A bit wider... but how much? Drilling template, one round, one elongated hole

[Deadeye]

The weekend warriors who mess up jobs at the weekend and then want us trades in asap to put it right and it ends up costing more so if in doubt or lacking the tools then just get it done properly.

The other solution is to go back before we had cordless drills and use a rawl plug tool, just hit and twist so a nice slow process and accurate, I can remember forty plus years ago using one of these to fix dozens of backboxes and conduit drops .

Speaking as a weekend warrior who regularly messes up jobs, I fervently wish that getting a tradesperson in equated even a little to "get it done properly". Mostly DIYers try to do it properly but get ambushed by substrate or poor/inappropriate tools (posidrive Vs Phillips being a common example) or access/location. A significant number of "pros" don't even try - they just do whatever is quickest and cheapest and will just about pass muster in the short term. Sure there are proper pros but they're not as common as you suggest!

 

[pe2dave]

As has been suggested the best option is two elongated holes at right angles with possibly another pair at 45 degrees if space allows so that there are options for which to use. Many electrical back boxes have excellent examples of this.

And to answer your question I would make them at least three times longer than the diameter of the screw and probably four times. Allow for larger screws to be used in case the substrate is complete rubbish and the original screw/plug does not work and a larger one is required. I once tried to drilled a six mm hole into plastered breeze block I got hole about six inches in dia. it was not breeze block but something with the consistency of Wheetabex but not as strong. The usual problem is for the hole to hit the morter between courses and some cheapskate has "forgotton" to add any cement so even Fischer plugs don't grip.

IMHO 3rd and 4th holes a bit OTT (not a heavy item being hung). "Allow for larger screws" ...Not keen, supplier has to 'guess'. As it is the screws are cr..
Seems reasonable if supplied ones not liked, bring your own (I did).
Agree about some walls, almost like take a brick out and cement something in

Re 3 or 4 times larger...
I've a (manufacturability) issue with this? Talking about a plastic moulding, quite thin. I reckon it would be too weak with such a long slot?
My gut is that 2.5 times would be the max before cost / value starts to become an issue.


Thanks though. Appreciated.

 

[pe2dave]

The weekend warriors who mess up jobs at the weekend and then want us trades in asap to put it right and it ends up costing more so if in doubt or lacking the tools then just get it done properly.

The other solution is to go back before we had cordless drills and use a rawl plug tool, just hit and twist so a nice slow process and accurate, I can remember forty plus years ago using one of these to fix dozens of backboxes and conduit drops .

chuckles. I *think* I still have a rawl...drill? is that the right term? with the bit firmly lodged inside.
Same issue though, 'expecting' customers to have the 'right' set of tools?
(Evil thoughts... stick it to the wall with 'no more nails' ;-) )