I'd just be worried about the rebar blowing the plaster out, when it comes out the other side. We welded a drill bit to the end of the rebar. Once we're through with our rebar/ bit thing, we use diamond grit hole saws to make a clean hole in the plaster. I've been eyeing the Lenox carbide hole saws, but I got a a big set of the diamond grit ones at Harbor freight for $29, cheap yes, but I consider my tools for this type of wall excavation to be relatively disposable. Another tool to consider for this work is a 1/2" regular chuck adapter for the Bosch SDS hammer drill, that allows you to chuck rebar, regular bits, hole saws, drill extensions, etc, in the Hammer drill. The Bosch is a beast of a drill in non hammer mode.
R. Walters r...@solarray.com Solar Engineer On Nov 20, 2010, at 1:04 AM, Phil Undercuffler wrote: > Good bit (sorry for the pun) about the carbide hole saws. Like you, I've > also got a box of bell hanger bits. However, straw bale walls start out at > 14" thick and can go deeper - 36" and more. I've tried extensions and even > the 4' long Jesus bits (you know, those ultra long flexible electrician bits > that you pray to Jesus wind up in the same zip code as the wall you're aiming > for), but for bale and Adobe, there's nothing like KISS rebar. Trust me. > > Phil Undercuffler > > On Nov 19, 2010 8:27 PM, "William Miller" <will...@millersolar.com> wrote: > > Friends: > > > > I keep a set of "grit edge" hole > > saws.http://www.lenoxtools.com/Pages/Product.aspx?id=CarbidegritHoleSaws > > These cut Stucco and plaster without degradation. > > > > If I want to pilot a deep hole, I remove the ~4" pilot bit and chuck in a > > bell hanger bit. Linked is an 1/4 by 18" bit that will replace the pilot > > bit. Use with care, this is a long skinny bit. http://tinyurl.com/2cnupu3 > > > > William Miller > > > > > > At 01:36 PM 11/19/2010, you wrote: > >>Having a fair bit of experience with bale, I ditto what Bill mentioned but > >>I'll add a simple way that I discovered to getting the inside and outside > >>holes to line up. > >> > >>Bale walls are seriously thick, so standard extension bits aren't long > >>enough. I found taking a 2 or foot length of 3/8" rebar chucked into a > >>half inch drill works nicely for boring a pilot hole all the way through > >>the wall. Once you have the pilot hole, it's a simple matter of drilling > >>out a hole large enough for your conduit on both sides of the > >>wall. Either use a small bit to drill a series of holes around the > >>perimeter and connect the dots with a cold chisel, or use a hole saw that > >>you don't mind sacrificing on the plaster. You don't actually have to > >>"drill" through the entire wall, as the straw can be pushed to the > >>side. I usually spin the rebar in the hole while chunking it back and > >>forth a few times to clear a path, then thread the conduit through the > >>hole using the rebar as a guide to be able to find the hole on the other > >>side. It really helps to have a second person on the other side, to help > >>guide it in the final inches. > >> > >>Rebar as a drill bit also works great with adobe walls. > >> > >>If you do a lot of this, take a minute to grind down a flat spot on the > >>end of the bar or it will tear up your drill chuck. Drill chucks can be > >>spendy. Ask me how I know... > >> > >> > >>Phil Undercuffler > >> > >> > >> > >>On Fri, Nov 19, 2010 at 11:27 AM, Bill Hoffer > >><<mailto:suneng...@gmail.com>suneng...@gmail.com> wrote: > >>Benn > >>I used PVC in the my bale walls with a Junction Box on both sides of the > >>penetration to protect the penetration (Outside a must!). I used EMT for > >>all my other wiring, but PVC seems better for an interior to exterior > >>penetration where the heat conduction of the EMT may cause some damaging > >>condensation towards the exterior of the bales. I used a hammer drill and > >>concrete bits to get through my stucco, it is tough stuff. I used 2 " > >>conduit so I had to make several smaller holes and knock it out by > >>hand. I did not have rebar in my bales, but heavyduty 6x6 mesh to get > >>through, as would be expected I never was able to hit the middle of the > >>grid, I just had to cut and hack saw when I hit something, pays to have a > >>sacrificial bit to find the metal. I then fashioned a home made bit out > >>of the conduit and used that to get through the bales by hand. That went > >>pretty easy and will allow you to locate the rebar without damaging an > >>expensive bit . Hard part is lining up to get a good mark on the opposite > >>side. I used foam to fill any gaps, replastered around the pipe and > >>fitting and caulked really well to seal against water on the outside. I > >>also located the JB on the outside of the building in a very protected > >>area for additional security. Water and straw bales do not play well > >>together! If anything I would favor a slight slope downward on the > >>outside so if there is a leak it will not follow the pipe inward into the > >>bales. > >> > >>Hope that helps! > >>Bill > >>On Fri, Nov 19, 2010 at 11:05 AM, benn kilburn > >><<mailto:b...@daystarsolar.ca>b...@daystarsolar.ca> wrote: > >>Wrenches, > >>Short of contacting the builder, i'm looking for your experiences, > >>practices and "look-out's" for penetrating a strawbale exterior wall with > >>conduit. > >>For the project in question there is currently a teck cable from a wind > >>gen entering the home by sharing a HRV vent opening that i want to fix > >>(not my original system by the way) and i will also be adding another > >>penetration for a PV array that i am relocating on the property. The > >>original penetration for the PV was done properly but its not in an ideal > >>location for the re-located array wiring. > >>I'm wondering if it is as simple as using a hole saw extension to go thru > >>the ~16" wall and use an LB/box on either side. I'm sure there is some > >>framework and/or rebar supporting the bales, how do you locate/avoid these > >>when there are no corners to measure from? (it is a round home) > >>Any knowledge if PVC or EMT will react in anyway with the bales? I'm > >>thinking that PVC would be best....? > >>... i am trying to contact the builder to address this, and also to ask a > >>few choice questions regarding the wiring methods (he?) used in the > >>original PV system set-up. > >>Cheers, > >>benn > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org >
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