Replies

1. 
   Lataxe | Jan 17, 2007 11:43pm | #1

   Mr Masher,

   I have used the Lee Valley bed and bench bolts a time or 6.  This is the process I prefer (its not the only method, of course):

   1) Decide where & how deep you want to countersink the bolt head in the leg or whatever.  Use a forstner bit to drill that depth of hole. If you are not countersinking the bolt head, go to step 2.

   1a) Select a f. bit size that will allow you to get a bolt driver of the correct size into the hole and on to the bolt head, so you can tighten the bolt in due course.

   1b) Use a drill press, or a handheld drill in one of those portable frames, to ensure 90 degree drilling.

   2) Measure the bolt shaft diameter and use a drill bit of that size or 0.5mm larger, centred in the small hole left by the forstner bit centrepoint, to drill right through the leg, avoiding breakout.

   2a) Make sure that bolt hole is also at 90 degrees.  

   3) Measure the projection of the threaded end of the bolt when it is pushed through the leg.  Include any bolt head washer(s) when you do this.  The brass crossnut will need to be centred on the threaded portion of the bolt, so the measurement of the bolt projection is to that point, rather than to the very end of the bolt.  Call this length B.  (See step 6)

   4) Locate the rail to be attached to the leg by making a stub tenon on its end and a matching shallow mortise in the leg.  The M&T should be centred on the bolt hole.  (You can omit this step but it does make life easier as it stops the rail rotating on the leg when the bolt is eventually tightened). 

   4a) An alternative to the stub M&T is to drill a couple of matching hole-pairs for dowels, to locate the rail-to-leg in the same centralised-on-bolt-hole way).

   5) With the rail temporarily clamped to the leg (that M&T or the dowels are helping now) drill down the bolt hole from the bolt head side, to elongate the bolt hole into the rail. 

   5b) It helps, with this clamping, if you do two opposing legs and their rail at the same time.

   5c) Drill deep enough into the rail end to ensure the full projection of the bolt through the leg and into the rail has plenty of room.

   6) Mark out the central point on the inside of the rail distance B (see step 3) from the rail end NOT including any tenon length. This hole will intersect with the bolt hole previously drilled into the rail end.  (Belt & braces - use a small square to scribe a line from the centre of the bolt hole around to the inside of the leg then  down the rail length, when the rail is clamped to the leg).

   6a) Noting the thickness of the rail and the thickness of the brass crossnut, calculate how deep to drill so the brass crossnut hole is aligned with the bolt hole.  (If you don't mind a hole on the outside of the rail as well, just drill right through the rail, avoiding breakout).

   6b) Drill the hole for the brass crossnut at 90 degrees into the inside of the rail, making it a diameter equal to the brass crossnut diameter + 2-5mm.  (It's OK to make a hole bigger than the crossnut diameter but not too much bigger.  The leeway makes final alignment of bolt to nut easier).

   7) You should now be able to push the crossnut into the rail hole, the bolt into the leg-to-rail hole and tighten the two, making a very secure knock-down joint.  (The slot in the brass crossnut must face out of its hole, so you can use a screwdriver to align the crossnut threads with the bolt end).

   Hope this helps and I haven't omitted anything crucial.  I bet this post gets "message truncated".  :-)

   Lataxe

    

    

1. 
   user-140952 | Jan 18, 2007 12:44am | #2

   Untruncated and very valuable.  Thanks