Drill and tap vs combination drill & tap for m8 fastener

[JHZR2]

Two of the belly pan bolts on my ML320 thread into a steel structural crossmember. The threads for the M6 bolts are loose. The structural item is maybe 1/4” thick steel, I’d guess. MB usually uses speed nuts, or has square holes with a press in metal female speed nut, but not these.

I’d like to drill and tap to M8, then use a threaded insert with loctite red to give me the M6 threads.

The question is what tool? It’s not a high consequence or very exact tolerance application. I just don’t want the fasteners to come out on a big bump.

So is a separate drill and tap really best, or can these combo units, when done with a slow hand drilll and a lot of oil, do good enough?

 

[D60]

Those are for sheetmetal only. I personally wouldn't try in greater than 14ga

 

[RooflessVW]

I would pop some rivnuts in.

https://www.rivetsonline.com/39316-kit-50-assorted-steel-metric-ribbed-l-series-rivet-nu/kit-39316

 

[Trav]

I just tap m6 bolts out to m7 and use m7 bolts (home depot, amazon bolt depot, etc) They look almost the same only it takes an 11mm socket not a 10. No oversize drilling required just run an m6 drill through and use the m7 tap. Not for every m6 bolt use but for many things like underbody panels it works a treat.

https://www.amazon.com/Irwin-Indust...qid=1757371869&sprefix=7mm+tap,aps,163&sr=8-3

 

[JHZR2]

I would pop some rivnuts in.

https://www.rivetsonline.com/39316-kit-50-assorted-steel-metric-ribbed-l-series-rivet-nu/kit-39316

That’s what should have been used in there imo.

 

[JHZR2]

Those are for sheetmetal only. I personally wouldn't try in greater than 14ga

Thanks. So this is good for reference regardless. So if doing any more substantial thickness, you HAVE to use a standard tap then?

What good are threads in sheetmetal? I can’t see how they’d have any holding power at all.

 

[Astro14]

I would pop some rivnuts in.

https://www.rivetsonline.com/39316-kit-50-assorted-steel-metric-ribbed-l-series-rivet-nu/kit-39316

Yep - Rivet nuts would be perfect for this. Drill them out, use an M6 rivet nut, and keep the same fasteners.

 

[JimPghPA]

If you can't find anything you need for that job, try McMaster-Carr online.

 

[slacktide_bitog]

I just found this now. They seem cool

The M8 ones seem like they'd be good for drilling/tapping holes in brake drums and rotors that don't already have holes. Most Japanese OE rotors and drums (and some aftermarket ones for the same cars) have M8-1.25 holes pre-drilled already, to help get the old one off without a hammer

Maybe a drill/tap would be good for adding the holes to rotors and drums that don't have them, as well as American and Euro cars that don't have them in the first place.

 

[slacktide_bitog]

I decided to try one to drill bolt holes in my drums. The drill/tap combo worked great. Make sure you have plenty of Tap Magic on hand

 

[oil pan 4]

I would pop some rivnuts in.

https://www.rivetsonline.com/39316-kit-50-assorted-steel-metric-ribbed-l-series-rivet-nu/kit-39316

Yep!

 

[paulo57509]

I love rivet nuts. aluminum is a lot easier to work with; they don't take a gorilla grip to install.

https://www.mcmaster.com/products/rivet-nuts/rivet-nuts-3~/

If you don't already have the tool, count this into the equation. Then you'll be looking for places to use rivet nuts!

I got my tool/starter assortment from work when we were on a 5S crusade, and management decided we didn't need to do spot repairs for our sheet metal fab supplier.

 

[D60]

I love rivet nuts. aluminum is a lot easier to work with; they don't take a gorilla grip to install.

https://www.mcmaster.com/products/rivet-nuts/rivet-nuts-3~/

If you don't already have the tool, count this into the equation. Then you'll be looking for places to use rivet nuts!

I got my tool/starter assortment from work when we were on a 5S crusade, and management decided we didn't need to do spot repairs for our sheet metal fab supplier.

Rivnuts are cool. If there's room for the wings I've come to appreciate plusnuts as they spread the load over a much greater area, kinda like an "X" wall toggle. Only necessary for greater loads where the relatively small expansion of a rivnut might pull out