Sizing boards for joinery

[GF SMITH]

New to the forum and woodworking.
I am building a cedar chest and the lid (3/4" x 20" x 45" ) will be 4 boards  3/4" x 5" X 45" joined together on edge. I plan on using my new joiner for a good joint between the boards. My question is, how much wider do I cut the 5" of each board in order to use my joiner to ensure a good fit between the boards and remain at 20"?

[Aram]

New to the forum and woodworking.
I am building a cedar chest and the lid (3/4" x 20" x 45" ) will be 4 boards  3/4" x 5" X 45" joined together on edge. I plan on using my new joiner for a good joint between the boards. My question is, how much wider do I cut the 5" of each board in order to use my joiner to ensure a good fit between the boards and remain at 20"?

Welcome to the forum.


Note: EDITED since first rushed post

The dreaded answer, "it depends." Are you relying on sizing boards to width, taking a single pass on the jointer (with no chance of more passes), and expecting the boards to glue up to final size? Or are you willing to trim it a bit to width after glue-up (<=== hint, I would totally do this).

If your boards are straight to begin with, then they will have to be oversized by your depth of cut, for each jointed edge. Are you jointing after a table saw cut? If not, and if you are using your jointer not just for a final pass, but to straighten your boards, then the answer depends on how much sideways curve your boards have. 

Answer assuming you have basically straight boards to start with: set jointer for a very light cut. Find a straight piece of scrap, and edge-joint the first few inches of it, leaving the rest. Use a double square to find out the depth of cut. If you are confident in your technique and assume 1 cut per joined side, then the rest is just math (amount to oversize is depth of cut times the number of jointed edges). 

If you have a table saw, or perhaps a band saw, or are adept with your longest hand plane, build the entire panel oversized by 1/4 inch, or whatever you are comfortable with, and trim the panel to size after you glue it. I can't imagine doing it any way but this.

Sorry for the long reply. One related thing. If you can manage it without tearout, flip every other edge around before you joint. That way, if your jointer is  hair off of 90 degrees, the mating surfaces will compensate (one will be over 90 deg, the other under by the same amount).

[jteneyck]

Unless there is some compelling design reason where each board has to be exactly the same width, build it oversize and trim to width after glue up.  That will allow you to joint each board as needed until you get good fitting joints.  It also will allow you to use clamps without having to pad them to prevent dents, etc., because you're going to trim/joint the edges afterwards.  Same thing in terms of final length; build it oversize and trim to length after glueup.  


John

[cputnam]

A mechanical jointer will not produce as good an edge as will a hand plane. Match each pair together and plane away. That said, I agree, glue up first and then trim to size.

[Kudzu]

Unless there is some compelling design reason where each board has to be exactly the same width, build it oversize and trim to width after glue up.

This. Typically you make your glue-up oversized and then trim it to fit.

How much you take off with a joiner will depend on how good the edge was to start with.  if it is straight one pass might be enough.  If it was a bow it might take several passes. Joiner isn't like a table saw where you set the width and one pass and you done.

[Gary G™]

When I’m being anal about the look—which is almost all the time—and I want all the boards to be the same width, I mill the inner ones to the final size.
I mill the 2 outer edge boards wider, then rip to finished size after the glue up.
I don’t use a jointer to get to final width—I typically use the table saw or planer (boards on edge) or hand plane—in this order.

[Dumb_Polack]

Gary?

You run boards through the loaner on edge??  Really?  

I wish I had your nerve in my tooth!!

[GF SMITH]

Thank you for your responses...great advice! 
I will run my boards, a little oversized, through the "jointer" and trim for size (length and width) after final glue-up. 

Another question:
Are there pros and cons joining the cedar boards with biscuits and/or dowels?

I'm glad I caught up with y'all.

[jteneyck]

Thank you for your responses...great advice! 
I will run my boards, a little oversized, through the "jointer" and trim for size (length and width) after final glue-up. 

Another question:
Are there pros and cons joining the cedar boards with biscuits and/or dowels?

I'm glad I caught up with y'all.

The obvious pro is easy alignment, especially if the boards aren't perfectly flat.  The con is making sure alignment of the biscuits or dowels doesn't make it worse.  Personally, I hate dowels because alignment has to be perfect between the mating boards but there are those who do well with them.  If you use either make sure to always register off a common face.  

John

[rwe2156]

Depends on how much you have to joint off. You might have to start with a 6" board. If they are pretty straight, joint one edge and rip to 5 1/4, still leaving enough for final jointing.

I recommend alternate the faces when running through the jointer this cancels out any slight discrepancy off 90 in fence.

If you plan on hand planing, be sure the grain direction on the face sides are the same.

Best not to plane down to finish thickness prior to glue up or you make like a little more difficult.