Helicoil M8 1

[blckwtr]

Hi;

What kind of bore and thread are needed for a M8 Helicoil? Is it enough to mark it as a hole and specify it with M8 Helicoil on the drawing?

Where can I find more information about this?

 

[desertfox]

Hi blckwtr

Try page 18 of this link:-

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

desertfox

 

[ornerynorsk]

Contact Helicoil (Emhart) and get the data from them directly. If you specify pre-drill and insert tap dimensions, you had better also specify the brand and part number that are to be used, as there are several knock-offs available that may or may not use the same specs. There are also several varieties and material choices of specific insert in each particular thread size, as well.

 

[drawoh]

blckwtr,

You need an M8 helical insert tap drill, as well as an insertion tool. The manufacturer's literature will tell what size tap drill to use. If you buy a helical thread insert kit, you should get everything.

JHG

 

[Tmoose]

As a point of reference I believe the metric Helicoil tap drill is usually pretty close to the nominal thread size being restored. Bad 8 mm thread? 8 mm tap drill. Handy since that is about the size hole that ripped when the threads "strip"

 

[drawoh]

Tmoose,

Just for the heck of it quite a few years ago, I tapped a 1/4-20UNC hole in a piece of aluminium. Then, I tapped it out again and installed a 10-32UNF insert. I don't think I achieved full strength, but it was quite strong. This is the sort of abuse those things were meant for.

If your M8 hole stripped, would you even use the tap drill before going in with the helical tap?

JHG

 

[Tunalover]

blckwtr-
I would be careful about calling out too much installation information on the drawing; laying out all those specs is an invitation to errors and scrapped parts. For example, the tap drill size can be omitted from the drawing as long as you say (for commercial helicoils) INSTALL IAW MANUFACTURER'S RECOMMENDATIONS and carefully call out the manufacturer and mfgr's part number.

Tunalover

 

[Tmoose]

"If your M8 hole stripped, would you even use the tap drill before going in with the helical tap? "

Yeah, I drill to the bottom of the original hole to clear out the good threads down there. I hate tapping holes drilled to minimum depth for tapping, or using bottom taps, or asking someone else to, either, unless there's a real good reason. Deep holes have lots of chip clearance, and can be tapped for longer than std inserts or even double inserts.

The helicoil site says refer to their catalog for tap drill sized, but I could not find the catalog.

These guys say the tap drill is a 5-10 thou larger than the nominal thread size anyhow. mighjt be right

http://www.thorintl.com/Drill-Sizes-HeliCoils-Metric.htm

 

[YoungTurk]

I'm with tunalover.

Have researched this previously and the best I came up with that the mfg provides specific taps for use with their product. Although it might just be an expensive standard tap, I do not believe that to be the case and would suggest going with mfg instructions. This assumes you can trust your techs...