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What is the name of this male screw driver?

steve-l

Titanium
Joined
Mar 2, 2012
Location
Geilenkirchen, Germany
I absolutely hate not having a tool when I need it. I ran into a need of a male screw driver that resembles the figure "8". I was repairing an old leaking Holly 650 CFM carb and when I removed the secondary fuel bowl. the metering block was held by 6 flat head screws requiring this driver. Does any body know the name of these drivers and where to purchase a set?
 
That's the one, but there are more than one size and was no name of the driver stated. I want to buy a set.


Well I don't know... Google came up with the name of the bit pretty quick, certainly you can google it for a "set"... or figure out what sizes you need and order individually?
 
As noted, they are clutch head and can be purchased pretty easily. I have a set of drivers from the 1960's....I have never needed to replace them as they seldom get used.
 
The obvious question is why are they used? What advantage do they have and are they still used. Or have phillps/robertson/torx replaced them? Was it just to keep people from monkeying with the equipment? I think that is why the tri-lobe is used on Asian made toys.
Bill D
 

That's what I always remembered on Holleys.

The obvious question is why are they used? What advantage do they have and are they still used. Or have phillps/robertson/torx replaced them? Was it just to keep people from monkeying with the equipment? I think that is why the tri-lobe is used on Asian made toys.
Bill D

Exactly the case. It's meant to keep Mr. Tinkerpaw from grabbing a beat-up screwdriver out of the kitchen drawer and turning screws to see what happens. Back in the day they were usually only available at parts stores and the assumption was that the guy willing to buy a special tool was more likely to be a gearhead.
 
OT: if you find an old Yankey post drive that is scrap cut off the collet chuck and the shafe...weld a T haddle ( 1/2 x 4") to it and you will have the best thight screw puller you ever saw..you can hold it dead straight and hold it down with your weight...and the Yankey bits are very good... not bad for gun and carb work..

Still I put them to the bench grinder and make hollow..
Yes now that you mention it, I/somebudy should put this on the gun smith forum
 
The obvious question is why are they used?

It doesn't matter so much why they were used. What matters is why we use them. If you are restoring a Holley carb from that era, you use them to be correct. Later Holley went to phillips head and made things easier. To the OP: Ebay has Snap-On clutch head screwdrivers. Don't do like me, I messed up and bought the wrong size first. I'm not at the shop so I can't tell you the right size. Sorry.
 
We first got one because that's how the various bits on a pop-up Starcraft camper (1977 vintage) were attached. Everything from outside skin and hold-downs to inside wood-to-wood joints. And as campers rattle down the road, stuff needs tightened up.
 
It appears the name of these is "Clutch head" Thank you all for the help. I believe these are no longer used, but they are still out there and these drivers are scarce and hard to find. There appears to also be metric versions of these as well. Only the metric versions are available in Europe and the inch versions are only available in the States.
 
As a point of trivia, there are two types of clutch-head drivers. One type, which is generally considered the lighter duty of the two, is a cylindrical center with two radial ribs . . . it does not fill the screw's drive recess, but rotates within the recess to the extent allowed by the clearance about the ribs. The second type is fundamentally a larger cylinder with diametrically-opposed lengthwise grooves.
 
Those clutch drivers are not used that much. I would get a set of hex driver bits instead of a set of full drivers.

A full set of all five sizes would run only about $10 or $20 in the longer sizes. Here's just one source:

McMaster-Carr

They even show the sizes.

 
Ease of assembly is frequently a big factor in fastener selection. A clutch-head screw will stay on the driver, whereas a slotted or Phillips will fall off. Allen heads work well, too. Back when your Holley was made, Allen & clutch were probably all that was available.

Now we have Torx, and all sorts of security bits, etc. to choose from.

I'm restoring my airplane and I'm replacing some of the non-structural hardware with Allen head screws. Some of the 70-year-old Phillips head screws are hard to get out and I'm tired of fighting them (or drilling them). I just spent about 5 hours removing 8 Phillips screws in a radio mounting tray.
 
I still have a set.I bought them for something besides carbs(that was just an extra benefit).
I can't remember just what.I would rather them than a Phillips any day.
 








 
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