1988 8hp rear cover rivets are tough!

[cprodave]

Got cover/cowl jammed on Model E8RECR due to failed rear cover latch. Trying to drill out rivets, those rivets are tough! Any suggestions for removing the rivets so I can install a Rear Hook Repair Kit? I have tried drilling and angle grinder and Dremel...

 

[cprodave]

Correction this is a 1998 model.

 

[iggyw1]

That sounds like tough rivets for sure if you cannot grind them off. I would try a center punch to just put a little bit of a dimple into it so your drill won't wander on you, and try a carbide drill to get thru the solid rivets.

 

[cprodave]

I used a punch to center start of drilling then a Cobalt drill (harder than carbide), it worked although rivet spun at times. Thanks to all.

 

[Tim Frank]

For future reference, carbide is harder than cobalt.
Having said that, in my experience most carbide bits are great for concrete, but not as much for metal.

 

[cprodave]

Hmmm, salesman at my local hardware store (an old Mom and Pop, has-everything store) told me the Cobalt ones were best he had (with "proud pricing" to match! Lol).

So are the "carbide" bits made of high speed steel plasma coated with Tungstan Carbide, Silicon Carbide or "other"? While "Cobalt" drills are steel alloy containing 5 to 8 weight percent Cobalt? Are Titanium Nitride coated drills good for drilling Stainless? Supposedly Carbide can drill through Cobalt although Carbide brittleness may result in fracture (see 2nd link--YouTube).

I'm not a machinist so any further hands-on experience drilling out fasteners is welcome.

https://home.howstuffworks.com/cobalt-drill-bits.htm

https://youtu.be/3tMaCJ3LSKM

 

[oldboat1]

Might be easier to do a fiberglass cutout -- replace with a new latch.

 

[cprodave]

I will keep the fiberglass cutout method in mind for the future. Thanks.

 

[Klink]

If the rivets are made of stainless steel (SS), it requires slower speeds drilling without creating heat or else you will harden the SS. The way to not heat up is to take a break or use water to keep it cool , or both. Also, you can drill with a smaller bit and then increase the size of the bit in increments. A rivet should be a piece of cake, as I am talking about drilling plate 1/4" thick or thicker.

 

[cprodave]

Klink, thanks for the tip. I did notice that lubricating with low viscosity fluid improved drilling progress.