I need to add some 1/4-20 threaded, blind holes to a 4" thick granite surface plate, and I found a diamond core drill that will make the holes. What is the best type of thread insert to use for this application?
If I were doing that, I think I would use Keenserts. That is a insert that is theaded on the OD. Looking in J & L they sell a similar insert called Re-Nu. The OD is 7/16-14. Should lock in well with epoxy. If you ever need to replace them, you could drill them out and glue in a new insert.
"Tim Killian" wrote: (clip) What is the best type of thread insert to use for this application? ^^^^^^^^^^^^^^ I'm not saying this is best, but I want to be sure a good possibility is not overlooked. Lok-tite and Permatex both make epoxy products that are intended for repairing stripped threads. You apply a release agent to the screw, gob on the epoxy, and insert the screw in the hole. In five minutes the screw can be removed, and you have a threaded hole.
Thanks to all for the suggestions. The surface plate is 4" thick, and I need to put in 12 holes, so going all the way through with a bit less than 1/2" diameter is not too appealing ;-)
We use helicoils all the time and I'm familiar with that type of insert. I was hoping someone made a high quality expanding insert with hardened internal threads specifically for use in stone materials. The galvanized stuff they sell at HD is really intended for one use only.
Maybe the best soluti> Do the holes have to be blind? Drill all the way through and put flanged
I would not use a helicoil. Youl milage may vary from mine, but if I tried epoxiing in a helicoil, I would end up with epoxy on the inside. There are a lot of threaded inserts intended to be used in concrete. Some expand into place. I think others have lead around the insert and you mash the lead with a tube so it expands to grip the concrete and the insert. Try looking at Fastenal or Grainger.