Heli-coils for CHEAPSKATES

[bct]

http://i41.photobucket.com/albums/e292/garetth123/b636a203.jpg
Went to NAPA awhile back to get some helicoils ,they are almost $40 when you buy the instilation kit or $12 if you just buy the coils. I already have a set of taps so i asked to see the installer, after a quick look i figured i can make this shit for .12 cents...here is how....cut a bolt, the size you need in the stripped out hole, on the angle othe thread pitch...use the threads as a guide..use a nut to steady it in the vice
http://i41.photobucket.com/albums/e292/garetth123/c99db1eb.jpg
Stand the bolt up and cut a cross in the end with a zip cut
http://i41.photobucket.com/albums/e292/garetth123/483c466b.jpg
Grind down the lowest 3/4s of the cross to the next thread down leaving a single "tooth" standing ...take the bolt and sharpen the tooth... like a chainsaw tooth
http://i41.photobucket.com/albums/e292/garetth123/de8b639c.jpg
You now have an installer on the cheap ,cuz it sucks to strip a bolt hole and pay for it...oh yea buy the coils(without the installer) first it will make the job easier...

[Maniacles]

Did you have the special helicoil taps? They aren't standard. They may have the same threads per inch as a normal tap, but they have a much larger diameter to compensate for the material thickness of the insert.

[Kojack]

Helicoils are pretty much useless without the special taps for them and that's where the big cost is. One exception that I've found is that you can drill and tap a hole to M8x1.25 and use a 1/4-20 helicoil in it. The thread pitch isn't a perfect match but close enough for a standard length helicoil. There are also thread inserts out there that use standard tap sizes. Jergens is one company that makes them. They're thicker walled than helicoils so that might limit their use. You can make your own by drilling and tapping the length of a bolt but it's tough to stay on center without a lathe.

[hesredbird]

Well, being an ex-die maker, I use to plug holes all the time. We had either cast iron or steel threaded rod in NF for English or just standard metric threads.
The hole to be re-tapped will be centered so just use a size big enough to cover the old threads. Drill the hole out using a standard tap drill for the appropriate tap size you are using. Drill & tap. Insert the plug using locktite. Cut off the stud that is sticking up and grind/file flush. Using the mounting object for a center finder, spot the new hole & drill & tap to the desired size. I have never used a helicoil in my life and I have plugged & re-tapped thousands of holes using this method. If you can't find cast iron plug stock, any non-hardened steel screw will work just fine.