Convenient though they may be, [Trevor Faber] found some serious shortcomings in shifting spanners: their worm gears are slow to adjust and prone to jamming, they don’t apply even force to all faces of a bolt head, and without a ratchet, they’re rather slow. To overcome these limitations, he designed his own adjustable ratchet wrench.
The adjustment mechanism is based on a pair of plates with opposing slots; the wrench faces are mounted on pins which fit into these slots, and one plate rotates relative to the other, the faces slide inwards or outwards. A significant advantage of this design is that, since one plate is attached to the wrench’s handle, some of the torque applied to the wrench tightens its grip on the bolt. To let the wrench loosen as well as tighten bolts, [Trevor] simply mirrored the mechanism on the other side of the wrench. Manufacturing proved to be quite a challenge: laser cutting wasn’t precise enough for critical parts, and CNC control interpolation resulted in some rough curves which caused the mechanism to bind, but after numerous iterations, [Trevor] finally got a working tool.
To use the wrench, you twist an outer ring to open the jaws, place them over the bolt, then let them snap shut. One nice touch is that you can close this wrench over a bolt, let go of it, and do something else without the wrench falling off the bolt. Recessed bolts were a bit of an issue, but a chamfer ought to improve this. It probably won’t be replacing your socket set, but it looks like it could make the odd job more enjoyable.
If you prefer a more conventional shifting wrench, you can make a miniature out of an M20 nut. It’s also possible to make a shifting Allen wrench.
Thanks to [Adam Foley] for the tip!
The high part count of precise components with tight tolerances and costly machining will make this very expensive if ever produced commercialy. That being said, I applaud the cleaver design, skill, and determination it took to create it
Although, kudos of identifying the most obvious problem: that the mechanism bends under stress and goes out of alignment, binding it up. Many Makers would be completely stymied by that, but he did get it to work by proper analysis and design.
Too bad it’s only for hex cap bolts.
I have standardized on 7.4 sided bolts.
Great work, loved watching the design process. Very
I’m an electronics design guy so everything mechanical engineers do is very cool and impressive to me even though I don’t understand much!
reminds me of https://www.youtube.com/watch?v=8IewMXUzt7U (and adjustable allen key)
very hard to make the moving parts of a tool like this rigid enough to actually be useful and not deform when you reef on it.
No.
Too complicated.
Useless for toolbox, not good for emergency kit either.
Most cars are 99% 3 or 4 size fasteners anyhow.
If you don’t already know what those sizes are, what are you going to do with an adjustable ratchet on the side of the road?
Dowse with it?
‘Holy ratchet, point to the broken part!’
Also ‘shifting spanners’?
Is that some sort of B&D gizmo?
What exactly is he intending to crank this socket down on?
The hex head has always been a defective design concept. By its very geometry, the forces rounding the head and bending/breaking the tool far exceed the forces making torque on the bolt. Fewer sides (square) are better, and splines (external Torx) are better.
Trevor’s design is brilliant, even with its limitations. I doubt that it can ever be made as strong as an equivalent socket. It’s bulky. It might be vulnerable to contamination with grit. Still, even if he’s the only person who ever owns one, he’s made something to be proud of.
Yes, but no… Fewer faces might be better for transferring forces but even turning a six-faced hex in tight spaces with a slightly angled wrench often is a pain. Imagine having only 90° “choices”… The problem with “torque needed is more than what the drive can take” is only a problem when the bolt or tool is low quality or not suided for the job. Or completely seized up for that matter :)
I feel that if you have trouble turning a nut/bolt because of cramped space, that’s a design flaw.
Well tough it happens all the time and you are in no position to redesign it
This is kind of dumb and embarrassing to admit, but I once found a bolt on the bottom of an engine where if you loosened it, your wrench would back up into the wall of the sump and jam, blocking the reversing switch. Of course I absent-mindedly did this before I noticed the trap.
So my wrench was simply stuck there, I couldn’t even re-tighten the bolt to free it. I tried to pipe-wrench the shaft, but this bolt was on the undercarriage and stuck pretty good. I had to drain the oil and remove the entire sump to get my wrench back and continue a totally unrelated task.
Design flaw? Oh yeah. But you better believe that afterwards I found a wrench with the reversing switch on the handle instead of the back of the head. Solutions to problems which shouldn’t exist… yet they do.
Fair enough.
But ‘design flaw’ isn’t a ‘feeling’ problem.
They are thinking problems.
Interference with bolts is almost inevitable.
Every ‘engine out’ mechanical procedure is not a ‘design flaw’ by definition.
Even if that mechanical procedure is routine maintenance.
I don’t choose such things, but not my money, people can buy all the mid engine V-10s as they can afford.
They know what they are buying, a shiny red status symbol w mechanical issues.
Cramped spaces are inherent to some things.
Such as supercars and econoboxes.
Might be your definition of ‘design flaw’ isn’t compatible with the car you chose.
FYI most cars with bad interference problems were upengined by MBAs.
In middle days it was V6-8s in chassis built for inline 4s.
In old days, you had lots of room, excepting big blocks.
Assuming you not fool enough to buy old days Euro, but I don’t have to tell those guys about the extra elbows they had installed in the forearms.
I digress.
I found screwdriwer ratchet but with x2 speed. Very nice project. I need it in metall (I see it in 3d print)