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+-- Thread: threaded insert trouble (/showthread.php?tid=7170908)
threaded insert trouble - overland - 12-17-2015
Tonight I tried to install two threaded inserts in the end of my maple bench. My intention was to use them to fasten a planing stop that could be moved up and down. I drilled the holes, but when I tried to screw in the inserts, they just tore apart. Was I using inferior inserts--these were 3/8", fairly large, from the local Ace Hardware--or was my whole plan misguided?
Re: threaded insert trouble - castguy2003 - 12-17-2015
What were they made off, brass or pot metal, Did they have sharp, machined threads, Did you drill a large enough pilot hole for a hard maple bench. Did you lube the threads with soap or wax?
Re: threaded insert trouble - overland - 12-18-2015
They look brass. They have sharp threads and seem to be the kind designed for hardwood. I drilled the size hole that was recommended--in this case 15/32nds. I lubed with wax. Should I have drilled a slightly larger hole?
Re: threaded insert trouble - C. in Indy - 12-18-2015
I had lost some battles with these inserts before, ripping them out along the milled slot.
I have fiddled with hole sizes. I have also tried to remember a more robust driving scheme, which is some sort of 'locked' bolt/nut combo which bottoms out against the insert body instead of applying all the torque just to the weak slot.
No charge for my cuss-words "still floating above Lake Michigan"...
Re: threaded insert trouble - JimBelair - 12-18-2015
overland said:
They look brass. They have sharp threads and seem to be the kind designed for hardwood. I drilled the size hole that was recommended--in this case 15/32nds. I lubed with wax. Should I have drilled a slightly larger hole?
I would go the larger hole route, then put a bit of epoxy on the insert threads to lock it in. Have a greased 3/8 bolt screwed into the insert to avoid any epoxy on those threads.
Re: threaded insert trouble - MarvW - 12-18-2015
Make sure the insert gets started straight up and down with zero tilt. One method is to first drill a shallow hole that is as big as the outside diameter of the threads. The hole should be such that the insert is a snug fit. Now drill the hole that the insert will thread into and make sure that hole is straight up and down. If your holes are not in alignment the insert will try to thread more on one side and will be stressed unevenly which will contribute to breakage. Do your drilling on a test piece of wood so you can debug your process.
If the outside thread on the insert is a standard size, you might consider pre-tapping the hole about half the length of the insert so the insert is only having to thread half the length. A standard tap will thread wood just fine.
Re: threaded insert trouble - johnnysuede - 12-18-2015
Important to note the slot goes in to the wood, they are not there for driving, they are there to help cut threads. I've installed this style in plywood and MDF wrong my whole life without trouble (probably 15-20), but I'm glad someone (can't remember who) showed the correct installation in a video. A bolt threaded most of the way into the insert, with a nut jammed tight against the insert is the best way to install.
Still backwards on the insert but close enough to show the setup. Oddly enough a google image search does not show one image of it being done 100% correct.
http://www.boatus.com/Assets/www.boatus....lation-wood.jpg
Re: threaded insert trouble - overland - 12-18-2015
I was doing it wrong, I can see that. Thanks for the superb advice.
Re: threaded insert trouble - Chuck Nickerson - 12-18-2015
overland said:
Should I have drilled a slightly larger hole?
The harder the wood, the larger I drill the holes. It's a great excuse to have Imperial, Metric, Numbered, and Letter drills.
With inserts I always buy extra and do a trial install or two.
YMMV
Re: threaded insert trouble - museumguy - 12-19-2015
johnnysuede said:
Important to note the slot goes in to the wood, they are not there for driving, they are there to help cut threads. I've installed this style in plywood and MDF wrong my whole life without trouble (probably 15-20), but I'm glad someone (can't remember who) showed the correct installation in a video. A bolt threaded most of the way into the insert, with a nut jammed tight against the insert is the best way to install.
Still backwards on the insert but close enough to show the setup. Oddly enough a google image search does not show one image of it being done 100% correct.
http://www.boatus.com/Assets/www.boatus....lation-wood.jpg
Interesting concept. I was always taught the slot was for the installation tool. Here's a link that I printed out and store with my inserts. http://www.mcmaster.com/#standard-threaded-inserts/=10b32wo
I do have the power drivers for each size insert, they do work really well. As stated before, the correct hole size is extremely important. In hardwoods, like maple, I drill a test hole the size recommended and check it out before drilling my actual work piece. Sometimes, I have to drill a slightly bigger hole, and as suggested, use a little epoxy. When all else fails, a bolt and jamnut works great also.