Breadboard End Design "Rules"?

Well, if not actually "rules" then guidelines:

1] Tenon length [projecting into the breadboard] as a proportion of breadboard width?
2] Given answer to item 1 above, anything other than tenon length/breadboard support inherently wrong with a wide [6"] breadboard, as opposed to narrower [3" - 4"]?
3] Max width [running along the edge of the table] of an individual tenon? [I understand the need to allow for wood movement in mortise design - that's not really my question].
4] Total amount/percentage of table width that should remain behind as tenons after the sawdust stops flying? Or, conversely, how much table should be removed between tenons to maintain structural integrity between the breadboard's mortises?
5] Would drawboring the pins through the slots in the outer tenons create too much friction for the tabletop movement to overcome? Well, without making splinters fly - I know you can't stop the top from moving, I'm just wondering if drawboring would cause the pins to bind, and buckle/break.

If it matters - table top will be QSWO, 42" wide, 1" thick [maybe up to 1-1/4", but I'm thinking 1"].


Gratzi

These are good questions. I was also inquiring about the recommended width of the breadboard ends. I guess it is up to the design and perhaps using PHI I could get a good idea *shrug* but always looking for suggestions.

shameless bump. This was in Design forum, but no response - and I know there are a lot of opinions running around out there. The Mod Squad was kind enough to relocate to Gen WW, to see if anyone has any input for me.

TIA

Kent

I don't know that here are "rules, or guidlines" to follow. I generally do whatever I feel is right. IMHO I put ends on breadboards simply to prevent warpage. (this doesn't guarantee it won't warp, depends on how you use and care for it) The deeper the tennon the weaker the edge and more prone to "snap off" I've dowelled ends, M&T ends, glue joint bit ends, haalf lap, T&G ends. I haven't really noticed any "one" to be the best method. My preference is to use a glue joint bit on the field panel, then use the same joint on the ends. I then drill in short dowels of contrasting color mainly for the look. (dowels don't need to be deeper than 3/8") Many years back I bought a prefab "cutting board" (didnt have much equipment then) and still use it to this day- no ends just edge glued wood. It doesnt twist or warp as long as I take care of it.
Unless you're hard set on having a "solid wood" BB most cab shops simply use MDF with solid edges and call it a lifetime - My folks BB is 35 + years old and still holding up. If you plan on actually using is with a good quality SHARP knife daily, I would go solid wood.

I use a slot cutter to cut the mortise so the depth is not all that much - but I've never had any problems with a fairly short tenon. If you make two passes with on a router table, and turn the board over between passes, you can guarantee the mortise is centered. Then make your tenon to fit the mortise.

MUCH more difficult is the making of the tenon - keeping it centered between the surfaces of the top and of even thickness. The problem is that the table top often has a bit of a cup to it. I've tried cutting the tenon on a table saw but you have to make sure the top is pressed down well at the blade so that the tenon is centered and of even thickness. I've tried on a router table and you have the same problems. A friend suggested using a hand held router so that you follow the cup of the top, but the problem is aligning the shoulders top and bottom.

I'd appreciate hearing how other people cut the tenon on breadboard ends.

Mike

[added note: I only glue the tenon into the mortise in the center of the table, maybe two inches worth. I then use two screws towards the outside of the breadboard and elongate the holes so the top can expand and contract. I counter bore the screw holes and plug them with wooden plugs. The width of the breadboard end is just based on what I think looks good - I've never used any "rule".]

Mike,

I just made some BB ends (probably the 4th set I've done so far) and in the past it was tough to get the top and bottom to line up evenly so the BB end piece was flush with both top and bottom. I used a technique I picked up from FWW (I think?) where I slipped a collar of sorts over the end of the table to use as an edge guide and clamped it in place. I used a piece of 4" wide or so 3/4" MDF top and bottom, about 6" longer on each side than the table width. I used offcuts of the table top material that were the same thickness as the table top and attached them in between the MDF to make the collar. Run it through your table saw to flush up the MDF and guarantee your pieces of MDF are flush and they will serve as your edge guide for a router or circular saw. I used a router and snuck up on my mortise size and it worked great.

Quote:

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Originally Posted by Matt Day

...... slipped a collar of sorts over the end of the table to use as an edge guide and clamped it in place. I used a piece of 4" wide or so 3/4" MDF top and bottom, about 6" longer on each side than the table width. I used offcuts of the table top material that were the same thickness as the table top and attached them in between the MDF to make the collar........

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Mike - thanks for the heads up. I can see that centering the tenon is the big issue. Your comments on cutting the mortise and assembly/glue match with what I understood - no issues there.

Matt - Found that info on FWW - thanks. Specific to the issue Mike raises, I don't see how this corrects for a bow in the table top? It seems that by using table top offcuts as "spacers" between the mdf [or ply in the FWW info] means that the mdf strips will bend to follow the curve in the [bowed] table top?? If I could make the collar out of something that stayed dead flat, in spite of any bow in the table top, then I can see how the collar would give me a known, flat, reference surface to cut the tenon, regardless of any imperfection in the table top's surface plane.


Hmmmmmm.....maybe I have to be prepared to deal with it by rasping the outer tenons as required to fit the mortises, and using some 1/64" shim material I have to fill the opposite side where I do. Then, if I start with the breadboard a hair "fat", I can plane/sand it back to match the top.

Of course, make the table top dead flat and there are no issues, right? :D 'Cept @ 42" finished width [and no access to a drum or wide-belt sander], I have to be prepared for the coriolis effect to cause a slight curve - couldn't be my glue-up skills.

Thanks, guys- I will ponder. I'm some weeks out from tacking this specific issue.

Kent

Well, I don't know what the rules are either, but I do have some points to consider. The wider the breadboard, the more leverage will be applied to the tenon if someone leans on the table end. I put ~6" wide breadboards on a Mesquite dining table I built but then I put curved, laminated aprons on the ends to help support it.

Tenon length, IMHO, needs only be long enough to accommodate the pins...the bigger diameter the pins, the longer the tenon needs to be. You do need some meat on the tenon outside of the pin holes to provide structural strength, especially in drawbored tenons.

For a 42" wide table, I'd break the tenon width up into three, equal-length tenons with two corresponding haunched areas (for lack of a proper description) In other words, make three tenons 1 1/4" long and ~8 3/8" wide with two areas that are only 1/2" long and ~8 3/8" wide.

That's how/what I did. Someone with more experience may have a better layout.

Cody - good point about "elbow leaners" at the table. Hadn't considered that. thanks. .

Yeah - I had kinda thought 3 tenons as well. 5 seemed like [a] overkill and [b] not necessary to prove I can make the tenons.

Question: The table top will be out of 5/4 rough. Net out as fat as I can make the boards. I understand that structurally, taking the pins al the way through the top helps, but I'm not sure I wanna do that. If I came up from the bottom to, say, 1/8" - 3/16" from the top surface, is there anything there to be concerned about?

Kent,
I don't have a drum sander either and built a table that's about 40" wide with BB ends and it's pretty much dead flat - don't be too concerned about a little bow. Even if you have a slight bow, the small footprint of a router will make the tenon consistently thick.

I recently built a trestle dining table with breadboard ends. The tabletop was 42" wide. The breadboard ends were 2-1/2" wide. My "stub" tenon was about 1/2" while the longer tenon extended to about 1-1/8" long. I made five "long" tenons that were each about 4" wide. My procedure went like this:

(1) route 3/8" wide groove, 1/2" deep into the breadboard ends

(2) cut five 3/8" wide mortises 1-1/4" deep into the breadboard ends (I used a mortiser)

(3) use an MDF "sleeve" as has been described in this thread as a straight edge to route each side of the tabletop to form tenons on the ends; sneak up on the thickness required to fit into the mortise (I left mine slightly thicker than required)

(4) form the five "long" tenons (I used a coping saw)

(5) plane the tenon by hand until it fits the mortises in the breadboard end (I used a Stanley #92 shoulder plane)

(6) mark, drill, elongate the outer holes, and pin the five tenons using a drawbore method with 3/8" dowels (I pinned from underneath the top so that no pin was visible); glue the center long tenon

Be sure to make the breadboard end stock a little bit thicker than your tabletop since your mortise might not be perfectly centered but your tenon most likely will be. You'll plane and sand that down flush after installation.

By the way, I started with 5/4 material and I ended up just a hair shy of 1" in thickness for the top.

resurecting this old thread.....

would like to hear opinions on attaching BB ends for less wide tops (~20") as might be seen on blanket chests...

On the NYWS design, Norm A. has the BBs 2.5" wide with a straight tounge and groove.... with the toungue 1/4" thick and only 3/8" tall. It appears that he glues this all the way accross.

Seems like it defeats the idea of providing for expansion and make it purely a cosmetic detail. But then the top isn't very wide.

I'm looking at cutting the groove with either a dado stack or a slot cutter on the router table and then using a rabbet bit with a pilot bearing to cut the tongue.... sneaking up on the thickness with mulitple passes, adjusting depth.

Fortunatley my top came out very flat, and I can press what minute bow there is flat against the router table.

Any thoughts on whether I'd be better off cutting the tongue first and then using shims on my dado stack to fit the groove to it?

Ay thoughts on gluing this up all the way across? There doesn't really seem to be enough room for pins or screws.