Loose Holes with Hilti SDS-Plus Rotary Hammer Drill

[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.