Plug & Screw fixing - a lot of them

[Argonaut]

Looking for some advice on plug & screw fixing.
I have a large quantity of raised garden beds ... so effectively a 100 wide brick wall, onto which I am fitting wooden cappings.
I will be fixing 5mm plastic spaces to maintain an airgap (keep wood off brick) ......
end result will be: http://tinyurl.com/zfxjsar

Have purchased 152 x 7.5 concrete fixing screws http://tinyurl.com/z9g7scr
I will counterbore holes so I can glue in wood plugs ... intend using router to do this.

There are 2 approaches ...

Fixing option A http://tinyurl.com/zzkvu2u
Where screws go in at 90 degree, would mean I need a jig of some sort to match angle of sloped section.

Fixing option B http://tinyurl.com/hrmgkkr
Or I simply dill in at 90 degree to surface of angled section - meaning fixing will be angled.
This 'may' give a better fixing, and would mean no jig needed router would go flat on sloped section.
Welcome thoughts on this.

Secondly .......
Screw is 11.1mm across head ......... so need to counter bore to 12mm (or 1/2")
Option would be to use either a screw digger: http://tinyurl.com/zxeef7h

with plug cutter: http://tinyurl.com/jm8qv65 concern is only tool steel, and more than 200 plugs to cut.
not sure if these would be any better: http://tinyurl.com/jjb8jnz

Welcome advice from those that have used these before.

 

[Phil Pascoe]

Buy your plugs from somewhere like http://www.applebywoodturnings.co.uk ? by the time you count your time and cost of a decent plug cutter it may be worthwhile.

 

[Wuffles]

Seconded, cutting plugs is boring (ha ha) unless you're trying to match exactly, in which case it'll be more worthwhile.


Sent from my iPhone using Tapatalk

 

[Argonaut]

No desire to cut 200+ plugs.

The wood is Treated softwood .... normal called Tanalized, but I think tantalizing is a bit of historic term ......... the wood does has the usual green tinge .. although this reduces the deeper you go in from surface.

1. can you get treated softwood pellets ?

2. if not could they be treated before fitting, (could soak in Cuprinol green overnight) concern is that may prevent glue from taking.

 

[Phil Pascoe]

As you've cut through the original treated surface, you'd be wise to treat it again. As such it wouldn't matter too much what the plugs were made of to start with - even if you used treated timber to make your plugs.
The colour reduces as you go deeper from the surface - the weaker the colour the weaker the preservative - this is why you treat all cut parts.

 

[Argonaut]

As you've cut through the original treated surface, you'd be wise to treat it again. As such it wouldn't matter too much what the plugs were made of to start with - even if you used treated timber to make your plugs.
The colour reduces as you go deeper from the surface - the weaker the colour the weaker the preservative - this is why you treat all cut parts.

Fully agree with all of that ........... and once whole job is finished the lot will be stained with brown outdoor stain anyway.

However - back to the question ... treat befor fixing (good saok & allow to dry) or just rely on painting on preservative once cut flush ?