Replies

1. 
   SgianDubh | Mar 30, 2003 01:39am | #1

   That's kind of a big subject there, Dave, but you're right to be concerned with expansion and contraction of the tenoned part into the mortice. I think there was a topic that discussed this just recently here, and you might be able to find it-- but I could be mistaken.

   Anyway, 5" to 5-1/4"  is quite a wide tenon, and I'd suggest that you do allow a little wiggle room. At that width, you're almost into needing to make a forked tenon. It's right on the borderline. If your tenon is exactly 5" wide, it would be a good idea to make the mortice just a bo'hair longer, say 5-1/32", or maybe 5-1/16" just to let the rail tenon have a bit of expansion/ shrinkage room in the mortise.

   Generally allow about 1/8" expansion and contraction per foot width. This is a bit too much for some woods, and maybe a bit too little for others, but it's a fair average.  Slainte.

   Website    The poster formerly known as Sgian Dubh.

   
   

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   Edited 3/29/2003 6:40:54 PM ET by Richard Jones

1. 
   LD | Mar 30, 2003 02:14am | #2

   OK, I understand about allowing some breathing room in the mortise.  I usually do that anyway to allow space for excess glue, but would it be wise to apply glue to the bottom 3.5 to 4 inches, and allow the top of the tenon to float?

   Dave

1. 
   SgianDubh | Mar 30, 2003 02:22am | #3

   No, Dave. You seem to be worrying more than necessary about the leg splitting because of it being glued. That's not a real problem in my experience. Just allow a bit of wiggle room and glue the whole thing up. If you're using a PVA type glue, such Titebond(sp) it never actually goes completely glass hard anyway. Slainte.Website    The poster formerly known as Sgian Dubh.

1. 
   LD | Apr 02, 2003 03:41am | #5

   Due to the complexity of the glue-up, I'll be using a urethane glue.  Does it allow some creep?

1. 
   SgianDubh | Apr 02, 2003 04:29am | #6

   Do you mean polyurethane glue, Dave? If it's that, it does have a long open time, which is useful in complex assemblies, and it's a non-creeper. It's also said to be a gap filling glue, but it seems to me that it fills the gap with foam, which I suspect gives under pressure. My opinion, for what it's worth, and if you're using polyurthane, and from what I understand you're doing, is that the glued joint will hold up fine.

   The only point that crosses my mind as a possible concern, now that it's been raised by Ben, is if you you have a very wide plank as a headboard-- say 20" or so, with a tenon at the extremities of the width, as he described. I didn't read your description as being a headboard of that type, so didn't concern myself with those technical concerns. Slainte.Website    The poster formerly known as Sgian Dubh.

2. 
   LD | Apr 02, 2003 04:35am | #7

   Thanks.  And yes, I meant poly.

3. 
   SgianDubh | Apr 02, 2003 05:01am | #8

   Now that I know it's polyurethane you're going to use, watch out for the stuff foaming out of the joint. It can be a bit difficult to peel off cleanly in awkward corners. The best strategy I've found is to partially pre-pre polish awkward corners especially film polishes, glue up, peel off the foam, and then apply the last coat or two of polish. The dried foam is more difficult to handle on open pored timbers like oak and ash than on fine grained stuff like cherry or maple-- it tends to get into the pores and show up under subsequent polish, and the more open grained the material the more it gets in. Slainte.Website    The poster formerly known as Sgian Dubh.

4. 
   ChasStanford | Apr 02, 2003 02:17pm | #9

   I'd say Dave ought to give hide glue a try.

5. 
   SgianDubh | Apr 02, 2003 04:34pm | #11

   I too like the liquid hide glue, Charles, if a long open time is required, and the final location is an interior application, as this bed should. Good point. I hadn't thought to mention.

   Dave, this stuff will certainly be much less trouble regarding squeeze out and cleaning up before polishing than polyurethane. Available at Home Despot and other non-specialised suppliers. Make sure you check the date it's made stamped on the bottle prior to buying. It has a definite shelf of only one year after manufacture, and is sold as Franklin's Liquid Hide glue in the US.Website    The poster formerly known as Sgian Dubh.

6. 
   LD | Apr 02, 2003 03:18pm | #10

   I assume by polishing, your talking about the applied finish?

   dave

7. 
   SgianDubh | Apr 02, 2003 04:37pm | #12

   Yes, Dave. Polishing means to apply the polish (or finish, in US parlance.) I tend to 'polish' or 'polish up' a job rather than 'finish' a job. I don't use American parlance much, so you'll have to translate my British English into Americanese, ha, ha. Slainte. Website    The poster formerly known as Sgian Dubh.

8. 
   LD | Apr 02, 2003 05:21pm | #13

   okey dokey.  That's americanese for "I understand".

2. 
   BenM | Apr 01, 2003 08:33pm | #4

   How wide is your headboard?  For example, if it's a one-piece headboard that's 18 inches wide it should have at least two tenons (per side) and one of those will have to allow for 18 inches of movement.