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Surely some people must still use dowel pins once in a while, even though biscuts have become so popular the last several years. I have used both types, Fluted (flutes running lengthwise down the pin) and Spiral (single groove twisting diagonally down the dowel), but have never determined that there was an advantage to using either type. It seems like the spiral would give more wood-to-wood contact, but the fluted might be an actually tighter joint because the glue would cause the flutes to swell in the joint.
My books by Joyce and Hoadley each have a couple of pages on dowel pins, but no info on the reason for the 2 designs. Can anyone shed some light on this? Thanks. GP.
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http://www.exceldowel.com/dowelpin.htm
Why not ask the people who make them?
*gp, Both types are intended to provide an escape route for the glue that's pushed into the bottom of the hole. It's simply down to avoiding an attempt to compress the liquid glue into the bottom of the hole. Apart from that I can think of no particular reason for either design except for a difference in manufacturing procedure. Sliante, RJ.
*Sgian & Rick, thanks for the replies. I checked out the link to Excel Dowel Co. provided by Rick, E-mailed the same question to them over the weekend, and recieved a prompt reply from Shaun Sanders at Excel. In case anyone else is interested, here is a summary of what he replied (wish I could scan the whole thing): Multi grooved (fluted) dowels generally work better in particleboard, MDF and plywood. MDF tends to split too easily when the diameter of the dowel is too large. A better recomendation, instead of trying to switch back and forth between the too types of dowels to avoid splitting, would be to enlarge the diameter of the hole slightly. Also, tests have shown that the fluted, multi groove pins used in part. board and plywood give much better bonding strength than spiral pins. As for solid wood applications, greater strength (pullout resistance) is obtained using the spiral groove pins. An execption to this is when a lot of tear out is produced in the hole in cross grain drilling. In this case (dealing with tear out), the multi-grove fluted pins offer better bond. But, in your typical solid wood applications, the joint is plenty strong using either dowel. One last point about ease of insertion: the direction of the multi-groove flutes make insertion of fluted pins easier than with the spiral pins, because the flutes tend to compress slightly when the fit is slightly too tight. END OF SUMMARY FROM EXCEL So I guess I'll keep using just whichever type I have on hand. I don't recall ever using dowels at all in MDF, but if I ever do I'll try to use fluted, and also use fluted when I have a whole bunch of dowels and I'm concerned about getting them all inserted after glue up. One more point from my own experience: instead of using slightly oversized holes to prevent too tight fit, I think it might be better to shrink the dowels. Last time I used them, the humidity was a little high, making the fit too tight. I spread a batch of dowels on a baking sheet and shoved them in the oven at the same time my wife was baking biscuits. I shut the oven off after 20 minutes, left the dowels in for about an hour. When they cooled down the fit was just right. Gave the biscuits a nice birch flavor too. Well, that's it. Thanks to Excel for providing the information. GP.
*That's interesting information gp, correcting my wrongly held assumptions. Thanks for getting back with it. Sliante, RJ
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