screw drive types

[scepticus]

Which do you prefer and why:

slotted, phillips, or robertson/square?

At WBS they only use slotted and I finally learned why. The reasoning is that if you need to remove a screw, slotted is pretty much the only one that you have a good chance of removing the paint or other goo that has filled the recess.

[Popeye]

plus a couple more weird screws too, like frearson, hex and torx. and i believe there's even one that turns under the wood (into a sleeve) with a magnet.

good point about slotted, robertson is the king for driveabilty. phillips i dont understand.

[Bruce Hooke]

For boatbuilding I use slotted screws for the reason you stated.

For most other things I use square drive screws from McFeely's. They are great - the driver almost never slips out accidentally and for getting into awkward places you can often put the screw on the driver and then use the driver to put the screw in place. One situation where I don't use square drives is on things were someone else might have to remove the screws and that someone else might not have a screwdriver for square drives (e.g., if I were crating something for shipping).

As I understand it phillips head screws are designed to release (cam out) the screwdriver if too much torque is applied. This is great for drywall, were overdriving can be a problem, and good for some types of metalwork where the torque climbs very fast when the screw head bottoms out. For woodworking, on the other hand, caming out is a very bad thing!

[Dan McCosh]

I've got lots of old square-drive screws installed and they drive you crazy when you try to extract them. I use Frearson mainly because that is how the silicon bronze fasteners come. Straight slot is tough with a power driver. Frearson isn't too bad clearing out the slot--a sharp-pointed pick takes a few seconds.

[Steve Paskey]

I once bought an old Lowell swampscott dory, full of slotted bronze screws that had been buggered up by someone who'd worked on the boat before I bought her. Removing them was a colossal pain -- worse than trying to pick paint out of something else.

[ 09-11-2003, 10:57 AM: Message edited by: Steve Paskey ]

[Popeye]

As I understand it phillips head screws are designed to release (cam out) the screwdriver if too much torque is applied

no sale. how many times has the bugger cammed out, BEFORE the screw was set. even with a brace and bit, difficult to drive. besides, with a variable speed drill and a drywall clutch, can control easily.

slots are similarly difficult to back out and easily broken. frearson rounds out (vrewww) with soft bronze in hard wood.

[Frank Wentzel]

I bought a Dewalt impact driver recently and found that it makes all screw types work much better. You don't have to lean on the driver so you can concentrate on control. Cam-out is virtually eliminated, even on worn screws.

/// Frank ///

[Keith Wilson]

Phillips I don't understand. Phillips screws were originally developed for automated driving. The only real advantage they have is that they're self-centering. If your automatic driver and the screw aren't lined up exactly, the bit will still go in. Self-centering isn't an issue driving (guided) by hand, whether with muscle or electrical power. I like square, myself. Slots are easier to get the paint out of after 30 years, though.

[ 09-11-2003, 12:06 PM: Message edited by: Keith Wilson ]

[Nicholas Carey]

Frearson aka Reed and Prince is my preference.

Similar to Phillips but much better design. Unlike a Phillips, the flutes are squared off and have a uniform taper so one size driver fits screws that size and smaller. A #14 driver can drive a #6 screw...assuming you've got room for it.

Also, since it's a taper, it's a friction fit with the driver, thus making it easier to hold on to the screw in awkward situations.

Unfortunately, Frearson screws and drivers are getting harder and harder to find. Another triumph of marketing over technological prowess :D

But square-driver screws—properly called Robertson drive— run a close second. Like the Frearson, the recess in a real Robertson screw is also tapered as it the driver; and like the Frearson, it too is a friction fit on the driver.

Keith Wilson écrit:
Phillips screws were originally developed for automated driving...The history and evolution of all screw design since the invention of the slot drive is the history and evolution of power-driving screws. Read Witold Rybczynski's One Good Turn: A Natural History of the Screwdriver and the Screw—it's fascinating reading.

BTW, the Phillips drive was invented only in 1933. Harry Phillips, a businessman from Portland, Oregon invented it to sell to the auto industry as an improved power driver. It was designed to slip of the screw once "sufficient" torque was reached. That little design flaw is actually a "feature". :mad:

As Cecil Sharp noted in his column The Straight Dope on this very topic, ...the cross-shaped indentation in the screw is so shallow that when you're done the screwdriver pops right out, before you get into trouble...back in the 1930s, Henry Phillips thought the automakers would find it handy making cars. The automakers were no brighter then than now, but eventually realized the usefulness of Henry's device, and it's been with us ever since.

The only problem is, easy as they are to get in, Phillips screws can be a bitch to get back out. The screwdriver pops out too readily, stripping the screw, gouging the work, and in general transferring to Joe Handyman all the problems that were formerly the province of the assembly line.

Once again, in other words, the little guy gets shafted by the dehumanizing forces of capitalism.The Robertson drive predates the Phillips driver by more than 20 years: it was invented and patented in 1908 by the Canadian Peter Lymburner Robertson-White. Supposedly, Ford used Robertson screws for years on the Model T, and Fisher Body used Robertson screws in its early products.

So one could argue that for a vintage boat, the Robertson drive is more "period" than either a Phillips or a Frearson (invented about the same time as the Phillips.)

[ 09-11-2003, 02:22 PM: Message edited by: Nicholas Carey ]

[Popeye]

i beg to differ

But square-driver screws—properly called Robertson drive— run a close second

second in what category, maximum torque maybe? cost? availability? stripping?, number of screw reuses?

The Frearson is cut way deep into the screw head recess thus weakening the screw head and strips out easily, especially in bronze. pffft.

[High C]

Square! It's great that they stick on the bit without being held. That gives you a free hand to hold the work, or cling to the ladder.

[Dave Williams]

Frank Wentzel said it. I've been meaning to make this comment for awhile. I've removed A LOT of fasteners in this rebuild. The first few were a pain and always washing out. Since the impact driver I've had very few failures. It cost some bucks but is a good tool (mine's a Makita)and saved me lots of problems.

[Ron Williamson]

I've grenaded plenty of PANHEAD Robertsons.There doesn't seem to be enough metal left in the head after punching out that little cube.
When removing paint from Robertsons,use an awl.
R

[Ed Harrow]

Someone on the FWW page suggested using in impact driver for drilling really big/deep holes. He said that there is absolutely no torque on the driver (unlike using Big Bertha). He's right, of course, as anyone who's ever used in impact wrench knows. I never thought about using one to back fasteners out (tho I have used the whack-em-with-a-hammer type with good results, you'd think I'da figured it out, wouldn't you (no, don't answer that question, LOL)).

[High C]

I've used impact hammer drills on concrete, and gotten a pretty sore forearm in the process. Never thought of trying one on screws. Does it punish the arm as when drillig in concrete?

[gapup]

Square drive and a dedicated screw driver. I'm sold on both, even though I recognise the potential problem of removal with material in the drive hole.

I've had a Makita driver for some months now. Using it everday on a major fish boat refit. After 40 years of avid woodworking, I don't know how I ever got along without it. Even useless phillips head screws drive with relative ease. Cam out is less a problem but care is still required.

Proper pilot holes, a wee dab of lube (sika, 3m etc) and a dedicated driver will go a long way toward keeping driven screws intact.

[Steve McMahon]

A trick for getting paint and goop out of a robertson head: Use a sacrificial robertson driver and heat the tip red hot with a propane torch. When you press it into the head of the screw it will vapourize any paint or goo. If you are worried about the heat on surrounding wood just keep a wet rag in the other hand to quench it. It has the added benefit of also helping to loosen the shank of the fastener. The you just use your good robertson driver to remove the screw. Don't try to use the "heated" driver for torquing because it will have very little temper left in it.

[KMAC]

Sometimes, after the philips screwdriver is chucked across the shop, I take a robertson bit and pound it into the screw head and voila.

Kent.