What is going wrong? To install plastic anchors I was taught to drill a small hole (exact size of anchor or slightly smaller.... lightly tap in anchor until fully recessed and face is flush with drywall... screw the screw into anchor slowly so it bites. Isn't this correct?? A large percentage of my anchors pull out (screw and anchor together)... Is there any reason this might be happening?
The Hole is too big:
It could be that your pilot holes are too big. When the screw is inserted, the anchor does not expand enough to bite into the surrounding hole. Keep in mind that most plastic anchors are tapered, so you want them to fit tightly in the hole. If you can push them in too easily, then the hole is too big. Some plastic anchors have a slight lip (collar) at the end, to prevent the anchor from slipping into the wall. When drilling the pilot hole, it must be smaller than this collar. So the anchor will not sit perfectly flush with the wall, when it's pushed into the hole.
Material is not stable enough:
Another common problem is that the material you are putting the anchor into, is not stable enough to hold the anchor in place. This can be particularly problematic with older plaster. You install the anchor, then when you insert the screw the expansion of the anchor crumbles the surrounding plaster. This causes the anchor to fall out, since it's essentially being held in place by dust.
Items are too heavy:
It could be that you are hanging too much weight on the anchors. Drywall and plaster are not designed to carry loads, so applying too much weight to a single point will cause the anchor to come loose.
Items are too thick"
You may also run into trouble if the item you are attaching to the wall is too thick. If the screw does not penetrate the anchor deep enough, the anchor will not expand enough to hold it in the hole.
Material is too hard:
You can even run into trouble if the material you are putting the anchor in is too solid. If you put the anchor in a material that is too solid (2" steel plate), when you put the screw in the anchor may actually not be able to expand. This can cause the anchor to deform and break, and again fall out of the hole.
Wrong size screw: (Thanks Joe).
If the screw is too small, it will not expand the anchor enough to bite into the wall. If the screw is too large, it can damage the anchor and/or surrounding material causing the anchor to fail.
The screw is too long:
If there is a solid surface behind the anchor, using a screw that's too long could cause the anchor to pull out of the hole as you tighten down the screw. You'll have to remove the screw and anchor, then drill the hole deeper to fix this.
For what it's worth, I really dislike the traditional, plastic anchors. When I buy something (like a shelf) I throw away the included plastic anchors. Having them pull out of the wall even one time is too much.
I buy the screw-in style anchors. They come in plastic and metal (see pictures) depending on how much weight you need supported. They are easy to install after drilling a pilot hole, and they don't pull loose. A vast improvement over the traditional plastic anchor.
The plastic anchor is good enough if want to hang a feather dream catcher on it.
These other metal ones with the big counter sunk cylinders on them are ok to hang a small picture frame on it.
If you need some more hanging wieght i would recomend using these on a drywall on the empty space.
Reasonably more hanging power- should hold a large picture frame 1-3kg
Heavy duty (bit more difficult to install- as your drilled hole needs to be prettyr precise) 1-5kg
MOre or less the concept behind using a butterfly anchor on a drywall
Here you will notice how the drywall is mounted on the wood studs. If you best hanging capacity then you want to find the Vertical (horizontal is not good idea for very heavy stuff like 50" tv's) stud and... (If you have metal studs you will need metal self tap'ing screws or butterfly anchors for metals studs)
use these screws (the black ones are the best) and screw them into the wooden studs- Use battery operated drill with a right screw head and when you are screwing it in to the wooden stud you should hear it scream and screech! Thats when its the tightest and best. Doing by hand is OK- but will take longer- DO NOT OVER TIGHTEN IT!
Here is my priceless set of guitars hung using the last method
I could hang my self on there and be confident that it wont rip out.
Please remember to make sure there are no electrics, gas or water pipes in the area you going to drill!
I had the same problem, a hole about 1/2 inch behind the screw hole in dead plaster where a coat rack came down.
I searched for solutions on the web, as just filling the hole and redrilling had never previously worked for me, the filler didn't bond well enough to the dead plaster behind, and the rawl plug just ended up rotating, or the filler came out (This is with polyfilla type filler; I hadn't tried epoxy)
I found something called wetnfix which is a pack of thin cotton discs impregnated with a gypsum based material which you dip in water, shake off excess, and wrap round the wall plug / rawl plug / anchor. You then put this in the hole (already drilled to depth, cleared of loose material etc) and leave for three minutes.
It says on the packet you can use more pads round each wall plug if the hole is bigger. I used two on one (good quality) wall plug, the other hole was bigger, and as it was going to be covered, I jammed in two smaller (good quality) wall plugs each with a wetnfix wrapped round it (I didn't want to use the whole pack of 20 on one hole!).
The manufacturer says 3 minutes to set, and add a minute for each extra pad used in the same hole.
I erred on the safe side and left it half an hour. I screwed the coat rack up and it went in beautifully. I had a to put a LOT of torque on the head held screwdriver to drive the screw fully in, and it was rock solid.
VERY impressed. I will always keep a pack of these around. I would keep them somewhere dry, as I imagine old ones could absorb water if damp and go off prematurely.