Heli-Coil Hand Installation Tools

Thank you for the reply.

I have read your reply about 4 times and I just can't quite fully grasp the procedure. I'm now mad at myself for not spending more time with the guys in the machine shop at my old job. A 1 minute demonstration would have helped a lot.

The most fundamental thing I don't yet grasp is what actually turns the Heli-Coil as you insert it. The unthreaded shaft has a slot to grab the tang. Thus, it seems like the unthreaded shaft provides the torque to turn the insert in. But the outer shaft has male threads to mate with the female threads on the inside of the insert. Either the outer shaft also turns as the insert is turned into the hole or the outer shaft remains stationary and the insert spirals off the outer shaft as it is inserted. I'm guessing that the second is true, but that leaves me very confused about the pocket.

I hit Google for a while after reading your post and I'm a little smarter than I was, but I still need a little more smarts.

Is the insertion tool you described the same as the "Type II", "Type III", "Type V" and "Type VII" prewinders from Heli-Coil? If so then the pictures on the Heli-Coil web site allow me to see the tool you are describing.

I'm also very interested in your rejections. You stated that for most installers you have about 1 in 10 damaged. What happens and what gets damaged? Is the damage to the insert or to the item you are installing the insert into? Is the damage an early break of the tang? Are your rejections due to installation depths by hand not always meeting a demanding distance specification?

Thanks for your reply,

Bruce

Thank you,

Bruce

pinion.ir

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what is helicoil ?

fitting the rosan fitting to the helicoil imho : is critical..any short cut will be unwise

improper seating imho is the primary reason for failure of helicoils..

if i may ..?..as not knowing what your fastening..or the material , but you intend to drill and possibly tap the hole for a helicoil.. why not tap the hole to recieve the attaching hardware?

if the material is strong enough for the helicoil.. it should be strong enough for the bolt/ screw..and any time i can upgrade my class of fastner , i'm very happy..

I plan to put 1/4-20 Heli-Coils into aluminum. I'm not a mechanical engineer but I'm pretty sure that the Heli-Coil threads will end up being a lot stronger than if I just tapped the aluminum. I understand your point, but I think that the insert will give me a better quality thread with a stronger material. The insert will spread stress out better.

This you are right and also the contact damages when tightening the screw is just a significant bit reduced. In fact we put helicoils where (of course not Al, in Grey Irons)

Where the L/D ratio is not good eg the flange thickness is not the recommended 1.5 times the bolt diameters and

Where frequent dismantling of bolts are required by customer, thereby gradually over time wearing out the threads.

There is some value to the peace of mind you get with the kit. I guess I'm trying to avoid spending the extra money for the extra kit stuff.

This would probably be easier if the catalog didn't list "threaded mandrel", "prewinder" and "non-captive prewinder" types of tools. Giving me choices makes me think that I should know what I am doing before I make a choice.

Thanks for the reply,

Bruce

I haven't mic-ed the drill provided to see whether it is a number or letter size, but I bet the tap is custom for the coil.

I did a little searching for videos and I think I now understand the prewinders. My notes on the videos are included here. I don't know if the links will automatically work, but a cut and paste of the URL will work.

http://www.youtube.com/watch?v=wLL2FEyafVk video showing prewinder
http://www.youtube.com/watch?v=RFYa6sjhh_E good video from Tennessee Technology Center (mandrel, not prewinder)

http://www.youtube.com/watch?v=LCtXiwlQsiU video from Heli-Coil describing strength of threads

http://www.youtube.com/watch?v=Om1spw_PInA "go gauge" repair trick for Heli-Coil

http://www.youtube.com/watch?v=7rUA48ZAZOg Time Sert (similar but not the same)
http://www.youtube.com/watch?v=2vON3beYvB4 another Time Sert video

Good Afternoon Bruce,

Yep, First off, SB gets another GA!! Now, with protocol satisfied, I'd like to put in my nickle's worth:

Back when dirt was young, I was at Philco-Ford and we made El-over-Az Dish Antennas. From the M.E. point of view, this meant we had approximately 750 lbs. (345 Kg.) of equipment rotating about a very small centerline on a 6 ft. x 6ft. by 1/2 inch aluminum plate. The standard attaching threads were 1/4-20 fasteners, CRES, into helicoils. Our machine shop in Palo Alto, CA made the plates to amazingly tight tolerances, time after time. The big 'rub' was that some of the electronics modules that were mounted on said plate had MTBF's on the order of only HUNDREDS of hours. Guess what?? The constant R&R by the customers people led to 'tear-out' and/or worse conditions. So much for the history lesson.....

My point here is that I was sent 'back East' with the hand tools and a box of raw Helicoils. While your stated installation requirement is only 100/200 threads (and you are probably NOT government funded, and these products ARE EXPENSIVE), we PRACTICED hand installation with every technician! Please understand that the learning curve is NOT great. But, as SB points out, there will be a 'yield' consideration even with floor level people that do this work day in and day out. PLEASE, take the time to practice this technique!!!! The cost of the raw material and parts WILL AMORTIZE itself over successful installations completely!! Lastly, you will find that all of a sudden, softer(and much lighter) materials such as aluminum become much more adventageous design partners when coupled with Helicoil inserts. Rather than finding this a design constraint, I believe you will find it opens new avenues of design possibilities...

That was NOT a sales pitch, but I did just recently, fix the block on my Ford E300 van with the application of two (2) Helicoils. Would have taken 14 hours, otherwise, to remove the engine and achieve the same result. So, whats your time worth??

Respectfully submitted,

GLB

I point not mentioned here (I may have missed it because I skipped through the posts quickly) is that the coils need to be set slightly below the surface. the pre-winder tool has an adjustable stop that allows you to get the coils a consistent distance below the surface.

One small note that may be of help to you is the it is the tang that does all the work to getting the coil in place. when twisting it effectively reduces the diameter of the coil as you twist it. I like to give it just a slight back twist after it seats all the way in.

I usually brake of the tang at the bottom with a punch as suggested previously. I also like to use a bit of thread locker when I put them in, it seems to help them stay put a bit better in aluminum and and make them just a bit easier to insert.