Which screws for plywood & choosing counter-sink bit

[Generic Eric]

Which screws for plywood are the best? I don't want much showing.  I have always had a question about choosing a counter-sink bit, there are always at least two.

Has any one used the kreg jig in their arcade cabinet?

[DNA Dan]

The kreg jig came up in another thread. Yes these can be quite useful in making your brackets. I just bought some furniture that was made using furniture grade plywood and a kreg type design. What they did was use some fairly skinny screws so that there was a lot of material remaining to screw through. If you look at the website, http://www.kregtool.com/PocketHole-Screws-and-Plugs-Prodlist.html these are specially designed screws. If I were to use a kreg jig I would use their screws because it seems to maximize the amount of material you keep on the cut, plus a flat head for good holding power. If they have drill bits specifically limiting the size of the hole, I would consider those as well.

What I would not do is buy kreg jig then use some cheap old trumpet style screws from a local hardware place. I think you'll find the performance is poor because they will have a tendency to "mushroom" out of the jig hole. This does not make the join as tight and solid as it could be.

Another factor with the Kreg and mushrooming is to make sure you have your driver set with a tension clutch, that means when you drive it in, it only goes in with so much force then the clutch enables. This will help you from 1) chewing out screws and 2) mushrooming the material.

EDIT: Here is the smallest kit they sell, the "jr." allows you to drill both holes at once.
http://www.kregtool.com/Kreg-Jigreg-Jr-Prodview.html

The more I look at this the more I drool over it! You can see the drill bit is specialty and so is the bit for the square head screws. I don't think a regular 1-2 " square bit will go deep enough.

[Woodshop Flunky]

I have used the Kreg pocket hole jig for years now, and it is my number one method for joinery on cabinet grade plywood.  It is also pretty much idiot proof.

When coupled with wood glue, these joints are super strong.  Also, you don't have to deal with a bunch of weird brackets to connect pieces... you can butt joint wood all day long and have a very strong product.

I love this jig.

[BobA]

+1 on the Kreg pocket hole jig and screws.  Use them all the time. 

http://www.kregtool.com/default.html

[DNA Dan]

Does adding a biscuit between the screws on larger pieces really gain you any strength? I am considering this as well.

[upprc04]

I used Kreg on my first bartop and was impressed how great it works.  I don't think you'll need biscuits between screws.  Just put a screw every so often and it is incredibly strong.

[javeryh]

I use biscuits when I'm working with plywood - they are extremely helpful when aligning pieces.  You don't even have to think about it.

[Woodshop Flunky]

I've used biscuits also, and they are really helpful for alignment.  I stick with pocket screws because they eliminate the need for clamps in most cases.

As far as strength goes, some added strength comes from the extra glue surface of the buscuit.  But, neither biscuits or pocket screws need the other for reasons of strength.

[Blanka]

Does not matter. They don't show if you insert them on the right side (the inside!). And use glue where you can. I never had to fill a screw hole on my cabs.

[D_Harris]

You generally don't countersink in plywood, because it promotes de-lamination.

Darren Harris
Staten Island, New York.

[DNA Dan]

I broke down a bought a Kreg jig. I went with the Kreg mini which is the cheapest they sell. It comes with the drill bit, but you have to buy the driver separately. I figure being able to mount perpendicular bracing pieces once the frame is built is really and invaluable asset. Where they get you is on that stupid welder's clamp for $20. I could have used a cheaper clamp, but I figure securing the tool properly is going to be very key to a nice finish. Overall I think I paid about $60 with the special screws too. Thanks for the tip!