Dowels: Spiral, or fluted? Or ???

[Phil Thien]

I'm nearly out of 3/8" dowels.

These were fluted. I don't even remember where I got them. They were just okay, some of them too loose, others too tight.

I'm going to need more this week and took a look at the Rockler and Woodcraft pages and they seem to have mostly spiral now instead of fluted. I would have sworn that both these places carried mostly fluted up to about a year or two ago.

What are the preferences here? I've always felt the fluted were a compromise because much of the surface of the dowel (the valleys) will never be in contact with the hole. And I've always thought spiral might be a compromise because I can imagine cases were NONE of the dowel will be in contact with the hole (if the dowel or hole are slightly out of round, for example).

[John TenEyck]

I prefer fluted if I buy them. The flutes are pressed in and when they soak up some glue they swell so there is more contact with the sides of the hole than you first might think. With spiral cut that ain't never so. When I need custom lengths I make my own from long stock, which I check with a pair of vernier calipers when I buy them. In that case, I cut a shallow lengthwise groove with a V- point router bit before cutting them to length, which provides a path for the glue to move.

[Phil Thien]

I prefer fluted if I buy them. The flutes are pressed in and when they soak up some glue they swell so there is more contact with the sides of the hole than you first might think. With spiral cut that ain't never so. When I need custom lengths I make my own from long stock, which I check with a pair of vernier calipers when I buy them. In that case, I cut a shallow lengthwise groove with a V- point router bit before cutting them to length, which provides a path for the glue to move.

I've heard some of the fluted ones have pressed flutes, and that others have die-cut flutes. Did I hear incorrectly?

[Bill Huber]

I use a lot of dowels and really like the expansible dowels from Lee Valley. I have taken them out of the bag where they were dry and put them in a joint to test and left it for awhile and it was really hard to get the joint apart.

http://www.leevalley.com/US/wood/page.aspx?p=32732&cat=1,250,43217,43228

[Tony Zaffuto]

Double Bill's suggestion for the LV dowels. Work very well and the wood swells in a fashion similar to biscuits.

[Peter Quinn]

I've always used spiral dowels for glue joints and had good success. The ones I use at work are 6" X 1/2" dowels, we have similar in 3/8" though not quite as long. Those from Lee Valley and others seem a bit short to me frankly. The longest ones are 2"? thats only 1" into each side of the joint. I can imagine a lot of situations where that is a bit less than I would like. In fact in most situations where I would use 1/2" dowels I'd also like far deeper penetration into both sides of the joint. Otherwise I like that compressed dowel idea. I wonder if they are available in longer lengths or even in blanks you cut to length?

[Phil Thien]

Hey Peter, what are you joining with those 6" jobbers, exteriod doors?

I've never seen dowels for joinery longer than maybe 2-1/2"

[Brian Penning]

I've always used spiral dowels for glue joints and had good success. The ones I use at work are 6" X 1/2" dowels, we have similar in 3/8" though not quite as long. Those from Lee Valley and others seem a bit short to me frankly. The longest ones are 2"? thats only 1" into each side of the joint. I can imagine a lot of situations where that is a bit less than I would like. In fact in most situations where I would use 1/2" dowels I'd also like far deeper penetration into both sides of the joint. Otherwise I like that compressed dowel idea. I wonder if they are available in longer lengths or even in blanks you cut to length?


I've bought 4" dowels direct from Dowelmax.

[Jon van der Linden]

I don't like the spiral dowels because they remove a considerable amount of material from the side, which makes the load bearing part much thinner than the nominal dimension. Slightly oversize dowels can be compressed a bit by rolling them on the floor or bench under a piece of wood (if you do it with your foot, just make sure you're holding on to something so you don't take off like a skateboarder!) If you need custom dowel lengths or dimensions you might be stuck making them.

[Rob Sack]

I remember reading somewhere that spiral dowels are a little stronger than fluted dowels. Whether or not this is true, I still prefer fluted dowels, since it seems to me that the glue has a better path of escape from the bottom of the hole. The glue is also spread more evenly around the entire joint. As far as "compressed" dowels, similar to biscuits, I wqould be careful. While I do use biscuits on occasion, excessive swelling, whether a biscuit or a compressed dowel, can creat a "bulge" on the surface of the wood and may even cause a joint to split under the right conditions.