I have a stainless threaded insert I need to install. It is 1/4 by 20, which I assume refers to the threads INSIDE the insert.
In order to put it into some white oak, I need to drill a hole...how big should the hole be?
Is trial and error the best way to find out?
Try this site. It lists the hole sizes depending on the coarseness of the external threads:
Probably 3/8" the various styles are slightly different size, the knife threaded ones I use recommend 23/64". BTW these are really great inserts from McMaster Carr use an Allen wrench to drive them in Joey
Except for one common mistake: His inserts are for wood, which have a different thread pattern (longer, sharper, possibly tapered) than the inserts on this site, which are for metal.
I use the McMaster knife edge threaded ones (steel not "pot metal") that install w/ an allen. I cut a short piece of allen wrench & put it in my Makita. so I could push on them
The ones I used weren't stainless, I put them into MDF, did the trial & error thing.
I think the od of them was close to 1/2" I think I used 7/16 or maybe
32nd less than 7/16. Bigger pilot hole IMO is better than too small, less apt to rip up the wood upon installation.If your insert is the SS slotted drive one, they suggest a 3/8" drilled hole; mihgt be a little tight for oak
here's the insertt info
90192A124 Hi-Strength Stl Knife-Thread Insert for Wood Hex Drive, 1/4"-20 Internal Thread, 25/32" Length hr bar Type Knife-Thread Inserts for Wood Material Type Steel Finish Plain Steel Type High-Strength Steel Drive High-Strength Hex Drive System of Measurement Inch Internal Thread Size 1/4"-20 Insert Length 25/32" Drill Size 3/8" Hex Key M6cheers Bob
yes 3/8" usually the standard. though a slightly larger hole works a bit better. on face grain the larger hole is better as it helps to keep face grain from pulling up. I wish those inserts were not so spendy from them. I use thousands and the difference between 1.00 and .20 is pretty big.
Steve-
Do you use EzLok type?
One dollar each is spendy, in the qty you use 25 cents would be more reasonable
Bob
looking at the site I already use them or ones just like them. I get steel ones like their knife thread ones. I can get them locally at two places. the brass ones are everywhere but they are not tough enough. the hex drive ones are way too flimsy and tend to strip out when you use a hex driver. I also get the drive in ones. the better hex driven ones cost too much and I can't just pick some up when I need them.
Most of the stainless inserts I've used, have a standard external thread, 1/4-20 internal has a 3/8-16 external (iirc), take your insert and check the external threads against a few bolts to see for sure.
I tap the hole to match the external thread. The tap will give a clearance drill size, but go a little under what it lists.
If you have a vernier or dial caliper, just measure the m> I have a stainless threaded insert I need to install. It is 1/4 by 20,
There is no need whatsoever for guesswork. Take a look here and follow the link to Tap & Drill sizes.
Perhaps, then, this link will be useful.
wood is different. I used the ones Steve mentions & I've gotten better results going larger than the mfr recommends; less "up-lift" on the face grain & less volcano cup on MDF.
YMMV
These made for wood inserts are not standard UNC thread.
cheers Bob
The hex drive ones that I use are steel (not stainless) & they drive & hold fine. The zinc alloy hex drive inserts suck.
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