Replies

1. 
   douglas2cats | Nov 23, 2007 03:22pm | #1

   Threaded rod or a bolt with the head cut off in a drill press works good to turn the first couple of threads in. After that a wratchet wrench and bolt to go the rest of the way. Leave the DP turned off. Just turn it by hand as you put a bit of downward feed pressure on it. If the "ends of rails" means into end-grain, I'd rethink that and try some cross-dowels (barrel bolts) instead.

   If you build it he will come.

2. 
   mufti | Nov 23, 2007 03:31pm | #2

             If you have a drill press Bob, turn the table to vertical, clamp the stock under the quill. Drill a pilot hole the size of the root of the insert and then use the stationary chuck to press the insert into position.

   Just beware of drilling the pilot too small otherwise you risk splitting the end grain, too big and the insert will not hold. Then you would have to use small versions of bed bolts, which, holding on cross grain, would be preferable in the first place.

3. 
   Routerman | Nov 24, 2007 05:09am | #3

   X-steel dowels maybe a better choice but you didn't ask that.

   For near perfect results use machine threaded tapped inserts, then drill, chamfer, tap, and essentially insert x hand.

    

   Routs & drills.

1. 
   nazard | Nov 24, 2007 05:24am | #4

   Herr Routerman,

   You are using HeliCoil inserts in wood.  Never in a thousand years would I ever thought of doing something like that.  Do you use the suggested tap drill size, or undersize the hole for a tighter thread %?  Aside from ease of installation, what are your other reasons for using HeliCoils rather than knife-thread inserts?

   -Nazard (very impressed with your application)

1. 
   Routerman | Nov 25, 2007 12:18am | #5

   Not helicoil, a genuine threaded insert.

   I do not use indicated drill for size X in wood, aluminum, or plastic. Drill size = root of thread.

   Why use them? They work everytime they're tried. Near zero failures; pull strength always substantial. Never strip, they look nice, insertion trivial, easy to lock.

   Can't believe the industry (knife/thread insert people) could actually sell such an obnoxious product for the woodworker. I thought there had to be something better and there was.

    

   Routs often.

1. 
   bob k | Nov 25, 2007 03:50am | #6

   Routerman: I'm very interested. Can you tell me more about what you mean by a genuine threaded insert? I have no knowledge of metal working techniques, if this idea comes from there. I want to try your suggested approach. Where would I look for these inserts? They are not to be found in the woodworking supply sources that I know of. ThanksBob K

2. 
   bob k | Nov 25, 2007 03:14pm | #7

   Routerman: Have visited your site and recommend everyone do so. I have your instincts, but not your experience. Have looked for inserts at McMaster-Carr and found many options. Have several questions and clarifications:1. When I make a run of KD chairs, I need to insert 160 inserts, 96 of them into end-grain of Baltic Birch plywood, so, after accuracy, I am also looking for speed. Are you saying that you know of no way to be accurate with a self-threading insert?2. You mentioned "steel dowels", a term I have only heard to refer to nails with derision. But now I'm thinking that is not what you meant. The stresses in my assembled chair will mostly be from wracking side-to-side. I went with truss screws and inserts, since these chairs ship flat and must be assembled by novice customers. Is there a better way to provide for easy assembly of this chair? I have attached a foto.Thanks for your advice. When I get through my current backlog of work, I am definitely going to build that router table fence.Bob K

   
1. 
   Routerman | Nov 25, 2007 07:13pm | #8

   Pull strength of threaded inserts is substantial but, as I thought, they are wrong for your application.

   To get max pull strength and sleep well, you need steel x-dowels, your truss heads are ok but I'd use a machine screw with another more attractive head.

   Now then, can you walk up to a cross dowel, insert it and have a perfect intersect with the screw? Not without semi-sophisticated fixturing. Once created (I know of no source for cross dowell drill fixturing that is worth a damn) things go fast, assembly is trivial & the connection won't fail. If there is failure it will be clear that the chair has been in a bar fight.

   Can I help? Not easily. From here it is a pay as you go deal. I regret that, but your requirerments are far beyond a simple forum discussion.

   Edited 11/25/2007 3:45 pm ET by Routerman

2. 
   bob k | Nov 25, 2007 10:43pm | #9

   10-4, Routerman, and thanks for your help.