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Using the Rotozip questions

tuanj's picture

I am a intermediate carpenter who's being forced against his will to install and tape drywall. The client is penny wise and pound foolish and thinks he's making out with me doing it, despite my best efforts at convincing him otherwise. The truth is, I'm okay at it but I have one more room to finish before I can move on. In this kitchen are 15 can lights in the ceiling, four sconces and lots of outlet boxes, all plastic. The way I see it the client didn't put any lights upstairs and now is making up for it in the kitchen.

At any rate, i figured it might be time to buy a saw for the rock and I've read some of the posts concerning use of cutting tools (including instructions on cut direction, etc.) and decided to buy a Rotozip (with vacuum). But I'm having second thoughts and thought I'd ask here before I dirty a $100 machine I may not use again for a while.

My first question is whether or not it makes sense to buy the saw if you're just pre-cutting (on horses) before installation (my current inclination) ? Or is the whole point (and justification for the purchase) of the saw to do things in place- fastening the perimeter in place and plunging into a center mark? With multiple can lights in all directions, I have to say, this last technique makes me a little unsure. And forget about those outlets, with umpteen wires all barely tucked inside.

Could you just use a lift to hold the rock in place and not fasten the perimeter? Or just tack it in a few places, using the lift to do th rest?

I have always measured and pre-cut with handsaw and have done well with it so naturally I am wary of switching gears from what works. I guess I would like to try what the pros do but at the same time, don't see any reason why I can't continue cutting on the flat-but with the Rotozip, if it's possible to do a neat job of it.

Thanks.

IMO, the only reason to use a (post #212445, reply #1 of 12)

IMO, the only reason to use a roto-zip is to cut in place. We use them all time and I wouldn't do it any other way. The time savings and precision beats layout cutting every time.  There is a small learning curve, but you can quicly beat it. Here are some tips:

1. Tuck your wires as far back as possible before hanging your sheet. Use a drywall bit and not a panel cutting bit. Don't set more than 1/4" deeper than sheetrock. Doesn't help the cut and only increases chance of snapping bit and nicking something that shouldn't be nicked.

2. Dont fasten too close to what your cutting out; just enough to hold the sheet in place. The only reason being is that your cut out will tend to bust out a small section at the end of your cut (outside of cut out) due to the device pushing hard against a small area of rock. You don't want a whole lot of pressure against the device. Once you're cut out, fasten away.

3. I always mark rough center, cut a small hole just big enough for my finger to fit in, push my finger in and find edge of device to double check that no wires are in the way and my planned path to edge of device is acurate and clear. One thing you don't want to do is travel around searching (and cutting) for a device you could swear was there, but isn't.

4. Once you work your way to known edge, slightly jump over the device and trace the outside witih light pressure.

5. Cut in the direction that naturally allows bit to hug the edge of device. To find this out yourself just plunge in piece of drywall and hold the tool loosly and you will see which direction the bit naturally causes the tool to wander. Use that direction to your advatage in order to hug the device without effort.

6. Use the tools to cut out around windows and doors as well. It will save layout time, and be spot on tight.

7. We also use a laser to pre-mark ceiling ducts, and devices on the subfloor with keil. We will mark centers of walll devics on the floor as well. Mostly this serves as a marker should a cut out get missed during the production fray.

8. The idea is to hang the biggest sheet possible and minimize butt joints. That will provide for a more professional look with less finishing time. Roto-ziips help you achieve that goal more easily.

Thanks, with that great info (post #212445, reply #3 of 12)

Thanks, with that great info I think I'm feeling brave enough to have a go at it; I've got a little practice time so I'l make a few mock-ups and give it a whirl. 

Another Use For Rotozip (post #212445, reply #4 of 12)

There is a diamond bit for the rotozip that can be used to cut tile and brick.  Had a paper holder that was attached to a tiled wall with flimsy plastic anchors.  Enlarged the hole with the diamond bit in the rotozip and installed a small toggle. 

not quite Zippety do-da yet (post #212445, reply #7 of 12)

Rotozip has been okay thus far but still having trouble with the plastic outlet boxes. The bit really wants to dig into the plastic edge and so it's been hard for me to achieve a good clean cut (fortunately just with practice pieces). Tried different depths, thinking with more to bear on, the bitt would wander less but this hasn't worked yet. The can lights however, have been a breeze, with metal sides providing nice, positive resistance. I'm still taking advice if you're offering. Thanks.

I'm remembering there's some (post #212445, reply #8 of 12)

I'm remembering there's some trick with the outlet boxes, but it's been 10 years or so, and I only dealt with them a little.

I THINK part of the trick was not to press so hard with the bit against the side of the box, so that friction didn't heat it up and melt the plastic. Use a light touch.  This of course is contrary to your intuition to try to hold it tight against whatever you're cutting against.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Make sure you're not too deep (post #212445, reply #9 of 12)

Make sure you're not too deep with the bit setting; just an 1/8" to1/4" max including the baldsectoin of bit.  If you'er digging in, then chances are you're digging in with the cutting part of the bit. Also keep the shoe flat against the rock and try not to angle in direction of your cut. Angling is a hangover from jab sawing. Roto zip is different animal; cuts best when perpendicular to the rock. If you're angling  toward your cut direction, this can cause the cutting edge to contact slightly before the bald (or guide tip) section. Also, don't hang out in one place too long 'cause that can cause friction melt. Just feel that device edge and keep things moving.

Another tip: Those blue boxes have two slight projections electrician uses for spaces face of box off studs. Anticipate them (YOu know they'll be on the stud side) and move around them slightly. They're just after you round the corners. If you put too much pressure there anticipating a straight line, you'll tend to get hung up a bit and burn in. Again, get a feel for their location and let the bit lightly roll around them. Don't fight it.

Just remember how 38 Special put it. That's right. "Hold on loosley, but don't let go. If you cling too tightly, your gonna--your gonna, lose control.".

A laminate trimmer can be (post #212445, reply #2 of 12)

A laminate trimmer can be used instead of a rotozip.  I'd use that if you already have one.

I was thinking about your (post #212445, reply #5 of 12)

I was thinking about your comment about your tool being $100. Seemed high to me. Checking around I see that you can buy the latest Rotozip corded model at CPO tools for about 60.00 right now. I believe it has dust extraction capability, but I don't see attaching this tool to a vac as very practical for production work. Wear a mask instead.

As for using a laminate trimmer; I wouldn't. It might work, but you'd be trashing the tool due to dust in pretty short order. I also belive the collet size for most laminate trimmers are 1/4". The roto zip bits are 1/8" and you'd have to use some type of adapter. Why try to adapt a $100 plus tool that will get trashed when you can buy a $60 that builit specifically for the job and will last a lot longer? I don't hang drywall every day, but some of our jobs are 150+ sheets when we do. I'm on my second rotozip in 15 years. I mIght just buy that newer one as a back up at $60. The cordless is a bit more, but too bulky to me and not worth the extra bucks and hassle of charging and hauling around extra batteries.

I used a laminate trimmer (post #212445, reply #6 of 12)

I used a laminate trimmer with a 1/4 to 1/8 bit adapter  to drywall a house,  It made the job a bit easier, the trimmer seemed unaffected for the little use it got, so it cost me about 5 bucks for the adapter, instead of 60 or whatever for a rotozip type tool.  I have to think the rotozip and the laminate trimmer would last about the same amount of time working drywall.  Drywall dust destroys about everything it touches equally.  I don't think a rotozip has any magical drywall dust tolerance. 

My shop vac did not fare as well as the trimmer.  RIP shopvac, but I did get a nice small roll around trashcan after it died.

Cheat! (post #212445, reply #10 of 12)

Hire a rocker to work with you - let him do his thing, and you help him out. Just tell your customer that 'your buddy' does rock, and you need some help with the panels anyway.

My client has refused to hire (post #212445, reply #11 of 12)

My client has refused to hire anyone else since I've been working for him; he's in his 70s but insists on helping every time I need a hand. So even if I wanted to hire another guy he wouldn't go for it.

Hanging is easy, I don't mind it, it's the damned taping I really don't care for. I've done some, I'm decent at it but  I'm still slow. So I've told him a million times, trust me, you'll be better off to hire a guy who only tapes for a living and you'll end up paying about the same maybe a tad more for better work-but he won't go for it.

One more partial day of hanging and I'm done with the zip gun. Worked well for all 13 cans (one f***up, easily fixed) but I didn't have time to get good enough and confident enough to do the plastic outlet boxes. I've always measured and cut by hand, and done really well so that's what I've been doing. Maybe at some point, when I have half a day to kill and a dozen outlet boxes to chew through, I'll try it again. Seems to me, you still have to measure to locate the centers and fastening the piece on the edges is more of a frig than i wanted to deal with just now. Floors to lay, cabinets to build, just didn't have the patience to try and master a skill.

I do like the filter attachment on the zipper although you have to empty it quite often; dust is minimal and one could get by without a mask.

Somewhere I've got a gizmo (post #212445, reply #12 of 12)

Somewhere I've got a gizmo that fits inside the box and holds a magnet.  You put that in the box, hang the drywall over it, and place another gizmo on the drywall.  If you get it right-side-up (I didn't once, on some fairly dear paneling) then the second gizmo is a templete for cutting the drywall.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville