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  1. #1
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    Threaded Inserts for Crib Hardware

    I'm finally just about done with the crib I've been working on for (what seems like) forever. I've got to be the slowest woodworker ever.

    Before I go and botch things up, I was hoping for some suggestions on working with the threaded inserts that came with the crib hardware. The hardware came with very rudimentary instructions. It certainly didn't come with any information on the proper size of the pilot hole to receive the threaded insert.

    If I make the hole too small, won't I risk damage to the wood where I'm inserting the, uh, insert? And if I make it too big, it won't have good holding power, no?

    How do I properly size these things? They don't seem to be a "standard" size, as far as my quick research has revealed.

    I'll try and get a picture posted up a little later this morning.

  2. #2
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    RE: Threaded Inserts for Crib Hardware

    The hole size for threaded inserts should be the diameter of the shaft (if there is any taper) at the narrowest measure of the shaft (bottom of gullet to gullet). Depending on where they are made, the inserts may differ slightly.

    On most, the hole diameter for a 1/4-20 threaded screw is 3/8", for 5/16-18 threaded screw is 1/2" and for 3/8-16 threaded screw is 3/8".
    :)
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    A THING OF BEAUTY IS A JOY FOREVER - John Keats

  3. #3
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    RE: Threaded Inserts for Crib Hardware

    There's no gullet down there. Measure above the first thread (gullet to gullet). That is close to midline of the shaft. This is how I do it for the ones with a taper. The ones I use mostly are fairly uniform in diameter. Some manufacturers have inserts made for them that have taper. If you choose to drill for the diameter at the top (the largest) the insert may have too much slop. I never experienced any splitting.
    :)
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    A THING OF BEAUTY IS A JOY FOREVER - John Keats

    http://www.constantines.com/ProductI...eners/119E.jpg

  4. #4
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    RE: Threaded Inserts for Crib Hardware

    Maybe I'll have to do some testing with small pieces of scrap that I can cut in half to recover the insert. I don't think I got any spare inserts with this hardware kit. :(

  5. #5
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    RE: Threaded Inserts for Crib Hardware

    I have not used that type of insert in wood. I have used inserts like yours in soft plastics where we molded a tapered hole to match the tapered root diameter.

    I think you're right to be concerned about splitting hard wood with that cylindrical wedge so testing seems appropriate. Keep in mind that your wood is well dried and unlikely to shrink much more so a tight fit may not be so risky as it would be in greener wood that has a lot of shrinking to do.
    Measure once... cut twice.

  6. #6
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    RE: Threaded Inserts for Crib Hardware

    Well, I just went to my local hardware store. I was in disbelief, bu they actually have these in stock, as well as a listing for the installation hole to drill. This is good, so I can do some testing for a good fit without worrying about not having spares in case I ruin a few trying to find a good fit for the installation hole size.

    Turns out that these are:

    10-32 internal threads with a suggested installation hole of .272-.290".
    and
    1/4-20 internal threads with a suggested installation hole of .295-.343".

  7. #7

    RE: Threaded Inserts for Crib Hardware

    odd.....

    Today I was looking for inserts like the one's Rob shows but without any luck. I found some brass one at Lowe's simular to the ones like Mike's, but I prefer the others.

    Anyone know where I can get a hold of some of these without having to order them online?



    "I just don't understand...
    I've cut it three times and it's still too short!"

    [link:www.mgsawmill.com|M&G Sawmill]. Makers of the finest sawdust in Texas.
    Oh, did I mention we have hardwood as well?

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  8. #8
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    RE: Threaded Inserts for Crib Hardware

    Brad,
    I'm going to need to go back and get some more in the next couple days once I evaluate my exact numerical need. I'll see if I can find out who the manufacture is while I'm there. Maybe your local hardware store can easily get them as well.

  9. #9

    RE: Threaded Inserts for Crib Hardware

    Rob,

    I did another drive around search today and found some very similar at HD. They were in the furniture/cabinet hardware section.
    Orange and black bubble pack labeled "HM" House-Mates Hardware.
    They are 1/4" x 20mm tapered. On the back of the package it says...
    "Crown Bolt Inc. Aliso Viejo, Ca. 92656". I didn't surf it, but they do have a website... www.crownbolt.com.

    I prefer the non-tapered like you have, but these well do.
    I used some to hold the melamine top on my router table and they worked great! I figured if they'll work in MDF, they'll working in just about anything.





    "I just don't understand...
    I've cut it three times and it's still too short!"

    [link:www.mgsawmill.com|M&G Sawmill]. Makers of the finest sawdust in Texas.
    Oh, did I mention we have hardwood as well?

    http://www.mgsawmill.com/images/flag.gif http://www.mgsawmill.com/images/texas.gif

  10. #10

    RE: Threaded Inserts for Crib Hardware

    Rob - partly yes - partly no.

    Normally - in metal and I beleive wood too, you get about 75% thread engagement. If you drill the hole the same size as you show in your sketch you would have 100% engagement. That is too tight.

    Sooo - short easy answer. The drill size should be just a little bigger than the "root" diameter of the screw. Root diameter "is" the proper term. Size is not critical, but you are looking for between 50% to 75% thread engagement. With a fastener like that in wood you "could" go 90%-95%, but I would not go much more than that. In metal - 90% is real tight.

    Easy way to find the right drill - hold up the screw. Take a small drill and hole the shank directly in front of the screw. With ONE eye - line up the drill DIRECTLY in dront of the screw. Can you see the root? If so the drill is too small. Can you see the threads - if not the drill is too big (unless you want a clearance hole). I've been doing it that way for more years than I care to remember. Works every time.

    Same story for just about all threaded fasteners.

    You could add a tiny bit of epoxy if you are really concerned, but I don't beleive you would meed it.

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