tapcons!! what am I doing wrong?

[theflyingpig]

Hi all,

I spent last weekend attempting to screw and glue 9mm ply to a concrete floor using concrete screws (tapcons). I used the concrete drill bit supplied with the box of 100 tapcons I bought for the job (5/32 bit), then when it was knackered a 4mm bit. for some reason the holes were clearly not big enough - I broke a few phillips drive bits, and only about one scew in ten would go in without snapping off - a very frustrating experience . .
I wondered if anyone had any experience of using tapcons and could suggest what I might be doing wrong . . .

thanks!

 

[Trazor]

The holes you have drilled are to small, no wonder you have problems.

I think you will need a 3/16" drill or 4.8 m/m drill, make sure you drill over depth, as the holes quickly fill up with concrete as you screw in...

 

[theflyingpig]

but the box clearly states (and comes with) a 5/32 drill bit . . . in saying that you must be right, unfortunitly I don't seem to be able to find imperial concrete drill bits for sale locally . . . so my next bit up will be a 5 mm - I did try witha 5mm masonary bit and the hole was too big but I suspect a masonary bit makes a slightly bigger hole than a concrete bit . . . .
anyway, thansk for your response - I have been in a dilemma over whether to hire a catridge hammer (ramset type thing) to finsih the job, but am not sure if the nails will drive in far enough (as tiling over ply with rubber i can't have anything proud of the ply)

cheers