Recoil inserts in a blind hole

[var10]

Hello Everyone,

I have an tapped alluminium part. Should the threads damage we were to use recoil to repair the thread. I have figured out most. I am using 6-32 size insert in some blind holes and thru holes. I am happy with the blind holes but the thru holes are 0.195inches long. But recoil catalogue specifies for a proper fit the hole needs to be 0.279inches. The insert is only 0.138in long (im only using a 1D). I feel it will be ok to install a insert here. If any one else thinks otherwise, please explain.

PS: The metal is already built.

Thanks,

V.

 

[desertfox]

hi

According to this link a 6-32 x1D only needs a hole length of 0.138.

http://www.recoilinserts.com/Item-Listing-Bulk-Inserts-Screw-Locking.acv

so I would think your okay

 

[var10]

Are you sure the length refered to in the table is hole depth? it looks like their just giving a value for 1D.

 

[desertfox]

Hi
yes sorry you are correct, I'm looking in this catalogue but can't find where it says 0.195in hole depth.

http://www.alcoa.com/fastening_systems/commercial/catalog/productcatalog/Alcoa_Recoil_Catalog.pdf

 

[var10]

I am not able to open this link. But I did get mine from alcoa recoil. If you scroll down to pg 25 - it says depth is .279.

 

[desertfox]

hi

Okay I've found it, reading it I think you do need the extra depth to be able to take the tang off the insert but also if you look on page 7 the insert shown is not flush with the top of the tapped hole its two or three threads in, so I think its to do with how the insert is installed.
Why not check with the supplier?

 

[var10]

couldn't find any tech reps in our place, only sales reps. Found one who sells "similar" stuff and he reckons it ok, but I am not satisfied and want to check with couple more people. Your correct, it is not flush it is one or two turns below the surface, but does it need to have a 0.279inch hole or is mine good enough?

 

[desertfox]

Hi

From a strength point of view it probably doesn't matter because the 0.138" length is the critical part, however if not having that extra length creates problems with the installation, which in turn effects the .138" engaged length then it will matter.
Ask the rep for a written statement that it will be okay and see what the reaction is.

 

[desertfox]

hi

Look on page 62 of the catalogue it says:-

Minimum Material Thickness
The recommended minimum material thickness for through-hole applications is equal to the nominal length of the insert plus
one pitch. This allows for proper countersinking and installation of the insert at 3/4 to 1-1/2 pitches below the surface of the
component. In design critical applications, the minimum thickness may be reduced by eliminating the countersink and installing
the insert to 1/4 to 1/2 pitch below the surface

So I think your hole is deep enough.

 

[var10]

There will be some degree of compression as the inserts are larger in diam than the hole and need to compensate the compression by stretching axially. I am just hoping this axial elongation would be smaller than 0.195inch because I do not have any tools or the physical part with me.

If its the case 1/4 pitch + nom length = 0.040+0.138 = 0.178inch and yes I am safe.

Thanks heaps

 

[Tmoose]

As long as the installed insert is fully supported it is fine.

There are more subtle concerns.
As pointed out by others the insert should always be installed slightly below the surface (and deeper if the fastener needs a counterbore).
The blind hole needs sufficient depth for tapping.