Needing a long drill bit that isn’t available.

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I was going out late Wednesday after school run ends, I hate children when they leave school or go to school. Being autistic I need everything worked out before I go to the store where I know I can get bits checked over by someone, checking I have correct size etc. only then I turn to places that I know area reliable to Order the items.

so only frame work in phase one - I have a back wall ready made, 78” wide, I have the n shape front section ready made except the bottom beam. On the front, it will have a folding fully open door, so according to my maths, I have put a stronger header in, and this ewill spread the weight down sistered posts. I am using 1.5”x2.5” cls stud walls, with 3 sistered, meaning my post is 4.5” deep. So, to align the wood, I need to drill through 120mm deep, using a 4ømm bit. Why 120mm if the sistered width is 115mm? I need to drill through the floor beam so I can pilot drill a bit so my screws will attach. I am using 120mm screws, so here I am countersinking them further than normal, this way I can plug the hole.

I very rarely buy anything from eBay unless I have good reputable transactions with them before, with this, I also need the items next day, 2 at max, where amazon comes into play, and with quicker easy returns.
 
You don't drill a pilot hole all the way through.

But it should be as long as the screw. Assuming that he is drilling in to softwood end grain, yeah, he could get way with a shorter pilot bit without splitting the timber.

In the OP's case, he needs both a pilot and clearance bit, and a countersink.
 
Hello

this is sort of urgent in many ways, can you help suggested anything?

basically, I need to join some wood together for my outdoor work area that is being built at the moment. I have sistered two posts together, glued and screwed, as this is the door opening area, it will take the weight of me, + workbench and at least a table saw and mitre saws. This is just shy of 90mm, and the screw will go in face grain, and it will be going into end grain. The size screws I have for this section is 120mm, which should give it plenty of strength, but I don’t have or can’t find a bit that is needed for the size of the wood to drill a pilot hole. I need a 4 ø 120mm long bit. I can’t go higher in ø size due to the small wooden strip, and I need this to connect to the frame of the work area.

i asked the guy in Screwfix and B&Q who suggested I cut the sistered posts into 3, drill and align with the next bit, do the same until I have a deep enough hole… another guy in screw fix said, drill with a bigger ø bit that is long enough then pack the hole with tooth picks then screw…


oh, I can’t screw at an angle as there needs to be a metal plate there.
I don’t understand what you are trying to achieve TBH.

What size screw are you using? - surely it’s more than 4mm.

You need the shank hole at least as big as the screw or the joint won’t pull up.

And in softwood you don’t need a full depth pilot hole, if one at all - use a decent screw and wax the thread.

or use special screws with a cutting point that create their own pilot hole
 
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Why not just buy a self drilling screw, like Scrwfix's turbo ?


Note, SF used the wrong pic; a 120mm screw is partly threaded. The end of the screw and the ribs on the shank drill the hole as it goes. If you're driving near to the end, you can adopt a pattern of winding it in and out, gradually going further. You can also use your PZ bit to countersink a hole before you begin, by pushing the bit against the wood and running the drill, then moving the handle of the drill in a circle. Turbo screws do have ribs underneath the head to help cut a countersink but driving near the end of the wood creates maximum opportunity for the head to split the wood
 
Hello

I just want to say, sorry my communication skills suck, and sorry for all the confusion. I am also newish at diy, I have built my kitchen bbq area in 2021 to try and get my depression under control due to suffering the loss of my cat. Suffering from severe depression anyway this pushed me over the edge, and needed something to keep my head busy. On top of this I am disabled, my legs don’t work the way most peoples do, and this causes huge amounts of pain that I take huge amounts of morphine to control.

This puts me in a “high” state when I am tired, in pain and having extra morphine. I do not tend to stop the talking or typing, so again sorry.

My mum is an amazing person and she knows nearly everything I need to know as she spent years helping my grandfather who was never happy how his homes were and he brought, remodelled, still wasn’t happy, sold, brought, remodelled… anyway this gave my mum the experience to become a school caretaker, site manager and she oversaw 3 school rebuilding/new build as a partial site Forman.

I am taking this project on my own, basically I want to see if I can do stuff, or do I have to heavily reply on my mum on this, turns out she is still extremely helpful and without her I couldn’t of even started this.


Anyway, as I am doing this on my own, I have watched YouTube, read articles etc. I now think I have been doing things wrong, I have 5x120mm screws, and I have read that I need to use a pilot hole 2 sizes down, so the centre of the screw won’t impact the wood which forces the wood to split, but shouldn’t be any bigger due to the thread of the screw still has something to bite on. Is this now not the case?

Oh and we couldn’t find the guy who supposedly sold extra long drill bits so that was a fail. I do have 4x119mm drill bits now. So nearly all the way, but I think the extra deep pilot hole that was needed for the support post/footing area is finished, just now needing the pilot holes for 100mm and 120mm screws.



So, can we explain exactly the correct way to do pilot hole depth and width for the following screw types

6x120mm
5x120mm - the size I have
5x100mm
5x80mm

Thank you
 
width for the following screw types
It's usually about 70% of the nominal size. You can measure it with calipers to find the "root" diameter.

So for a 6mm screw you want a 4.2mm pilot, but 4mm will be close enough. And a 3.5mm pilot for a 5mm screw.
Don't try and drill it all in one go, the drill's flutes will clog and you can sanp the drill and leave it stuck in the wood. You drill down a little bit and pull the drill fully out whilst it's still spinning, then go in a bit further next time and pull the drill all the way out again. Repeat until you are at full depth.
 
Yeah, this is what I read, with the drilling a smaller size so the screw teeth have something to bite on. I plan to have a guide of screw size to drill bit size, so hopefully I can print that off and laminate it and I can then leave it somewhere handy.


Regarding the drilling, yeah I get a spring centre punch, line it up to where I need to drill, and push on the correct spot, then I drill in a smaller bit, normally 2 sizes down, so a 4ø hole, I use a 2ø drill about 4-5 mm down, then I use the correct size, drill about 4-5 mm, pull the bit out, clean the flutes out, drill another 3-4mm and keep doing this until I get to the right depth.
 

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