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Steel rods as "dowels" in wood?

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Forum topic by ruthie posted 03-08-2010 09:49 AM 8739 views 0 times favorited 6 replies Add to Favorites Watch
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ruthie

2 posts in 2467 days


03-08-2010 09:49 AM

In the construction of a pedestal base for a large dining/poker table for my young-adult daughter, I used four “pine rounds” (1.25” thick edge-glued pine panel cut into 15” diameter circles), mainly for the decorative effect. The 4 circles were stacked and used as a middle section of the pedestal…

Poker table side

pedestal*

I joined the stack together by inserting 4 wooden dowel rods, evenly spaced, through all 4 pieces, ending in the bottom “round.” I also used glue on the surfaces of the four rounds. Both the top and bottom rounds were screwed to their adjacent sections of the pedestal. Well, after several years of use, the table suffered a little unforeseen assault! During her absence, my daughter’s dining room ceiling fell onto one edge of the table top!! (Broken water pipe and flooding in the room above.) The table’s pedestal snapped in two. Yikes! The dowels pulled out of the bottom pine round, as shown here…

Broken Pedestal Both Sections

Bottom section

In putting it back together, I would like to drill channels a few inches from each wooden dowel, and drop in some steel rods (“dowels”) for added strength. I would extend these all the way through the four pine rounds, and into the end grain of hidden 2×4’s (behind each fluted panel where the feet are located). Here’s my question: Would this “brilliant idea” be in reality asking for more trouble? Would this invite potential cracking because of wood movement and steel rod “unforgivingness”!? Should I forget the steel rods, simply re-glue everything, and just keep it away from falling ceilings? Any ideas are appreciated. Thanks!

ruthie


6 replies so far

View richgreer's profile

richgreer

4541 posts in 2537 days


#1 posted 03-08-2010 03:42 PM

With all that flat surface on each side of each round, it sure seems like you should be able to glue these rounds together so well that they will be as strong as a single piece of wood. It looks like you have a finish on the flat surface of the rounds. You would have to sand that off. Dowels would help with alignment. I would probably cut a channel in the round, with a router, about 1/2 inch in from the outside to catch any squeeze out – but that step would be optional.

I see no need for steel rods – - but that is just my opinion.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View SKFrog16's profile

SKFrog16

661 posts in 2663 days


#2 posted 03-08-2010 03:49 PM

Hey ruthie, Welcome to LI’s. I have a 6’ round table, now in storage, that is a pedestal. It has 2 – 4X6 half lapped and crossed in the center legs, a center pedestal with the top mounting plate on top of the pedestal. This whole assembly is held together by a 1/2” threaded steel rod. All though the table is now in storage, I have never experienced any radical movement in the wood. The legs are oak, pedestal is turned hard pine in 3 pieces, and the table top is hard pine also. I will say this however, the hole for the rod is drilled 1” in diameter to allow for wood movement.
A recess is drilled in both the top and bottom the exact diameter of the washers for the rod, which centers the rod to the hole.
I see no reason why you could not do the same. I don’t think you need 4 rods, I think one down the center would work just fine. By the way, the center section of my pedestal has 2 dowels top and bottom to align the other pedestal sections.

-- Methods are many,Principles are few.Methods change often,Principles never do.

View mstenner's profile

mstenner

57 posts in 2617 days


#3 posted 03-08-2010 04:35 PM

First, the question about movement. It’s true that steel rod won’t get longer and shorter, but then again, neither will wood dowels (at least, not by much) along their length.

As best I can tell, the failure mode you experienced here was not that the wooden dowels were too weak. They didn’t break, right? They just pulled out of the shallow hole in the bottom round. Sinking steel (or wood) much deeper would likely help with that. I would probably a) bore deep holes in each direction from the split (using dowel centers to align them) and b) then use dowels again. If you do go with steel, you’ll need to use epoxy (or polyurethane glue, etc) to glue it up.

I agree with Rich that sanding and gluing the actual mating surface would be a big help (maybe even sufficient, but I’m a sucker for overbuilding). Sanding them flat and parallel to the table surface (so the table is parallel to the ground) might be a challenge, though.

-- -Michael

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ruthie

2 posts in 2467 days


#4 posted 03-08-2010 07:01 PM

Thanks for the great comments, guys. These will definitely help me arrive at a decision on how to proceed. It sure is nice to have this forum.

ruthie

#5 posted 03-08-2010 07:07 PM

Also make sure you get an adhesive or epoxy that will adhere to BOTH metal and wood, if you happen to use the metal dowel pins…Oh, sorry, Michael just said that above. LOL
I hope the repair goes well!!

-- Lane Custom Guitars and Basses

View Don Newton's profile

Don Newton

714 posts in 3081 days


#6 posted 03-08-2010 07:27 PM

Welcome Ruthie,
There should be no issues using the threaded rods. You may want to reconsider a change in design. The failure of the construction was caused by an extreme circumstance. If you had originally used the threaded rod you undoubtedly would have experienced much more damage to the table. Drill out the dowels and rebuild it the same way.

-- Don, Pittsburgh

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