Doweling questions

[Corey]

A few doweling questions in regards to combining some 3.5" x 3/4" boards.

1) What size dowel would you use? My instructor recommended 1/4".

2) How far in to the board should I go with the dowel?

3) Any tips on lining the dowels up?

4) Hand drill (power) or drill press?

I bought a couple of different aids and don't know whether I should use them or not. One is a set of little "plugs" with one end having a point that you insert into one hole. Then when you push the boards together, the hole for your other board is marked from the point of the little plug. These weren't that expensive.

The other aid I bought is a dowel jig where you clamp the pieces of wood together with the jig and then move a guide with drill holes from the one board to the next to make sure you are on the same plane of the two boards. I'm not sure how the jig works on lining your hole up along the width of the wood (centering on the 3/4" part).

Tkanks

[patriarch]

"Corey" wrote in news:zO25d.522$me5.134@trnddc06:

Measure the commercial dowels you buy at the hardware store, and add 1/16" to each end, for glue spacing. Commercial dowels, because the spirals or flutes are already in them.

The doweling jig should be self-centering for the board thickness. Mark the surface with a pencil line.

Drill press, if you can, because you want the holes perfectly square to the edge in both x and y axis.

Known as dowel centers.

For edge gluing, there are few, if any, reasons to dowel. They add little or no strength, and, as you're finding, the alignment is problematic. A biscuit or plate joiner is far easier to use successfully, but there is little reason to use one here. See the thread on gluing up a table top.

Doweling can make sense when the joints are cross-grain or end grain, or where the parts can be jigged for exact accuracy. Mostly used for production work today, on automated lines, so I'm told. They helped with some stretchers on a hall table I built sometime last year, where I wanted to make a stronger joint, yet hadn't planned adequately for a mortise and tenon. (I often design as I go, and redesign in process. Don't try this for your first projects.)

Does any of this help?

Patriarch

[Leon]

That would be a good size if you feel the need to join with a dowel. Is the joint or panel going to be under some kind of stress? In not, the glued joint will be stronger than the wood itself. Use the dowel to help strengthen the whole panel if there is going to be stress. In that case I would use deep holes and long dowels.

See above.

Dowel indexing pins.

Hand drill WITH a doweling jig.

Yes # 3 answer above.

Yes, # 4 answer above.

[Corey]

"patriarch [e-mail]"

Well, I bought dowel rods that are about 4' long. I looked for ready cut dowels, but I didn't find any (shopping at Lowes). I did buy a set of tapered plug cutters that someone recomended though - to cover the screws later.

The instructor recommended the dowels. Not sure if he recommended for strength or for preventing the boards from slipping while gluing (I read a tip somewhere to dowel to avoid the slippage).

Of course it does. I think I end up with better help here than in class. It's tough to get time in with the instructor with the other attendees.

Thanks

[Corey]

Building a bookcase of red oak. Not sure what's going on it. I doubt there will be a set of encyclopedias though. I think it's going to be for my daughter's room. So some kid books, some knicknacks, maybe some snowglobes.

[Mike Hide]

I hate to contradict but why are dowels being used at all . If alignment is a problem the biscuits are a solution, a better one is probably a routed spline .

In my view glued dowels or biscuits for that matter detract from the joint because they both introduce undue stresses into the joint due to their transverse grain direction . In short if you use them leave them dry. A spline does not induce stresses into the joint.

Modern glues [tightbond etc] when cured are as strong as the parent wood ,so the use of dowels does not increase joint strength.

A series of brads along the length of one of the boards with their heads nipped off a 1/32" above the surface then the other board aligned and tapped together will accurately mark both boards where the dowel holes should be drilled [after removing the nipped off brads of course ]. I would use 3/8" dowels in this case and to drill the holes a 3/8" BRAD tip bit is essential.

If you do not use dowels, the nipped brads alone will prevent the boards from moving when pressure is applied .....mjh

[Leon]

Forget the dowels. The joint will be strong enough. My reference was more if you had a lot of weight placed on an unsupported panel where the break would be along the grain of the wood.