advice on cutting rock piece

[james3370]

i have this large unique rock piece i want to use as the base piece for the center structure of my rock wall in my new build.

front:


sides:


back:


my plan is to place rocks under the back (where the can of paint is now LOL) & use this as a large cave structure. probably stack some more rocks on top of it too w/ other caves/pass-thrus

my question is this.......i want to cut the front out w/ an arched opening similar to this:


would the best way to do this be to drill holes like where i put the blue dots & then use a hammer & chisel to take out the part i want to remove???? as you can see in the back pic above, part of that area is quite thick.......

i think this will be quite a unique/interesting piece when the rock wall & center structure are finished

 

[reef2]

a angle grinder and diamond bit would make quick work of it.

 

[james3370]

but do you think i should "score" the edges where i want to cut so hopefully the whole thing doesn't shatter into pieces??

 

[stylolvr]

I've always known base/live rock to be fairly soft and brittle - easy to work with. The grinder would work well, but the hole and chisel method would as well, but would just take a little longer. After the major cutting is done, some smoothing of the edges for a more natural look would probably be nice.

 

[stylolvr]

Let us know what you use, and how well it works.

 

[coralnut99]

It looks like a piece of fiji. It's quite a bit softer than Florida limestone. I would shy away from taking hammer and chisel to it, even after drilling relief holes. The angle grinder might be slower, but a safer approach. That's just my two bits.

 

[iamwrasseman]

be easy , drilling the holes is a good start but make them close and try not to chisel as to put pressure on the rock you might end up with rubble good luck

 

[~sp0ok~]

i had a very (large piece of LR) in my old 55g tank and i used a grinder to cut it was a little hard at frist but did the job and and just smooth the edges



good luck

 

[Esquare]

I've used my bandsaw to cut LR (regular blade) but the drill and chisel method might give you the most realistic look.

 

[commonstranger]

James I might drill some holes but I wouldnt go that deep. Then I would break out the chisel. Just a reminder that this is a center piece rock and you want it to look good. Just take your time with the chisel and I know the extra work will pay off. Little by Little will get you what you want.

 

[sandalscout]

Yeah, I think the angle grinder would give you the best control and finish.... Besides, if you don't have one, it's an excuse to get one! (less than $20 at harbor freight if nothing else). Let us know how it turns out.

 

[jvdb]

I've used tungsten carbide blades in my sawzall to cut live rock before.

http://www.amazon.com/Milwaukee-48-00-1430-Tungsten-Carbide-Sawzall/dp/B00004U0U2

Designed to cut through hardwood flooring, cast iron, stainless steel, fiberglass materials, ceramic tile, stone, plaster, and more

 

[james3370]

<a href=showthread.php?s=&postid=13986639#post13986639 target=_blank>Originally posted</a> by sandalscout
Yeah, I think the angle grinder would give you the best control and finish.... Besides, if you don't have one, it's an excuse to get one! (less than $20 at harbor freight if nothing else). Let us know how it turns out.

funny you mention that cause i have a list from the harbor freight website for me to get tomorrow.....there is one right by the mall less than 1/2 mile from me

decent 4 1/2" angle grinder for 19.99 .....set of 5 masonry bits for 3.00 .....and a 4 1/2" diamond coated wheel for $24.99 ......3" masonry chisel for $3.99

think that should just about do it :rollface:

 

[DMBillies]

On the drilling holes... LR is quite soft and I've broken my share of rock using a masonry bit. The key is using a small bit and going slow. I'd say it could hurt to go that route + the angle grinder. Whatever you choose, patience is the answer or you'll end up with 2 or more busted up pieces. Never know where there are pockets or faults in the rock.

 

[james3370]

^^^^yeah that's why the 5-piece masonry bit set....start w/ very small holes & step-drill bigger

 

[gflat65]

With a diamond tip bandsaw, you have pin point control and the rocks don't crumble very often at all. You have limits on how big the rock can be (3" throat, I think?). ~$200 on ebay. It won't look as natural as other methods (smooth cut), but would give you what you are looking for.

 

[sandhillcrane]

I've used this dremel bit to cut thru liverock.

http://www.dremel.com/en-us/AttachmentsAndAccessories/Pages/AttachmentsDetail.aspx?pid=543

Cuts like butter. I've used chisels before but they usually shattered the liverock.