With a fiberglass cutting disc it's a mini cutoff wheel. Cuts metal just fine.



The teeny ones you pictured will vanish instantly, but the fiberglass ones last a lot longer.

--Ian

(Edit: As I said, I wouldn't recommend going out and buying one just for this purpose, but if you've got one available it will certainly do it)

 

Even better than the above is the EZ-Lock kit:

https://www.homedepot.com/p/Dremel-E...Z406/100484370







These are basically miniature angle-grinder blades, and come with a handy quick-change collet. This is the shaft that I have in my dremel 90% of the time. The EZ-change discs are slightly larger and thicker than the screw-type version, and seem to made of sterner stuff. I very rarely break them.

This is the first tool I think of when tasked with "I need to cut through a bolt in a tight space." I've used them on tool steel, hardened steel shafts, steel plate, etc. Sometimes you use up more than one disc on a job, but the small size allows you to get them into places which are otherwise inaccessible.

 

I never knew those even existed. I'll certainly give them a shot.

 

You might be able to plunge cut it with an oscillating multi tool with a carbide bit.

 

I'd loosen the rest of the bolts, wedge a pry bar in to get some pressure put on the bolt/nut, then rattle gun it off. Threads fucked, might as well **** the rest of them.

 

I have a Ryobi version of the Dremel and it is good quality. Sometimes the access requires a smaller tool like the Ryobi. I prefer the air cut-off wheel for slightly larger jobs and the angle grinder with a cut-off wheel for the ones with good access. You can never have enough cutting tool variety in your arsenal.

 

My first few (Sch. 40) manifold were cut with these. IIRC For Sav's I ended up using the quick connect wheels Mr. Perez noted.

 

Successfully annihilated the nut with those fiberglass wheels. That was probably the biggest nut I've ever busted

 

Pos+Cat given for this tip - never knew about them and will come in handy in future.

I've used a Dremel with regular cut-off wheels to cut a nut off a sway bar that the owner manager to round off beautifully.
That took ages and several cutting wheels due to them wearing quickly and snapping if I used the wrong angle.
When I finished I looked like a WWI fighter ace, there was black crap all over my face except where the safety goggles had been.

Tip: If you start rounding off a nut/bolt, switch to another tool, the one you're using is just making things worse!

Unfortunately those nut-busters/crackers tend not to fit in the spaces where you need them and often you can't even fit it over the nut because they're so thick :(
I've got 2 in my collection though because they're worth trying first.

 

Drill a pilot hole in the nut, then a larger hole, then air chisel to split the nut.

 

I like the EZ dremel wheels. I've had a few of them separate though so be mindful!

 

The dremel metal cutting discs work well, but IME don't last very long (they get chewed up quick). But at least they don't just shatter at a slight touch like the brown dremel discs!