Coach screws

[guest27]

Not that I have a need to coach screws - I find they shred their heads and go off line OK by themselves - however - what is the correct drill to pilot coach screws - I am guessing it is less than the thread dia - else they would not work, but should be at least the core dia or the wood will split?

SO what is the proper job?

R

[themoudie]

Aye Rog,

Pilot hole full depth of coach screw, dia. less than thread of the screw.

Bore to depth of distance between top of thread and below head [if head to be left proud] with drill slightly larger than shank dia. of screw. If head to be sunk then bore to depth of shank + head.

If head to be sunk, bore to depth with drill to allow head below surface, may wish to include washer thickness if using below head.

Finally, oil, grease or copper grease coach screw before screwing into hole.

All should now be tickety boo.

My regards, Bill.

[Steve Lake]

Sounds about right to me.....although I tend to adjust the pilot dia slightly dependant on the hardness of the wood (or its tendency to split)...and the size of the piece you are screwing into

if the wood is soft (pitch pine, rammin, etc) and provided it is a decent sized piece, then i make the pilot hole slightly less in dia (i find the bolts can pull the thread in soft wood, and this helps to stop that happening) but if the bolt is a decent length and has a good thread depth then Bill is spot on.

One other thing...if there are going to be 2 (or more) bolts in close proximity, try and 'stagger' them across the run of the grain...if they line up along the grain you are more likely to get a split.

pip pip

[guest27]

Thank you sirs - now I know need to find another excuse...

R