hi my name is Martin Smith I'm an amateur DIY er and I've been looking online for how to best cut holes through plaster and laughs I haven't found it anywhere so I'm posting this in case it helps anybody right now I'm installing a central a/c system called space pack little circular round holes in your ceiling so I got to cut a bunch of these holes this would work just as well for recessed lighting as well I'm using a combination of a dremel cordless Tremmel and the five forty five diamond cutting wheel along with a couple three and a half inch hole saws first things first our fire hazards you want to make sure that you go upstairs if you're doing this in second floor of your house go up in your attic make sure that there aren't any wires that you've pulled back of any fiberglass insulation or cotton batting this is an old house so it's got cotton batting and then fiberglass on top of that pull all that back so that any sparks that are caused by drilling through the concrete aren't going to catch anything on fire as far as the other safety things I've got goggles masks are always good you can google that if you need any safety tips I'm not going to go into that today so first things first we've cleared off we've made sure that there are no wires we're going to be drilling we've pulled back any fiber glass or any other insulation and we're going to start by mapping out the hole and tape it so the reason I'm taping here is to give the plaster and lath around the hole a little bit of extra support when I make my first cuts I start off and do a pilot hole stick a screwdriver up there and make go back up and make sure that I'm in the right place I am where I think I am and that we're good to go then for this process we're using two hole saws one is our sacrificial hole saw through trial-and-error we found that obviously you're by metal carbide or you're by metal hole saw is gonna get eaten up pretty quickly with the concrete or plaster so we had one that was already struggling has become our initial pilot hole / finish off pulse on as you can see the teeth they're really really worn down once we have our power hole we're going to stick this up there get a very quick hit to give us our circle so now we have our circle mark exactly three and a half inches and then we're going to take our dremel and I've already done this step but I'm going to show you again how I do this the cutting wheel because there's only a quarter inch and in radius isn't going to go as deep as we absolutely need it to so what I'm going to do is I'm going to plant this top edge here against the ceiling and I'm going to pivot against that edge until I'm sunk as deep as I can go at that point I'm going to go counterclockwise around as deep as this this was going to let me go and cut basically as much of that I can do with this type of disc stabbing discs has already done about ten holes and showing barely anywhere so and it really does cut through butter cut through like butter so if you take a look up here real quick I've done that already glasses I've already scored this all the way around I'm going to show you really quickly how I do this or rather I'm not really going to show you but because I'd have to have this on and have the vacuum on that's another good point is having a second set of hands to hold a vacuum while you do this is a really good idea because there's a lot of dust so I'm going to turn it on this disc is best between 1,500 and 2,000 rpms over 15,000 20,000 whatever it is 15 to 20 rpms whatever the multiplier is I'm going to play my edge and bury my desk once that's Doug in there I'm just going to nice and easily go around semicircle right or in a counterclockwise motion and go as deep as I can you can see I've done that here so the second step is put this guy down grab my sacrificial hole saw pilot bowl and I'm going to hit this until I feel like it's hitting wood because this guy's already born down pretty good I'm going to smell the burning and so that's when I know how to stop once I've done that my plaster should actually come out like puck and I'm going to see if that's going to happen here I'm going to take my flat head and just very very easily and carefully because I do not want to crack around here pop out my puck so what you can see here is there's the thickness of my concrete and if you zoom in here real quick you can see the lath underneath the lath is pretty hard so the the hole saw that whose teeth are pretty worn down the sacrificial balsa burns that laughs versus cuts it so now that I've cut all the way through to the laughs I'm going to just clean up in the edges with my screwdriver make sure that my good hole song isn't going to get eaten up and hit that laughs with my good hole saw you can see his teeth is are nice and sharp and that's going to make that a really nice clean cut let me do that now I'm going to take my sacrificial hole saw finish off the hole get my vacuum you go at the same time and then I'll hit this hit the tree this out real quick and finish off the hole so you'll see how it works here grab that vacuum all right so here is my puck it kind of broke that time but I've got most of my plaster out now I'm going to go if you look up here real quick there's some concrete that's coming through the laughs I'm just going to take that punch it back up into my attic clean off the edges I've still got the tape on there to give my edges a little bit of support I don't know if that helps or not but it seems to Norway I would have the vacuum going at this point but just you come here now so I'm going to trade out my hole saw it it actually works out really well having two hole size because the color is the same I'm just going to pull off that hole saw it's just that my good hole saw I'm going to go so we're gonna hit the vacuum again all right now scenes here at a nice clean hole now some of my laughs came out of the hole saw but a nice clean hole three and a half inches and I didn't crack anything I've done about 12 holes now this way and it's it works really well once you get good at it you can do it in probably about ten minutes per hole this the reason I won with this is there's another product out there called hole pro it looks fantastic it's got two carbide cutting bits google it it's about a hundred and twelve dollars with this solution I'm probably less than half that I'm not factoring in the Dremel so if you're a DI wire and you're not going to do a whole ton of these repeatedly then this is a great way to go if you're a pro then you're probably not watching this anyways but a whole pro might be a good idea because you'll you'll chew through these blades through time hope this helped different somebody and thanks for watching