Threaded inserts in bocote - Woodworking Talk - Woodworkers Forum
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post #1 of 11 Old 05-21-2020, 07:46 PM Thread Starter
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Threaded inserts in bocote

Our son sent me a piece of bocote so I could make him a small table. He also sent metal legs. I had planned to send the table disassembled and was going to use threaded inserts to prevent damage to the wood that would be caused by placing screws directly in the wood and removing several times.
However, when I screwed the insert into the bocote, the wood raised around the insert and developed cracks. It looked similar to a volcano... I have attached a poor photo that may help.

What can I do to make the inserts behave? Or should I just go ahead and drill pilot holes and use wood screws? BTW - I did drill the correct size hole for the insert.
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post #2 of 11 Old 05-21-2020, 07:57 PM
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One of the tricks I've seen is to get a lag bolt with a thread size similar to the thread on the insert. Stainless steel lags work best because their threads are cut, not stamped so they're a lot sharper. File a notch in one side of the lag bolt so it cuts like a tap. Then, thread the wood with the lag. Remove the lag, sand away any damage caused by the the tapping process and then install the insert. Using some epoxy to lubricate the insert will also help it stay put.
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post #3 of 11 Old 05-21-2020, 08:04 PM
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Drill the hole just large enough so the insert just drops in, then coat it with epoxy and drop it in. Should hold as well or better than threading it in.

Alexis de Tocqueville was a very smart man.
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post #4 of 11 Old 05-24-2020, 06:07 PM Thread Starter
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Thanx gentlemen. I think my next step will be to drill a hole 1/32 over sized and see how much damage that does and how secure it feels. If necessary, I can add epoxy too.
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post #5 of 11 Old 05-24-2020, 06:27 PM
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The correct size for a threaded insert is usually the correct size for softwoods. Bocote is hard and dense, trying to get an insert to cut its own threads in it is going to be a pretty considerable fight, as youre finding out. Alchymest has the right idea, drill a hole big enough for the insert to drop in and just epoxy it in place. Anything else is going to risk splitting the wood.

That said, if youre feeling adventurous, you can actually tap machine screw thread in hardwoods, you just have to have a lot more threads in the material to be viable, compared to metal. Id say 8-10 complete threads should allow a bolt to hold pretty well

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post #6 of 11 Old 05-24-2020, 06:37 PM
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a photo of the inserts you are using would help put
us all on the same page.

.

I am a painter: that's what I do, I like to paint things.
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post #7 of 11 Old 05-24-2020, 08:10 PM Thread Starter
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Thanx again. I'm thinking that if I drill a hole 1/32 larger than the body, that will ease entry of the insert, and the threads will still have some purchase. I will probably still add epoxy. My concern is I'm not sure the inserts will go in straight. Here is a link to the same type of inserts I am using.

https://smile.amazon.com/Z-Threaded-...6-f96e7b0f409c
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post #8 of 11 Old 05-24-2020, 09:02 PM
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Quote:
Originally Posted by RonBenson View Post
Thanx again. I'm thinking that if I drill a hole 1/32 larger than the body, that will ease entry of the insert, and the threads will still have some purchase. I will probably still add epoxy. My concern is I'm not sure the inserts will go in straight. Here is a link to the same type of inserts I am using.
Easy way to be sure the inserts go in straight - (if you have a drill press). Get a bolt of the same thread size as the insert, and a jam nut. The bolt should be threaded only part way. Cut the head off the bolt, screw the jam nut on the bolt, then screw the bolt into the insert, snugging the jam nut down against the insert. Chuck the smooth part of the bolt in the drill press, with as much of the smooth part in the chuck as possible. Tighten the chuck until the bolt can barely slide in the chuck. Put the wood on the drill press table, lower the drill quill until the insert touches the wood, then put a little pressure on the drill press handle as you turn the nut to thread the insert into the wood. Once you get it started, lock the quill and finish screwing the insert in. The bolt should slide down out of the chuck as you do this.

Alexis de Tocqueville was a very smart man.
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post #9 of 11 Old 05-25-2020, 05:46 PM
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fwiw - anyone thinking of using thread inserts:


do _not_ rely on the package 'recommended' hole size.
I have used inserts from the same purchase/bag in various woods - hard maple, red oak, white oak, poplar.
every single species requires a slightly different hole size to (a) insert cleanly (b) not break out (c) hold good.
brass inserts take a different hole than "same size" stainless inserts.
many designs to insert - different make will require different hole sizes.
I never use (sigh, anymore) and highly do not recommend any of the pot metal cast inserts. don't ask, it was ugly.

those are strictly for "cheapest stuff from China..."



test drill, try it.
test drill again, try it.


brutal, but regrets the only way to make them work.


and, if you screw up - over drill, fill with epoxy. holds quite well.
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post #10 of 11 Old 05-25-2020, 06:24 PM
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Quote:
Originally Posted by Alchymist View Post
Easy way to be sure the inserts go in straight - (if you have a drill press). Get a bolt of the same thread size as the insert, and a jam nut. The bolt should be threaded only part way. Cut the head off the bolt, screw the jam nut on the bolt, then screw the bolt into the insert, snugging the jam nut down against the insert. Chuck the smooth part of the bolt in the drill press, with as much of the smooth part in the chuck as possible. Tighten the chuck until the bolt can barely slide in the chuck. Put the wood on the drill press table, lower the drill quill until the insert touches the wood, then put a little pressure on the drill press handle as you turn the nut to thread the insert into the wood. Once you get it started, lock the quill and finish screwing the insert in. The bolt should slide down out of the chuck as you do this.
i was going to suggest the drill press method. it also works when you can't get a metal tap to start straight
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post #11 of 11 Old 05-26-2020, 08:48 AM
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or make a jig for awkward places....


Threaded inserts in bocote-img_0505.jpg
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