Long Allen Keys

The disc sander on my Draper belt & disc sander has been slipping. I thought that this was the belt sander but tightening the belt had no affect. I then realised that the disc itself was slipping on its shaft.There is an inspection hole in the belt guard and I can see a socket headed grub screw but my allen keys are too short to reach. Screwfix mention long allen keys in their catalogue but how long is a long allen key?

Thanks

Kevin

Reply to
Kevin Rayner
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Reply to
Adrian

================= Screwfix long series: Imperial = 1/16" = 3" - 3/8" = 7" . The metric part of the set are shorter - 1.5mm = 45mm - 10mm = 115mm. Sizes in between in proportion.

Cic.

Reply to
Cicero

In message , Kevin Rayner writes

Not being funny, but it depends on the size (i.e. a 6mm one tends to be larger than a 3mm one)

for normal long reach allen keys, somewhere between 4" and 6",

Reply to
raden

Not disagreeing of course, but from an engineering viewpoint, why is that? I've often wondered as I reach for a longer screwdriver to shift a stubborn screw, to which the same principle applies... From my A-level physics many moons ago I remember that torque (Nm) = force applied (N) x radius (m); so if the radius stays constant, how does torque increase? Isn't it independent of shaft length according to this equation?

David

Reply to
Lobster

A question that has erked me for some time. The only answer I could come up with is that we rarely have the sharp end of the driver 100% in the screw slot and given an angle of perhaps 10 degrees from the core of the screw we can impart a significantly greater torque.

Arthur.

Reply to
Arthur

They vary with size - like spanners. However, there's only two common sizes. B&Q had the long ones last time I looked in both metric and AF.

Reply to
Dave Plowman (News)

I *think* a longer screwdriver usually has a larger handle so you get better purchase on it.

Reply to
Dave Plowman (News)

You are right - the length makes no difference in the case of the screwdriver (other than the fact the bigger driver may have a bigger handle as Dave mentioned).

In the case of the Allen key however, I think you may have answered your own question! You need to remember that the key is L shaped, and you can use either the long or short section of the L to apply torque to the bolt. Hence if you use the short part of the L, you are then applying leverage to the long bit - say 4" on a typical key. A long reach key at

6" will therefore give you 50% more torque since your radius increases by 50%
Reply to
John Rumm

Or 2 hands (e.g. yankee driver)

Reply to
Chris Hodges

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