Loose Holes with Hilti SDS-Plus Rotary Hammer Drill

[Alan Lightstone]

Have a problem that I'm not sure of the answer to.

I have a workshop/garage that has almost entirely cinder block walls. When we bought the house, I knew I'd be doing a lot of drilling into the blocks, so I bought a very good rotary Hilti Hammer Drill.

The drill goes through the blocks with ease. Much better than my previous Makita (which was no slouch either).

The problem is, that many of the holes are slightly too large, and often, Tapcons are too loose in the holes. I've tried, at times, to use one size smaller drill bit, but it seems almost random when the holes are too big. I'm not drilling massive numbers of holes, just occasional use.

Is it a dull bit (It has happened with a few different sized holes, and I have replaced the bits)? Some other technique thing? Something I'm missing?

[Tom M King]

Try a lighter duty hammer drill. I have two that get the most use. One is an SDS-Max, that I use for holes starting at 1-1/8", for frostproof wall hydrants, and up in size. The other is a regular one with a standard chuck, that gets used for all smaller holes in masonry. It gets used for smaller holes, including ones into soft brick for anchors. I've never tried to use the big one to drill the small holes, but I expect it would be a little too violent to drill an accurate sized small hole.

The small one is the Bosch in the background of the tools on the chimney top. I last used it setting anchors in cinder blocks, and it worked fine.

http://historic-house-restoration.com/images/CIMG1762.JPG

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[Mike Kreinhop]

I have a Bosch hammer drill for my heavy-duty concrete applications. However, I never use it for the German equivalent of the cinder block. I learned after a few botched attempts that the impact of the hammer drill was a bit too much for the blocks and tended to make larger holes and destroy the inner partitions of the block. Instead, I use a smaller drill hammer with a masonry drill to make the holes.

The difference between the hammer drill and the drill hammer is significant, mainly with the force of the impacts. It takes a little longer to bore a 10mm hole in the German blocks, but the plastic anchors fit snugly and don't pull out under load.

[Mark Bolton]

Best trick in the world when you get an oversized hole for a tapcon is to take a piece of 12 or 14 gauge copper wire (strip some out of romex or steal some ground wire out of romex) and cut a small piece, bend an small leg on one end (shape of an L) and stick one leg in the hole and run your tapcon. Will save you every time.

Often times in ripe cinder block the holes will oversize a little bit. Other than taking a diamond wheel on an angle grinder and grazing the edges of the carbide on the bit there isnt a great solution if your drill/block is consistently drilling oversized.

The copper wire trick works like a charm every time

[Gregory King]

Alan, I worked in the university buildings for most of my career. Brick on the outside applied over concrete blocks. No doubt, we've drilled a good many of these. We found the best solution was the soft lead anchors. 1/4 " or 5/16" x 1.5" long. Then use the appropriate screw. Never had an issue after that

[Tom M King]

I really like these Greenlee anchors, and their setting tools. The tool sets the anchor as flush with the surface as you want it, and not at all dependent on the hole depth, as long as you drill it a little deeper than you acturally need it, so they work in through holes too. The setting tools aren't cheap though. They come in a bunch of different sizes.

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[Tom M King]

I use little, round rare earth magnets to locate exactly where a hole needs to be. The one on a piece of masonry ductape, in the earlier picture holds the place over the threaded insert. Roll one around the outside, and it will find the one on the inside. Need another marking method for steel boxes though-headless machine screw, and lipstick.

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[Alan Lightstone]

Tom:

I can't quite get my head around how those Greenlee screw expanders work. Can you explain?

[Ryan Yeaglin]

Using an SDS type drill for tap-cons is like using a sledge hammer to pound in 4 penny finish nails, WAY over kill, they work great if you want to your drilling concrete for wedge anchors or the like. A battery drill or corded drill with hammer function is all you need. Me personally I don't care for Tap-cons and prefer many of the other style anchors mainly because tap -cons strip out and are very picky about the hole diameter. Plastic insert anchors work well for mounting elect rial boxes and the like, Drive style anchors (drive rivets) work well and only require a 1/4" hole, the lead expanding anchors work, but require a large hole. If it's going to be a heavy application, I would suggest through drilling and using a 3"x3"x1/4" flat-bar wall plate with thread rod.

[Tom M King]

You screw the threaded rod into the insert, and stick the whole assembly in place, with the insert in the hole. The knurled knob is just to operate that screw. With it in place, you tap the outer end of the knurled knob with a hammer which pushes the lead sleeve down around the harder inside part, that includes the dovetail end, expanding the lead sleeve without moving the threaded part, locking it in place. To finish, you use the knurled knob to unscrew the treaded rod, which removes the installer, and leaves a REally secured threaded insert in place. They are very strong.

I think they come in sizes from no. 10 up through 3/8". I bought all the installers off ebay over a long period of time. They don't give those to you.

The one you use a simple tool to pound the insert in the hole need a closely correct depth on the hole, and also are easily screwed up in the process, and you need a range of fastener lengths to fit in different hole depths. With these, you know what length fasteners you can use to start with, and they will work in a through hole as easily as they do in something solid.

I believe Greenlee calls them "caulk in anchors".

edited to add: Greenlee calls them "caulking anchors", so I was close. These tools use the same anchors as this simple pound in the bottom of a hole tool. but do a much more precise fit. https://www.greenlee.com/us/en/caulking-anchors They call the tool a "screw expander".

Best found used, on ebay: https://www.amazon.com/Greenlee-868-Anchor-Expander-Caulking/dp/B001SGP1I6

[John Lanciani]

Using an SDS type drill for tap-cons is like using a sledge hammer to pound in 4 penny finish nails, WAY over kill, they work great if you want to your drilling concrete for wedge anchors or the like. A battery drill or corded drill with hammer function is all you need. Me personally I don't care for Tap-cons and prefer many of the other style anchors mainly because tap -cons strip out and are very picky about the hole diameter. Plastic insert anchors work well for mounting elect rial boxes and the like, Drive style anchors (drive rivets) work well and only require a 1/4" hole, the lead expanding anchors work, but require a large hole. If it's going to be a heavy application, I would suggest through drilling and using a 3"x3"x1/4" flat-bar wall plate with thread rod.

Ive installed literally 1,000’s of tapcons into poured concrete by drilling with an SDS rotary hammer and setting the screws with a cordless impact driver and I’d peg my failure rate at less than 2%. The issue here is the block, they tend to be coarse and fairly fragile if drilled in the cores. Setting anchors into the webs solves most of the problems but is not always possible.

Tapcons are one of those things that people either love and rely on or they hate them and have bad luck. I’m not sure if it’s technique, tooling, or just plain mojo. They are always my first choice for light to medium duty anchoring in masonry.

[Frank Pratt]

A rotary hammer is sometimes overkill for cinder block. Because it's so soft, the relatively violent hammering action of the rotary hammer just makes for a bigger, sloppier hole. Try turning off the hammer action & see how it does. The drilling will be slower, but the block is so soft that it will still drill it fine.

[Charlie Knauer]

Check and make sure the masonary bit is not bent. The bit for a TapCon is not that big in diameter and will bend easily.
I have noticed guys at work setting the drill down bit first. It don't take much to bend the bit.

[John K Jordan]

I didn't get to read all the posts. Are these "cinder" blocks? I use a bit SDS hammer drill for concrete but never for cinder block unless it's filled with concrete. For cinder block I use a carbide masonry bit in a non-hammer drill.

JKJ



Have a problem that I'm not sure of the answer to.

I have a workshop/garage that has almost entirely cinder block walls. When we bought the house, I knew I'd be doing a lot of drilling into the blocks, so I bought a very good rotary Hilti Hammer Drill.

The drill goes through the blocks with ease. Much better than my previous Makita (which was no slouch either).

The problem is, that many of the holes are slightly too large, and often, Tapcons are too loose in the holes. I've tried, at times, to use one size smaller drill bit, but it seems almost random when the holes are too big. I'm not drilling massive numbers of holes, just occasional use.

Is it a dull bit (It has happened with a few different sized holes, and I have replaced the bits)? Some other technique thing? Something I'm missing?

[Bruce Wrenn]

Seldom do I use TapCons by them selves. My weapon of choice is to use Alligator brand anchor sleeves. Drill hole for correct size, then use either TapCon, or screw to do fastening. For real fun, try fastening into masonry blocks that were frozen while wet. They have absolutely no strength, just crumbling beneath fasteners, or drill bits.

[Alan Lightstone]

Keep the information coming.

It’s depressing that the SDS rotary might be overkill because I spent a lot of money on it to make drilling these holes easy. And it really does drill the holes easily. And when it does drill the right size it’s a pleasure, But too many times they are slightly too big.

Mostly these are for cinder blocks although a few of the locations are solid concrete.

The next one I drill I’ll try turning off the hammer action to see if that makes things better.

Those Greenlee connectors look interesting, but I have a whole bunch of tapcons at home I haven’t used.

[Tom M King]

Another good fastening system for cinder blocks is Togglers. I used them not long ago for handicap railings in a shower that was built over cinder block walls. You can even buy them off Amazon. They work just like they tell you they will, even though it might look like that there would be no way that's a reliable method.

https://toggler.com/products/snaptoggle-heavy-duty-toggle-bolts-304-stainless-steel-channels

[Mark Bolton]

You'll never get anywhere with the hammer turned off. You'll just roach the the bit. It will get so hot the carbide insert will fall out. I've never had an issue with a drill thatd too powerful. You can use your variable speed to drill slower if needed. Tspcons are very fussy with hole diameter and have very little tolerance.

[Alan Lightstone]

You'll never get anywhere with the hammer turned off. You'll just roach the the bit. It will get so hot the carbide insert will fall out. I've never had an issue with a drill thatd too powerful. You can use your variable speed to drill slower if needed. Tspcons are very fussy with hole diameter and have very little tolerance.

Yeah, I was concerned about that. I haven't drilled into cement/cinder block without a hammer drill in many years.

[Alan Lightstone]

Seldom do I use TapCons by them selves. My weapon of choice is to use Alligator brand anchor sleeves. Drill hole for correct size, then use either TapCon, or screw to do fastening. For real fun, try fastening into masonry blocks that were frozen while wet. They have absolutely no strength, just crumbling beneath fasteners, or drill bits.

Bruce:

These look interesting. So you drill the correct sized hole, place the Alligator sleeve, then do you have a preference for using a TapCon through it vs a screw? Would a TapCon fit if the screw hole size was correct and not oversized?

[Alan Lightstone]

Is anyone using adhesives with anchors, such as Inject-TITE or just 5 min epoxy or construction adhesive?
Seems messy, and overkill, but I ran across it on Alligators website.
https://toggler.com/products/inject-tite-fs-fast-set

[Dave Sabo]

Bruce:

These look interesting. So you drill the correct sized hole, place the Alligator sleeve, then do you have a preference for using a TapCon through it vs a screw? Would a TapCon fit if the screw hole size was correct and not oversized?



those togglers are only designed to be used with a bolt.

[Mark Bolton]

Is anyone using adhesives with anchors, such as Inject-TITE or just 5 min epoxy or construction adhesive?
Seems messy, and overkill, but I ran across it on Alligators website.
https://toggler.com/products/inject-tite-fs-fast-set

Chemical or adhesive bond is my preferred fastener period but they have issues of their own. They are pricey, slower, buying mixing tips is expensive, and in hollow block applications you will need a SS screen and the correct material for a hollow block application. We started using chemical bond capsules a long time ago on horizontal applications (was before products like redhead and so on were as readily available).

Once you get your routine down with the tapcons you'll be fine and they are cheap and easy. Im telling you, try the copper wire trick. There is a pair of old ratty linesmens pliers and several hanks of bare copper wire in my rotary hammer box for a reason ;-)

[Frank Pratt]

You'll never get anywhere with the hammer turned off. You'll just roach the the bit. It will get so hot the carbide insert will fall out. I've never had an issue with a drill thatd too powerful. You can use your variable speed to drill slower if needed. Tspcons are very fussy with hole diameter and have very little tolerance.

Not in cinder block. You can drill all day long & the bit will be fine. A cordless drill with hammer function (not a rotary hammer) will drill a hole in cinder block faster with the hammer function engaged, but not a huge difference. I've drilled 10's of thousands of holes in cinder block throughout my career, much of it with no hammer drill.

Proper technique needs to be used with a rotary hammer, particularly with regards to how much pressure to exert on the drill. It should be just enough to keep the tip in contact with the bottom of the hole & no more.

[Mark Bolton]

Different strokes I guess, and there are different types of block, old dark grey cinder, cinder, lime, and so on. They all have their own nuances. Sure in super soft block it is what it is. I apply pretty much zero force with a rotary hammer period. A rotary hammer generates its own blow, zero pressure, light on horizontal or overhead of course to takeup the throw in the hammer. Hammer drill, your feed pressure generates the blow, how hard you push is on the operator.

My work has nearly always run lime. You'll get a bit with no hammer but its a waste of time in my opinion. I have personally never drilled a single hole in masonry without some sort of hammer/rotary hammer, since I left my teens but again different strokes for different folks. Have a couple old Dewalt 1/2" hammer drills from way back that virtually never come out of the cabinet unless its a loaner. SDS max and a small SDS have drilled everything from a tapcon to 1 1/4" hole bore chemical bond fasteners.

[Chris Fournier]

As others have said a standard hammer drill is ideal for Tapcons in cinder block, I've never had an issue. Also I feel that a cordless drill with a properly set clutch beats an impact driver when using Tapcons, You want that screw to go in nice and smooth and snug up just right otherwise the Tapcon breaks out the hole diameter.

[Bill Dufour]

I suppose you could put some hydraulic? cement in the hole and squish the tapcon into the hole. Wait a while before tightening. I use pure cement to set hold down bolts into concrete. I wait 2-3 days before applying finger tight nuts. Much cheaper then the epoxy and no weaker then the existing concrete. Time is not really an issue on a seismic retrofit for my own house.
Bil lD

[Mark Bolton]

Much cheaper then the epoxy and no weaker then the existing concrete.

Bill, do you have any information on the tested strength of bedding fasteners in straight type I or type II portlant cement in a seismic situation? Sounds like a great solution if its allowed. It would be a heck of a lot cheaper than most any approved seismic mechanical fastener on the market. Straight portland is insanely weak is the only reason I ask.

[Frank Pratt]

I suppose you could put some hydraulic? cement in the hole and squish the tapcon into the hole. Wait a while before tightening. I use pure cement to set hold down bolts into concrete. I wait 2-3 days before applying finger tight nuts. Much cheaper then the epoxy and no weaker then the existing concrete. Time is not really an issue on a seismic retrofit for my own house.
Bil lD

You'll need to back that up with some engineering data. Epoxy anchor systems are not cheap & if the cement actually worked, I'm sure that construction companies everywhere would be using the method. The fact is though, that new cement does not bond well to old concrete.

[Bill Dufour]

I have no data it just seems that pure cement is no weaker then the existing cement. I did wash the holes with water so they were damp so the cement had water to hydrate as it cured. The big problem with this method is you need to wait one week or longer to load the anchors. I used some epoxy capsules and after two bolts I had to leave the crawlspace for fresh air. They have sand in them to save on the expensive epoxy?
I am not really worried since all the load should be in shear with no real uplift forces on the bolts. If I was closer to a fault I would have to think some more. I did find one anchor bolt installed in the entire mudsill. (with a round washer)
Rumor has it that they used to pound spikes into the mudsill underside and turn it over and press it into the wet cement. This was to prevent movement during a quake. Was this done in the east or in tornado /hurricane country? It may have really been just to hold thing in place as the house was being built.
Bil lD

[Frank Pratt]

I have no data it just seems that pure cement is no weaker then the existing cement.

It's the strength of the bond between the new & old, which is very weak, not the strength of the cement or concrete that's in question.

[Mark Bolton]

They have sand in them to save on the expensive epoxy?

They dont have "sand" in them to save on any materials. They have aggregate within the capsule just like concrete is a mix of cement (the epoxy) and aggregate (the sand and stone in concrete) for strength. Even the inner and outer glass capsule (as well as the other contents) becomes part of the aggregate in the final mix.

There are two types of bond outbound of a mechanical bond (wedge anchor, sleeve, drive, tapcon, etc.), an adhesive bond which would be akin to construction adhesive that sticks to the the mating surface, and then these capsule type fasteners which are a chemical bond. They actually eat into the concrete and become chemically bound to the surrounding material. They are expensive, the capsules do smell strongly, but they are mindblowing and they are usually set for initial loading within minutes as opposed to hours or days.

Straight portland or even hydraulic cement is extremely fragile, kinda like glass.

[Lisa Starr]

Forget the Tapcons. Get some soft lead sheet, drill a hole with your drill, cut a small rectangular strip from the lead, roll it into a cylinder and pound it into the hole. Run the screw, eye screw or whatever else you'd like in. Tapcons are iffy at best and frustrating to work with. You can purchase small pieces of lead from McMaster-Carr.

Another tip, make sure you are only drilling the blocks and not the mortar joints, as they are sometimes too soft.

[Alan Lightstone]

Another tip, make sure you are only drilling the blocks and not the mortar joints, as they are sometimes too soft.

I think that's part of the issue. The walls are stucco'd, so I never know when I randomly hit a mortar joint. But I think it's only part of the issue.

[Frank Pratt]

Forget the Tapcons. Get some soft lead sheet, drill a hole with your drill, cut a small rectangular strip from the lead, roll it into a cylinder and pound it into the hole. Run the screw, eye screw or whatever else you'd like in. Tapcons are iffy at best and frustrating to work with. You can purchase small pieces of lead from McMaster-Carr

That would be the hard way. Faster, easier & probably cheaper to just buy some lead or plastic anchors.

I agree that Tapcons can be frustrating to use. Driving them with an impact driver rather than a drill make a huge difference. The driver bit won't cam out nearly as much & the impact nature of the driver seems to make them go in better.

[Steve Rozmiarek]

Tom King, that ball bearing trick is clever.

[Alan Lightstone]

Best trick in the world when you get an oversized hole for a tapcon is to take a piece of 12 or 14 gauge copper wire (strip some out of romex or steal some ground wire out of romex) and cut a small piece, bend an small leg on one end (shape of an L) and stick one leg in the hole and run your tapcon. Will save you every time.

Often times in ripe cinder block the holes will oversize a little bit. Other than taking a diamond wheel on an angle grinder and grazing the edges of the carbide on the bit there isnt a great solution if your drill/block is consistently drilling oversized.

The copper wire trick works like a charm every time

I have to try this sometime.

The L stays on the surface, with the copper wire going into the hole?

Does the copper wire get sucked in enough that the copper wire isn't noticeable and is inside the hole?

[Mark Bolton]

I have to try this sometime.

The L stays on the surface, with the copper wire going into the hole?

Does the copper wire get sucked in enough that the copper wire isn't noticeable and is inside the hole?

The bent leg just gives you something to hold on to when your sticking it in the hole and so the piece doesnt just slide into a hollow block. If its not a through hole you dont need the bent leg. You can clip it off if needed after youve run the screw.

[Tom M King]

Tom King, that ball bearing trick is clever.

They aren't ball bearings. They're round, rare earth magnets. You can get them cheap on ebay-direct from China with cheap, or free shipping.

[Mark Bolton]

They aren't ball bearings. They're round, rare earth magnets. You can get them cheap on ebay.

That is a handy trick. We always just mounted counterflashing like that with drive anchors drilled in from the front. But being able to control the fastener tightness with the threaded anchor would be handy as I hate the puckers. I pretty much quit face fastening the counter flashing and just cut the kerf for the counter flashing in the masonry deep and then would brake the counter flashing with a 90 into the kerf and an open hem so the open hem would key the flashing into the sawn kerf in the masonry. Always worked real slick but you will never get it back out without destroying it if you push it in too far lol.

[Tom M King]

I like to use Bronze machine screws, and washers for copper flashing. Those threaded inserts are nice for machine screws. Someone will need to get it back off sometime in the future. I didn't bend that job on a brake because it was on an old museum house, and I didn't want it to look too modern. I use a brake for new houses.

For modern, standing seam roofs, I use stainless machine screws, regardless of the color of the roof, and no one notices. Steel roofing is harder to mark, because the magnets don't work. I use little stubs of machine screws, and lipstick.