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TomB wrote: ↑Tue Jan 21, 2020 5:10 pmI did not buy a kit. I walked in and asked the counterman to find me a thread insert and he came up with several insert bags each with 3 inserts (they varied in length). Then he went to another shelf and came up with taps. I took the 3 that he had out as going with the insert. One is 3/8-24 class 2A while the other two are 8 and 10M. A week latter I stopped at another Fastenal (in Albany) but got less help. While there I saw insertion tools and picked up one that fit the size inserts I had. I don't have the short bar for the tang but I have sets of punches. I looked on the internet and found I should be using a 25/64 drill and I have them. Tomorrow morning I'll get into shop and see if this will all work.
Thanks to all for the advice.
Tom
I'm going to go out on a limb and say that the first Fastenal guy wasn't much help to you, either. If the insert is for a 3/8"-24 thread, the 3/8-24 tap isn't going to do you any good. That's the thread you'll end up with after the helicoil is inserted. The tap that the helicoil set comes with is going to be something odd, but bigger and also a 24 tpi. If the other taps are M8 and M10, those are for metric threads and of even less use to you. I think if you do some reading on the web, you'll find that the guys at most Fastenal stores are about as helpful as a modern day auto parts counter kid. IOW, they aren't. And if they are selling you junk you don't need and can't use, then they are even worse. The tap that comes with the helicoil kit is specially made to fit the outside of the insert.
Given what you seem to have on hand now, I would probably drill and tap for the 1/2"-13 using the 33/64" and then use the other inserts. I would highly recommend testing this in another part first, though. Odd that you found it wouldn't thread into a 1/2" nut drilled to that size, though, as John hasn't found them to thread in that difficult.
In answer to your question the tang can be broken off with just the tap of a punch and then your fastener can go all the way through. As long as you have the correct tap a helicoil is a good and fairly easy repair. It sounds like others have given you sound advice as well. You will have to let us know what ends up working for you.
I'm going to go out on a limb and say that the first Fastenal guy wasn't much help to you, either. If the insert is for a 3/8"-24 thread, the 3/8-24 tap isn't going to do you any good. That's the thread you'll end up with after the helicoil is inserted. The tap that the helicoil set comes with is going to be something odd, but bigger and also a 24 tpi. If the other taps are M8 and M10, ....
Dave
I'm pretty sure the 3/8-24 tap that I ended up with is not a standard 3/8-34 UNF. The major diameter is .430 inch. When I compare it to a 3/8UF24 from my tap set it is bigger. (Major Diameter of standard tap is .375".) I suspect what happened to the counter man was he went to the shelf with helicoils and pulled one for 3/8-24. Then he want to a table and looked up the taps to use with the 3/8-24 insert. That gave him 3 possible taps which he did not understand and at the time neither did I. But in retrospect I now think the M8 and M10 metric threads can be fixed with the same helicoil if one uses a different tap. The counterman had all the right answers he just did not know how to interpret them.
It surprises me that the markings on the taps do not indicate extra fat taps. It is labeled STI 3/8-24 HSS while my standard tap is labeled 3/8NF24. Seems like a more valid labeling would be STI 3/8-24 2BSI HSS, thereby providing the manufacturer, size, class, standard insert thread and material.
My genuine Heli-Coil taps, and a few other brands as well, and all are labeled with the size of the thread being repaired, and STI. (ie; 3/8-24 STI)
STI for Screw Threaded Insert.
The Heli-Coil brand also has the tap drill size on the tap. Others.....some do, and some don't.
Here's a vid of a critter called a Gardsert. No fancy-dancy bastard size taps required, or installation tools either. I stumbled upon these guys at Mine Expo in Las Vegas some 20-plus years ago, and have used a bunch of 'em since.
They work quite well, and as well as other thread repair inserts. Drill a hole, and thread them in.
They have a thicker wall than regular inserts, so there are some places they won't work.
That gave him 3 possible taps which he did not understand and at the time neither did I. But in retrospect I now think the M8 and M10 metric threads can be fixed with the same helicoil if one uses a different tap. The counterman had all the right answers he just did not know how to interpret them.
It surprises me that the markings on the taps do not indicate extra fat taps. It is labeled STI 3/8-24 HSS while my standard tap is labeled 3/8NF24. Seems like a more valid labeling would be STI 3/8-24 2BSI HSS, thereby providing the manufacturer, size, class, standard insert thread and material.
Tom
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No each if the metric sizes will require the specific tap AND insert to match that thread. I have been using Heli-coils since the 60's and they still are my preference. On smaller taps it is some times [most of the time] very hard to read the markings. Quick and dirty way to be sure you are not trying to use a STI tap is run the tap into the appropriate nut.
I like helicoils but they're very expensive.
I just bought a noname helicoil-like set. Looks good but haven't used it yet. it was about 1/4 the cost of a helicoil brand set.
Helicoils are stronger than the original thread, and the hard plating makes them resistant to tearing. The load is spread over a wider area of metal too.
I also use nut-serts, that go in like big pop rivets. Great for thin walled things but they protrude behind.
I also made my own inserts for an old Mercedes engine, because the head bolts were 'wet', the ends were in the waterjacket.
I didn't think helicoils would be good there, so I made mild steel inserts with closed ends. Fine outer thread allowed thinner wall and smaller drill holes in the old block.
rohamm wrote:J-B weld would have us believe you could fill the hole with their metal-filled epoxy, then drill and tap it.
You could, but it won't hold much before failure. Unless it was a plastic part that the j-b weld strength exceeded the strength of the material, I wouldn't do it. In fact even on a plastic part I would use a thread insert and just use the j-b weld to help retain the insert, unless the drawings calls for something else. What the engineer wants the engineer gets, even if I think it might be a bad idea. [emoji12]
I drilled out my parts to the required Diameter, taped the holes with the STI bit I had bought at Fastenal and inserted the helicoil-like inserts. First one was listed as 1.5D long and it was too long. Took it out grabbing a end and pulling with needle nose pliers. Replaced it with a 1D long insert. It seemed to be the right length as it left about a turn and half of the STI thread showing on either side. I broke off the tang with a punch About a 5/16 dia punch in a 3/8 dia inner thread. I put one of the thru shafts in. It did not thread in easily and I had to use a wrench. When I decided to take it out and see what was wrong I found a part of the helicoil wire had pulled out ot the STI thread. It acted like a cross thread and stripped part of the threads off my thru shafts.
I've order some new eccentric thru shafts, bought some steel stock with a thickness suitable to replace the holder part that had the threads disappear and I will get started this week fabricating a part that will not require inserts. I would have saved myself money if I had done that first. Fabricating it will means I will have a steel rather than cast holder but I don't think that will make any difference.
Thanks to all who offered me guidance on this repair effort.
