Any machinists in here? Have a thread question.

[buck]

I am drilling out a hole and returning it to it's original size and pitch thread with a helicoil. The original size was 6x1.0 mm. I purchased an individual helicoil from a local store, but it was not in kit form.

Here's what I need to know. I believe the coil to be 8mm in diameter, but I don't know what pitch the threads need to be tapped in to get the original 6x1.0 bolt to match up.

I figured I would use a 8x1.0 and be fine, but I'm starting to think that's wrong. I believe the helicoil will use a different pitch to give me the final thread I am looking for.

I have looked until I'm blue in the face trying to find a kit online that tells me what tap is included so I know what tap to use on mine. Not having any luck finding the tap size I need at all.

Input???

[Underdog88]

Go to and ACE Hdwr store and match bolts. They all have a thread fitter thingy too... holes for all sizes labeled and an extended thing to match..

[buck]

I know what you're talking about, don't think that will work.

The helicoil tends to move to whatever size gauge you put it on due to it's flexibility. I can't get a true reading on it.

There has to be some sort of chart out there that I'm missing somewhere.

[afr]

you need to put the bolt in it then measure the threads or take it back and get the kit
JMO

[Ratickle]

I believe it's all here, but I'd still buy the kit. Doesn't heli coil make different size kits for larger holes that are stripped/drilled out worse than others?

I've always used the complete kit.



http://www.helicoil.in/pdf/HeliCoil%20Catalogue.pdf

[buck]

you need to put the bolt in it then measure the threads or take it back and get the kit
JMO

Tried that...

When I put the bolt in the helicoil so I can measure the threads on the outside of the helicoil the helicoil stretches out of shape, here's why. The bolt is only threaded at the base by the head. I'd say about 6 complete threads, the rest of the bolt is smooth. It's sort of a factory set bolt that seats in a groove to hold a plug in place. Due to this unthreaded part of the bolt pushing on the tang of the helicoil and moving the threads I can't get an exact pitch of the threads when threaded in all the way.

The local store does not have a complete kit. That would have been my first choice if it was an option. I was lucky to even find the coil I needed in stock here locally. Leaving on a trip in 4 days and don't have time to order the complete kit and get it fixed in time.

Ratickly, I found and studied that chart earlier today. I think we've already established the fact that I'm an idiot, but I don't see where that chart gives me the actual tap size needed for each helicoil. I realize it says it, but it's not in layman. Example...it doesn't say when installing helicoil size 6x1.0 you need a tap that is 8x1.0.

I'm thinking about just buying a standard bolt without the nonthreaded part in a 6x1.0 thread and running it into my coil to see if that helps.

Buck

[afr]

just screw it on loose you only need to read the first two or three threads
take it to your closest machine shop let them measure it

[buck]

Thanks for the input all...

I purchased another 6x1.0 bolt that was goofy looking like the one I needed to install. I placed this inside the helicoil and put a thread gauge on the outside. Came up with 8x1.0 like I had suspected. Just didn't feel good about it without seeing something in writing.

I also noticed that the kits always used a different pitch thread that what the final thread of the coil would be. Kinda made me nervous.

Either way it's done and installed. Hopefully I did a good job of keeping any aluminum shavings out of my head. I guess I'll find out when I get to the dunes next weekend. I ran it for about 15 minutes and did an oil change when I got done just to be safe.

Peace....