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DLB wrote:Quantifying rotational free play, the fit between tool and fastener. I evaluated two Eklind 5/32" and two Bondhus 4MM Long T-Handles in one near new (used once) arbor set screw that came from SS on a conical sanding disc. I renewed one of the Eklinds right before I did this, ground the end using vise grips as a heat sink, touched up a slight chamfer with a flat file, same way I normally do it. Measured the free play at no torque, just rocked the fully seated tool CW and CCW to the points of contact with a magnetic angle finder sitting across the T.
Used Eklind - 15 degrees free rotation
Renewed Eklind - 12 degrees
Both near new Bondhus 4MM - 6 degrees.

- David

These are the results you would expect - are they not? An over sized wrench fits more snugly than a smaller wrench. The only question, in my mind, is into what percentage of 5/32" sockets will a 4mm wrench fit?

My 4mm wrench cannot be fully inserted into any of the set screws I tested. My 5/32" hex wrench fits snugly and inserts fully into all of the set screws I tested (about a dozen----just enough to convince me).

dusty wrote:These are the results you would expect - are they not? An over sized wrench fits more snugly than a smaller wrench. The only question, in my mind, is into what percentage of 5/32" sockets will a 4mm wrench fit?

Yes, though we disagree on whether it is over sized. To me the best fit would occur with a hypothetical 5/32" tool at the upper end of the range and a socket head at the lower end of the range. By definition that's a snug fit, both are 0.1562. And that tool would fit better in every case, and as a bonus it would say 5/32" on it. It would even provide acceptable fit on those 4MM socket heads and I wouldn't have to remember which screws are 5/32" and which are 4 MM. The best tool to me, for this application, would fall into the overlapping range in the specs therefore between 0.1555 and 0.1562. Unfortunately, I have no known way of procuring such a tool. I could try Snap-on, a company that in my experience provides better fitting tools, albeit for a premium price. Instead I tried the Bondhus 4MM and am happy to report that it provides the same functionality, though I accept that I or others could perhaps find some fasteners that it does not fit. (I don't have the measuring capacity to confirm that it does or does not fall within that range.) I stand by my previous statement, it is possible for a 4MM tool to fit ALL 5/32" applications. It is equally possible for a 5/32" to fit ALL 4MM applications. Either would fit into that overlapping range.

- David

DLB wrote: Used Eklind - 15 degrees free rotation
Renewed Eklind - 12 degrees
Both near new Bondhus 4MM - 6 degrees.

In trying to quantify improved fit I chose a new sanding arbor setscrew thinking it would be less controversial, eliminating wear as a variable. However in measuring a few more setscrews I have to say that it might also be the worst tool to fastener fit in my shop. Those numbers are a relatively poor fit for all four tools.

- David

I don't have a PowerPro so I'll probably never face this challenge but if I should I think I would also buy a couple boxes of 5/32" set screws and begin a standardization routine. I never was excited about making a change to metric and still am not.

I'll keep following this saga but I'll probably not have much more to offer. Unless....I find metric set screws in the double tilts. My 5/32" hex wrench fits snugly and inserts fully into all of the set screws I tested (about a dozen----just enough to convince me). My 5/32" hex wrench fits snugly and inserts fully into all of the set screws I tested (about a dozen----just enough to convince me).