Color your Pozis bronze

[mklotz]

Chances are that you have dozens of 1/4" screwdriver bits in your tool cache. Some will be Phillips and some will probably be Pozidrive bits. What's "Pozidrive" you ask? Read the Wikipedia excerpt below to learn the difference between these two designs.

Using either screwdriver form in the other screw form can cause problems as discussed in the last paragraph of the Wiki quote. In order to keep things separated, I use a bronze Sharpie to color the tips of all the Pozidrive drivers. The photograph below shows a Pozidrive on the left and an ordinary Phillips driver on the right.

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Quote from Wikipedia article entitled "List of Screw Drives"
https://en.wikipedia.org/wiki/List_o...rives#Pozidriv

The Pozidriv is an improved version of the Phillips screw drive. Pozidriv was jointly patented by the Phillips Screw Company and American Screw Company. The name is thought to be a portmanteau of the words "positive" and "drive." Its advantage over Phillips drives is its decreased likelihood to cam out, which allows greater torque to be applied.[7][20][21][22] In ANSI standards, it is referred to as "Type IA."[23] It is very similar to, and essentially compatible with, the Supadriv screw drive.[24]

Pozidriv drive bits are often designated by the letters "PZ" plus a size code of 0, 1, 2, 3, 4 or 5 (by order of increasing size);[7] the numerical bit size codes do not necessarily correspond to nominal screw size numbers.

Attempting to use a Phillips screwdriver bit is likely to cause damage because the design difference between them is fairly significant even though at first glance they appear to be very similar.[7] A Phillips driver has an angle on the flanks, a pointed tip and rounded corners. The Pozidriv screwdrivers have straight sided flanks, a blunt tip and additional smaller ribs at 45° to the main slots.[7] The Pozidriv was designed specifically to allow much greater torque to be applied because of its more positive engagement.[7]

The Pozidriv screws are visually distinguishable from Phillips by a set of radial indentations (or "tick marks") set at 45° from the main cross recess on the head of the screw.[7] The manufacturing process for Pozidriv screwdriver bits is slightly more complex. The Phillips driver has four simple slots cut into it, whereas in the Pozidriv each slot is the result of two machining processes at right angles. The result of this is that the arms of the cross are parallel-sided with the Pozidriv, and tapered with the Phillips.[20]

The chief disadvantage of Pozidriv screws is that they are visually quite similar to Phillips; thus many people are unaware of the difference and/or do not own the correct drivers for them, and often use an incorrect screwdriver. This results in difficulty with removing the screw and damage to the recess and/or driver, often rendering any subsequent use of a correct screwdriver unsatisfactory. Phillips screwdrivers will loosely fit in and turn Pozidriv screws, but will cam out if enough torque is applied, potentially damaging the screw head and or driver. Because the drive wings on a Pozidriv screwdriver are square edged, their fit in a Phillips screw head is even worse, so they are more likely to slip or tear out the screw head.[7]
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[PJs]

Thanks Marv, a fascinating topic especially in today's world of screws and head types. I Like your idea of a sharpie color code for the Pozi's. I always thought they would take off better than they have, but the key is to be aware when you pick up a "Crosspoint" type screw to check for the indents then the appropriate bit for it and vice versa. With the advent of portable drivers the proliferation of technologies in thread styles, head types, etc. it's an absolute must to have a good selection of bit types and sizes...and some spares of the common types.

Another good Wiki is their list of screw drives. Although a cursory explanation it does have some pointers as to the uses for the head types and derivations.

A few months back I helped my son build a good sized loft in his garage for storage. What shocked me was the diversity of screw types for wood now at the big box store...starting to think you need a degree to choose the appropriate types for the applications. We used my impact driver and bought Robertson head screws (2") for 5/8 ply into the rafters and runners we put in. Luckily and each box came with a bit...smart on the maker. After about 75 it snapped and thank goodness we both had a couple of sets because we snapped off a couple more. Next store run we picked up some Impact rated Roberstons and was pleasantly surprised how well they held up. Turns out after some later research, there has been a lot of metallurgical study to get the ductility just right for the impact driver bits. They will still cam out, but this link kind of gives a clue why, particularly on Phillips.

The most fascinating to me is the thread technology now for the various applications, like wood, plastic decking, drywall, sheet rock etc. Even though Machine screws are generally what we use, it's a whole new world out there with some cool designs. Now if we could come up with some good re-purposing uses for dead bits....

Thanks for posting this and hope others chime in to this great subject. ~PJ

[mklotz]

Back (yeah, waaay back) in my youth, the first time I saw a socket head cap screw I said to myself, "Now why don't they do that with wood screws so the driver doesn't slip out of the slot?" It was only much later that I encountered Robertson screws. I absolutely love them along with those sheet metal (?) screws that have a drill point on the tip and a hex head. With a magnetic socket tip for the electric screwdriver, one-handed angled screw driving is a piece of cake.

[Paul Jones]

Marv and PJs,

I too love to use the Robertson screws for my wood projects. I also use the Kreg® screws with Kreg® pocket screws and I think having square recess drive head on these screws is probably the only way to achieve the very snug fit required for pocket screw assembly.

Thank you and PJs for the discussion.
Paul

[PJs]

Back (yeah, waaay back) in my youth, the first time I saw a socket head cap screw I said to myself, "Now why don't they do that with wood screws so the driver doesn't slip out of the slot?" It was only much later that I encountered Robertson screws. I absolutely love them along with those sheet metal (?) screws that have a drill point on the tip and a hex head. With a magnetic socket tip for the electric screwdriver, one-handed angled screw driving is a piece of cake.

I hear you about the way back machine. SHCS, button head, & flat head sockets are my favorite but those self starting sheet metal, hex head cap screws are the bom like you said. I learned a ton from the Machinery's Handbook years ago about sheet metal screw types...thread forming, cutting, self starting, etc. and the thread pitches...smart people out there and the screw machines are amazing now. I've used the Roberston's before but never that many (~300) in one sitting on my knees in a low overhead space...my knees started whining just telling the story above. Probably could have used a nail gun but screws are usually better in my book and it was a good learning for my son and I. Think next we should invent a magazine loader for screws with a driver/drill. I've seen them for flooring with a plastic cartridge, but looks like they get some miss fires and periodic jams.

One of my other favorites is Torx. They've become more of a standard now on automotive, motorcycles and even self assemble furniture. My 05' Triumph Sprint 1050 St had them everywhere and had to tool up to do anything on it. Bondhus has a nice selection of Torx and ball allen stuff and their T-handles are second to none in my book. Very positive and once you have enough selection of bits you can handle all the flavors.

~PJ

[mklotz]

Of course, the price one pays for all these choices in screw head styles is having to maintain an ever-growing collection of driver bits. And living in a backward country determined to keep using the inferial system, many of those bits have to be kept in double sets - metric and (spit) inferial.

[Frank S]

I must own half a dozen bit driver sets. Each set consisting of 30 to 50 different specialty bits. When I happen to break or damage one of the bits I put in in my wallet so that it makes a distinctive bulge to remind me that it needs replacing.
My wife picked up my wallet once and asked me why it had 3 bumps in it. I said to remind that the next time I am at the specialty tool store I need to buy replacements for the damaged bits.
But you have a tool box full of replacement driver bits.
Yep I said but none exactly like those that's why they are there, now unless you need money out of my billfold leave it alone.

[mklotz]

Also, one ends up with a bunch of duplicates. Just last night, while pawing through a tool bag, I discovered a near complete extra set of 3" long Torx bits.

I'm thinking of repurposing them to make accessories for the drill and/or electric screwdriver. A file marks them so they should be machinable. Might require carbide but that's OK. Now the question is what to make?

One idea I've thought of is an adapter so the 1/4" screwdriver chuck can accept the smaller 4 mm bits in the miniature set one also has to maintain to work on the ever tinier fasteners in modern electronics. The screwdriver has too much torque to trust it driving small screws but it would be great for removing them, especially the extra long ones used in some of the gear I have. Also, all the subminiature metric sockets I have use a 4 mm fitting so that's another application.

Anybody have any other ideas for accessories to make? The low RPM of the screwdriver has to be good for something besides annoying screws. Slow paint stirrer? Hone driver?

[PJs]

One idea I've thought of is an adapter so the 1/4" screwdriver chuck can accept the smaller 4 mm bits in the miniature set one also has to maintain to work on the ever tinier fasteners in modern electronics. The screwdriver has too much torque to trust it driving small screws but it would be great for removing them, especially the extra long ones used in some of the gear I have. Also, all the subminiature metric sockets I have use a 4 mm fitting so that's another application.

Interesting Idea and was thinking that the optional Dremel Chuck has infernal internal threads. Might be possible to thread the end of one of the long Torx to accept that chuck...haven't mic'd it out but maybe. The idea of a tiny chuck works for me because of some of those deep recessed screws in electronics now days is always too small to get a standard bit holder extension in, let alone my small driver set. Trying to broach a 1/4" hex to a 4mm female hex is out of my league but could see the advantage of that.

Found this also on Amazon...kind of fits your idea but for tiny (0-.0312)?

A couple of things I've thought of are small punches or drifts/pin and disposable scribe points. Not sure if the metal can be heat treated but would be easy to try. I would guess they are probably RC25-35 as they are and probably fine on brass and softer materials. I save all my broken circuit board drills for scribe points...hate to waste good carbide. I chuck them up in the mini and use my Dremel holder to grind the points. 10 minutes will do a few.

Happy Thanksgiving to All! ~PJ

[mklotz]

The spindle thread (not to be confused with the 3/4-12 nose thread) on the Dremel is 0.275 x 40 tpi. I know that for a fact because that's what I cut when I made this pin vise...

Since the maximum dimension across flats of any screwdriver bit is 0.25" that's a non starter. I've thought of making an adaptor for the Dremel adjustable chuck but I would just start with round stock and carve the hex in after cutting the thread.

I save broken circuit board drills too as well as center drills with the tip broken off. Mounted in a pin vise or homemade handle, they make very nice deburring tools for small holes. And, of course, they can be ground into scribers.

Several years ago I was gifted a package of the old style phonograph needles. They work great in my homemade beam compass...

http://www.homemadetools.net/forum/t...-verburg-27353

as well as in several scribers.