HeliCoil to make hole smaller?
HeliCoil to make hole smaller?
(OP)
Hello All,
Ive made a rather stupid and annoying mistake when specifying a tapped hole which should have been M4, but is infact M5. Am I right in thinking I can use a m4 helicoil to reduce the size of the thread. I know this is not the typical use for a helicoil but i'm in need of a solution rather swiftly.
Thanks in advance.
Ive made a rather stupid and annoying mistake when specifying a tapped hole which should have been M4, but is infact M5. Am I right in thinking I can use a m4 helicoil to reduce the size of the thread. I know this is not the typical use for a helicoil but i'm in need of a solution rather swiftly.
Thanks in advance.





RE: HeliCoil to make hole smaller?
Chris, CSWA
SolidWorks '15
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RE: HeliCoil to make hole smaller?
Or are you proposing drilling & re-tapping to accept an M4 helicoil insert?
Not sure typical Heli-Coil will work but there due to the little material you have to remove but there are other types of thread inserts that may.
http://www.mcmaster.com/#standard-threaded-inserts...
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: HeliCoil to make hole smaller?
Now what you can try to do is use the Helicoil as it's intended to be used, that is by drilling out the original hole and use THE Helicoil tap to create a new 'threaded' hole to accept the M4 Helicoil, if that's even possible since Helicoils are generally intended to 'repair' a damaged threaded-hole with a LIKE-SIZED THREAD. If you have an M5 threaded hole there may not be enough material left to even allow you to drill and chase a properly-sized threaded-hole for the M4 helicoil insert.
John R. Baker, P.E.
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To an Engineer, the glass is twice as big as it needs to be.
RE: HeliCoil to make hole smaller?
Have you looked into "Twinserts"?
http://www.stanleyengineeredfastening.com/sites/ww...
RE: HeliCoil to make hole smaller?
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: HeliCoil to make hole smaller?
Just for the heck of it once, I tapped a 1/4-20UNC hole, then I re-tapped it and I installed a 10-32UNF helical thread insert. The resulting thread feels fairly strong. On a non-critical application, I might do this.
The solid replacement inserts sound like a good idea. Carr Lane carries them too. You can also search for Keenserts.
--
JHG
RE: HeliCoil to make hole smaller?
I wouldn't go closing up an exchanger or anything with them, but they do hold up well...
www.linkedin.com/pub/nathan-brink/35/861/18
RE: HeliCoil to make hole smaller?
Filling a M5 hole and re-tapping for M4 won't leave much material behind (in the filler0.
choices ...
1) live with the M5 bolt (change the mating part), or
2) drill out the M5 hole to something like M8, fill with an interference fit plug, drill and tap.
another day in paradise, or is paradise one day closer ?
RE: HeliCoil to make hole smaller?
Boellhoff (OEM of Helicoil, no rel.) does have an option where the thread is cold formed instead of cut. So it might just work if your material allows that and if the forming works and the residual strength after "helicoiling" covers your requirements.
And, somebody manufacturing this kind of thing perhaps has seen the same issue already & could point you towards a solution.
For small numbers, I'd redrill bigger, insert a plug etc as above, by others.
Regards
R.
RE: HeliCoil to make hole smaller?
RE: HeliCoil to make hole smaller?
The process involved drilling the hole to 5mmØ, tapping for M6 and and using a 6M/M4 thread reducer with a little thread-lock.
Thanks for all the replies hopefully someone will find the solution helpful.