Shopsmith "Toolbox"

[dusty]

This should cause even more confusion.

https://googleads.g.doubleclick.net/pag ... _type=text

[jsburger]

Thanks Dusty. So, if I am reading this correct then an M5 socket head screw has a 4.0mm socket head with 4.020mm to 4.084mm acceptable range in manufacturing, which is 0.1582677" to 0.1607874". By comparison, an Imperial #10 screw with a 5/32" socket head should have a manufacturing range of 0.1562" to 0.1587". From this, it looks like an M5 socket head just barely falls inside the upper range of a #10 socket head, but not by much (by about 4 thousandths which is 17% of the range). Of course, this assumes the wrench is an ideal size at nominal value. Anyone know how much variance to expect on the size of hex (Allen style) wrenches for comparison?

Good grief, you are quoting garden variety hex head screws to 7 decimal places. I doubt space certified hardware is spec to that.

[RFGuy]

Dusty,

Thanks. I think this information helps. So, hex wrenches at 5/32" size should be 0.1547" to 0.1562" actual size. So, the max size of the wrench is 0.1562" which is at the bottom end of the Imperial #10 socket head size (0.1562" to 0.1587" manufacturing range). In others words, a 5/32" wrench should never be larger than the minimum possible opening of a 5/32" socket head. In the worst case, this means a wrench on the high side of variance is never any larger than the low side variance of the socket head, i.e. it should always fit.

In summary, some 4.0mm wrenches may fit in some 5/32" socket head screws. Perhaps if one finds too much play in certain 5/32" socket head screws because of variance in the screw, the choice of a 4.0mm wrench may be just the thing to prevent starting to round over the points inside the screw because it may be a better fit.

[RFGuy]

Good grief, you are quoting garden variety hex head screws to 7 decimal places. I doubt space certified hardware is spec to that.

Calm down Charlie Brown ....I did that on purpose. Yes, I know I should have rounded these off, but I just wanted it to be clear where those numbers came from, i.e. I converted them in translating from Metric to Imperial.

[jsburger]

OK, here is an interesting data point.

Three days ago I received my Shaper Origin work station. The two halves of the station store together flat and are held by two 4mm cam lock fasteners. The Work Station comes with a 4mm ball end hex wrench. I know, all bets are off. It is shipped in the stored position and the cam locks were so tight the Shaper hex wrench would not loosen them. It actually slipped in the socket. A 5/32" hex wrench did the job. I think in this case a 4mm ball end is the reason. The fasteners were just too tight for the ball end.

[DLB]

...In summary, some 4.0mm wrenches may fit in some 5/32" socket head screws...

I don't want to nitpick the objective data when I started this with subjective data, but I want to better understand that conclusion. If I'm looking at the same thing, the range for a metric hex key is 3.95 - 4.00 MM. Converted, and rounded off , 0.1555 - 0.1575". Fastener range is 0.1562 - 0.1587". I would summarize as some 4 MM wrenches may fit all 5/32" socket heads and all may fit some. 'tis an important distinction in this context. Are we looking at the same thing?

- David

[RFGuy]

...In summary, some 4.0mm wrenches may fit in some 5/32" socket head screws...

I don't want to nitpick the objective data when I started this with subjective data, but I want to better understand that conclusion. If I'm looking at the same thing, the range for a metric hex key is 3.95 - 4.00 MM. Converted, and rounded off , 0.1555 - 0.1575". Fastener range is 0.1562 - 0.1587". I would summarize as some 4 MM wrenches may fit all 5/32" socket heads and all may fit some. 'tis an important distinction in this context. Are we looking at the same thing?

- David

David,

Sorry, maybe I am muddying the waters here and that was not my intent. I tried using a 4.0mm metric hex wrench in several 5/32" socket head screws in my shop and it didn't work. To try to help understand this, I put some measured numbers to what I am seeing just in my shop. Next, based on some technical documents that Dusty linked to, I made comments above regarding how much variance an Imperial hex wrench has and also how much variance a socket head screw has. I haven't see a similar document for variance allowed on metric socket head screws, but I attempted to extrapolate from the available data. Do you have data on how much a metric hex wrench can vary? If I extrapolate the allowed variance on the Imperial hex wrenches (data from Dusty), to a Metric hex wrench then they can go all the way down to 3.96mm (0.156"). So, a Metric wrench, theoretically, on the low end of the variance can cover all possible 5/32" socket head screws. I don't know if this extra detail answers your question, but I made a correct statement that some 4.0mm hex wrenches will work in some 5/32" socket head screws. I feel pretty confident in this statement since my 4.0mm hex wrench didn't work in several 5/32" socket head screws in my shop, but I know yours did work.

[DLB]

I got those numbers, 3.95 - 4 MM, from this chart within the link Dusty posted: https://amesweb.info/Tools/Hexagon-Sock ... Chart.aspx

- David

[dusty]

One more source of collaborating reference data. This one includes metric and imperial.

https://www1.mscdirect.com/PDF/FASTENERS/HexKeys.pdf

[DLB]

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