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civvywood

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Hi, I’m new to all this and am starting my first project and wondered what diameter screws are best for making the Paul Sellers saw trestles? Next project after that will be the workbench. Does it really matter what screw diameter I use? What would you recommend?

I’m also confused about what head type I should get, there seems to be a lot to choose from. For example at screwfix Woodscrews | Wood Screws | Screws | Screwfix.com I get all these different head types.

Thanks!
 

Peter Sefton

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I would consider getting a pack like this, I am sure it will cover most of your needs.


The most common screw size we use is 4 in various lengths as shown within the link, this is not the same as the old No 4 gauge.
 

Beanwood

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Get the ones which fit your screwdriver.
Not as silly as it seems. If you really are unaware @civvywood , there are different drive types.
The majority in my world are PZ2 - where 2 is the size. PZ1 for small things, PZ3 for BIG things.
The wrong screwdriver can make a mess very quickly.
I think the majority in the link @Peter Sefton posted wll be PZ2. So you need a PZ2 scredriver, or PZ2 bits for your drill/driver.
 

Phil Pascoe

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PZ2 will cover most things, PZ1 and PH2 occasionally. If you are making trestles etc. use a larger gauge screw - not so much because the screw is stronger, but because the head is larger so you pull things up tight without burying it too deeply. Use TurboGold, Spax, Reisser or one of the better brands - cheap screws usually are junk (the basic range from Toolstation being exceptionally bad). When the head shears off or strips on a cheap one it will be in a hinge or a handle - then you'll know why you should have spent a few quid more.
 
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Sideways

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Be aware if you're new to this that Pozidrive (pz2 typically) and Philips (ph2 etc) are similar looking but subtly different. The screws you buy are almost certain to be PZ. Make sure your screwdriver or bits are the same type and size. It will reduce the chances of the screwdriver twisting out when you are tightening the screws down.
Me, I'd start with a (1500 or whatever it is) mixed pack of Forgefast torx head screws from toolstation. I like torx as it's super secure between the driver and the screw head.
 

Richard_C

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Old style slotted screws might be needed if you are restoring or the heads form part of the overall look, but suffer the disadvantage that the screwdriver blade must be exactly perpendicular to the slot to avoid damage. Along came Phillips, which are cross head and sometimes found on factory assembled or far Eastern goods, but Phillips was superseded by posidrive - pz - in most uses many years ago. They are the "new normal" and allow for the driver to be a bit off straight without coming out and make for much faster assembly. As others have said, commonly 3 sizes, pz1 will go up to about 2mm dia screws, pz 3 maybe above 5mm dia but everything in between - most things - are pz2.

Torx is becoming more common, a sort of star shape which you see a lot in mass produced metal things, cars. I bet your car door hinges are held by Torx. They come in a huge variety of sizes, I have drivers from barely visible for cameras and phones up to 40mm for cars etc. They are really good for fast efficient automated assembly and some woodworkers are using them. I got some decking screws last autumn, surprised to find Torx heads, last batch were pz.

If you are starting out, pz probably easiest to get in the sizes you want.

For amateurs the number you use, therefore cost, isn't likely to be a significant part of your total expenses so you can afford to err towards quality. I am a DIY er and converted to Reisser 3 years ago and value the speed, never had one break, and less likely to split when you screw near the end of things.
 

Phil Pascoe

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You say you are just starting out - consider Torx or Robertson (square drive). Most of us have too many PZ2 in stock to change over without its costing an arm and a leg.
 

marcros

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tool station used to do some excellent paslode branded torx head screws. sadly they stopped selling them, and I am now running out of several sizes.

the downside of torx is said to be when there is paint in the head and you want to remove them. I dont doubt this to be true, but most of my use is for one time assembly so I dont see it as a huge issue (for myself).
 
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AES

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For the OP, both (all 3 actually) of the types Philips, "Posi" (actually "Pozidrive" or "PZ" for short) and torx all have "sunken heads", so CAN suffer from the problem of getting filled up with paint if you need to get them out again. Generally speaking though (but not always) these can be eased by using a screwdriver (or bit) of the correct type and giving a couple of sharpish raps with a hammer. That will usually break the paint seal in the head enough to be able to get the screw out. But if you're making something where you won't paint it, and/or need to get a screw out later, don't worry about it.

Finally, and perhaps most important for the OP, although several posts have (correctly) said that there are subtle differences between Philips and PZ screws, no one has said how to identify the difference.

It's actually quite easy and applies in 99% of cases (no promises re cheapo Chinese screws):

Philips - screw head seen from on top - just a simple cross (that's the cross of the screwdriver head goes into);

PZ - as above - the simple cross as above, PLUS a 2nd cross, much shallower, and set at right angles to the deep "driving cross".

With screwdrivers (and bits) it's a little more difficult, especially in the small sizes. So hold the screwdriver/bit point upwards against the light:

If it's Phillips you should see that the "edge/"s of the parts that actually do the driving inside the head of the screw taper down in a straight line to a pretty sharp point;

If it's PZ, the straight line down to the "point" usually has a slight kink in it, AND the point isn't a point at all but a quite small "half ball-type" type of thing.

HTH
 

recipio

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Buy a set of pozidrive bits and get a screw extractor set at the same time. :giggle: I often have to repair work where some 'tradesman' has taken a Phillips bit to a Pozidrive screw and mangled it. As for screws I would suggest a 5mm head when appropriate and always use a drill/countersink bit. It sets my teeth on edge to see some young apprentice driving a screw straight into wood.
 

Cabinetman

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You have bought yourself a big selection of bits which will come in handy but if you’re doing much work you need a top quality bit like Wera, they will outperform and outlast the others which appear to be made of cheese sometimes. Ian
 

thetyreman

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best solution is to get a wera kraftform kompact screwdriver, it has the PZ1, PZ2, PH1, PH2 and 2 standard size flathead screwdriver heads, and all fits within the body of the screwdriver, so you can't loose any bits, you can always buy more bits as and when you need them, such as torx, robertson or triwing
 
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Beanwood

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You have bought yourself a big selection of bits which will come in handy but if you’re doing much work you need a top quality bit like Wera, they will outperform and outlast the others which appear to be made of cheese sometimes. Ian
I KNOW we're getting a bit off topic here, but I agree with this - it's a big selection, but many of which I wouldn't personally use on a drill/driver (i.e. all the flat bits)
With an impact driver you'll break cheaper pz2 bits surprisingly often - and always at the most inconvenient time, so I'd suggest a pack of something like these: https://www.amazon.co.uk/Wera-Bit-B...ements=p_89:Wera&rnid=1632651031&s=diy&sr=1-2
These will fit into the bit holder from your kit. I personally prefer 50mm pz2 bits, as they fit my impact driver without needing a bit holder - but they seem harder to find.
 

sometimewoodworker

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If I were starting today and would often be using an impact (a little difficult) or variable speed driver I certainly would not choose either Philips or pozidrive as camout is way too easy. I would standardise on torx. You will find cam out virtually a non issue.
I have slotted, pozidrive, Philips, square and torx as I’ve got stocks from years ago. The first 3 are better if not using power.
Unfortunately neither torx or square are easily available here and pozidrive is as rare so I have little choice but to use Philips when I need a size I don’t have in stock.
 

JobandKnock

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I personally prefer 50mm pz2 bits, as they fit my impact driver without needing a bit holder - but they seem harder to find.
Toolstation carry the Wera impaktor in 50mm length in both PZD#2 and PZD#3 sizes. The downside, to my mind, is that they aren't magnetic (that and they aren't cheap)
 
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MARK.B.

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All good advice above, as recipio say's drill a pilot hole first and let the drill bit do most of the work, a screw no matter how large or small is only held by the depth of the threads cutting into the sides of the hole, when working close to an edge especially in harder woods you will increase the chances of the wood splitting and ruining the piece if you don't pilot hole first.
 

Tim Nott

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If you are using a powered driver, slotted screws are nearly impossible to drive - the bit slips outof the slot. Pozidriv (for wood) or Phlips (for metal) are better but can still jump out the screw socket. Torx, which I've used for at least 15 years are far superior, with a non slip parallel sided star-shaped socket.
 

Trainee neophyte

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My advice is to always buy bulk of whatever size you need. If you need four screws for a project, get a big box anyway, because in a very short space of time you will have what amounts to an endless supply of screws in all lengths. It's worth it, I promise.

Nothing is more annoying than having to stop work and go shopping for two screws.
 
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