Removal of rusty dynabolts from bricks

[Russ42]

I have quite a few places where dynabolts have been put into the bricks in the past and have since rusted up badly making them thus far impossible to get out. The rusting is expanding the bolts and breaking the bricks (see photo)

The bolt itself has broken off inside the surrounding metal cylinder. I have a plan A and a plan B.

A. try to drill out the metal cylinder until the drill hits the bolt. Then.......try to drill out the bolt and cylinder together. Perhaps, in the process, the drill bit will grip the cylinder and cause it to spin, thus making it possible to remove.

B. use a  "Vacuum Diamond Dry Drilling Tile Drill Bit" to drill it out. I foresee problem with this.

1. The hole produced will be large and must be filled.

2. if the drill tries to drill the metal of the bolt, it will lose the diamond chips on the end and be rendered useless.

Is there a tried and tested method of removing these pesky things

[MitchellMc]

Great work, @Russ42! 

Many thanks for updating us on your success.

Mitchell

[redracer01]

Hello @Russ42 

That's good to hear! I'm glad you got the bolts out and just need to patch up the wall. We will definitely add this solution to be our regular methods of removing dynabolts in brick work! If you decide to touch up the paint on the wall remember that you need to bring a sample at least the size of a 10 cent coin so they can do a proper colour match. 

Cheers, 

Red

[Beavau]

Hi Russ

I'm not sure how old this thread is.

I have the exact issue with MANY cut off rusted bolts breaking brickwork on 50 year old strata factory units. We plan to paint but need to make sure no future cracking bricks from rust expansion.

I assume you used a diamond tip hole saw. How deep did you go, and how long do you think think the holesaw will last? My estimate is we have about 50 to do. Any tips?

Cheers

[MitchellMc]

Welcome to the Bunnings Workshop community @Beavau. It's great to have you join us, and many thanks for your question about drilling brick.

Let me mention @Russ42, so they are alerted to your question, and hopefully, they can answer it for you. We have these diamond core bits, but I'd be keen to hear what was used here. In any case, I'd believe the key to the longevity of the bit would be water-cooling and only light pressure on the tool. Dedicate a few days to the job and take the holes nice and slow. Allow the bit to do the cutting, and don't force it, or you'll ruin the diamond tip.

Mitchell

[Russ42]

Thanks Mitch, I have done what you have suggested and it worked great. Now I have holes in the bricks but will just put some sikaflex in them. They are not pretty but all I can think of. I have the same problem with bolts in a 90mm thick beam. I can't use the diamond core bits but I can a hole saw for wood, although it will not get all the way through, even if I take the head off the other end. Any suggestions there? I have tried belting it out, screwing it out, belting and screwing it out, heating it up and beltin........you get the picture..... They are rusted it.

[Beavau]

Thanks Mitch and @Russ42,

Russ, so you used a diamond tip hole saw with an inside diameter slightly larger than the rusting bolt. Did you find that the contact with the bolt caused extra wear on the hole saw? What depth did you have to go? If you go to say 40mm is that sufficient to allow the bolt to be loosened and worked out? Or did you drill the full depth of the bolt.

Your experience in having already done this is appreciated. I've searched heaps, and your posts are the only ones talking about this method.

Cheers

[MitchellMc]

Hi @Russ42,

Maybe hole saw from either side and then drill a hole to get a long jigsaw blade in there. Hopefully you could then and cut out the remaining central section. 

Mitchell

[Russ42]

Yes, that is the best I can do too. Unfortunately, my hole saws have a central drill bit to guide the saw which will be inhibited by the bolt. I will see if I can (gently) saw it without the guiding drill bit (wearing glasses, gloves, etc.) Better still, I could drill arround the bolt with a smallish drill bit instead of trying with the hole saw. Perhaps once I get both ends cleared out I can press them out with a decent clamp or belt them out, clean it up and glue in a dowel. They are 4 brackets holding 4 posts which are holding 2 verandahs. I don't want to move the posts away from where they are as they are sitting on concrete footings which are serviceable. Thanks Mitch

[MitchellMc]

You can create a timber jig for your hole saw @Russ42. That will stop it from skipping around without the central drill bit.

I believe @Beavau was keen to find out whether you used my initial recommendation of drilling out the Dynabolt bolt with a cobalt drill bit and compacting the sleeve. Or, did you use a diamond-tipped core drill bit and drill around the entire Dynabolt? From your images and the now over-sized holes, it appears you've used the core bit.

Mitchell

[Russ42]

Great idea with the jig thanks Mitch. Will use it for the bolts in the wood. My hole saws are not much more than toys so will have to be careful with it.

As you said, I used the core drill on the dynabolts which worked fine and did it pretty easily.