Magnetic half-stop device

Paul Brainard · Post by **Paul Brainard** » 6 Mar 2023 9:07 am

Hey thought I'd throw this out there, I recently stumbled across this gadget which is designed to "lock" a guitar trem for playing/bending strings, until you apply enough force on the trem bar to release it - then there is no additional tension after it releases:

https://super-vee.com/mag-lok-anti-deflection-device

I saw it on a gig, the guitar layer had one on his strat & I realized it might be a great solution for a pedal steel half-stop with a clear point of action but no additional spring tension carrying through the rest of the range. Also when the magnet kicks back in on release it creates a well-defined stop that direction as well.

I installed one on a Shobud Pro-1 that didn't have a half-stop assist - just the 9th string - and it works pretty well! The wire end that plugs into the spring hole on the trem block of a strat fits into a bell crank hole, I did have to bend it at a sharper angle to get it to stay. Then held it at the spot where I wanted it to kick in and screwed the other end to the body. Of course it isn't readily adjustable - although there is about 1/4" of play in the slot that the screw goes through (with a lock washer) so you can fine-tune it.

But it strikes me as a great concept for this, like many folks I'm sure I find that if I put enough spring tension on a 1/2 stop to make it solid enough to use easily, it makes the rest of the travel a bear. And it's always hard to get a precise stop on the way back up. . . This solves both problems. Probably wouldn't be hard to alter the design a bit to make it adjustable & attach right to a bellcrank. Maybe could just use a regular knee lever stop with a screw passing from it through the mounting slot on the device and a nut on the inside. . .

Marty Broussard · Post by **Marty Broussard** » 6 Mar 2023 2:09 pm

Jon Light · Post by **Jon Light** » 6 Mar 2023 3:51 pm

Thanks for the post. Interesting, indeed.

I'm wondering -- in contrast to the standard spring device where you push past the stop point and push thru the resistance, when you break the magnetic stop point, without the spring resistance, does your leg just fly thru to the end stop out of control?

Paul Brainard · Post by **Paul Brainard** » 6 Mar 2023 5:02 pm

John - no, it just has the same resistance that the lower had before it reached the magnet's point of detente. It's like a little bump in the road. . .

I guess if you are really used to the extra tension in the second part of the lower, it might take a while to re-train your leg to ease up after the stop. I didn't find it to be a problem. It's a pretty subtle amount of effort required to "break" the magnetic bond, at least compared to the leverage on RKR. But enough to know it's there.

Paul Brainard · Post by **Paul Brainard** » 6 Mar 2023 9:29 pm

Here is a pic of the underside with the gadget installed - sorry I don't have a close-up of it. . . I just added it to the bellcrank on string 2, would probably be ideal to put it on its own one.

Derek Puckett · Post by **Derek Puckett** » 6 Mar 2023 10:50 pm

Is it adjustable? How do you adjust where it stops?

John Larson · Post by **John Larson** » 7 Mar 2023 6:15 am

This would even be a cool idea to add to whole step pedals like the A pedal on an emmons setup to feel a bump when half pedaling.

Chris Brooks · Post by **Chris Brooks** » 7 Mar 2023 6:28 am

It would, John! It would enable, say, a half-pedal on that A pedal to produce a minor chord in pedals-down position; and an augmented chord in no-pedals.

I half-pedal by "feel" but always say a little prayer first

Doug Earnest · Post by **Doug Earnest** » 7 Mar 2023 6:29 am

Mr Zumsteg made a magnetic half stop a few years ago. I never saw it but would bet that it was perfect. I do remember he said it was tedious to build.

It should be a great way to go and as was said it eliminates the problem of progressive effort on the lever.

Jon Light · Post by **Jon Light** » 7 Mar 2023 7:01 am

Just ordered one. While I wait I'll spend some time trying to come up with an adjustable mount.
Then we'll see if I can teach myself to feel a feeler stop. I've never had luck with them but I've always had a longing for having them.
Cool.

Paul Brainard · Post by **Paul Brainard** » 7 Mar 2023 7:02 am

Derek - it is not made to be adjustable, but when you screw it to the body the bracket for doing so has a slot for the screw to go through that is abiut 1/4" long, so you could loosen the screw and slide it that much one way or the other. However it might be possible to come up with another way to attach it that give you an adjustment.

Doug - I vaguely remember something about that now that you mention it, I wonder if they are available at all? Not surprising that Bruce would have though of this already!

John Larson · Post by **John Larson** » 7 Mar 2023 7:05 am

Chris Brooks wrote:It would, John! It would enable, say, a half-pedal on that A pedal to produce a minor chord in pedals-down position; and an augmented chord in no-pedals.

I half-pedal by "feel" but always say a little prayer first

That's one of those "feel" things that makes harmonics seem easy by comparison.

Ian Worley · Post by **Ian Worley** » 9 Mar 2023 11:45 am

This is a cool idea. Making something similar that is more readily adjustable would be fairly easy. It's functionally the same concept as the Wolf half-stop unit, but the Wolf uses a mechanical ball plunger instead of a magnet to create a precise center detente. Does the magnet create a precisely tunable center point, or is there some play?

I'm curious about how strong the magnetic stop is relative to string/spring tension you're pulling against, how readily the lever returns to neutral when you release it from the full lower? I'm assuming the magnet is not nearly strong enough to inadvertently catch it at the half-stop position on return without your leg there doing most of the work. On the Wolf unit the strength of the 'stop' at the midway point is adjustable by screwing the ball plunger in or out, it creates a distinct hitch in the lever's motion but it's not strong enough to hold or hinder the return to neutral when released. I'm thinking you could do something similar with a rare earth magnet mounted on a threaded plug that could be raised or lowered in the housing to alter the strength of the stop, a non-magnetic shaft with a steel insert embedded at the center stop point. The Mag-Lok shaft is acrylic but it could be brass, aluminum, non-magnetic SS, etc.

John McClung · Post by **John McClung** » 10 Mar 2023 2:58 am

following...

Bobby D. Jones · Post by **Bobby D. Jones** » 10 Mar 2023 10:23 pm

You would need a way to very fine adjust the half step.
I just drew this as a lay out of the parts that would make an easy adjustable way to use the magnet. By using a tuning nut as the adjuster, You can use the same WRENCH to adjust the 1/2 stop, Under the guitar.
By using a Bell Crank, Would allow a lot of adjustment, To fit it to about any guitar.

It would take the Magnet and guitar to size and fit the 1/2 stop to the guitar.
Comments or changes welcome.

J D Sauser · Post by **J D Sauser** » 12 Mar 2023 12:12 am

I think that the use of rare earth magnets could also be cosidered to “stabalize” scissor-all-pull changers in hi-raise or hi-lower situations from lifing off the contrary scissor.
Half Stops using a magnet to create a feel-stop instead of dragging along the added and increasing resistance of a spring or “empty”-pull does indeed seem like a easy to experiment with proposition.

Thanks for presenting it here.

… JD.

Hans Holzherr · Post by **Hans Holzherr** » 6 Jul 2023 5:07 am

I just came across this thread and am pleased to tell that I have recently designed a magnetic half stop that is accurately adjustable and works really well, with a "positive", very well defined half position. I don't remember trying out a ball plunger half stop, so I can't compare right now, but in a few weeks I will be able to try out just such a guitar (Schild).

It's also hard to compare my design with the device presented here by Paul as long as we don't have close-ups. In my device the magnetic force is highly leveraged and its strength adjustable.

Please note that I am not in the production stage yet. My current concern is an intercontinental move at the end of July, and I won't have my pedal steel until a month later.

Ian Worley · Post by **Ian Worley** » 6 Jul 2023 8:30 am

Hans Holzherr wrote:...It's also hard to compare my design with the device presented here by Paul as long as we don't have close-ups...

https://super-vee.com/mag-lok-101

John McClung · Post by **John McClung** » 6 Jul 2023 8:41 am

Hope this shows the device. Not sure what it looks like...

Jon Light · Post by **Jon Light** » 6 Jul 2023 9:32 am

I had an idea, different from a half-stop...something else....and I came to realize that it wouldn't work. So this awaits a different inspiration.

Bobby D. Jones · Post by **Bobby D. Jones** » 7 Jul 2023 9:59 pm

Reverb has those Mag Locks, The price is 59.95 + postage.
That would make a very usable half stop, If precision adjustment for the half stop was in the design when installed.

I have been running a plunger type half stop through my mind, For a while. On my S12 U I would like to have a half stop for the 2nd string lower D# to D to C# at stop.

I have several small firearm ball end plungers and springs left in my old police armor's kit. Need to draw my idea on paper, And make 1 to prove theory and drawn design.

Ian Worley · Post by **Ian Worley** » 8 Jul 2023 10:12 am

Bobby D. Jones wrote:...I have been running a plunger type half stop through my mind...

This is the Wolf half stop design. It's mentioned above, but do a forum search and you'll find multiple threads with discussion, pics, etc. It's very simple mechanically, just a shaft with a rounded detent for the plunger ball in the center of its length, it passes through an aluminum block, the ball plunger threads into on side of the block. Peter Schild makes a similar unit for his guitars, slightly different functionally, I believe the shaft is turned down on one end so that it doesn't contact the ball plunger until it reaches the half-stop point, but it's the same basic concept.

Bobby D. Jones · Post by **Bobby D. Jones** » 9 Jul 2023 8:33 pm

I found the post about the half stop Mr. Wolf had made. With larger pull rods that would work, But on my GFI with 3/32" rods that notch may weaken the rod, And it could break.

I found the parts laying around to make the precise adjustment I mentioned in previous post, Except the aluminum sleeve, I had to make it.

Here is a picture of the adjustment, It came out like the drawing I posted. The Aluminum sleeve, 2 GFI 6 hole Bell Cranks, A pivot block I made for a knee lever lock, A Nylon Tuner, And a piece of 3/32" rod. The rod could be longer or shorter to make the adjuster easier to access and operate under the guitar.

Now to the spring loaded pop-it half stop.

Fred Treece · Post by **Fred Treece** » 10 Jul 2023 10:05 am

This is awesome. I’ll take 3 of whoever’s design goes into production first.

Len Amaral · Post by **Len Amaral** » 11 Jul 2023 4:57 am

I have a Mag-Loc on my G&L Strat and it is a nifty device. You can bend a string without the vibrato tailpiece moving and the vibrato block is stable. A very simple install also. Made a huge difference in playing this guitar.