I have to cut a 1/2" diameter hardened bolt (twice) with a DeWalt oscillating saw. I've used their best steel cutting blade and not very happy with the results so I know they won't do the job. Friend said Imperial high carbon is good but not sure which blade to buy. The best DeWalt blades wouldn't last more than two or three drywall screws before the teeth were flat so I'm pretty sure trying to cut through a half inch cross member to body mount hardened bolt on my wife's T&C that they just won't get it done. Where the bolt is there is no way other than a straight in oscillating saw it my only chance at this point of getting it out. Broke the head of the bolt off, so I welded a nut to the and this just created more problems as the plate with the nut in the frame channel just twisted and turned. I can see the plated through a triangulated hole in the side of the frame channel and if I can cut the bolt below the plate I think I can get it out.........one shot so I need the best, toughest oscillating saw blade. Thanks.

Mike

Any way to use a Dremel tool? I know that does not answer your question

I do not believe the bolts are hardened. The location along with the access to the top and bottom of the fastener would determine my plan of attack.
Drilling is an option but one has the be dead center and straight to be successful. Is the other side a captive nut ??? If so that can alter the approach.
Can you provide a couple of pic's of it's location, top and bottom ?

Use a cut off wheel to cut an X in the head of the bolt, then a good cold chisel and hammer to knock the head off, or an air hammer with a good chisel. Same as removing a solid rivet.

Having the head of a body bolt break off is a new one on me, I've seen a lot of body mount failures, but not the bolt head issue.

Got an old fashioned Sawzall? That is going to be your best bet on cutting that body mount bolt. It may not be a grade 8 bolt, but it has been aged hard, they cut hard with a good sawzall blade. I usually am lucky if I can get a new blade to cut a 2nd bolt.

The bolt passes through a metal sleeve inside the rubber bushing, for the bolt head to break off, the bolt must be froze inside the metal sleeve. The top of the bolt is screwed into a captive nut, it really doesn't take much force to break the nut captive enclosure. If indeed, the bolt is seized in the metal sleeve, your going to have to cut the bolt off above the rubber bushing, and then your going to have to gain access to the captive nut and probably replace it and the nut encasement, then patch the access hole you made to gain access. You will have to replace the upper and lower bushings, the bolt, the captive nut, and the large bottom washer. Also expect to have to repair the metal around the hole in the subframe, Often dust & grit wear the metal near the rubber bushing very thin, if you don't fix that now, you will get to do this again in a year or two. Gene

For sure more photos are needed and have them in a few. I was asking about the oscillating saw blades to get ready if plans A-J didn't work and knowing Moparts members ALWAYS come up with lots of great ideas, suggestions and plans. I have two DeWALT "sawzall" battery and corded that may reach over the suspension cast aluminum support? I just need to remove or "lift" the rear heater lines out of harms way and maybe add some way of limiting the blade travel into the opening?

The broken head and a some shank and the new bolt from our local Mopar dealer parts department. Also the old and new body damper. Also the under engine/trans cross member support. The body dampers are mounted in the upper left and right rectangular holes when assembled. The bolt looks to have rolled threads so just assume the bolts are fairly hardened???

The remaining 4 inches (?) of the broken bolt is still up in the "frame" channel along with a 1/4" (?) rectangular plate with a 14mm x 2.0 thread (welded?) nut in the center. In one photo you can see maybe an inch of the bolt through the plate nut and up into another hole above it. When I push the broken bolt up you can see the plate. I need to cut the bolt just under the plate and it will drop out and down through the aluminum suspension support. Hopefully if the is done the remaining bolt still in the plate nut that is sticking above the plate won't interfere with pulling the plate out through the side of the triangulated opening in the frame channel (the second photo is the driver's side that came out cleanly, just to show the opening, you can just see the top of the nut or threaded collar?)

Had to use that old rusty piece of the original damper mount to lift the lines out of the way I welded a nut to the broken bolt (not pretty I know ) and then heated the crap out of it and hoped it would free the remaining bolt from the plate nut, no luck doing that, only twisted the plate in the channel.....how it does that I have no idea, Went inside and hoped to find access from up top, no luck there. Then found the triangular opening behind the lines and started to figure out how I can cut that bolt??

I first bought a Dremel MM485U carbide cutting technology
oscillating saw blade for my Milwaukee,
“Cuts hardened materials”
but when using it to cut grout the blade teeth broke off rather than wore down.

It might have done better gently cutting a steel bolt like the picture on the Dremel package illustrates,
but I am doubtful.

I bought a Bosch OSC134C “Premium Carbide” to replace the Dremel but have not used it.

Since you have the broken bolt,
mount it in a vice and try cutting that stub of the shank.

A recip saw with a Diablo blade would be far faster.
The pictures hint that you could possibly cut with a recip blade to a shallow depth,
turn the bolt with your welded on nut,
cut a fresh surface to a shallow depth,
turn the nut more, etc.
This could at least reduce the amount to finish off with the oscillating blade.

Since you have a worn out Dewalt Oscillating blade
you might ponder
cutting a section of hacksaw blade and riveting it onto the old Dewalt,
or tack welding, brazing, etc.

Good luck.

They make mini hacksaws with handles inline with the blade.

You need to drive a wedge between the subframe and the rail along side of the bolt. You only need a gap big enough to fit a sazall blade between the two pieces. Then cut the bolt in the gap, between the channel and the subframe, where you put the wedge. The reason the plate is twisting in the channel is because it was only held in place with sheet metal strips, and now those are broken. Re Read my 1st post. I've done this probably a hundred times. Gene

Gene and all I GOT IT OUT/CUT TONIGHT!!! Cut it with the 20V DeWALT sawzall and a Diablo (Swiss made) 20T" blade 8" length. Moved the lines up with bungee cords and zip ties, cut the top of the bolt above the plate first which wiped out the first inch of the tip of the blade. I used a Dremel cutoff wheel and removed that from the blade, took a bottle/pin jack and pushed the bolt up and in as high as it would go and got under the plate and cut the bolt under the plate, Had to gauge just how far I could go in with the blade to avoid hitting the backside of the channel as the blade replicated and held it steady for what seemed like forever waiting for the blade to hit. Got the plate out and thought I would just make a new plate and weld a new nut to it but then got determined to get the remaining piece of the cut bolt out just for principle. Got the torch out and heated the crap out of it and realized that I could have never applied as much heat as I had to if it were in the channel. Got the piece out cleaned the threads with a tap, primed it and going to finish it with some good paint. Anti seize, new dampers and back in after I tackle the steering rack (removed also) and the cross threaded upstream 02 sensor bung in the exhaust.

THANKS AGAIN Gene and ALL.......as always this place ROCKS!

Mike

Pretty tough Diablo carbide blade but that bolt was almost too tough for it. First cut took out the first inch or so of the teeth. Second cut for some reason didn't do too much damage ?? Yes I did hit the body/channel wall once or twice and bent the blade...straightened it and carried on, didn't take as long as I thought. Thanks again.

Surprise to me but Diablo does make oscillating saw carbide tooth metal cutting blades

https://www.diablotools.com/products/DOU125CGP

https://www.diablotools.com/products/DOS125CF3

Assorted set

https://www.diablotools.com/products/DOU5S

Having cut as many of these bolts off as I have, I just don't picture an oscillating blade doing the job. I believe the cut process of the oscillating blade isn't as an effective cut as the inline saw with the hardened bolts. I have an oscillating feature on my sawzall, all it does with hardened bolts is kill the blades. Gene

Yes, I have my doubts too.
I have also witnessed that the Fein cuts much better than my Milwaukee M12.