If you expose the acid to concrete surface through some sort of a pipe (made of acid-resistant material) that will not leak any acid outside it's diameter ; it should work very seamlessly. Also attack doesn't have to start from the surface, you can drill a very tiny hole through the concrete and fill it with the acid until you reach the desired diameter, melt it from inside as you will. On Tue, Aug 20, 2013 at 2:43 PM, Carl Denk wrote: > Sorry to say, but acid will attack the surface, and take forever for the > depth specified, and to control the size of holes is difficult if not > impossible. Also not a very safe material to work with, and the fumes > are very noxious. :( A very high pressure water jet or laser would > work, but for this application, cost prohibitive. The suggestion of a > local small contractor is very good. > On 8/20/13 8:16 AM, Yigit Turgut wrote: > > Hi Russell, > > > > You -might consider- some sort of acid for this task as well. > > No I am not talking about LSD, muratic or hydrocloric acid -might- do t= he > > trick. > > > > y. > > > > > > On Tue, Aug 20, 2013 at 1:46 PM, RussellMc wrote: > > > >> Short: > >> > >> Ideas sought for low cost low effort way of cutting a say 4"/100 mm di= a > >> hole (or larger) through 6" / 150mm concrete. > >> Aggregate but no steel. > >> Can take some days if effective and wholly hands-off. > >> > >> Note: 20mm tungsten carbide tipped drill bit + hammer-drill is low cos= t > >> (but costly on me) but far far from low effort. > >> > >> _________________________ > >> > >> I'm enlarging a drain hole through the base of a wall in an old concre= te > >> swimming pool. > >> > >> A walled garden will/may happen in due course: > >> http://bit.ly/SECRET_GARDEN > >> > >> So far it's a malodorous ex-duckpond. > >> > >> Concrete is about 6" / 150mm. Reasonable amount of aggregate but no > obvious > >> steel where I am drilling. I have drilled a hole with a 20mm carbide > tipped > >> bit and can enlarge that somewhat by butchery. I need a substantially > >> larger hole that can handle mud sludge and garden ooze that will > invariably > >> happen even with care. I'd guess a 100 mm square hole or a wider lower > slot > >> would suffice. (200mm x 50mm maybe - may be a bit low). > >> Access is reasonable but not stunning. > >> > >> I can make a large enough hole in time with successive 20mm holes. The= se > >> are hard on the bit, the drill and me - quite a suibstantial amount of > >> effort required for one hole through. > >> I've been thinking about other possible methods that could be achieved > at > >> modest cost. Any superior ones would be welcome. > >> > >> - Fire / heat : > >> > >> - Set up gas air feed through the hole with flame burning within the > hole > >> proper if possible. Expectation is that the concrete strutcure will be > >> weakened and aid mechanical enlargement. > >> > >> - Gas torch on wall face.I recall concrete "spalling" under a tight ga= s > >> flame. No experience of "gas cutting" concrete. > >> > >> - Electric radiant heater against wall. Hmm - electric paint stripper > worth > >> a try. Could heat Nichrome element in hole. > >> > >> Cut: > >> > >> - DIY hole saw: Most hole saws are not targeted at this sort of depth = - > and > >> a suitable carbide or diamond faced one is liable to be costly for one > off > >> use. > >> > >> I could probably "relatively easily" [tm] fabricate a rotary cutter > with a > >> long arm (6"+) and a carbide cutter from a drill or similar on the end > such > >> that the cutting face is large than the driving rod so that it can cut > a 6" > >> plus deep hole. Single arm may do. Two for balance not a terrible idea= .. > 3 > >> maybe even better. Arm flex not important if cutter can be maintained > >> against wall. Drive this at moderate speed with whatever motor suits, > and > >> mount the assembly on a hinge or parallelogram assembly and apply spri= ng > >> pressure or weight so it sits against wall and drills. Slow (hours to > days) > >> but unimportant if it works. Can water lubricate with hose misting. > >> > >> - Water jet? Best available would be domestic "water blaster". This > worked > >> excessively well on a stucco surfaced house long ago when due care was > not > >> taken :-). I'd expect it to be too slow on concrete. I don't think thi= s > >> justifies me trying to implement or hire or ... a garnet / grit / ... > >> cutter. > >> > >> - Perhaps a swinging impactor / chisel would allow a hole to be slowly > >> chiselled - horizontal pile-driver style. Not hard to set up given a > slow > >> turning shaft. > >> > >> Cut / burn hybrid: > >> > >> - LASER: Do not have CO2 which may well work. Have large glass HeNe of > yore > >> - but probably in 10 mW if that range =3D forget it. > >> > >> Hmm. DVD LASERS? > >> > >> Freeze? > >> Dissolve? > >> > >> Explosives: No :-). While my experiences of long ago are probably stil= l > up > >> to fabricating sometjing that would 'do the job', how large a job it d= id > >> would be uncertain, possible repercussions are severe and regulatory > >> authorities would be sure to not come to the party. > >> > >> Or ... ? > >> > >> Or hire something (again) :-). > >> > >> > >> Russell > >> -- > >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > >> View/change your membership options at > >> http://mailman.mit.edu/mailman/listinfo/piclist > >> > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .