Attaching Things to Concrete or Masonry Block Walls

I'll get to the subject of the title of this piece eventually. Please bear with me while I grumble a bit.

If I had my life to live over again, I'd devote myself to disinventing the telephone; I hate the things with a passion. But, they are a fact of life and I do have to have one -- even in my workshop.

Some recent rearrangement of things in the workshop has rendered the phone's old perch inoperative, so I have to make a shelf for it. I figure the material in the following photograph is wretched enough to be fit for the cursed instrument.

Once I've built the shelf, I'll have to attach it to a masonry block wall with 3/16" Tapcons^[1]. Tapcons are excellent fasteners; I really like the results I get from the things. But any method of fastening things to concrete or masonry is fraught with peril because of the difficulty of getting holes situated with any degree of precision. You can start the hole where you please, but the drill is going to seek the path of least resistance, and concrete and masonry can present large variations in density and hardness as you proceed with a drill.

I've never seen anyone address this difficulty with any helpful information. For whatever it's worth, I'll share what I've learned about it here. If anyone knows of a surefire method for getting holes drilled in concrete exactly where they're wanted, I'd like to hear about it.

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Here's the little patch of bare wall that I had in mind for the shelf to go on. I've spotted the upper two of three Tapcon locations as carefully as I could and centre-punched them. Something I've found helpful is to pencil little circles around the punch marks. They serve as a 'target' that can help you correct any drill wander that wants to happen just as you're starting a hole.

Another thing I do is to build a bit of adjustability into the item to be mounted. That's simply a matter of drilling oversize holes for the Tapcons. If all goes well, you'll be able to adjust the item's position to compensate for slight misplacement of the Tapcons' holes.

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And as it turned out, all went well. Here's the shelf installed and dead level.

The two upper holes through the back of the shelf were 1/4" diameter for 3/16" screws. That gave me enough slop that I could level the shelf successfully, even though my Tapcon hole placements weren't exactly perfect. In the event that a Tapcon hole ends up badly misplaced, and you have to greatly enlarge a mounting hole to get an item levelled, you can use fender washers to make the installation sound.

The single Tapcon at the lower end of the shelf's back was easy to install. The hole through the shelf there was 5/32" -- the size of a Tapcon drill for 3/16" screws. That gave me a guide hole for drilling the third Tapcon hole, after I'd levelled the shelf and securely tightened the two upper screws.

Anyway, it's done. Here it is with the phone in place and on hold.

If you were wondering what the red hook in the opening photograph was for, now you know.

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Addendum -- MONDAY, APRIL 25, 2011

Well, my face is about as red as that 'hold' hook. Shortly after I'd installed the shelf, my son came by, examined the 'hold' hook, and proceeded to show me how you put one of these old phones on 'hold'. It's really simple and easy -- no hook is needed.

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Update -- THURSDAY, AUGUST 30, 2012

A reader kindly clued me in to the truly correct way to put an old phone on hold. It looks like this.

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Note:

[1]Here's the Tapcon website. I have no financial interest in promoting their products, I'm just trying to be informative here.

The Tapcon screws work as advertised. They're widely available. Use their drills in a hammer drill and follow their instructions, and you'll be pleased with the results.

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Pumice Stone Brush Repair

The loose pumice stone in the following photograph is not atypical; I've had to deal with this sort of thing before. Some makers of mass-produced goods are uninterested in making anything that actually works right; they're only interested in making facsimiles of stuff that might cause money to change hands in their direction. So, it comes as no surprise that my wife's newly-purchased pumice stone brush came apart.

Clear silicone sealant is ideal as an adhesive here. The sealant 'flows' into the stone's pores, and really gets a grip on it. The key to a permanent repair is to fully coat both mating surfaces with sealant before assembling the pieces. Here they are coated and ready for assembly.

And here it is back together, with what little squeeze-out there was wiped away.

And here it is set up with a gravity clamp while the sealant cures.

The hard-copy, bound book is not dead yet, not by a long shot.

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Twist Drill Shank Modifications

I'm on record as having praised K&S Engineering's telescoping brass tubing product to the sky for its usefulness and versatility, so I feel obliged to exhibit new uses that I find for it. There's one example of a use here, where I used it to sleeve an oversize bore in a barbeque's valve knobs that I was repairing. Following is an example of the converse, where the tubing serves to increase a diameter rather than decrease it. Here's a photograph that explains a lot.

Pictured is my elderly Craftsman 3/8" drill, with a modified 1/16" drill in its chuck. There was a little problem with chucking a 1/16" drill in this drill's chuck -- the chuck is worn and will no longer close down to 1/16". (I needed to drill a lot of small pilot holes for 1 1/2" finishing nails to do a problematic baseboard installation job -- long story.)

Brass tubing to the rescue.

A short length of 3/32" outside diameter tubing (just over 1/16" inside diameter) glued onto the shank of a 1/16" twist drill with CA adhesive gave me a means of chucking the drill securely in the worn chuck. The arrangement worked nicely and got the job done.

A variation on this sort of drill modification can be helpful when what you need is not so much a longer than normal drill, but a drill with a longer than normal reach. You do the same as what I did to make the 1/16" drill fit the worn chuck, but you use a longer length of tubing. Here's an example of a 'lengthened' 3/32" drill.

The tubing's outside diameter here was 1/8"; hence, its inside diameter is a slip fit over a 3/32" drill shank.

The tubing and the glue bond are entirely strong enough for the drilling of small diameter holes in wood. But if a more robust extended-reach drill is needed, one can be made by using steel rod instead of tubing. here's an example of an extended 1/8" drill.

That's 6mm diameter rod salvaged from an old laser printer. These are easy to make if you have a lathe. Just use the drill that you mean to extend to bore a hole in the end of a length of rod, degrease the parts with lacquer thinner and assemble with CA adhesive. The adhesive bond will likely take anything you can dish out.

Should you ever want to take one of these apart, just heat the glue joint gently with a propane torch. CA adhesive is not all that heat resistant. It will soften and let go.

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An Unorthodox Tee-Nut Application

A typical tee-nut is a threaded barrel with a big spiky flange at one end of it. Tee-nuts are great for installing steel female threads in wood for fastening things together; but there are other ways they can be put to use. Here's an example.

I needed a nut plate recently to span a 1 1/8" diameter hole in the back of a piece of furniture, so I could secure an ill-fitting lamp cord grommet. On the face of it, such a thing can be easily made -- just drill and tap a hole in a suitable length of 1/8" thick mild steel flat and there's your nut plate. But tapping even mild steel with a small diameter tap like 6-32 is fraught with peril, and I avoid doing it if there's a reasonably elegant alternative. Here's a way to make a nut plate using a tee-nut. The resulting part is actually superior to one with a tapped thread.

Pictured below are the ingredients.

At the left is an unmodified 6-32 tee-nut. Beside it to the right is an identical nut that's had its spikes broken off, and the resulting rough spots filed. At the very right is a two-inch length of 1/2" wide, 1/8" thick steel flat that's been prepared to accept the modified tee-nut. Note the countersink to partially accept the radius at the base of the tee-nut's barrel.

There are two ways you can go about this. That hole in the steel flat can be drilled for a slip fit, or for an interference fit for the tee-nut's barrel.

In this case, the tee-nut I'm using has a barrel diameter of 3/16". So, for a slip fit in the steel rectangle you'd use a 3/16" (0.1875") drill. A No. 13 (0.185") drill gives an interference fit. Either case requires press-fitting in the vise to mash the radius at the base of the nut's barrel into the countersink. Here's a shot of the parts in the vise being pressed together using a 5mm socket wrench as a pressing 'anvil'.

An interference-fitted version will be ready for use right out of the vise. A slip-fitted version needs to be glued together with CA adhesive.

Here are finished examples of both versions.

The upper one is a glued, slip-fitted nut plate. The lower one is the press-fitted version. Either one will work fine.

Here's a shot of the glued, slip-fitted item on the job.

A very strong nut plate, and no tap got broken or dulled to make it. ('Sorry about the glary photo. I still have much to learn about photography.)

This technique is an inexpensive alternative to Rivet Nuts in any situation where the back of the material is accessible.

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