finish and then glue or the other way around?
   
2. After I planned the 3 boards for top and glued them, the panel ended up being slightly under 3/4" -  is that too thin for the top?
   
3. How should I attach the top to allow for expansion?
   

This is the book from which I found the plans:

[jteneyck]

Following your question:


1)  My rule of thumb is whichever way is easier with respect to finishing.  If you finish first you can't make any adjustments with how parts fit together afterwards.  That alone generally drives me towards finishing last.  But there are some cases, like when you have a lot of slats or spindles really close together that would be nearly impossible to finish after assembly, that make it much easier to finish first.  Sometimes I use a hybrid approach.  For example, I would finish hardwood panels that go into frame and panel construction before assembly.  Plywood panels, like you are using, I don't.  

2)  My opinion is that top will be plenty rigid enough even if only 5/8" thick.  

3)  Several ways to attach the top with respect to expansion.  The easiest is probably fixed screws at the rear, and screws in slotted holes at the front and anywhere along the sides.  That keeps the top aligned to the back but allows for expansion.  

John

[jppierson]

Finish the inside surfaces as desired/required before assembly so taping the tenons would be a good thing, as well as avoiding finish inside the mortises.

If you look at antique furniture, the surfaces that are unseen often still have saw marks they didn't bother to finish as a matter of efficiency. Mating surfaces must be smooth and tight for good mechanical connection. Glue is NOT a gap filler.

From the looks of the desk design, the 3/4 should suffice, it isn't like you will be stacking a tremendous amount of weight over a long period of time on the top anyway.

Yes, you MUST account for wood movement of the top. There are a variety of methods to allow for movement, the choice is yours based on access to the underside of the top during assembly. Often, the center ends of the top are securely fastened, then as you move away from the center the fastener shanks are placed in elongated holes so the top can move seasonally, or button blocks are used where one edge of the button fits into a groove in the side that allows the button to pivot. Alternatively, you can securely fasten the front edge of the top use similar fastening strategy to allow all movement toward the back. Another options is bread board ends on the ends of the top. In this case movement is allowed inside the tenon of the breadboard end, and the bread board end is fastened to the sides, this technique is often used on tabletops.

[ez-duzit]

Apply the finish last.

[Cpl_Eyeball]

I have never attempted to glue a project this size before - with this many tenons, do I have to use a glue with long open time to allow me to square everything up?

[John S in VA]

I have never attempted to glue a project this size before - with this many tenons, do I have to use a glue with long open time to allow me to square everything up?

Don't try to glue everything at once. Break it down into sub assemblies you can glue and square at a pace comfortable for you, like two legs and a panel. Once you have those done connect them to form a drawer case, and so on.

[jteneyck]

Don't try to glue everything at once. Break it down into sub assemblies you can glue and square at a pace comfortable for you, like two legs and a panel. Once you have those done connect them to form a drawer case, and so on.

This ^.  Glue up the end panels first.  That's just 6 joints.  Then glue the stretchers to the end panels.  That's 12 joints, but only 6 on each side, so do one side first, then the other, then clamp it all square.  If that seems too daunting use TB Extend or liquid hide glue.  

John

[brianwelch]

I have been working on a desk for my daughter already for at least 2 years on and off (mostly off).  This is my first project using mortise and tenon joints and I think I am just afraid to take the next step with gluing everything and the drawer slides installation.  What words of wisdom can you offer to give me that much needed nudge?

Questions:

1. Should I tape the tenons, apply the finish and then glue or the other way around?
   
2. After I planned the 3 boards for top and glued them, the panel ended up being slightly under 3/4" -  is that too thin for the top?
   
3. How should I attach the top to allow for expansion?
   

This is the book from which I found the plans:

I am by no means an expert, but recently experienced the issue of excess glue squeezeout preventing uniform color where I was staining/sealing the wood afterwards...I was admittedly a little careless, but it is unlikely that even with 100% attention to taping/protecting that there would not have been some issue as a result...

[thewalnutguy]

My choice is to finish first as much as possible. That way it's easy to finish right up to an edge, sanding between coats. During glue-up, any squeee ut can easily be removed from the surface, especially if a bit of wax has been applied to the exposed surface prior to glue-up. 
For clamping top to carcass, I make up some small cleats, about 3/8  thick for majority of length, 1/8" for about a quarter of an inch. Dado/route a 1/8" thick slot into the edge of the carcass piece for the tongue of the above pieces to slide in, then screw the piece to the underside of the top. 

[stav]

There was a Woodsmith Tip email that went out a couple of weeks ago where they demonstrated a method for glue up that limited squeeze out and provided a good bond. I think the jist of it was that most people use way too much glue and have poor application technique.  

You can view them here https://www.woodsmithvideotips.com/tips

I can't find the specific one in my inbox.